Tag Archives: quantum mechanics

The Meaning of Spacetime: Juan Maldacena public lecture webcast (Free tickets to attend in person at Perimeter Institute [Waterloo, Canada] available Monday, July 17 at 9 am ET)

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Thank you Perimeter Institute for Theoretical Physics (PI) for getting your notice to me so I have time to post it before tickets are made available. Not that I imagine a huge following in Waterloo (Canada) but it feels better to get the information out early.

The lecture is on July 27, 2023; the tickets are being given away on July 17, 2023.

Here’s more from a July 14, 2023 PI notice (received via email),

The Meaning of Spacetime: Black Holes, wormholes and quantum entanglement
THURSDAY, JULY 27 [2023] at 7:00 pm ET

Juan Maldacena, Institute for Advanced Study

What is spacetime, exactly? And how does it impact our understanding of important phenomena in our universe?

According to Einstein’s theory of gravity, spacetime is both curved and dynamical. The theory had two surprising predictions: black holes and the expansion of the universe. In both cases, there are regions of spacetime that are outside the reach of the classical theory, the so-called “singularities.” To address them, we need a quantum mechanical description of spacetime

Juan Maldacena studies black holes, string theory, and quantum field theory. In his July 27 [2023] Perimeter Public Lecture webcast, he will describe some ideas that arose from the study of quantum aspects of black holes. They involve an interesting connection between the basic description of quantum mechanics and the geometry of spacetime. He will also delve into how wormholes are related to quantum entanglement.

Don’t miss out! Free tickets to attend this event in person will become available on Monday, July 17 [2023] at 9 am ET [emphases mine]

Reserve Your Seat

If you didn’t get tickets for the lecture, not to worry – you can always catch the livestream on our website or watch it on YouTube after the fact

Watch Online

I found a bit more information about Maldacena on the event page,

Maldacena began his studies in his native Argentina, before completing a PhD at Princeton University in 1996. He has been a professor at the Institute for Advanced Study in Princeton since 2001. He is a member of the American Physical Society, the American Academy of Arts and Sciences, and The World Academy of Sciences, among many other honours. Maldacena was also one of the inaugural laureates of the prestigious Breakthrough Prize in Fundamental Physics in 2012.

The tickets go quickly. Not Beyoncé concert- or BTS concert-level quick but don’t dawdle.

The physics of the multiverse of madness

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The Dr. Strange movie (Dr. Strange in the Multiverse of Madness released May 6, 2022) has inspired an essay on physics. From a May 9, 2022 news item on phys.org

If you’re a fan of science fiction films, you’ll likely be familiar with the idea of alternate universes—hypothetical planes of existence with different versions of ourselves. As far from reality as it sounds, it is a question that scientists have contemplated. So just how well does the fiction stack up with the science?

The many-worlds interpretation is one idea in physics that supports the concept of multiple universes existing. It stems from the way we comprehend quantum mechanics, which defy the rules of our regular world. While it’s impossible to test and is considered an interpretation rather than a scientific theory, many physicists think it could be possible.

“When you look at the regular world, things are measurable and predictable—if you drop a ball off a roof, it will fall to the ground. But when you look on a very small scale in quantum mechanics, the rules stop applying. Instead of being predictable, it becomes about probabilities,” says Sarah Martell, Associate Professor at the School of Physics, UNSW Science.

…

A May 9, 2022 University of New South Wales (UNSW; Australia) press release originated the news item,

The fundamental quantum equation – called a wave function – shows a particle inhabiting many possible positions, with different probabilities assigned to each. If you were to attempt to observe the particle to determine its position – known in physics as ‘collapsing’ the wave function – you’ll find it in just one place. But the particle actually inhabits all the positions allowed by the wave function.

This interpretation of quantum mechanics is important, as it helps explain some of the quantum paradoxes that logic can’t answer, like why a particle can be in two places at once. While it might seem impossible to us, since we experience time and space as fixed, mathematically it adds up.

“When you make a measurement in quantum physics, you’re only measuring one of the possibilities. We can work with that mathematically, but it’s philosophically uncomfortable that the world stops being predictable,” A/Prof. Martell says.

“If you don’t get hung up on the philosophy, you simply move on with your physics. But what if the other possibility were true? That’s where this idea of the multiverse comes in.”

