Tag Archives: quantum entanglement

Congratulate China on the world’s first quantum communication network

China has some exciting news about the world’s first quantum network; it’s due to open in late August 2017 so you may want to have your congratulations in order for later this month.

An Aug. 4, 2017 news item on phys.org makes the announcement,

As malicious hackers find ever more sophisticated ways to launch attacks, China is about to launch the Jinan Project, the world’s first unhackable computer network, and a major milestone in the development of quantum technology.

Named after the eastern Chinese city where the technology was developed, the network is planned to be fully operational by the end of August 2017. Jinan is the hub of the Beijing-Shanghai quantum network due to its strategic location between the two principal Chinese metropolises.

“We plan to use the network for national defence, finance and other fields, and hope to spread it out as a pilot that if successful can be used across China and the whole world,” commented Zhou Fei, assistant director of the Jinan Institute of Quantum Technology, who was speaking to Britain’s Financial Times.

An Aug. 3, 2017 CORDIS (Community Research and Development Research Information Service [for the European Commission]) press release, which originated the news item, provides more detail about the technology,

By launching the network, China will become the first country worldwide to implement quantum technology for a real life, commercial end. It also highlights that China is a key global player in the rush to develop technologies based on quantum principles, with the EU and the United States also vying for world leadership in the field.

The network, known as a Quantum Key Distribution (QKD) network, is more secure than widely used electronic communication equivalents. Unlike a conventional telephone or internet cable, which can be tapped without the sender or recipient being aware, a QKD network alerts both users to any tampering with the system as soon as it occurs. This is because tampering immediately alters the information being relayed, with the disturbance being instantly recognisable. Once fully implemented, it will make it almost impossible for other governments to listen in on Chinese communications.

In the Jinan network, some 200 users from China’s military, government, finance and electricity sectors will be able to send messages safe in the knowledge that only they are reading them. It will be the world’s longest land-based quantum communications network, stretching over 2 000 km.

Also speaking to the ‘Financial Times’, quantum physicist Tim Byrnes, based at New York University’s (NYU) Shanghai campus commented: ‘China has achieved staggering things with quantum research… It’s amazing how quickly China has gotten on with quantum research projects that would be too expensive to do elsewhere… quantum communication has been taken up by the commercial sector much more in China compared to other countries, which means it is likely to pull ahead of Europe and US in the field of quantum communication.’

However, Europe is also determined to also be at the forefront of the ‘quantum revolution’ which promises to be one of the major defining technological phenomena of the twenty-first century. The EU has invested EUR 550 million into quantum technologies and has provided policy support to researchers through the 2016 Quantum Manifesto.

Moreover, with China’s latest achievement (and a previous one already notched up from July 2017 when its quantum satellite – the world’s first – sent a message to Earth on a quantum communication channel), it looks like the race to be crowned the world’s foremost quantum power is well and truly underway…

Prior to this latest announcement, Chinese scientists had published work about quantum satellite communications, a development that makes their imminent terrestrial quantum network possible. Gabriel Popkin wrote about the quantum satellite in a June 15, 2017 article Science magazine,

Quantum entanglement—physics at its strangest—has moved out of this world and into space. In a study that shows China’s growing mastery of both the quantum world and space science, a team of physicists reports that it sent eerily intertwined quantum particles from a satellite to ground stations separated by 1200 kilometers, smashing the previous world record. The result is a stepping stone to ultrasecure communication networks and, eventually, a space-based quantum internet.

“It’s a huge, major achievement,” says Thomas Jennewein, a physicist at the University of Waterloo in Canada. “They started with this bold idea and managed to do it.”

Entanglement involves putting objects in the peculiar limbo of quantum superposition, in which an object’s quantum properties occupy multiple states at once: like Schrödinger’s cat, dead and alive at the same time. Then those quantum states are shared among multiple objects. Physicists have entangled particles such as electrons and photons, as well as larger objects such as superconducting electric circuits.

Theoretically, even if entangled objects are separated, their precarious quantum states should remain linked until one of them is measured or disturbed. That measurement instantly determines the state of the other object, no matter how far away. The idea is so counterintuitive that Albert Einstein mocked it as “spooky action at a distance.”

Starting in the 1970s, however, physicists began testing the effect over increasing distances. In 2015, the most sophisticated of these tests, which involved measuring entangled electrons 1.3 kilometers apart, showed once again that spooky action is real.

Beyond the fundamental result, such experiments also point to the possibility of hack-proof communications. Long strings of entangled photons, shared between distant locations, can be “quantum keys” that secure communications. Anyone trying to eavesdrop on a quantum-encrypted message would disrupt the shared key, alerting everyone to a compromised channel.

But entangled photons degrade rapidly as they pass through the air or optical fibers. So far, the farthest anyone has sent a quantum key is a few hundred kilometers. “Quantum repeaters” that rebroadcast quantum information could extend a network’s reach, but they aren’t yet mature. Many physicists have dreamed instead of using satellites to send quantum information through the near-vacuum of space. “Once you have satellites distributing your quantum signals throughout the globe, you’ve done it,” says Verónica Fernández Mármol, a physicist at the Spanish National Research Council in Madrid. …

Popkin goes on to detail the process for making the discovery in easily accessible (for the most part) writing and in a video and a graphic.

Russell Brandom writing for The Verge in a June 15, 2017 article about the Chinese quantum satellite adds detail about previous work and teams in other countries also working on the challenge (Note: Links have been removed),

Quantum networking has already shown promise in terrestrial fiber networks, where specialized routing equipment can perform the same trick over conventional fiber-optic cable. The first such network was a DARPA-funded connection established in 2003 between Harvard, Boston University, and a private lab. In the years since, a number of companies have tried to build more ambitious connections. The Swiss company ID Quantique has mapped out a quantum network that would connect many of North America’s largest data centers; in China, a separate team is working on a 2,000-kilometer quantum link between Beijing and Shanghai, which would rely on fiber to span an even greater distance than the satellite link. Still, the nature of fiber places strict limits on how far a single photon can travel.

According to ID Quantique, a reliable satellite link could connect the existing fiber networks into a single globe-spanning quantum network. “This proves the feasibility of quantum communications from space,” ID Quantique CEO Gregoire Ribordy tells The Verge. “The vision is that you have regional quantum key distribution networks over fiber, which can connect to each other through the satellite link.”

China isn’t the only country working on bringing quantum networks to space. A collaboration between the UK’s University of Strathclyde and the National University of Singapore is hoping to produce the same entanglement in cheap, readymade satellites called Cubesats. A Canadian team is also developing a method of producing entangled photons on the ground before sending them into space.

I wonder if there’s going to be an invitational event for scientists around the world to celebrate the launch.

Brain stuff: quantum entanglement and a multi-dimensional universe

I have two brain news bits, one about neural networks and quantum entanglement and another about how the brain operates on more than three dimensions.

Quantum entanglement and neural networks

A June 13, 2017 news item on phys.org describes how machine learning can be used to solve problems in physics (Note: Links have been removed),

Machine learning, the field that’s driving a revolution in artificial intelligence, has cemented its role in modern technology. Its tools and techniques have led to rapid improvements in everything from self-driving cars and speech recognition to the digital mastery of an ancient board game.

Now, physicists are beginning to use machine learning tools to tackle a different kind of problem, one at the heart of quantum physics. In a paper published recently in Physical Review X, researchers from JQI [Joint Quantum Institute] and the Condensed Matter Theory Center (CMTC) at the University of Maryland showed that certain neural networks—abstract webs that pass information from node to node like neurons in the brain—can succinctly describe wide swathes of quantum systems.

An artist’s rendering of a neural network with two layers. At the top is a real quantum system, like atoms in an optical lattice. Below is a network of hidden neurons that capture their interactions (Credit: E. Edwards/JQI)

A June 12, 2017 JQI news release by Chris Cesare, which originated the news item, describes how neural networks can represent quantum entanglement,

Dongling Deng, a JQI Postdoctoral Fellow who is a member of CMTC and the paper’s first author, says that researchers who use computers to study quantum systems might benefit from the simple descriptions that neural networks provide. “If we want to numerically tackle some quantum problem,” Deng says, “we first need to find an efficient representation.”

