Tag Archives: Erwin Schrödinger

The reddest red and Schrödinger’s red pixel

Caption: Schrödinger’s red pixel by quasi-bound-states in-the-continuum Credit: 123RF

Science keeps moving. First, there was the June 2022 news and, then, there was the August 2022 news.

A June 8, 2022 Agency for Science, Technology and Research (A*STAR) press release (also on EurekAlert but published June 7, 2022 as an ‘article highlight’) announces more research into structural colour along with some colour theory from Erwin Schrödinger,

The brilliant and often iridescent colours that we see in some species of birds, beetles and butterflies arise from a regular arrangement of nanostructures that scatter selective wavelengths of light more strongly to generate colour. These colours are called structural colours, which usually range from blues to greens, and even magenta. However, vibrant or saturated reds are elusive and notably absent from the structural colour range in both natural and synthetic realms.

To achieve highly saturated reds, the material needs to absorb light from all wavelengths shorter than ~600 nm and reflect the remaining longer wavelengths, doing both as completely as possible. This sharp transition from absorption to reflection was prescribed theoretically by none other than Erwin Schrödinger of quantum theory fame. However, the physics of resonators tell us that high-order optical resonances in blue will also occur as soon as we have a fundamental resonance in red. This combination of blue and red thus results in the magenta observed in nature. It is therefore challenging to achieve the Schrödinger’s red pixel, which would produce the most saturated red in the world. Current nanoantenna-based approaches are insufficient to simultaneously satisfy the above conditions.

Researchers from the Agency for Science, Technology and Research’s (A*STAR) Institute of Materials Research and Engineering (IMRE), National University of Singapore (NUS) and Singapore University of Technology and Design (SUTD) have collaborated to design and realise reds at the ultimate limit of saturation as predicted by theory, where the team worked together on conceptualisation methodology, fabrications, characterisations and simulations. This research was published in Science Advances on 23 February 2022.

The design consists of regularly arranged silicon nanoantennas in the shape of ellipses. These produce possibly the most saturated and brightest reds with ~80% reflectance, exceeding the reds in the standard red, green and blue gamut (sRGB) and other well-known red pigments, e.g. cadmium red .

The nanoantennas support two partially overlapping quasi bound-states-in-the-continuum modes, where the optimal dimensions of the silicon nanoantenna arrays are derived by using a gradient descent algorithm to enable the antennas to achieve sharp spectral edges at red wavelengths. At the same time, high-order modes at blue or green wavelengths are suppressed via engineering the substrate‑induced diffraction channels and the absorption of amorphous silicon.

Potential uses for Schrödinger’s red include developing a polarisation dependent encryption method, with plans to scale up the Schrödinger’s red pixel for applications like functional nanofabrication devices such as optical spectrometers and reflective displays with high colour saturation.

“With this new design that can achieve the most saturated and brightest reds, we can exploit its sensitivity to polarisation and illumination angle on potential applications for information encryption. This proposed concept and design methodology could also be generalised to other Schrödinger’s colour pixels. The highly-saturated red achieved could be potentially scaled up through methods such as deep ultraviolet and nano-imprint lithography, to reach the dimensions of reflective displays based on multilayer film configuration, which could lead to potential applications like compact red filters, highly saturated reflective displays, nonlocal metasurfaces, and miniaturised spectrometers”, said Dr. Dong Zhaogang, Deputy Department Head of Nanofabrication at A*STAR’s IMRE.

“The creation of the record-high saturation and brightness in red opens up possibilities for a plethora of applications related to anti-counterfeiting technologies, high-calibre colour display and more, which were previously perceived as unachievable with structural colour. It showcases a wonderful synergy between conceptual breakthrough, powerful algorithm and advanced nanofabrication”, said Prof. Cheng-Wei Qiu, Dean’s Chair Professor at NUS.

“This work in structural colours goes to show that we can sometimes outdo evolution through clever use of the tools in nanofabrication and accurate optical simulations”, said Prof. Joel Yang, Provost Chair Professor and Associate Professor in Engineering Product Development at SUTD.

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

Schrödinger’s red pixel by quasi-bound-states-in-the-continuum by Zhaogang Dong, Lei Jin, Soroosh Daqiqeh Rezaei, Hao Wang, Yang Chen, Febiana Tjiptoharsono, Jinfa Ho, Sergey Gorelik, Ray Jia Hong Ng, Qifeng Ruan, Cheng-Wei Qiu and Joel K. W. Yang. Science Advances Vol 8, Issue 8 DOI: 10.1126/sciadv.abm4512 Published 23 Feb 2022

This paper is open access.