The quantum multiverse

Like it is depicted in many science fiction films, the many-worlds interpretation suggests our reality is just one of many. The universe supposedly splits or branches into other universes any time we take action – whether it’s a molecule moving, what you decide to eat or your choice of career. 

In physics, this is best explained through the thought experiment of Schrodinger’s cat. In the many-worlds interpretation, when the box is opened, the observer and the possibly alive cat split into an observer looking at a box with a deceased cat and one looking at a box with a live cat.

“A version of you measures one result, and a version of you measures the other result. That way, you don’t have to explain why a particular probability resulted. It’s just everything that could happen, does happen, somewhere,” A/Prof. Martell says.

“This is the logic often depicted in science fiction, like Spider-Man: Into the Spider-Verse, where five different Spider-Man exist in different universes based on the idea there was a different event that set up each one’s progress and timeline.”

This interpretation suggests that our decisions in this universe have implications for other versions of ourselves living in parallel worlds. But what about the possibility of interacting with these hypothetical alternate universes?

According to the many-worlds interpretation, humans wouldn’t be able to interact with parallel universes as they do in films – although science fiction has creative licence to do so.

“It’s a device used all the time in comic books, but it’s not something that physics would have anything to say about,” A/Prof. Martell says. “But I love science fiction for the creativity and the way that little science facts can become the motivation for a character or the essential crisis in a story with characters like Doctor Strange.”

“If for nothing else, science fiction can help make science more accessible, and the more we get people talking about science, the better,” A/Prof. Martell says.

“I think we do ourselves a lot of good by putting hooks out there that people can grab. So, if we can get people interested in science through popular culture, they’ll be more interested in the science we do.” 

The university also offers a course as this October 6, 2020 UNSW press release reveals,

From the morality plays in Star Trek, to the grim futures in Black Mirror, fiction can help explore our hopes – and fears – of the role science might play in our futures.

But sci-fi can be more than just a source of entertainment. When fiction gets the science right (or right enough), sci-fi can also be used to make science accessible to broader audiences. 

“Sci-fi can help relate science and technology to the lived human experience,” says Dr Maria Cunningham, a radio astronomer and senior lecturer in UNSW Science’s School of Physics. 

“Storytelling can make complex theories easier to visualise, understand and remember.”

Dr Cunningham – a sci-fi fan herself – convenes ‘Brave New World’: a course on science fact and fiction aimed at students from a non-scientific background. The course explores the relationship between literature, science, and society, using case studies like Futurama and MacGyver.

She says her own interest in sci-fi long predates her career in science.

“Fiction can help get people interested in science – sometimes without them even knowing it,” says Dr Cunningham.

“Sci-fi has the potential to increase the science literacy of the general population.”

Here, Dr Cunningham shares three tricky physics concepts best explained through science fiction (spoilers ahead).

…

Cunningham goes on to discuss the Universal Speed Limit, Time Dilation, and, yes, the Many Worlds Interpretation.

The course, “Brave New World: Science Fiction, Science Fact and the Future – GENS4015” is still offered but do check the link to make sure it takes you to the latest version (I found 2023). One more thing, it is offered wholly on the internet.

2022 Nobel Prize for Physics winners proved the existence of quantum entanglement

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In early October 2022, Alain Aspect, John Clauser and Anton Zeilinger were jointly awarded the 2022 Nobel Prize in Physics for work each scientist performed independently of the others.

Here’s more about the scientists and their works from an October 4, 2022 Nobel Prize press release,

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2022 to

Alain Aspect
Institut d’Optique Graduate School – Université Paris-
Saclay and École Polytechnique, Palaiseau, France

John F. Clauser
J.F. Clauser & Assoc., Walnut Creek, CA, USA

Anton Zeilinger
University of Vienna, Austria

“for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”

Entangled states – from theory to technology

Alain Aspect, John Clauser and Anton Zeilinger have each conducted groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated. Their results have cleared the way for new technology based upon quantum information.

The ineffable effects of quantum mechanics are starting to find applications. There is now a large field of research that includes quantum computers, quantum networks and secure quantum encrypted communication.

One key factor in this development is how quantum mechanics allows two or more particles to exist in what is called an entangled state. What happens to one of the particles in an entangled pair determines what happens to the other particle, even if they are far apart.