On paper and, more importantly, on computers, physicists have many ways of representing quantum systems. Typically these representations comprise lists of numbers describing the likelihood that a system will be found in different quantum states. But it becomes difficult to extract properties or predictions from a digital description as the number of quantum particles grows, and the prevailing wisdom has been that entanglement—an exotic quantum connection between particles—plays a key role in thwarting simple representations.

The neural networks used by Deng and his collaborators—CMTC Director and JQI Fellow Sankar Das Sarma and Fudan University physicist and former JQI Postdoctoral Fellow Xiaopeng Li—can efficiently represent quantum systems that harbor lots of entanglement, a surprising improvement over prior methods.

What’s more, the new results go beyond mere representation. “This research is unique in that it does not just provide an efficient representation of highly entangled quantum states,” Das Sarma says. “It is a new way of solving intractable, interacting quantum many-body problems that uses machine learning tools to find exact solutions.”

Neural networks and their accompanying learning techniques powered AlphaGo, the computer program that beat some of the world’s best Go players last year (link is external) (and the top player this year (link is external)). The news excited Deng, an avid fan of the board game. Last year, around the same time as AlphaGo’s triumphs, a paper appeared that introduced the idea of using neural networks to represent quantum states (link is external), although it gave no indication of exactly how wide the tool’s reach might be. “We immediately recognized that this should be a very important paper,” Deng says, “so we put all our energy and time into studying the problem more.”

The result was a more complete account of the capabilities of certain neural networks to represent quantum states. In particular, the team studied neural networks that use two distinct groups of neurons. The first group, called the visible neurons, represents real quantum particles, like atoms in an optical lattice or ions in a chain. To account for interactions between particles, the researchers employed a second group of neurons—the hidden neurons—which link up with visible neurons. These links capture the physical interactions between real particles, and as long as the number of connections stays relatively small, the neural network description remains simple.

Specifying a number for each connection and mathematically forgetting the hidden neurons can produce a compact representation of many interesting quantum states, including states with topological characteristics and some with surprising amounts of entanglement.

Beyond its potential as a tool in numerical simulations, the new framework allowed Deng and collaborators to prove some mathematical facts about the families of quantum states represented by neural networks. For instance, neural networks with only short-range interactions—those in which each hidden neuron is only connected to a small cluster of visible neurons—have a strict limit on their total entanglement. This technical result, known as an area law, is a research pursuit of many condensed matter physicists.

These neural networks can’t capture everything, though. “They are a very restricted regime,” Deng says, adding that they don’t offer an efficient universal representation. If they did, they could be used to simulate a quantum computer with an ordinary computer, something physicists and computer scientists think is very unlikely. Still, the collection of states that they do represent efficiently, and the overlap of that collection with other representation methods, is an open problem that Deng says is ripe for further exploration.

Here’s a link to and a citation for the paper,

Quantum Entanglement in Neural Network States by Dong-Ling Deng, Xiaopeng Li, and S. Das Sarma. Phys. Rev. X 7, 021021 – Published 11 May 2017

This paper is open access.

Blue Brain and the multidimensional universe

Blue Brain is a Swiss government brain research initiative which officially came to life in 2006 although the initial agreement between the École Politechnique Fédérale de Lausanne (EPFL) and IBM was signed in 2005 (according to the project’s Timeline page). Moving on, the project’s latest research reveals something astounding (from a June 12, 2017 Frontiers Publishing press release on EurekAlert),

For most people, it is a stretch of the imagination to understand the world in four dimensions but a new study has discovered structures in the brain with up to eleven dimensions – ground-breaking work that is beginning to reveal the brain’s deepest architectural secrets.

Using algebraic topology in a way that it has never been used before in neuroscience, a team from the Blue Brain Project has uncovered a universe of multi-dimensional geometrical structures and spaces within the networks of the brain.

The research, published today in Frontiers in Computational Neuroscience, shows that these structures arise when a group of neurons forms a clique: each neuron connects to every other neuron in the group in a very specific way that generates a precise geometric object. The more neurons there are in a clique, the higher the dimension of the geometric object.

“We found a world that we had never imagined,” says neuroscientist Henry Markram, director of Blue Brain Project and professor at the EPFL in Lausanne, Switzerland, “there are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to eleven dimensions.”

Markram suggests this may explain why it has been so hard to understand the brain. “The mathematics usually applied to study networks cannot detect the high-dimensional structures and spaces that we now see clearly.”

If 4D worlds stretch our imagination, worlds with 5, 6 or more dimensions are too complex for most of us to comprehend. This is where algebraic topology comes in: a branch of mathematics that can describe systems with any number of dimensions. The mathematicians who brought algebraic topology to the study of brain networks in the Blue Brain Project were Kathryn Hess from EPFL and Ran Levi from Aberdeen University.

“Algebraic topology is like a telescope and microscope at the same time. It can zoom into networks to find hidden structures – the trees in the forest – and see the empty spaces – the clearings – all at the same time,” explains Hess.

In 2015, Blue Brain published the first digital copy of a piece of the neocortex – the most evolved part of the brain and the seat of our sensations, actions, and consciousness. In this latest research, using algebraic topology, multiple tests were performed on the virtual brain tissue to show that the multi-dimensional brain structures discovered could never be produced by chance. Experiments were then performed on real brain tissue in the Blue Brain’s wet lab in Lausanne confirming that the earlier discoveries in the virtual tissue are biologically relevant and also suggesting that the brain constantly rewires during development to build a network with as many high-dimensional structures as possible.

When the researchers presented the virtual brain tissue with a stimulus, cliques of progressively higher dimensions assembled momentarily to enclose high-dimensional holes, that the researchers refer to as cavities. “The appearance of high-dimensional cavities when the brain is processing information means that the neurons in the network react to stimuli in an extremely organized manner,” says Levi. “It is as if the brain reacts to a stimulus by building then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc. The progression of activity through the brain resembles a multi-dimensional sandcastle that materializes out of the sand and then disintegrates.”

The big question these researchers are asking now is whether the intricacy of tasks we can perform depends on the complexity of the multi-dimensional “sandcastles” the brain can build. Neuroscience has also been struggling to find where the brain stores its memories. “They may be ‘hiding’ in high-dimensional cavities,” Markram speculates.

###

About Blue Brain

The aim of the Blue Brain Project, a Swiss brain initiative founded and directed by Professor Henry Markram, is to build accurate, biologically detailed digital reconstructions and simulations of the rodent brain, and ultimately, the human brain. The supercomputer-based reconstructions and simulations built by Blue Brain offer a radically new approach for understanding the multilevel structure and function of the brain. http://bluebrain.epfl.ch

About Frontiers

Frontiers is a leading community-driven open-access publisher. By taking publishing entirely online, we drive innovation with new technologies to make peer review more efficient and transparent. We provide impact metrics for articles and researchers, and merge open access publishing with a research network platform – Loop – to catalyse research dissemination, and popularize research to the public, including children. Our goal is to increase the reach and impact of research articles and their authors. Frontiers has received the ALPSP Gold Award for Innovation in Publishing in 2014. http://www.frontiersin.org.

Here’s a link to and a citation for the paper,

Cliques of Neurons Bound into Cavities Provide a Missing Link between Structure and Function by Michael W. Reimann, Max Nolte, Martina Scolamiero, Katharine Turner, Rodrigo Perin, Giuseppe Chindemi, Paweł Dłotko, Ran Levi, Kathryn Hess, and Henry Markram. Front. Comput. Neurosci., 12 June 2017 | https://doi.org/10.3389/fncom.2017.00048

This paper is open access.

Dancing quantum entanglement (Ap. 20 – 22, 2017) and performing mathematics (Ap. 26 – 30, 2017) in Vancouver, Canada

I have listings for two art/science events in Vancouver (Canada).

Dance, poetry and quantum entanglement

From April 20, 2017 (tonight) – April 22, 2017, there will be 8 p.m. performances of Lesley Telford’s ‘Three Sets/Relating At A Distance; My tongue, your ear / If / Spooky Action at a Distance (phase 1)’ at the Scotiabank Dance Centre, 677 Davie St, Yes, that third title is a reference to Einstein’s famous phrase describing his response of the concept of quantum entanglement.