Math error, colour theory, and perception

An August 10, 2022 news item on phys.org announced a math error made by Erwin Schrödinger and others,

A new study corrects an important error in the 3D mathematical space developed by the Nobel Prize-winning physicist Erwin Schrödinger and others, and used by scientists and industry for more than 100 years to describe how your eye distinguishes one color from another. The research has the potential to boost scientific data visualizations, improve TVs and recalibrate the textile and paint industries.

“The assumed shape of color space requires a paradigm shift,” said Roxana Bujack, a computer scientist with a background in mathematics who creates scientific visualizations at Los Alamos National Laboratory. Bujack is lead author of the paper by a Los Alamos team in the Proceedings of the National Academy of Sciences on the mathematics of color perception.

“Our research shows that the current mathematical model of how the eye perceives color differences is incorrect. That model was suggested by Bernhard Riemann and developed by Hermann von Helmholtz and Erwin Schrödinger—all giants in mathematics and physics—and proving one of them wrong is pretty much the dream of a scientist,” said Bujack.

While the Los Alamos National Laboratory work was published in April 2022 (online) and May 2022 (in print), their news announcement doesn’t seem to have been made until August. I can’t be certain but I believe this should have an impact on the work from A*STAR as that team’s paper cites: E. Schrödinger, Theorie der Pigmente von größter Leuchtkraft. Ann. Phys. 367, 603–622 (1920).

An August 10, 2022 Los Alamos National Laboratory (LANL) news release (also on EurekAlert) provides more information about the discovery,

Modeling human color perception enables automation of image processing, computer graphics and visualization tasks.

“Our original idea was to develop algorithms to automatically improve color maps for data visualization, to make them easier to understand and interpret,” Bujack said. So the team was surprised when they discovered they were the first to determine that the longstanding application of Riemannian geometry, which allows generalizing straight lines to curved surfaces, didn’t work.

To create industry standards, a precise mathematical model of perceived color space is needed. First attempts used Euclidean spaces—the familiar geometry taught in many high schools; more advanced models used Riemannian geometry. The models plot red, green and blue in the 3D space. Those are the colors registered most strongly by light-detecting cones on our retinas, and—not surprisingly—the colors that blend to create all the images on your RGB computer screen.

In the study, which blends psychology, biology and mathematics, Bujack and her colleagues discovered that using Riemannian geometry overestimates the perception of large color differences. That’s because people perceive a big difference in color to be less than the sum you would get if you added up small differences in color that lie between two widely separated shades.

Riemannian geometry cannot account for this effect.

“We didn’t expect this, and we don’t know the exact geometry of this new color space yet,” Bujack said. “We might be able to think of it normally but with an added dampening or weighing function that pulls long distances in, making them shorter. But we can’t prove it yet.”

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

The non-Riemannian nature of perceptual color space by Roxana Bujack, Emily Teti, Jonah Miller, Elektra Caffrey, and Terece L. Turton. Proceedings of the National Academy of Sciences (PNAS) 119 (18) e2119753119 DOI: https://doi.org/10.1073/pnas.2119753119 Published: April 29, 2022

This paper is behind a paywall.

Entanglement and biological systems

I think it was about five years ago thatI wrote a paper on something I called ‘cognitive entanglement’ (mentioned in my July 20,2012 posting) so the latest from Northwestern University (Chicago, Illinois, US) reignited my interest in entanglement. A December 5, 2017 news item on ScienceDaily describes the latest ‘entanglement’ research,

Nearly 75 years ago, Nobel Prize-winning physicist Erwin Schrödinger wondered if the mysterious world of quantum mechanics played a role in biology. A recent finding by Northwestern University’s Prem Kumar adds further evidence that the answer might be yes.

Kumar and his team have, for the first time, created quantum entanglement from a biological system. This finding could advance scientists’ fundamental understanding of biology and potentially open doors to exploit biological tools to enable new functions by harnessing quantum mechanics.

A December 5, 2017 Northwestern University news release (also on EurekAlert), which originated the news item, provides more detail,

“Can we apply quantum tools to learn about biology?” said Kumar, professor of electrical engineering and computer science in Northwestern’s McCormick School of Engineering and of physics and astronomy in the Weinberg College of Arts and Sciences. “People have asked this question for many, many years — dating back to the dawn of quantum mechanics. The reason we are interested in these new quantum states is because they allow applications that are otherwise impossible.”

Partially supported by the [US] Defense Advanced Research Projects Agency [DARPA], the research was published Dec. 5 [2017] in Nature Communications.