For a long time, the question was whether the correlation was because the particles in an entangled pair contained hidden variables, instructions that tell them which result they should give in an experiment. In the 1960s, John Stewart Bell developed the mathematical inequality that is named after him. This states that if there are hidden variables, the correlation between the results of a large number of measurements will never exceed a certain value. However, quantum mechanics predicts that a certain type of experiment will violate Bell’s inequality, thus resulting in a stronger correlation than would otherwise be possible.

John Clauser developed John Bell’s ideas, leading to a practical experiment. When he took the measurements, they supported quantum mechanics by clearly violating a Bell inequality. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables.

Some loopholes remained after John Clauser’s experiment. Alain Aspect developed the setup, using it in a way that closed an important loophole. He was able to switch the measurement settings after an entangled pair had left its source, so the setting that existed when they were emitted could not affect the result.

Using refined tools and long series of experiments, Anton Zeilinger started to use entangled quantum states. Among other things, his research group has demonstrated a phenomenon called quantum teleportation, which makes it possible to move a quantum state from one particle to one at a distance.

“It has become increasingly clear that a new kind of quantum technology is emerging. We can see that the laureates’ work with entangled states is of great importance, even beyond the fundamental questions about the interpretation of quantum mechanics,”says Anders Irbäck, Chair of the Nobel Committee for Physics.

There are some practical applications for their work on establishing quantum entanglement as Dr. Nicholas Peters, University of Tennessee and Oak Ridge National Laboratory (ORNL), explains in his October 7, 2022 essay for The Conversation,

Unhackable communications devices, high-precision GPS and high-resolution medical imaging all have something in common. These technologies—some under development and some already on the market all rely on the non-intuitive quantum phenomenon of entanglement.

Two quantum particles, like pairs of atoms or photons, can become entangled. That means a property of one particle is linked to a property of the other, and a change to one particle instantly affects the other particle, regardless of how far apart they are. This correlation is a key resource in quantum information technologies.

For the most part, quantum entanglement is still a subject of physics research, but it’s also a component of commercially available technologies, and it plays a starring role in the emerging quantum information processing industry.

…

Quantum entanglement is a critical element of quantum information processing, and photonic entanglement of the type pioneered by the Nobel laureates is crucial for transmitting quantum information. Quantum entanglement can be used to build large-scale quantum communications networks.

On a path toward long-distance quantum networks, Jian-Wei Pan, one of Zeilinger’s former students, and colleagues demonstrated entanglement distribution to two locations separated by 764 miles (1,203 km) on Earth via satellite transmission. However, direct transmission rates of quantum information are limited due to loss, meaning too many photons get absorbed by matter in transit so not enough reach the destination.

Entanglement is critical for solving this roadblock, through the nascent technology of quantum repeaters. An important milestone for early quantum repeaters, called entanglement swapping, was demonstrated by Zeilinger and colleagues in 1998. Entanglement swapping links one each of two pairs of entangled photons, thereby entangling the two initially independent photons, which can be far apart from each other.

…

Perhaps the most well known quantum communications application is Quantum Key Distribution (QKD), which allows someone to securely distribute encryption keys. If those keys are stored properly, they will be secure, even from future powerful, code-breaking quantum computers.

…

I don’t usually embed videos that are longer than 5 mins. but this one has a good explanation of cryptography (both classical and quantum),

The video host, Physics Girl (website), is also known as Dianna Cowern.

If you have the time, do read Peters’s October 7, 2022 essay, which can also be found as an October 10, 2022 news item on phys.org.

I wonder if there’s going to be a rush to fund and commercialize more quantum physics projects. There’s certainly an upsurge in activity locally and in Canada (I assume the same is true elsewhere) as my July 26, 2022 posting “Quantum Mechanics & Gravity conference (August 15 – 19, 2022) launches Vancouver (Canada)-based Quantum Gravity Institute and more” makes clear.

Quantum Mechanics & Gravity conference (August 15 – 19, 2022) launches Vancouver (Canada)-based Quantum Gravity Institute and more

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I received (via email) a July 21, 2022 news release about the launch of a quantum science initiative in Vancouver (BTW, I have more about the Canadian quantum scene later in this post),

World’s top physicists unite to tackle one of Science’s greatest
mysteries

Vancouver-based Quantum Gravity Society leads international quest to
discover Theory of Quantum Gravity

Vancouver, B.C. (July 21, 2022): More than two dozen of the world’s
top physicists, including three Nobel Prize winners, will gather in
Vancouver this August for a Quantum Gravity Conference that will host
the launch a Vancouver-based Quantum Gravity Institute (QGI) and a
new global research collaboration that could significantly advance our
understanding of physics and gravity and profoundly change the world as
we know it.