An April 19, 2017 article by Janet Smith for the Georgia Straight features the dancer’s description of the upcoming performances,

One of the clearest definitions of quantum entanglement—a phenomenon Albert Einstein dubbed “spooky action at a distance”—can be found in a vampire movie.

In Jim Jarmusch’s Only Lovers Left Alive Tom Hiddleston’s depressed rock-star bloodsucker explains it this way to Tilda Swinton’s Eve, his centuries-long partner: “When you separate an entwined particle and you move both parts away from the other, even at opposite ends of the universe, if you alter or affect one, the other will be identically altered or affected.”

In fact, it was by watching the dark love story that Vancouver dance artist Lesley Telford learned about quantum entanglement—in which particles are so closely connected that they cannot act independently of one another, no matter how much space lies between them. She became fascinated not just with the scientific possibilities of the concept but with the romantic ones. …

 “I thought, ‘What a great metaphor,’ ” the choreographer tells the Straight over sushi before heading into a Dance Centre studio. “It’s the idea of quantum entanglement and how that could relate to human entanglement.…It’s really a metaphor for human interactions.”

First, though, as is so often the case with Telford, she needed to form those ideas into words. So she approached poet Barbara Adler to talk about the phenomenon, and then to have her build poetry around it—text that the writer will perform live in Telford’s first full evening of work here.

“Barbara talked a lot about how you feel this resonance with people that have been in your life, and how it’s tied into romantic connections and love stories,” Telford explains. “As we dig into it, it’s become less about that and more of an underlying vibration in the work; it feels like we’ve gone beyond that starting point.…I feel like she has a way of making it so down-to-earth and it’s given us so much food to work with. Are we in control of the universe or is it in control of us?”

Spooky Action at a Distance, a work for seven dancers, ends up being a string of duets that weave—entangle—into other duets. …

There’s more information about the performance, which concerns itself with more than quantum entanglement in the Scotiabank Dance Centre’s event webpage,

Lesley Telford’s choreography brings together a technically rigorous vocabulary and a thought-provoking approach, refined by her years dancing with Nederlands Dans Theater and creating for companies at home and abroad, most recently Ballet BC. This triple bill features an excerpt of a new creation inspired by Einstein’s famous phrase “spooky action at a distance”, referring to particles that are so closely linked, they share the same existence: a collaboration with poet Barbara Adler, the piece seeks to extend the theory to human connections in our phenomenally interconnected world. The program also includes a new extended version of If, a trio based on Anne Carson’s poem, and the duet My tongue, your ear, with text by Wislawa Szymborska.

Here’s what appears to be an excerpt from a rehearsal for ‘Spooky Action …’,

I’m not super fond of the atonal music/sound they’re using. The voice you hear is Adler’s and here’s more about Barbara Adler from her Wikipedia entry (Note: Links have been removed),

Barbara Adler is a musician, poet, and storyteller based in Vancouver, British Columbia. She is a past Canadian Team Slam Champion, was a founding member of the Vancouver Youth Slam, and a past CBC Poetry Face Off winner.[1]

She was a founding member of the folk band The Fugitives with Brendan McLeod, C.R. Avery and Mark Berube[2][3] until she left the band in 2011 to pursue other artistic ventures. She was a member of the accordion shout-rock band Fang, later Proud Animal, and works under the pseudonym Ten Thousand Wolves.[4][5][6][7][8]

In 2004 she participated in the inaugural Canadian Festival of Spoken Word, winning the Spoken Wordlympics with her fellow team members Shane Koyczan, C.R. Avery, and Brendan McLeod.[9][10] In 2010 she started on The BC Memory Game, a traveling storytelling project based on the game of memory[11] and has also been involved with the B.C. Schizophrenia Society Reach Out Tour for several years.[12][13][14] She is of Czech-Jewish descent.[15][16]

Barbara Adler has her bachelor’s degree and MFA from Simon Fraser University, with a focus on songwriting, storytelling, and community engagement.[17][18] In 2015 she was a co-star in the film Amerika, directed by Jan Foukal,[19][20] which premiered at the Karlovy Vary International Film Festival.[21]

Finally, Telford is Artist in Residence at the Dance Centre and TRIUMF, Canada’s national laboratory for particle and nuclear physics and accelerator-based science.

To buy tickets ($32 or less with a discount), go here. Telford will be present on April 21, 2017 for a post-show talk.

Pi Theatre’s ‘Long Division’

This theatrical performance of concepts in mathematics runs from April 26 – 30, 2017 (check here for the times as they vary) at the Annex at 823 Seymour St.  From the Georgia Straight’s April 12, 2017 Arts notice,

Mathematics is an art form in itself, as proven by Pi Theatre’s number-charged Long Division. This is a “refreshed remount” of Peter Dickinson’s ambitious work, one that circles around seven seemingly unrelated characters (including a high-school math teacher, a soccer-loving imam, and a lesbian bar owner) bound together by a single traumatic incident. Directed by Richard Wolfe, with choreography by Lesley Telford and musical score by Owen Belton, it’s a multimedia, movement-driven piece that has a strong cast. …

Here’s more about the play from Pi Theatre’s Long Division page,

Long Division uses text, multimedia, and physical theatre to create a play about the mathematics of human connection.

Long Division focuses on seven characters linked – sometimes directly, sometimes more obliquely – by a sequence of tragic events. These characters offer lessons on number theory, geometry and logic, while revealing aspects of their inner lives, and collectively the nature of their relationships to one another.

Playwright: Peter Dickinson
Director: Richard Wolfe
Choreographer: Lesley Telford, Inverso Productions
Composer: Owen Belton
Assistant Director: Keltie Forsyth

Cast:  Anousha Alamian, Jay Clift, Nicco Lorenzo Garcia, Jennifer Lines, Melissa Oei, LInda Quibell & Kerry Sandomirsky

Costume Designer: Connie Hosie
Lighting Designer: Jergus Oprsal
Set Designer: Lauchlin Johnston
Projection Designer: Jamie Nesbitt
Production Manager: Jayson Mclean
Stage Manager: Jethelo E. Cabilete
Assistant Projection Designer: Cameron Fraser
Lighting Design Associate: Jeff Harrison

Dates/Times: April 26 – 29 at 8pm, April 29 and 30 at 2pm
Student performance on April 27 at 1pm

A Talk-Back will take place after the 2pm show on April 29th.

Shawn Conner engaged the playwright, Peter Dickinson in an April 20, 2017 Q&A (question and answer) for the Vancouver Sun,

Q: Had you been working on Long Division for a long time?

A: I’d been working on it for about five years. I wrote a previous play called The Objecthood of Chairs, which has a similar style in that I combine lecture performance with physical and dance theatre. There are movement scores in both pieces.

In that first play, I told the story of two men and their relationship through the history of chair design. It was a combination of mining my research about that and trying to craft a story that was human and where the audience could find a way in. When I was thinking about a subject for a new play, I took the profession of one of the characters in that first play, who was a math teacher, and said, “Let’s see what happens to his character, let’s see where he goes after the breakup of his relationship.”

At first, I wrote it (Long Division) in an attempt at completely real, kitchen-sink naturalism, and it was a complete disaster. So I went back into this lecture-style performance.

Q: Long Division is set in a bar. Is the setting left over from that attempt at realism?

A: I guess so. It’s kind of a meta-theatrical play in the sense that the characters address the audience, and they’re aware they’re in a theatrical setting. One of the characters is an actress, and she comments on the connection between mathematics and theatre.

Q: This is being called a “refreshed” remount. What’s changed since its first run 

A: It’s mostly been cuts, and some massaging of certain sections. And I think it’s a play that actually needs a little distance.

Like mathematics, the patterns only reveal themselves at a remove. I think I needed that distance to see where things were working and where they could be better. So it’s a gift for me to be given this opportunity, to make things pop a little more and to make the math, which isn’t meant to be difficult, more understandable and relatable.

You may have noticed that Lesley Telford from Spooky Action is also choreographer for this production. I gather she’s making a career of art/science pieces, at least for now.

In the category of ‘Vancouver being a small town’, Telford lists a review of one of her pieces,  ‘AUDC’s Season Finale at The Playhouse’, on her website. Intriguingly, the reviewer is Peter Dickinson who in addition to being the playwright with whom she has collaborated for Pi Theatre’s ‘Long Division’ is also the Director of SFU’s (Simon Fraser University’s) Institute for Performance Studies. I wonder how many more ways these two crisscross professionally? Personally and for what it’s worth, it might be a good idea for Telford (and Dickinson, if he hasn’t already done so) to make readers aware of their professional connections when there’s a review at stake.