Quantum entanglement is one of quantum mechanics’ most mystifying phenomena. When two particles — such as atoms, photons, or electrons — are entangled, they experience an inexplicable link that is maintained even if the particles are on opposite sides of the universe. While entangled, the particles’ behavior is tied one another. If one particle is found spinning in one direction, for example, then the other particle instantaneously changes its spin in a corresponding manner dictated by the entanglement. Researchers, including Kumar, have been interested in harnessing quantum entanglement for several applications, including quantum communications. Because the particles can communicate without wires or cables, they could be used to send secure messages or help build an extremely fast “quantum Internet.”

“Researchers have been trying to entangle a larger and larger set of atoms or photons to develop substrates on which to design and build a quantum machine,” Kumar said. “My laboratory is asking if we can build these machines on a biological substrate.”

In the study, Kumar’s team used green fluorescent proteins, which are responsible for bioluminescence and commonly used in biomedical research. The team attempted to entangle the photons generated from the fluorescing molecules within the algae’s barrel-shaped protein structure by exposing them to spontaneous four-wave mixing, a process in which multiple wavelengths interact with one another to produce new wavelengths.

Through a series of these experiments, Kumar and his team successfully demonstrated a type of entanglement, called polarization entanglement, between photon pairs. The same feature used to make glasses for viewing 3D movies, polarization is the orientation of oscillations in light waves. A wave can oscillate vertically, horizontally, or at different angles. In Kumar’s entangled pairs, the photons’ polarizations are entangled, meaning that the oscillation directions of light waves are linked. Kumar also noticed that the barrel-shaped structure surrounding the fluorescing molecules protected the entanglement from being disrupted.

“When I measured the vertical polarization of one particle, we knew it would be the same in the other,” he said. “If we measured the horizontal polarization of one particle, we could predict the horizontal polarization in the other particle. We created an entangled state that correlated in all possibilities simultaneously.”

Now that they have demonstrated that it’s possible to create quantum entanglement from biological particles, next Kumar and his team plan to make a biological substrate of entangled particles, which could be used to build a quantum machine. Then, they will seek to understand if a biological substrate works more efficiently than a synthetic one.

Here’s an image accompanying the news release,

Featured in the cuvette on the left, green fluorescent proteins responsible for bioluninescence in jellyfish. Courtesy: Northwestern University

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

Generation of photonic entanglement in green fluorescent proteins by Siyuan Shi, Prem Kumar & Kim Fook Lee. Nature Communications 8, Article number: 1934 (2017) doi:10.1038/s41467-017-02027-9 Published online: 05 December 2017

This paper is open access.

Prime Minister Trudeau, the quantum physicist

Prime Minister Justin Trudeau’s apparently extemporaneous response to a joking (non)question about quantum computing by a journalist during an April 15, 2016 press conference at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada has created a buzz online, made international news, and caused Canadians to sit taller.

For anyone who missed the moment, here’s a video clip from the Canadian Broadcasting Corporation (CBC),

Aaron Hutchins in an April 15, 2016 article for Maclean’s magazine digs deeper to find out more about Trudeau and quantum physics (Note: A link has been removed),

Raymond Laflamme knows the drill when politicians visit the Perimeter Institute. A photo op here, a few handshakes there and a tour with “really basic, basic, basic facts” about the field of quantum mechanics.

But when the self-described “geek” Justin Trudeau showed up for a funding announcement on Friday [April 15, 2016], the co-founder and director of the Institute for Quantum Computing at the University of Waterloo wasn’t met with simple nods of the Prime Minister pretending to understand. Trudeau immediately started talking about things being waves and particles at the same time, like cats being dead and alive at the same time. It wasn’t just nonsense—Trudeau was referencing the famous thought experiment of the late legendary physicist Erwin Schrödinger.

“I don’t know where he learned all that stuff, but we were all surprised,” Laflamme says. Soon afterwards, as Trudeau met with one student talking about superconductivity, the Prime Minister asked her, “Why don’t we have high-temperature superconducting systems?” something Laflamme describes as the institute’s “Holy Grail” quest.

“I was flabbergasted,” Laflamme says. “I don’t know how he does in other subjects, but in quantum physics, he knows the basic pieces and the important questions.”

Strangely, Laflamme was not nearly as excited (tongue in cheek) when I demonstrated my understanding of quantum physics during our interview (see my May 11, 2015 posting; scroll down about 40% of the way to the Ramond Laflamme subhead).