For roughly 100 years, the world’s understanding of physics has been
based on Albert Einstein’s General Theory of Relativity (GR), which
explored the theory of space, time and gravity, and quantum mechanics
(QM), which focuses on the behaviour of matter and light on the atomic
and subatomic scale. GR has given us a deep understanding of the cosmos,
leading to space travel and technology like atomic clocks, which govern
global GPS systems. QM is responsible for most of the equipment that
runs our world today, including the electronics, lasers, computers, cell
phones, plastics, and other technologies that support modern
transportation, communications, medicine, agriculture, energy systems
and more.

While each theory has led to countless scientific breakthroughs, in many
cases, they are incompatible and seemingly contradictory. Discovering a
unifying connection between these two fundamental theories, the elusive
Theory of Quantum Gravity, could provide the world with a deeper
understanding of time, gravity and matter and how to potentially control
them. It could also lead to new technologies that would affect most
aspects of daily life, including how we communicate, grow food, deliver
health care, transport people and goods, and produce energy.

“Discovering the Theory of Quantum Gravity could lead to the
possibility of time travel, new quantum devices, or even massive new
energy resources that produce clean energy and help us address climate
change,” said Philip Stamp, Professor, Department of Physics and
Astronomy, University of British Columbia, and Visiting Associate in
Theoretical Astrophysics at Caltech [California Institute of Technology]. “The potential long-term ramifications of this discovery are so incredible that life on earth 100
years from now could look as miraculous to us now as today’s
technology would have seemed to people living 100 years ago.”

The new Quantum Gravity Institute and the conference were founded by the
Quantum Gravity Society, which was created in 2022 by a group of
Canadian technology, business and community leaders, and leading
physicists. Among its goals are to advance the science of physics and
facilitate research on the Theory of Quantum Gravity through initiatives
such as the conference and assembling the world’s leading archive of
scientific papers and lectures associated with the attempts to reconcile
these two theories over the past century.

Attending the Quantum Gravity Conference in Vancouver (August 15-19 [2022])
will be two dozen of the world’s top physicists, including Nobel
Laureates Kip Thorne, Jim Peebles and Sir Roger Penrose, as well as
physicists Baron Martin Rees, Markus Aspelmeyer, Viatcheslav Mukhanov
and Paul Steinhardt. On Wednesday, August 17, the conference will be
open to the public, providing them with a once-in-a-lifetime opportunity
to attend keynote addresses from the world’s pre-eminent physicists.
… A noon-hour discussion on the importance of the
research will be delivered by Kip Thorne, the former Feynman Professor
of physics at Caltech. Thorne is well known for his popular books, and
for developing the original idea for the 2014 film “Interstellar.” He
was also crucial to the development of the book “Contact” by Carl Sagan,
which was also made into a motion picture.

“We look forward to welcoming many of the world’s brightest minds to
Vancouver for our first Quantum Gravity Conference,” said Frank
Giustra, CEO Fiore Group and Co-Founder, Quantum Gravity Society. “One
of the goals of our Society will be to establish Vancouver as a
supportive home base for research and facilitate the scientific
collaboration that will be required to unlock this mystery that has
eluded some of the world’s most brilliant physicists for so long.”

“The format is key,” explains Terry Hui, UC Berkley Physics alumnus
and Co-Founder, Quantum Gravity Society [and CEO of Concord Pacific].
“Like the Solvay Conference nearly 100 years ago, the Quantum Gravity
Conference will bring top scientists together in salon-style gatherings. The
relaxed evening format following the conference will reduce barriers and
allow these great minds to freely exchange ideas. I hope this will help accelerate
the solution of this hundred-year bottleneck between theories relatively
soon.”

“As amazing as our journey of scientific discovery has been over the
past century, we still have so much to learn about how the universe
works on a macro, atomic and subatomic level,” added Paul Lee,
Managing Partner, Vanedge Capital, and Co-Founder, Quantum Gravity
Society. “New experiments and observations capable of advancing work
on this scientific challenge are becoming increasingly possible in
today’s physics labs and using new astronomical tools. The Quantum
Gravity Society looks forward to leveraging that growing technical
capacity with joint theory and experimental work that harnesses the
collective expertise of the world’s great physicists.”