Final comment: I’m not sure how quantum entanglement or mathematics with the pieces attributed to concepts from those fields but I’m sure anyone attempting to make the links will find themselves stimulated.

ETA April 21, 2017: I’m adding this event even though the tickets are completely subscribed. There will be a standby line the night of the event (from the Peter Wall Institute for Advanced Studies The Hidden Beauty of Mathematics event page,

02 May 2017

7:00 pm (doors open at 6:00 pm)

The Vogue Theatre

918 Granville St.

Vancouver, BC

Register

Good luck!

Entangling a single photon with a trillion atoms

Polish scientists have cast light on an eighty-year old ‘paradox’ according to a March 2, 2017 news item on plys.org,

A group of researchers from the Faculty of Physics at the University of Warsaw has shed new light on the famous paradox of Einstein, Podolsky and Rosen after 80 years. They created a multidimensional entangled state of a single photon and a trillion hot rubidium atoms, and stored this hybrid entanglement in the laboratory for several microseconds. …

In their famous Physical Review article, published in 1935, Einstein, Podolsky and Rosen considered the decay of a particle into two products. In their thought experiment, two products of decay were projected in exactly opposite directions—or more scientifically speaking, their momenta were anti-correlated. Though not be a mystery within the framework of classical physics, when applying the rules of quantum theory, the three researchers arrived at a paradox. The Heisenberg uncertainty principle, dictating that position and momentum of a particle cannot be measured at the same time, lies at the center of this paradox. In Einstein’s thought experiment, it is possible to measure the momentum of one particle and immediately know the momentum of the other without measurement, as it is exactly opposite. Then, by measuring the position of the second particle, the Heisenberg uncertainty principle is seemingly violated, an apparent paradox that seriously baffled the three physicists.

A March 2, 2017 University of Warsaw press release (also on EurekAlert), which originated the news item, expands on the topic,

Only today we know that this experiment is not, in fact, a paradox. The mistake of Einstein and co-workers was to use one-particle uncertainty principle to a system of two particles. If we treat these two particles as described by a single quantum state, we learn that the original uncertainty principle ceases to apply, especially if these particles are entangled.

In the Quantum Memories Laboratory at the University of Warsaw, the group of three physicists was first to create such an entangled state consisting of a macroscopic object – a group of about one trillion atoms, and a single photon – a particle of light. “Single photons, scattered during the interaction of a laser beam with atoms, are registered on a sensitive camera. A single registered photon carries information about the quantum state of the entire group of atoms. The atoms may be stored, and their state may be retrieved on demand.” – says Michal Dabrowski, PhD student and co-author of the article.

The results of the experiment confirm that the atoms and the single photon are in a joint, entangled state. By measuring position and momentum of the photon, we gain all information about the state of atoms. To confirm this, polish scientists convert the atomic state into another photon, which again is measured using the state-of-the-art camera developed in the Quantum Memories Laboratory. “We demonstrate the Einstein-Podolsky-Rosen apparent paradox in a very similar version as originally proposed in 1935, however we extend the experiment by adding storage of light within the large group of atoms. Atoms store the photon in a form of a wave made of atomic spins, containing one trillion atoms. Such a state is very robust against loss of a single atoms, as information is spread across so many particles.” – says Michal Parniak, PhD student taking part in the study.

The experiment performed by the group from the University of Warsaw is unique in one other way as well. The quantum memory storing the entangled state, created thanks to “PRELUDIUM” grant from the Poland’s National Science Centre and “Diamentowy Grant” from the Polish Ministry of Science and Higher Education, allows for storage of up to 12 photons at once. This enhanced capacity is promising in terms of applications in quantum information processing. “The multidimensional entanglement is stored in our device for several microseconds, which is roughly a thousand times longer than in any previous experiments, and at the same time long enough to perform subtle quantum operations on the atomic state during storage” – explains Dr. Wojciech Wasilewski, group leader of the Quantum Memories Laboratory team.

The entanglement in the real and momentum space, described in the Optica article, can be used jointly with other well-known degrees of freedom such as polarization, allowing generation of so-called hyper-entanglement. Such elaborate ideas constitute new and original test of the fundamentals of quantum mechanics – a theory that is unceasingly mysterious yet brings immense technological progress.

Here’s a link to and a citation for the paper,

Einstein–Podolsky–Rosen paradox in a hybrid bipartite system by Michał Dąbrowski, Michał Parniak, and Wojciech Wasilewski. Optica Vol. 4, Issue 2, pp. 272-275 (2017) •https://doi.org/10.1364/OPTICA.4.000272

This paper appears to be open access.

2016 thoughts and 2017 hopes from FrogHeart

This is the 4900th post on this blog and as FrogHeart moves forward to 5000, I’m thinking there will be some changes although I’m not sure what they’ll be. In the meantime, here are some random thoughts on the year that was in Canadian science and on the FrogHeart blog.

Changeover to Liberal government: year one

Hopes were high after the Trudeau government was elected. Certainly, there seems to have been a loosening where science communication policies have been concerned although it may not have been quite the open and transparent process people dreamed of. On the plus side, it’s been easier to participate in public consultations but there has been no move (perceptible to me) towards open government science or better access to government-funded science papers.

Open Science in Québec

As far as I know, la crème de la crème of open science (internationally) is the Montreal Neurological Institute (Montreal Neuro; affiliated with McGill University. They bookended the year with two announcements. In January 2016, Montreal Neuro announced it was going to be an “Open Science institution (my Jan. 22, 2016 posting),

The Montreal Neurological Institute (MNI) in Québec, Canada, known informally and widely as Montreal Neuro, has ‘opened’ its science research to the world. David Bruggeman tells the story in a Jan. 21, 2016 posting on his Pasco Phronesis blog (Note: Links have been removed),

The Montreal Neurological Institute (MNI) at McGill University announced that it will be the first academic research institute to become what it calls ‘Open Science.’  As Science is reporting, the MNI will make available all research results and research data at the time of publication.  Additionally it will not seek patents on any of the discoveries made on research at the Institute.

Will this catch on?  I have no idea if this particular combination of open access research data and results with no patents will spread to other university research institutes.  But I do believe that those elements will continue to spread.  More universities and federal agencies are pursuing open access options for research they support.  Elon Musk has opted to not pursue patent litigation for any of Tesla Motors’ patents, and has not pursued patents for SpaceX technology (though it has pursued litigation over patents in rocket technology). …

Then, there’s my Dec. 19, 2016 posting about this Montreal Neuro announcement,

It’s one heck of a Christmas present. Canadian businessmen Larry Tannenbaum and his wife Judy have given the Montreal Neurological Institute (Montreal Neuro), which is affiliated with McGill University, a $20M donation. From a Dec. 16, 2016 McGill University news release,

The Prime Minister of Canada, Justin Trudeau, was present today at the Montreal Neurological Institute and Hospital (MNI) for the announcement of an important donation of $20 million by the Larry and Judy Tanenbaum family. This transformative gift will help to establish the Tanenbaum Open Science Institute, a bold initiative that will facilitate the sharing of neuroscience findings worldwide to accelerate the discovery of leading edge therapeutics to treat patients suffering from neurological diseases.

‟Today, we take an important step forward in opening up new horizons in neuroscience research and discovery,” said Mr. Larry Tanenbaum. ‟Our digital world provides for unprecedented opportunities to leverage advances in technology to the benefit of science.  That is what we are celebrating here today: the transformation of research, the removal of barriers, the breaking of silos and, most of all, the courage of researchers to put patients and progress ahead of all other considerations.”

Neuroscience has reached a new frontier, and advances in technology now allow scientists to better understand the brain and all its complexities in ways that were previously deemed impossible. The sharing of research findings amongst scientists is critical, not only due to the sheer scale of data involved, but also because diseases of the brain and the nervous system are amongst the most compelling unmet medical needs of our time.

Neurological diseases, mental illnesses, addictions, and brain and spinal cord injuries directly impact 1 in 3 Canadians, representing approximately 11 million people across the country.