As Jon Butterworth comments in his April 16, 2016 posting on the Guardian science blog, the response says something about our expectations regarding politicians,

This seems to have enhanced Trudeau’s reputation no end, and quite right too. But it is worth thinking a bit about why.

The explanation he gives is clear, brief, and understandable to a non-specialist. It is the kind of thing any sufficiently engaged politician could pick up from a decent briefing, given expert help. …

Butterworth also goes on to mention journalists’ expectations,

The reporter asked the question in a joking fashion, not unkindly as far as I can tell, but not expecting an answer either. If this had been an announcement about almost any other government investment, wouldn’t the reporter have expected a brief explanation of the basic ideas behind it? …

As for the announcement being made by Trudeau, there is this April 15, 2016 Perimeter Institute press release (Note: Links have been removed),

Prime Minister Justin Trudeau says the work being done at Perimeter and in Canada’s “Quantum Valley” [emphasis mine] is vital to the future of the country and the world.

Prime Minister Justin Trudeau became both teacher and student when he visited Perimeter Institute today to officially announce the federal government’s commitment to support fundamental scientific research at Perimeter.

Joined by Minister of Science Kirsty Duncan and Small Business and Tourism Minister Bardish Chagger, the self-described “geek prime minister” listened intensely as he received brief overviews of Perimeter research in areas spanning from quantum science to condensed matter physics and cosmology.

“You don’t have to be a geek like me to appreciate how important this work is,” he then told a packed audience of scientists, students, and community leaders in Perimeter’s atrium.

The Prime Minister was also welcomed by 200 teenagers attending the Institute’s annual Inspiring Future Women in Science conference, and via video greetings from cosmologist Stephen Hawking [he was Laflamme’s PhD supervisor], who is a Perimeter Distinguished Visiting Research Chair. The Prime Minister said he was “incredibly overwhelmed” by Hawking’s message.

“Canada is a wonderful, huge country, full of people with big hearts and forward-looking minds,” Hawking said in his message. “It’s an ideal place for an institute dedicated to the frontiers of physics. In supporting Perimeter, Canada sets an example for the world.”

The visit reiterated the Government of Canada’s pledge of $50 million over five years announced in last month’s [March 2016] budget [emphasis mine] to support Perimeter research, training, and outreach.

It was the Prime Minister’s second trip to the Region of Waterloo this year. In January [2016], he toured the region’s tech sector and universities, and praised the area’s innovation ecosystem.

This time, the focus was on the first link of the innovation chain: fundamental science that could unlock important discoveries, advance human understanding, and underpin the groundbreaking technologies of tomorrow.

As for the “quantum valley’ in Ontario, I think there might be some competition here in British Columbia with D-Wave Systems (first commercially available quantum computing, of a sort; my Dec. 16, 2015 post is the most recent one featuring the company) and the University of British Columbia’s Stewart Blusson Quantum Matter Institute.

Getting back to Trudeau, it’s exciting to have someone who seems so interested in at least some aspects of science that he can talk about it with a degree of understanding. I knew he had an interest in literature but there is also this (from his Wikipedia entry; Note: Links have been removed),

Trudeau has a bachelor of arts degree in literature from McGill University and a bachelor of education degree from the University of British Columbia…. After graduation, he stayed in Vancouver and he found substitute work at several local schools and permanent work as a French and math teacher at the private West Point Grey Academy … . From 2002 to 2004, he studied engineering at the École Polytechnique de Montréal, a part of the Université de Montréal.[67] He also started a master’s degree in environmental geography at McGill University, before suspending his program to seek public office.[68] [emphases mine]

Trudeau is not the only political leader to have a strong interest in science. In our neighbour to the south, there’s President Barack Obama who has done much to promote science since he was elected in 2008. David Bruggeman in an April 15, 2016  post (Obama hosts DNews segments for Science Channel week of April 11-15, 2016) and an April 17, 2016 post (Obama hosts White House Science Fair) describes two of Obama’s most recent efforts.

ETA April 19, 2016: I’ve found confirmation that this Q&A was somewhat staged as I hinted in the opening with “Prime Minister Justin Trudeau’s apparently extemporaneous response … .” Will Oremus’s April 19, 2016 article for Slate.com breaks the whole news cycle down and points out (Note: A link has been removed),

Over the weekend, even as latecomers continued to dine on the story’s rapidly decaying scraps, a somewhat different picture began to emerge. A Canadian blogger pointed out that Trudeau himself had suggested to reporters at the event that they lob him a question about quantum computing so that he could knock it out of the park with the newfound knowledge he had gleaned on his tour.