About Quantum Gravity Society

Quantum Gravity Society was founded in Vancouver, Canada in 2020 by a
group of Canadian business, technology and community leaders, and
leading international physicists. The Society’s founding members
include Frank Giustra (Fiore Group), Terry Hui (Concord Pacific), Paul
Lee and Moe Kermani (Vanedge Capital) and Markus Frind (Frind Estate
Winery), along with renowned physicists Abhay Ashtekar, Sir Roger
Penrose, Philip Stamp, Bill Unruh and Birgitta Whaley. For more
information, visit Quantum Gravity Society.

About the Quantum Gravity Conference (Vancouver 2022)

The inaugural Quantum Gravity Conference (August 15-19 [2022]) is presented by
Quantum Gravity Society, Fiore Group, Vanedge Capital, Concord Pacific,
The Westin Bayshore, Vancouver and Frind Estate Winery. For conference
information, visit conference.quantumgravityinstitute.ca. To
register to attend the conference, visit Eventbrite.com.

The front page on the Quantum Gravity Society website is identical to the front page for the Quantum Mechanics & Gravity: Marrying Theory & Experiment conference website. It’s probable that will change with time.

This seems to be an in-person event only.

The site for the conference is in an exceptionally pretty location in Coal Harbour and it’s close to Stanley Park (a major tourist attraction),

The Westin Bayshore, Vancouver
1601 Bayshore Drive
Vancouver, BC V6G 2V4
View map

Assuming that most of my readers will be interested in the ‘public’ day, here’s more from the Wednesday, August 17, 2022 registration page on Eventbrite,

Tickets:

  • Corporate Table of 8 all day access – includes VIP Luncheon: $1,100
  • Ticket per person all day access – includes VIP Luncheon: $129
  • Ticket per person all day access (no VIP luncheon): $59
  • Student / Academia Ticket – all day access (no VIP luncheon): $30

Date:

Wednesday, August 17, 2022 @ 9:00 a.m. – 5:15 p.m. (PT)

Schedule:

  • Registration Opens: 8:00 a.m.
  • Morning Program: 9:00 a.m. – 12:30 p.m.
  • VIP Lunch: 12:30 p.m. – 2:30 p.m.
  • Afternoon Program: 2:30 p.m. – 4:20 p.m.
  • Public Discussion / Debate: 4:20 p.m. – 5:15 p.m.

Program:

9:00 a.m. Session 1: Beginning of the Universe

  • Viatcheslav Mukhanov – Theoretical Physicist and Cosmologist, University of Munich
  • Paul Steinhardt – Theoretical Physicist, Princeton University

Session 2: History of the Universe

  • Jim Peebles, 2019 Nobel Laureate, Princeton University
  • Baron Martin Rees – Cosmologist and Astrophysicist, University of Cambridge
  • Sir Roger Penrose, 2020 Nobel Laureate, University of Oxford (via zoom)

12:30 p.m. VIP Lunch Session: Quantum Gravity — Why Should We Care?

  • Kip Thorne – 2017 Nobel Laureate, Executive Producer of blockbuster film “Interstellar”

2:30 p.m. Session 3: What do Experiments Say?

  • Markus Aspelmeyer – Experimental Physicist, Quantum Optics and Optomechanics Leader, University of Vienna
  • Sir Roger Penrose – 2020 Nobel Laureate (via zoom)

Session 4: Time Travel

  • Kip Thorne – 2017 Nobel Laureate, Executive Producer of blockbuster film “Interstellar”

Event Partners

  • Quantum Gravity Society
  • Westin Bayshore
  • Fiore Group
  • Concord Pacific
  • VanEdge Capital
  • Frind Estate Winery

Marketing Partners

  • BC Business Council
  • Greater Vancouver Board of Trade

Please note that Sir Roger Penrose will be present via Zoom but all the others will be there in the room with you.

Given that Kip Thorne won his 2017 Nobel Prize in Physics (with Rainer Weiss and Barry Barish) for work on gravitational waves, it’s surprising there’s no mention of this in the publicity for a conference on quantum gravity. Finding gravitational waves in 2016 was a very big deal (see Josh Fischman’s and Steve Mirsky’s February 11, 2016 interview with Kip Thorne for Scientific American).