“As internationally-recognized leaders in the field of brain research, we are uniquely placed to deliver on this ambitious initiative and reinforce our reputation as an institution that drives innovation, discovery and advanced patient care,” said Dr. Guy Rouleau, Director of the Montreal Neurological Institute and Hospital and Chair of McGill University’s Department of Neurology and Neurosurgery. “Part of the Tanenbaum family’s donation will be used to incentivize other Canadian researchers and institutions to adopt an Open Science model, thus strengthening the network of like-minded institutes working in this field.”

Chief Science Advisor

Getting back to the federal government, we’re still waiting for a Chief Science Advisor. Should you be interested in the job, apply here. The job search was launched in early Dec. 2016 (see my Dec. 7, 2016 posting for details) a little over a year after the Liberal government was elected. I’m not sure why the process is taking so long. It’s not like the Canadian government is inventing a position or trailblazing in this regard. Many, many countries and jurisdictions have chief science advisors. Heck the European Union managed to find their first chief science advisor in considerably less time than we’ve spent on the project. My guess, it just wasn’t a priority.

Prime Minister Trudeau, quantum, nano, and Canada’s 150th birthday

In April 2016, Prime Minister Justin Trudeau stunned many when he was able to answer, in an articulate and informed manner, a question about quantum physics during a press conference at the Perimeter Institute in Waterloo, Ontario (my April 18, 2016 post discussing that incident and the so called ‘quantum valley’ in Ontario).

In Sept. 2016, the University of Waterloo publicized the world’s smallest Canadian flag to celebrate the country’s upcoming 150th birthday and to announce its presence in QUANTUM: The Exhibition (a show which will tour across Canada). Here’s more from my Sept. 20, 2016 posting,

The record-setting flag was unveiled at IQC’s [Institute of Quantum Computing at the University of Waterloo] open house on September 17 [2016], which attracted nearly 1,000 visitors. It will also be on display in QUANTUM: The Exhibition, a Canada 150 Fund Signature Initiative, and part of Innovation150, a consortium of five leading Canadian science-outreach organizations. QUANTUM: The Exhibition is a 4,000-square-foot, interactive, travelling exhibit IQC developed highlighting Canada’s leadership in quantum information science and technology.

“I’m delighted that IQC is celebrating Canadian innovation through QUANTUM: The Exhibition and Innovation150,” said Raymond Laflamme, executive director of IQC. “It’s an opportunity to share the transformative technologies resulting from Canadian research and bring quantum computing to fellow Canadians from coast to coast to coast.”

The first of its kind, the exhibition will open at THEMUSEUM in downtown Kitchener on October 14 [2016], and then travel to science centres across the country throughout 2017.

You can find the English language version of QUANTUM: The Exhibition website here and the French language version of QUANTUM: The Exhibition website here.

There are currently four other venues for the show once finishes its run in Waterloo. From QUANTUM’S Join the Celebration webpage,

2017

  • Science World at TELUS World of Science, Vancouver
  • TELUS Spark, Calgary
  • Discovery Centre, Halifax
  • Canada Science and Technology Museum, Ottawa

I gather they’re still looking for other venues to host the exhibition. If interested, there’s this: Contact us.

Other than the flag which is both nanoscale and microscale, they haven’t revealed what else will be included in their 4000 square foot exhibit but it will be “bilingual, accessible, and interactive.” Also, there will be stories.

Hmm. The exhibition is opening in roughly three weeks and they have no details. Strategy or disorganization? Only time will tell.

Calgary and quantum teleportation

This is one of my favourite stories of the year. Scientists at the University of Calgary teleported photons six kilometers from the university to city hall breaking the teleportation record. What I found particularly interesting was the support for science from Calgary City Hall. Here’s more from my Sept. 21, 2016 post,

Through a collaboration between the University of Calgary, The City of Calgary and researchers in the United States, a group of physicists led by Wolfgang Tittel, professor in the Department of Physics and Astronomy at the University of Calgary have successfully demonstrated teleportation of a photon (an elementary particle of light) over a straight-line distance of six kilometres using The City of Calgary’s fibre optic cable infrastructure. The project began with an Urban Alliance seed grant in 2014.

This accomplishment, which set a new record for distance of transferring a quantum state by teleportation, has landed the researchers a spot in the prestigious Nature Photonics scientific journal. The finding was published back-to-back with a similar demonstration by a group of Chinese researchers.

The research could not be possible without access to the proper technology. One of the critical pieces of infrastructure that support quantum networking is accessible dark fibre. Dark fibre, so named because of its composition — a single optical cable with no electronics or network equipment on the alignment — doesn’t interfere with quantum technology.

The City of Calgary is building and provisioning dark fibre to enable next-generation municipal services today and for the future.

“By opening The City’s dark fibre infrastructure to the private and public sector, non-profit companies, and academia, we help enable the development of projects like quantum encryption and create opportunities for further research, innovation and economic growth in Calgary,” said Tyler Andruschak, project manager with Innovation and Collaboration at The City of Calgary.

As for the science of it (also from my post),

A Sept. 20, 2016 article by Robson Fletcher for CBC (Canadian Broadcasting News) online provides a bit more insight from the lead researcher (Note: A link has been removed),

“What is remarkable about this is that this information transfer happens in what we call a disembodied manner,” said physics professor Wolfgang Tittel, whose team’s work was published this week in the journal Nature Photonics.

“Our transfer happens without any need for an object to move between these two particles.”

A Sept. 20, 2016 University of Calgary news release by Drew Scherban, which originated the news item, provides more insight into the research,

“Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel.

Experiment draws on ‘spooky action at a distance’

The experiment is based on the entanglement property of quantum mechanics, also known as “spooky action at a distance” — a property so mysterious that not even Einstein could come to terms with it.

“Being entangled means that the two photons that form an entangled pair have properties that are linked regardless of how far the two are separated,” explains Tittel. “When one of the photons was sent over to City Hall, it remained entangled with the photon that stayed at the University of Calgary.”

Next, the photon whose state was teleported to the university was generated in a third location in Calgary and then also travelled to City Hall where it met the photon that was part of the entangled pair.

“What happened is the instantaneous and disembodied transfer of the photon’s quantum state onto the remaining photon of the entangled pair, which is the one that remained six kilometres away at the university,” says Tittel.

Council of Canadian Academies and The State of Science and Technology and Industrial Research and Development in Canada

Preliminary data was released by the CCA’s expert panel in mid-December 2016. I reviewed that material briefly in my Dec. 15, 2016 post but am eagerly awaiting the full report due late 2017 when, hopefully, I’ll have the time to critique the material, and which I hope will have more surprises and offer greater insights than the preliminary report did.

Colleagues

Thank you to my online colleagues. While we don’t interact much it’s impossible to estimate how encouraging it is to know that these people continually participate and help create the nano and/or science blogosphere.

David Bruggeman at his Pasco Phronesis blog keeps me up-to-date on science policy both in the US, Canada, and internationally, as well as, keeping me abreast of the performing arts/science scene. Also, kudos to David for raising my (and his audience’s) awareness of just how much science is discussed on late night US television. Also, I don’t know how he does it but he keeps scooping me on Canadian science policy matters. Thankfully, I’m not bitter and hope he continues to scoop me which will mean that I will get the information from somewhere since it won’t be from the Canadian government.

Tim Harper of Cientifica Research keeps me on my toes as he keeps shifting his focus. Most lately, it’s been on smart textiles and wearables. You can download his latest White Paper titled, Fashion, Smart Textiles, Wearables and Disappearables, from his website. Tim consults on nanotechnology and other emerging technologies at the international level.

Dexter Johnson of the Nanoclast blog on the IEEE (Institute of Electrical and Electronics Engineers) website consistently provides informed insight into how a particular piece of research fits into the nano scene and often provides historical details that you’re not likely to get from anyone else.

Dr. Andrew Maynard is currently the founding Director of the Risk Innovation Lab at the University of Arizona. I know him through his 2020 Science blog where he posts text and videos on many topics including emerging technologies, nanotechnologies, risk, science communication, and much more. Do check out 2020 Science as it is a treasure trove.