The Canadian blogger who tracked this down is J. J. McCullough (Jim McCullough) and you can read his Oct. 16, 2016 posting on the affair here. McCullough has a rather harsh view of the media response to Trudeau’s lecture. Oremus is a bit more measured,

… Monday brought the countertake parade—smaller and less pompous, if no less righteous—led by Gawker with the headline, “Justin Trudeau’s Quantum Computing Explanation Was Likely Staged for Publicity.”

But few of us in the media today are immune to the forces that incentivize timeliness and catchiness over subtlety, and even Gawker’s valuable corrective ended up meriting a corrective of its own. Author J.K. Trotter soon updated his post with comments from Trudeau’s press secretary, who maintained (rather convincingly, I think) that nothing in the episode was “staged”—at least, not in the sinister way that the word implies. Rather, Trudeau had joked that he was looking forward to someone asking him about quantum computing; a reporter at the press conference jokingly complied, without really expecting a response (he quickly moved on to his real question before Trudeau could answer); Trudeau responded anyway, because he really did want to show off his knowledge.

Trotter deserves credit, regardless, for following up and getting a fuller picture of what transpired. He did what those who initially jumped on the story did not, which was to contact the principals for context and comment.

But my point here is not to criticize any particular writer or publication. The too-tidy Trudeau narrative was not the deliberate work of any bad actor or fabricator. Rather, it was the inevitable product of today’s inexorable social-media machine, in which shareable content fuels the traffic-referral engines that pay online media’s bills.

I suggest reading both McCullough’s and Oremus’s posts in their entirety should you find debates about the role of media compelling.

Atoms can be in two places at once

A Jan. 20, 2015 news item on Nanowerk offers a brief history of quantum mechanics,

Can a penalty kick simultaneously score a goal and miss? For very small objects, at least, this is possible: according to the predictions of quantum mechanics, microscopic objects can take different paths at the same time. The world of macroscopic objects follows other rules: the football always moves in a definite direction. But is this always correct? Physicists of the University of Bonn have constructed an experiment designed to possibly falsify this thesis. Their first experiment shows that Caesium atoms can indeed take two paths at the same time.

Almost 100 years ago physicists Werner Heisenberg, Max Born und Erwin Schrödinger created a new field of physics: quantum mechanics. Objects of the quantum world – according to quantum theory – no longer move along a single well-defined path. Rather, they can simultaneously take different paths and end up at different places at once.

A Jan. 20, 2015 Universität Bonn (University of Bonn) press release, which originated the news item, describes both the experiment and the thought process which led to the experiment,

At the level of atoms, it looks as if objects indeed obey quantum mechanical laws. Over the years, many experiments have confirmed quantum mechanical predictions. In our macroscopic daily experience, however, we witness a football flying along exactly one path; it never strikes the goal and misses at the same time.

“There are two different interpretations,” says Dr. Andrea Alberti of the Institute of Applied Physics of the University of Bonn. “Quantum mechanics allows superposition states of large, macroscopic objects. But these states are very fragile, even following the football with our eyes is enough to destroy the superposition and makes it follow a definite trajectory.”

But it could also be that footballs obey completely different rules than those applying for single atoms. “Let us talk about the macro-realistic view of the world,” Alberti explains. “According to this interpretation, the ball always moves on a specific trajectory, independent of our observation, and in contrast to the atom.”

In collaboration with Dr. Clive Emary of the University of Hull in the U.K., the Bonn team has come up with an experimental scheme that may help to answer this question. “The challenge was to develop a measurement scheme of the atoms’ positions which allows one to falsify macro-realistic theories,” adds Alberti.

The physicists describe their research in the journal “Physical Review X:” With two optical tweezers they grabbed a single Caesium atom and pulled it in two opposing directions. In the macro-realist’s world the atom would then be at only one of the two final locations. Quantum-mechanically, the atom would instead occupy a superposition of the two positions.

“We have now used indirect measurements to determine the final position of the atom in the most gentle way possible,” says the PhD student Carsten Robens. Even such an indirect measurement (see figure) significantly modified the result of the experiments. This observation excludes – falsifies, as Karl Popper would say more precisely – the possibility that Caesium atoms follow a macro-realistic theory. Instead, the experimental findings of the Bonn team fit well with an interpretation based on superposition states that get destroyed when the indirect measurement occurs. All that we can do is to accept that the atom has indeed taken different paths at the same time.

“This is not yet a proof that quantum mechanics hold for large objects,” cautions Alberti. “The next step is to separate the Caesium atom’s two positions by several millimetres. Should we still find the superposition in our experiment, the macro-realistic theory would suffer another setback.”