Some thoughts on this conference and the Canadian quantum scene

This conference has a fascinating collection of players. Even I recognized some of the names, e.g., Penrose, Rees, Thorne.

The academics were to be expected and every presenter is an academic, often with their own Wikipedia page. Weirdly, there’s no one from the Perimeter Institute Institute for Theoretical Physics or TRIUMF (a national physics laboratory and centre for particle acceleration) or from anywhere else in Canada, which may be due to their academic specialty rather than an attempt to freeze out Canadian physicists. In any event, the conference academics are largely from the US (a lot of them from CalTech and Stanford) and from the UK.

The business people are a bit of a surprise. The BC Business Council and the Greater Vancouver Board of Trade? Frank Giustra who first made his money with gold mines, then with Lionsgate Entertainment, and who continues to make a great deal of money with his equity investment company, Fiore Group? Terry Hui, Chief Executive Office of Concord Pacific, a real estate development company? VanEdge Capital, an early stage venture capital fund? A winery? Missing from this list is D-Wave Systems, Canada’s quantum calling card and local company. While their area of expertise is quantum computing, I’d still expect to see them present as sponsors. *ETA December 6, 2022: I just looked at the conference page again and D-Wave is now listed as a sponsor.*

The academics? These people are not cheap dates (flights, speaker’s fees, a room at the Bayshore, meals). This is a very expensive conference and $129 for lunch and a daypass is likely a heavily subsidized ticket.

Another surprise? No government money/sponsorship. I don’t recall seeing another academic conference held in Canada without any government participation.

Canadian quantum scene

A National Quantum Strategy was first announced in the 2021 Canadian federal budget and reannounced in the 2022 federal budget (see my April 19, 2022 posting for a few more budget details).. Or, you may find this National Quantum Strategy Consultations: What We Heard Report more informative. There’s also a webpage for general information about the National Quantum Strategy.

As evidence of action, the Natural Science and Engineering Research Council of Canada (NSERC) announced new grant programmes made possible by the National Quantum Strategy in a March 15, 2022 news release,

Quantum science and innovation are giving rise to promising advances in communications, computing, materials, sensing, health care, navigation and other key areas. The Government of Canada is committed to helping shape the future of quantum technology by supporting Canada’s quantum sector and establishing leadership in this emerging and transformative domain.

Today [March 15, 2022], the Honourable François-Philippe Champagne, Minister of Innovation, Science and Industry, is announcing an investment of $137.9 million through the Natural Sciences and Engineering Research Council of Canada’s (NSERC) Collaborative Research and Training Experience (CREATE) grants and Alliance grants. These grants are an important next step in advancing the National Quantum Strategy and will reinforce Canada’s research strengths in quantum science while also helping to develop a talent pipeline to support the growth of a strong quantum community.

…

Quick facts

Budget 2021 committed $360 million to build the foundation for a National Quantum Strategy, enabling the Government of Canada to build on previous investments in the sector to advance the emerging field of quantum technologies. The quantum sector is key to fuelling Canada’s economy, long-term resilience and growth, especially as technologies mature and more sectors harness quantum capabilities.

Development of quantum technologies offers job opportunities in research and science, software and hardware engineering and development, manufacturing, technical support, sales and marketing, business operations and other fields.

The Government of Canada also invested more than $1 billion in quantum research and science from 2009 to 2020—mainly through competitive granting agency programs, including Natural Sciences and Engineering Research Council of Canada programs and the Canada First Research Excellence Fund—to help establish Canada as a global leader in quantum science.

In addition, the government has invested in bringing new quantum technologies to market, including investments through Canada’s regional development agencies, the Strategic Innovation Fund and the National Research Council of Canada’s Industrial Research Assistance Program.

Bank of Canada, cryptocurrency, and quantum computing

My July 25, 2022 posting features a special project, Note: All emphases are mine,

… (from an April 14, 2022 HKA Marketing Communications news release on EurekAlert),

Multiverse Computing, a global leader in quantum computing solutions for the financial industry and beyond with offices in Toronto and Spain, today announced it has completed a proof-of-concept project with the Bank of Canada through which the parties used quantum computing to simulate the adoption of cryptocurrency as a method of payment by non-financial firms.