2017 hopes and dreams

I hope Canada’s Chief Science Advisor brings some fresh thinking to science in government and that the Council of Canadian Academies’ upcoming assessment on The State of Science and Technology and Industrial Research and Development in Canada is visionary. Also, let’s send up some collective prayers for the Canada Science and Technology Museum which has been closed since 2014 (?) due to black mold (?). It would be lovely to see it open in time for Canada’s 150th anniversary.

I’d like to see the nanotechnology promise come closer to a reality, which benefits as many people as possible.

As for me and FrogHeart, I’m not sure about the future. I do know there’s one more Steep project (I’m working with Raewyn Turner on a multiple project endeavour known as Steep; this project will involve sound and gold nanoparticles).

Should anything sparkling occur to me, I will add it at a future date.

In the meantime, Happy New Year and thank you from the bottom of my heart for reading this blog!

Teleporting photons in Calgary (Canada) is a step towards a quantum internet

Scientists at the University of Calgary (Alberta, Canada) have set a distance record for the teleportation of photons and you can see the lead scientist is very pleased.

Wolfgang Tittel, professor of physics and astronomy at the University of Calgary, and a group of PhD students have developed a new quantum key distribution (QKD) system.

Wolfgang Tittel, professor of physics and astronomy at the University of Calgary, and a group of PhD students have developed a new quantum key distribution (QKD) system.

A Sept. 21, 2016 news item on phys.org makes the announcement (Note: A link has been removed),

What if you could behave like the crew on the Starship Enterprise and teleport yourself home or anywhere else in the world? As a human, you’re probably not going to realize this any time soon; if you’re a photon, you might want to keep reading.

Through a collaboration between the University of Calgary, The City of Calgary and researchers in the United States, a group of physicists led by Wolfgang Tittel, professor in the Department of Physics and Astronomy at the University of Calgary have successfully demonstrated teleportation of a photon (an elementary particle of light) over a straight-line distance of six kilometres using The City of Calgary’s fibre optic cable infrastructure. The project began with an Urban Alliance seed grant in 2014.

This accomplishment, which set a new record for distance of transferring a quantum state by teleportation, has landed the researchers a spot in the prestigious Nature Photonics scientific journal. The finding was published back-to-back with a similar demonstration by a group of Chinese researchers.

A Sept. 20, 2016 article by Robson Fletcher for CBC (Canadian Broadcasting News) online provides a bit more insight from the lead researcher (Note: A link has been removed),

“What is remarkable about this is that this information transfer happens in what we call a disembodied manner,” said physics professor Wolfgang Tittel, whose team’s work was published this week in the journal Nature Photonics.

“Our transfer happens without any need for an object to move between these two particles.”

A Sept. 20, 2016 University of Calgary news release by Drew Scherban, which originated the news item, provides more insight into the research,

“Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel.

Experiment draws on ‘spooky action at a distance’

The experiment is based on the entanglement property of quantum mechanics, also known as “spooky action at a distance” — a property so mysterious that not even Einstein could come to terms with it.

“Being entangled means that the two photons that form an entangled pair have properties that are linked regardless of how far the two are separated,” explains Tittel. “When one of the photons was sent over to City Hall, it remained entangled with the photon that stayed at the University of Calgary.”

Next, the photon whose state was teleported to the university was generated in a third location in Calgary and then also travelled to City Hall where it met the photon that was part of the entangled pair.

“What happened is the instantaneous and disembodied transfer of the photon’s quantum state onto the remaining photon of the entangled pair, which is the one that remained six kilometres away at the university,” says Tittel.

City’s accessible dark fibre makes research possible

The research could not be possible without access to the proper technology. One of the critical pieces of infrastructure that support quantum networking is accessible dark fibre. Dark fibre, so named because of its composition — a single optical cable with no electronics or network equipment on the alignment — doesn’t interfere with quantum technology.

The City of Calgary is building and provisioning dark fibre to enable next-generation municipal services today and for the future.

“By opening The City’s dark fibre infrastructure to the private and public sector, non-profit companies, and academia, we help enable the development of projects like quantum encryption and create opportunities for further research, innovation and economic growth in Calgary,” said Tyler Andruschak, project manager with Innovation and Collaboration at The City of Calgary.

“The university receives secure access to a small portion of our fibre optic infrastructure and The City may benefit in the future by leveraging the secure encryption keys generated out of the lab’s research to protect our critical infrastructure,” said Andruschak. In order to deliver next-generation services to Calgarians, The City has been increasing its fibre optic footprint, connecting all City buildings, facilities and assets.

Timed to within one millionth of one millionth of a second

As if teleporting a photon wasn’t challenging enough, Tittel and his team encountered a number of other roadblocks along the way.

Due to changes in the outdoor temperature, the transmission time of photons from their creation point to City Hall varied over the course of a day — the time it took the researchers to gather sufficient data to support their claim. This change meant that the two photons would not meet at City Hall.

“The challenge was to keep the photons’ arrival time synchronized to within 10 pico-seconds,” says Tittel. “That is one trillionth, or one millionth of one millionth of a second.”

Secondly, parts of their lab had to be moved to two locations in the city, which as Tittel explains was particularly tricky for the measurement station at City Hall which included state-of-the-art superconducting single-photon detectors developed by the National Institute for Standards and Technology, and NASA’s Jet Propulsion Laboratory.

“Since these detectors only work at temperatures less than one degree above absolute zero the equipment also included a compact cryostat,” said Tittel.

Milestone towards a global quantum Internet

This demonstration is arguably one of the most striking manifestations of a puzzling prediction of quantum mechanics, but it also opens the path to building a future quantum internet, the long-term goal of the Tittel group.

The Urban Alliance is a strategic research partnership between The City of Calgary and University of Calgary, created in 2007 to encourage and co-ordinate the seamless transfer of cutting-edge research between the university and The City of Calgary for the benefit of all our communities. The Urban Alliance is a prime example and vehicle for one of the three foundational commitments of the University of Calgary’s Eyes High vision to fully integrate the university with the community. The City sees the Alliance as playing a key role in realizing its long-term priorities and the imagineCALGARY vision.

Here’s a link to and a citation for the paper,

Quantum teleportation across a metropolitan fibre network by Raju Valivarthi, Marcel.li Grimau Puigibert, Qiang Zhou, Gabriel H. Aguilar, Varun B. Verma, Francesco Marsili, Matthew D. Shaw, Sae Woo Nam, Daniel Oblak, & Wolfgang Tittel. Nature Photonics (2016)  doi:10.1038/nphoton.2016.180 Published online 19 September 2016

This paper is behind a paywall.

I’m 99% certain this is the paper from the Chinese researchers (referred to in the University of Calgary news release),

Quantum teleportation with independent sources and prior entanglement distribution over a network by Qi-Chao Sun, Ya-Li Mao, Si-Jing Chen, Wei Zhang, Yang-Fan Jiang, Yan-Bao Zhang, Wei-Jun Zhang, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Xiao Jiang, Teng-Yun Chen, Li-Xing You, Xian-Feng Chen, Zhen Wang, Jing-Yun Fan, Qiang Zhang & Jian-Wei Pan. Nature Photonics (2016)  doi:10.1038/nphoton.2016.179 Published online 19 September 2016

This too is behind a paywall.

Connecting chaos and entanglement

Researchers seem to have stumbled across a link between classical and quantum physics. A July 12, 2016 University of California at Santa Barbara (UCSB) news release (also on EurekAlert) by Sonia Fernandez provides a description of both classical and quantum physics, as well as, the research that connects the two,

Using a small quantum system consisting of three superconducting qubits, researchers at UC Santa Barbara and Google have uncovered a link between aspects of classical and quantum physics thought to be unrelated: classical chaos and quantum entanglement. Their findings suggest that it would be possible to use controllable quantum systems to investigate certain fundamental aspects of nature.

“It’s kind of surprising because chaos is this totally classical concept — there’s no idea of chaos in a quantum system,” Charles Neill, a researcher in the UCSB Department of Physics and lead author of a paper that appears in Nature Physics. “Similarly, there’s no concept of entanglement within classical systems. And yet it turns out that chaos and entanglement are really very strongly and clearly related.”