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

Ideal negative measurements in quantum walks disprove theories based on classical trajectories by Carsten Robens, Wolfgang Alt, Dieter Meschede, Clive Emary, und Andrea Alberti. Physical Review X, 20.1.2015 (DOI: 10.1103/PhysRevX.5.011003)

This is an open access paper,

Seeing quantum entanglement and using quantum entanglement to build a wormhole

Kudos to the team from the Vienna Center for Quantum Science and Technology for the great musical accompaniment on their video showing quantum entanglement in real time,

A Dec. 4, 2013 news item on Nanowerk provides more details,

Einstein called quantum entanglement “spooky action at a distance”. Now, a team from the Vienna Center for Quantum Science and Technology has reported imaging of entanglement events where the influence of the measurement of one particle on its distant partner particle is directly visible (“Real-Time Imaging of Quantum Entanglement”).

The Dec. 4, 2013 Andor news release, which originated the news item, gives more details about the team’s work and about the Andor camera which enabled it,

The key to their success is the Andor iStar 334T Intensified CCD (ICCD) camera, which is capable of very fast (nanosecond) and precise (picosecond) optical gating speeds. Unlike the relatively long microsecond exposure times of CCD and EMCCD cameras which inhibits their usefulness in ultra-high-speed imaging, this supreme level of temporal resolution made it possible for the team to perform a real-time coincidence imaging of entanglement for the first time.

“The Andor iStar ICCD camera is fast enough, and sensitive enough, to image in real-time the effect of the measurement of one photon on its entangled partner,” says Robert Fickler of the Institute for Quantum Optics and Quantum Information. “Using ICCD cameras to evaluate the number of photons from a registered intensity within a given region opens up new experimental possibilities to determine more efficiently the structure and properties of spatial modes from only single intensity images. Our results suggest that triggered ICCD cameras will advance quantum optics and quantum information experiments where complex structures of single photons need to be investigated with high spatio-temporal resolution.”

According to Antoine Varagnat, Product Specialist at Andor, “The experiment produces pairs of photons which are entangled so as to have opposite polarisations. For instance, if one of a pair has horizontal polarisation, the other has vertical, and so on. The first photon is sent to polarising glass that transmits photons of one angle only, followed by a detector to register photons which make it through the glass. The other photon is delayed by a fibre, then its entangled property is coherently transferred from the polarisation to the spatial mode and afterwards brought to the high-speed, ultra-sensitive iStar camera.

“The use of the ICCD camera allowed the team to demonstrate the high flexibility of the setup in creating any desired spatial-mode entanglement. Their results suggest that visual imaging in quantum optics not only provides a better intuitive understanding of entanglement but will also improve applications of quantum science,” concludes Varagnat.

Research into quantum entanglement was instigated in 1935 by Albert Einstein, Boris Podolsky and Nathan Rosen, in a paper critiquing quantum mechanics. Erwin Schrödinger also wrote several papers shortly afterwards. Although these first studies focused on the counterintuitive properties of entanglement with the aim of criticising quantum mechanics, entanglement was eventually verified experimentally and recognised as a valid, fundamental feature of quantum mechanics. Nowadays, the focus of the research has changed to its utilization in communications and computation, and has been used to realise quantum teleportation experimentally.

The team’s work is chronicled in this study,

Real-Time Imaging of Quantum Entanglement by Robert Fickler, Mario Krenn, Radek Lapkiewicz, Sven Ramelow & Anton Zeilinger. Scientific Reports 3, Article number: 1914 doi:10.1038/srep01914 Published 29 May 2013

This is an open access paper.

Meanwhile, researchers at the University of Washington (Seattle, Washington state) explore the quantum entanglement phenomenon with an eye to wormholes (from the De.c 3, 2013 University of Washington news release [also on EurekAlter]),

Quantum entanglement, a perplexing phenomenon of quantum mechanics that Albert Einstein once referred to as “spooky action at a distance,” could be even spookier than Einstein perceived.

Physicists at the University of Washington and Stony Brook University in New York believe the phenomenon might be intrinsically linked with wormholes, hypothetical features of space-time that in popular science fiction can provide a much-faster-than-light shortcut from one part of the universe to another.

But here’s the catch: One couldn’t actually travel, or even communicate, through these wormholes, said Andreas Karch, a UW physics professor.

Quantum entanglement occurs when a pair or a group of particles interact in ways that dictate that each particle’s behavior is relative to the behavior of the others. In a pair of entangled particles, if one particle is observed to have a specific spin, for example, the other particle observed at the same time will have the opposite spin.

The “spooky” part is that, as research has confirmed, the relationship holds true no matter how far apart the particles are – across the room or across several galaxies. If the behavior of one particle changes, the behavior of both entangled particles changes simultaneously, no matter how far away they are.

Recent research indicated that the characteristics of a wormhole are the same as if two black holes were entangled, then pulled apart. Even if the black holes were on opposite sides of the universe, the wormhole would connect them.

Black holes, which can be as small as a single atom or many times larger than the sun, exist throughout the universe, but their gravitational pull is so strong that not even light can escape from them.

If two black holes were entangled, Karch said, a person outside the opening of one would not be able to see or communicate with someone just outside the opening of the other.

“The way you can communicate with each other is if you jump into your black hole, then the other person must jump into his black hole, and the interior world would be the same,” he said.

The work demonstrates an equivalence between quantum mechanics, which deals with physical phenomena at very tiny scales, and classical geometry – “two different mathematical machineries to go after the same physical process,” Karch said. The result is a tool scientists can use to develop broader understanding of entangled quantum systems.

“We’ve just followed well-established rules people have known for 15 years and asked ourselves, ‘What is the consequence of quantum entanglement?'”

The researchers have provided an illustration, which looks more like a ‘smiley face’ to me. Are wormholes smiley faces in space,

Alan Stonebraker/American Physical Society This illustration demonstrates a wormhole connecting two black holes.

Alan Stonebraker/American Physical Society
This illustration demonstrates a wormhole connecting two black holes.

Here’s a link to and a citation for the research paper on quantum entanglement and wormholes,

Holographic Dual of an Einstein-Podolsky-Rosen Pair has a Wormhole by Kristan Jensen and Andreas Karch. Phys. Rev. Lett. 111, 211602 (2013) [5 pages] Published 20 November 2013

This paper is behind a paywall.

ETA Dec. 11, 2013: There’s a news item today, Dec. 11, 2013, on Nanowerk which casts an interesting light on Andor,

Nanotechnology specialist Oxford Instruments is to take over Belfast-based scientific camera maker Andor in a £176million deal.
The Andor board last night agreed a 525p a share offer, giving a 31 per cent premium over the closing price before Oxford’s initial 500p a share pitch in November.

The two companies have been in talks since July [2013].

Shares in Andor rose 10p to 515p and Oxford Instruments gained 8p to 1566p.

It looks like their Dec. 4, 2013 news release was a leadup to this business news.

Quantum teleportation from a Japan-Germany collaboration

An Aug. 15, 2013 Johannes Gutenberg University Mainz press release (also on EurekAlert) has somewhat gobsmacked me with its talk of teleportation,

By means of the quantum-mechanical entanglement of spatially separated light fields, researchers in Tokyo and Mainz have managed to teleport photonic qubits with extreme reliability. This means that a decisive breakthrough has been achieved some 15 years after the first experiments in the field of optical teleportation. The success of the experiment conducted in Tokyo is attributable to the use of a hybrid technique in which two conceptually different and previously incompatible approaches were combined. “Discrete digital optical quantum information can now be transmitted continuously – at the touch of a button, if you will,” explained Professor Peter van Loock of Johannes Gutenberg University Mainz (JGU). As a theoretical physicist, van Loock advised the experimental physicists in the research team headed by Professor Akira Furusawa of the University of Tokyo on how they could most efficiently perform the teleportation experiment to ultimately verify the success of quantum teleportation.

The press release goes on to describe quantum teleportation,

Quantum teleportation involves the transfer of arbitrary quantum states from a sender, dubbed Alice, to a spatially distant receiver, named Bob. This requires that Alice and Bob initially share an entangled quantum state across the space in question, e.g., in the form of entangled photons. Quantum teleportation is of fundamental importance to the processing of quantum information (quantum computing) and quantum communication. Photons are especially valued as ideal information carriers for quantum communication since they can be used to transmit signals at the speed of light. A photon can represent a quantum bit or qubit analogous to a binary digit (bit) in standard classical information processing. Such photons are known as ‘flying quantum bits.

Before explaining the new technique, there’s an overview of previous efforts,

The first attempts to teleport single photons or light particles were made by the Austrian physicist Anton Zeilinger. Various other related experiments have been performed in the meantime. However, teleportation of photonic quantum bits using conventional methods proved to have its limitations because of experimental deficiencies and difficulties with fundamental principles.