Initiated in the 15th century, classical physics generally examines and describes systems larger than atoms and molecules. It consists of hundreds of years’ worth of study including Newton’s laws of motion, electrodynamics, relativity, thermodynamics as well as chaos theory — the field that studies the behavior of highly sensitive and unpredictable systems. One classic example of chaos theory is the weather, in which a relatively small change in one part of the system is enough to foil predictions — and vacation plans — anywhere on the globe.

At smaller size and length scales in nature, however, such as those involving atoms and photons and their behaviors, classical physics falls short. In the early 20th century quantum physics emerged, with its seemingly counterintuitive and sometimes controversial science, including the notions of superposition (the theory that a particle can be located in several places at once) and entanglement (particles that are deeply linked behave as such despite physical distance from one another).

And so began the continuing search for connections between the two fields.

All systems are fundamentally quantum systems, according [to] Neill, but the means of describing in a quantum sense the chaotic behavior of, say, air molecules in an evacuated room, remains limited.

Imagine taking a balloon full of air molecules, somehow tagging them so you could see them and then releasing them into a room with no air molecules, noted co-author and UCSB/Google researcher Pedram Roushan. One possible outcome is that the air molecules remain clumped together in a little cloud following the same trajectory around the room. And yet, he continued, as we can probably intuit, the molecules will more likely take off in a variety of velocities and directions, bouncing off walls and interacting with each other, resting after the room is sufficiently saturated with them.

“The underlying physics is chaos, essentially,” he said. The molecules coming to rest — at least on the macroscopic level — is the result of thermalization, or of reaching equilibrium after they have achieved uniform saturation within the system. But in the infinitesimal world of quantum physics, there is still little to describe that behavior. The mathematics of quantum mechanics, Roushan said, do not allow for the chaos described by Newtonian laws of motion.

To investigate, the researchers devised an experiment using three quantum bits, the basic computational units of the quantum computer. Unlike classical computer bits, which utilize a binary system of two possible states (e.g., zero/one), a qubit can also use a superposition of both states (zero and one) as a single state. Additionally, multiple qubits can entangle, or link so closely that their measurements will automatically correlate. By manipulating these qubits with electronic pulses, Neill caused them to interact, rotate and evolve in the quantum analog of a highly sensitive classical system.

The result is a map of entanglement entropy of a qubit that, over time, comes to strongly resemble that of classical dynamics — the regions of entanglement in the quantum map resemble the regions of chaos on the classical map. The islands of low entanglement in the quantum map are located in the places of low chaos on the classical map.

“There’s a very clear connection between entanglement and chaos in these two pictures,” said Neill. “And, it turns out that thermalization is the thing that connects chaos and entanglement. It turns out that they are actually the driving forces behind thermalization.

“What we realize is that in almost any quantum system, including on quantum computers, if you just let it evolve and you start to study what happens as a function of time, it’s going to thermalize,” added Neill, referring to the quantum-level equilibration. “And this really ties together the intuition between classical thermalization and chaos and how it occurs in quantum systems that entangle.”

The study’s findings have fundamental implications for quantum computing. At the level of three qubits, the computation is relatively simple, said Roushan, but as researchers push to build increasingly sophisticated and powerful quantum computers that incorporate more qubits to study highly complex problems that are beyond the ability of classical computing — such as those in the realms of machine learning, artificial intelligence, fluid dynamics or chemistry — a quantum processor optimized for such calculations will be a very powerful tool.

“It means we can study things that are completely impossible to study right now, once we get to bigger systems,” said Neill.

Experimental link between quantum entanglement (left) and classical chaos (right) found using a small quantum computer. Photo Credit: Courtesy Image (Courtesy: UCSB)

Experimental link between quantum entanglement (left) and classical chaos (right) found using a small quantum computer. Photo Credit: Courtesy Image (Courtesy: UCSB)

Here’s a link to and a citation for the paper,

Ergodic dynamics and thermalization in an isolated quantum system by C. Neill, P. Roushan, M. Fang, Y. Chen, M. Kolodrubetz, Z. Chen, A. Megrant, R. Barends, B. Campbell, B. Chiaro, A. Dunsworth, E. Jeffrey, J. Kelly, J. Mutus, P. J. J. O’Malley, C. Quintana, D. Sank, A. Vainsencher, J. Wenner, T. C. White, A. Polkovnikov, & J. M. Martinis. Nature Physics (2016)  doi:10.1038/nphys3830 Published online 11 July 2016

This paper is behind a paywall.

Testing technology for a global quantum network

This work on quantum networks comes from a joint Singapore/UK research project, from a June 2, 2016 news item on ScienceDaily,

You can’t sign up for the quantum internet just yet, but researchers have reported a major experimental milestone towards building a global quantum network — and it’s happening in space.

With a network that carries information in the quantum properties of single particles, you can create secure keys for secret messaging and potentially connect powerful quantum computers in the future. But scientists think you will need equipment in space to get global reach.

Researchers from the National University of Singapore (NUS) and the University of Strathclyde, UK, have become the first to test in orbit technology for satellite-based quantum network nodes.

They have put a compact device carrying components used in quantum communication and computing into orbit. And it works: the team report first data in a paper published 31 May 2016 in the journal Physical Review Applied.

A June 2, 2016 National University of Singapore press release, which originated the news item, provides more detail,

The team’s device, dubbed SPEQS, creates and measures pairs of light particles, called photons. Results from space show that SPEQS is making pairs of photons with correlated properties – an indicator of performance.

Team-leader Alexander Ling, an Assistant Professor at the Centre for Quantum Technologies (CQT) at NUS said, “This is the first time anyone has tested this kind of quantum technology in space.”

The team had to be inventive to redesign a delicate, table-top quantum setup to be small and robust enough to fly inside a nanosatellite only the size of a shoebox. The whole satellite weighs just 1.65-kilogramme.

Towards entanglement

Making correlated photons is a precursor to creating entangled photons. Described by Einstein as “spooky action at a distance”, entanglement is a connection between quantum particles that lends security to communication and power to computing.

Professor Artur Ekert, Director of CQT, invented the idea of using entangled particles for cryptography. He said, “Alex and his team are taking entanglement, literally, to a new level. Their experiments will pave the road to secure quantum communication and distributed quantum computation on a global scale. I am happy to see that Singapore is one of the world leaders in this area.”

Local quantum networks already exist [emphasis mine]. The problem Ling’s team aims to solve is a distance limit. Losses limit quantum signals sent through air at ground level or optical fibre to a few hundred kilometers – but we might ultimately use entangled photons beamed from satellites to connect points on opposite sides of the planet. Although photons from satellites still have to travel through the atmosphere, going top-to-bottom is roughly equivalent to going only 10 kilometres at ground level.

The group’s first device is a technology pathfinder. It takes photons from a BluRay laser and splits them into two, then measures the pair’s properties, all on board the satellite. To do this it contains a laser diode, crystals, mirrors and photon detectors carefully aligned inside an aluminum block. This sits on top of a 10 centimetres by 10 centimetres printed circuit board packed with control electronics.

Through a series of pre-launch tests – and one unfortunate incident – the team became more confident that their design could survive a rocket launch and space conditions. The team had a device in the October 2014 Orbital-3 rocket which exploded on the launch pad. The satellite containing that first device was later found on a beach intact and still in working order.

Future plans

Even with the success of the more recent mission, a global network is still a few milestones away. The team’s roadmap calls for a series of launches, with the next space-bound SPEQS slated to produce entangled photons. SPEQS stands for Small Photon-Entangling Quantum System.

With later satellites, the researchers will try sending entangled photons to Earth and to other satellites. The team are working with standard “CubeSat” nanosatellites, which can get relatively cheap rides into space as rocket ballast. Ultimately, completing a global network would mean having a fleet of satellites in orbit and an array of ground stations.

In the meantime, quantum satellites could also carry out fundamental experiments – for example, testing entanglement over distances bigger than Earth-bound scientists can manage. “We are reaching the limits of how precisely we can test quantum theory on Earth,” said co-author Dr Daniel Oi at the University of Strathclyde.

Here’s a link to and a citation for the paper,

Generation and Analysis of Correlated Pairs of Photons aboard a Nanosatellite by Zhongkan Tang, Rakhitha Chandrasekara, Yue Chuan Tan, Cliff Cheng, Luo Sha, Goh Cher Hiang, Daniel K. L. Oi, and Alexander Ling. Phys. Rev. Applied 5, 054022 DOI: http://dx.doi.org/10.1103/PhysRevApplied.5.054022 Published 31 May 2016

This paper is behind a paywall.

Nanodevices and quantum entanglement

A May 30, 2016 news item on phys.org introduces a scientist with an intriguing approach to quantum computing,

Creating quantum computers which some people believe will be the next generation of computers, with the ability to outperform machines based on conventional technology—depends upon harnessing the principles of quantum mechanics, or the physics that governs the behavior of particles at the subatomic scale. Entanglement—a concept that Albert Einstein once called “spooky action at a distance”—is integral to quantum computing, as it allows two physically separated particles to store and exchange information.

Stevan Nadj-Perge, assistant professor of applied physics and materials science, is interested in creating a device that could harness the power of entangled particles within a usable technology. However, one barrier to the development of quantum computing is decoherence, or the tendency of outside noise to destroy the quantum properties of a quantum computing device and ruin its ability to store information.

Nadj-Perge, who is originally from Serbia, received his undergraduate degree from Belgrade University and his PhD from Delft University of Technology in the Netherlands. He received a Marie Curie Fellowship in 2011, and joined the Caltech Division of Engineering and Applied Science in January after completing postdoctoral appointments at Princeton and Delft.

He recently talked with us about how his experimental work aims to resolve the problem of decoherence.

A May 27, 2016 California Institute of Technology (CalTech) news release by Jessica Stoller-Conrad, which originated the news item, proceeds with a question and answer format,

What is the overall goal of your research?

A large part of my research is focused on finding ways to store and process quantum information. Typically, if you have a quantum system, it loses its coherent properties—and therefore, its ability to store quantum information—very quickly. Quantum information is very fragile and even the smallest amount of external noise messes up quantum states. This is true for all quantum systems. There are various schemes that tackle this problem and postpone decoherence, but the one that I’m most interested in involves Majorana fermions. These particles were proposed to exist in nature almost eighty years ago but interestingly were never found.

Relatively recently theorists figured out how to engineer these particles in the lab. It turns out that, under certain conditions, when you combine certain materials and apply high magnetic fields at very cold temperatures, electrons will form a state that looks exactly as you would expect from Majorana fermions. Furthermore, such engineered states allow you to store quantum information in a way that postpones decoherence.

How exactly is quantum information stored using these Majorana fermions?

The fascinating property of these particles is that they always come in pairs. If you can store information in a pair of Majorana fermions it will be protected against all of the usual environmental noise that affects quantum states of individual objects. The information is protected because it is not stored in a single particle but in the pair itself. My lab is developing ways to engineer nanodevices which host Majorana fermions. Hopefully one day our devices will find applications in quantum computing.

Why did you want to come to Caltech to do this work?

The concept of engineered Majorana fermions and topological protection was, to a large degree, conceived here at Caltech by Alexei Kiteav [Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics] who is in the physics department. A couple of physicists here at Caltech, Gil Refeal [professor of theoretical physics and executive officer of physics] and Jason Alicea [professor of theoretical physics], are doing theoretical work that is very relevant for my field.

Do you have any collaborations planned here?

Nothing formal, but I’ve been talking a lot with Gil and Jason. A student of mine also uses resources in the lab of Harry Atwater [Howard Hughes Professor of Applied Physics and Materials Science and director of the Joint Center for Artificial Photosynthesis], who has experience with materials that are potentially useful for our research.

How does that project relate to your lab’s work?

There are two-dimensional, or 2-D, materials that are basically very thin sheets of atoms. Graphene [emphasis mine]—a single layer of carbon atoms—is one example, but you can create single layer sheets of atoms with many materials. Harry Atwater’s group is working on solar cells made of a 2-D material. We are thinking of using the same materials and combining them with superconductors—materials that can conduct electricity without releasing heat, sound, or any other form of energy—in order to produce Majorana fermions.

How do you do that?

There are several proposed ways of using 2-D materials to create Majorana fermions. The majority of these materials have a strong spin-orbit coupling—an interaction of a particle’s spin with its motion—which is one of the key ingredients for creating Majoranas. Also some of the 2-D materials can become superconductors at low temperatures. One of the ideas that we are seriously considering is using a 2-D material as a substrate on which we could build atomic chains that will host Majorana fermions.

What got you interested in science when you were young?

I don’t come from a family of scientists; my father is an engineer and my mother is an administrative worker. But my father first got me interested in science. As an engineer, he was always solving something and he brought home some of the problems he was working. I worked with him and picked it up at an early age.

How are you adjusting to life in California?

Well, I like being outdoors, and here we have the mountains and the beach and it’s really amazing. The weather here is so much better than the other places I’ve lived. If you want to get the impression of what the weather in the Netherlands is like, you just replace the number of sunny days here with the number of rainy days there.

I wish Stevan Nadj-Perge good luck!

An atom without properties?

There’s rather intriguing Swiss research into atoms and so-called Bell Correlations according to an April 21, 2016 news item on ScienceDaily,

The microscopic world is governed by the rules of quantum mechanics, where the properties of a particle can be completely undetermined and yet strongly correlated with those of other particles. Physicists from the University of Basel have observed these so-called Bell correlations for the first time between hundreds of atoms. Their findings are published in the scientific journal Science.

Everyday objects possess properties independently of each other and regardless of whether we observe them or not. Einstein famously asked whether the moon still exists if no one is there to look at it; we answer with a resounding yes. This apparent certainty does not exist in the realm of small particles. The location, speed or magnetic moment of an atom can be entirely indeterminate and yet still depend greatly on the measurements of other distant atoms.

An April 21, 2016 University of Basel (Switzerland) press release (also on EurekAlert), which originated the news item, provides further explanation,

With the (false) assumption that atoms possess their properties independently of measurements and independently of each other, a so-called Bell inequality can be derived. If it is violated by the results of an experiment, it follows that the properties of the atoms must be interdependent. This is described as Bell correlations between atoms, which also imply that each atom takes on its properties only at the moment of the measurement. Before the measurement, these properties are not only unknown – they do not even exist.

A team of researchers led by professors Nicolas Sangouard and Philipp Treutlein from the University of Basel, along with colleagues from Singapore, have now observed these Bell correlations for the first time in a relatively large system, specifically among 480 atoms in a Bose-Einstein condensate. Earlier experiments showed Bell correlations with a maximum of four light particles or 14 atoms. The results mean that these peculiar quantum effects may also play a role in larger systems.

Large number of interacting particles

In order to observe Bell correlations in systems consisting of many particles, the researchers first had to develop a new method that does not require measuring each particle individually – which would require a level of control beyond what is currently possible. The team succeeded in this task with the help of a Bell inequality that was only recently discovered. The Basel researchers tested their method in the lab with small clouds of ultracold atoms cooled with laser light down to a few billionths of a degree above absolute zero. The atoms in the cloud constantly collide, causing their magnetic moments to become slowly entangled. When this entanglement reaches a certain magnitude, Bell correlations can be detected. Author Roman Schmied explains: “One would expect that random collisions simply cause disorder. Instead, the quantum-mechanical properties become entangled so strongly that they violate classical statistics.”

More specifically, each atom is first brought into a quantum superposition of two states. After the atoms have become entangled through collisions, researchers count how many of the atoms are actually in each of the two states. This division varies randomly between trials. If these variations fall below a certain threshold, it appears as if the atoms have ‘agreed’ on their measurement results; this agreement describes precisely the Bell correlations.

New scientific territory

The work presented, which was funded by the National Centre of Competence in Research Quantum Science and Technology (NCCR QSIT), may open up new possibilities in quantum technology; for example, for generating random numbers or for quantum-secure data transmission. New prospects in basic research open up as well: “Bell correlations in many-particle systems are a largely unexplored field with many open questions – we are entering uncharted territory with our experiments,” says Philipp Treutlein.

Here’s a link to and a citation for the paper,

Bell correlations in a Bose-Einstein condensate by Roman Schmied, Jean-Daniel Bancal, Baptiste Allard, Matteo Fadel, Valerio Scarani, Philipp Treutlein, Nicolas Sangouard. Science  22 Apr 2016: Vol. 352, Issue 6284, pp. 441-444 DOI: 10.1126/science.aad8665

This paper is behind a paywall.