What makes the experiment in Tokyo so different is the use of a hybrid technique. With its help, a completely deterministic and highly reliable quantum teleportation of photonic qubits has been achieved. The accuracy of the transfer was 79 to 82 percent for four different qubits. In addition, the qubits were teleported much more efficiently than in previous experiments, even at a low degree of entanglement.

The concept of entanglement was first formulated by Erwin Schrödinger and involves a situation in which two quantum systems, such as two light particles for example, are in a joint state, so that their behavior is mutually dependent to a greater extent than is normally (classically) possible. In the Tokyo experiment, continuous entanglement was achieved by means of entangling many photons with many other photons. This meant that the complete amplitudes and phases of two light fields were quantum correlated. Previous experiments only had a single photon entangled with another single photon – a less efficient solution. “The entanglement of photons functioned very well in the Tokyo experiment – practically at the press of a button, as soon as the laser was switched on,” said van Loock, Professor for Theory of Quantum Optics and Quantum Information at Mainz University. This continuous entanglement was accomplished with the aid of so-called ‘squeezed light’, which takes the form of an ellipse in the phase space of the light field. Once entanglement has been achieved, a third light field can be attached to the transmitter. From there, in principle, any state and any number of states can be transmitted to the receiver. “In our experiment, there were precisely four sufficiently representative test states that were transferred from Alice to Bob using entanglement. Thanks to continuous entanglement, it was possible to transmit the photonic qubits in a deterministic fashion to Bob, in other words, in each run,” added van Loock.

Earlier attempts to achieve optical teleportation were performed differently and, before now, the concepts used have proved to be incompatible. Although in theory it had already been assumed that the two different strategies, from the discrete and the continuous world, needed to be combined, it represents a technological breakthrough that this has actually now been experimentally demonstrated with the help of the hybrid technique. “The two separate worlds, the discrete and the continuous, are starting to converge,” concluded van Loock.

The researchers have provided an image illustrating quantum teleportation,

Deterministic quantum teleportation of a photonic quantum bit. Each qubit that flies from the left into the teleporter leaves the teleporter on the right with a loss of quality of only around 20 percent, a value not achievable without entanglement. Courtesy University of Tokyo

Deterministic quantum teleportation of a photonic quantum bit. Each qubit that flies from the left into the teleporter leaves the teleporter on the right with a loss of quality of only around 20 percent, a value not achievable without entanglement. Courtesy University of Tokyo

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

Deterministic quantum teleportation of photonic quantum bits by a hybrid technique by Shuntaro Takeda, Takahiro Mizuta, Maria Fuwa, Peter van Loock & Akira Furusawa. Nature 500, 315–318 (15 August 2013) doi:10.1038/nature12366 Published online 14 August 2013

This article  is behind a paywall although there is a preview capability (ReadCube Access) available.

Art of Science in Dublin

An Irish hit musical inspired by Schrödinger? As Dublin gears up to for its 2012 City of Science experience (mentioned in my April 29, 2011 posting), it seems that various organizations are hosting events in preparation. The Dublin Contemporary 2011 organization is hosting The Art of Science event on Oct. 20, 2011 at 7 pm. From the Art of Science webpage,

The Art of Science: How Nobel Prize winner Erwin Schrödinger’s time in Dublin influenced Rough Magic’s Musical “Improbable Frequency” and other probabilities

7PM
RSVP to dc2011events@gmail.com

Erwin Schrödinger came to Dublin in 1939 as first Professor of Theoretical Physics in the newly constituted Dublin Institute for Advanced Study. By this stage he had completed his primary work on quantum physics, including the eponymous Schrödinger Wave Equation and the “Schrödinger’s Cat” thought-experiment, an illustration of the paradox arising when quantum concepts meet human (or feline) reality. Probably (a risky choice of word here) the most significant contribution from his time in Dublin is the 3 lecture series “What is Life”? Professor of Physics at Trinity College Dublin, Iggy McGovern discusses the significant years that Schrödinger spent living in Dublin.

If the first half of the 20th century was the era of physics, then the second half would be the era of biology – thanks largely to Schrödinger’s book,  ‘What is Life?’ Mary Mulvihill takes a whirlwind look at some of the key developments in the world of science in the 20th century, and examines our changing public perceptions of science and technology.

How did Schrödinger end up being the inspiration for the hit Irish musical “ Improbable Frequency” ? Lynne Parker, Artistic Director of Rough Magic questions the great divide between Art & Science and Arthur Riordan expands on how the famous physicist came to appear in his musical “Improbable Frequency”.

You can read more about the speakers on the Art of Science page and here are a few snippets from the musical,