“We are proud to be a trusted partner of the first G7 central bank to explore modelling of complex networks and cryptocurrencies through the use of quantum computing,” said Sam Mugel, CTO [Chief Technical Officer] at Multiverse Computing. “The results of the simulation are very intriguing and insightful as stakeholders consider further research in the domain. Thanks to the algorithm we developed together with our partners at the Bank of Canada, we have been able to model a complex system reliably and accurately given the current state of quantum computing capabilities.”

…

Multiverse Computing conducted its innovative work related to applying quantum computing for modelling complex economic interactions in a research project with the Bank of Canada. The project explored quantum computing technology as a way to simulate complex economic behaviour that is otherwise very difficult to simulate using traditional computational techniques.

By implementing this solution using D-Wave’s annealing quantum computer, the simulation was able to tackle financial networks as large as 8-10 players, with up to 2^90 possible network configurations. Note that classical computing approaches cannot solve large networks of practical relevance as a 15-player network requires as many resources as there are atoms in the universe.

…

Quantum Technologies and the Council of Canadian Academies (CCA)

In a May 26, 2022 blog posting the CCA announced its Expert Panel on Quantum Technologies (they will be issuing a Quantum Technologies report),

The emergence of quantum technologies will impact all sectors of the Canadian economy, presenting significant opportunities but also risks. At the request of the National Research Council of Canada (NRC) and Innovation, Science and Economic Development Canada (ISED), the Council of Canadian Academies (CCA) has formed an Expert Panel to examine the impacts, opportunities, and challenges quantum technologies present for Canadian industry, governments, and Canadians. Raymond Laflamme, O.C., FRSC, Canada Research Chair in Quantum Information and Professor in the Department of Physics and Astronomy at the University of Waterloo, will serve as Chair of the Expert Panel.

“Quantum technologies have the potential to transform computing, sensing, communications, healthcare, navigation and many other areas,” said Dr. Laflamme. “But a close examination of the risks and vulnerabilities of these technologies is critical, and I look forward to undertaking this crucial work with the panel.”

As Chair, Dr. Laflamme will lead a multidisciplinary group with expertise in quantum technologies, economics, innovation, ethics, and legal and regulatory frameworks. The Panel will answer the following question:

In light of current trends affecting the evolution of quantum technologies, what impacts, opportunities and challenges do these present for Canadian industry, governments and Canadians more broadly?

…

The Expert Panel on Quantum Technologies:

Raymond Laflamme, O.C., FRSC (Chair), Canada Research Chair in Quantum Information; the Mike and Ophelia Lazaridis John von Neumann Chair in Quantum Information; Professor, Department of Physics and Astronomy, University of Waterloo

Sally Daub, Founder and Managing Partner, Pool Global Partners

Shohini Ghose, Professor, Physics and Computer Science, Wilfrid Laurier University; NSERC Chair for Women in Science and Engineering

Paul Gulyas, Senior Innovation Executive, IBM Canada

Mark W. Johnson, Senior Vice-President, Quantum Technologies and Systems Products, D-Wave Systems

Elham Kashefi, Professor of Quantum Computing, School of Informatics, University of Edinburgh; Directeur de recherche au CNRS, LIP6 Sorbonne Université

Mauritz Kop, Fellow and Visiting Scholar, Stanford Law School, Stanford University

Dominic Martin, Professor, Département d’organisation et de ressources humaines, École des sciences de la gestion, Université du Québec à Montréal

Darius Ornston, Associate Professor, Munk School of Global Affairs and Public Policy, University of Toronto

Barry Sanders, FRSC, Director, Institute for Quantum Science and Technology, University of Calgary

Eric Santor, Advisor to the Governor, Bank of Canada

Christian Sarra-Bournet, Quantum Strategy Director and Executive Director, Institut quantique, Université de Sherbrooke

Stephanie Simmons, Associate Professor, Canada Research Chair in Quantum Nanoelectronics, and CIFAR Quantum Information Science Fellow, Department of Physics, Simon Fraser University

Jacqueline Walsh, Instructor; Director, initio Technology & Innovation Law Clinic, Dalhousie University

You’ll note that both the Bank of Canada and D-Wave Systems are represented on this expert panel.

The CCA Quantum Technologies report (in progress) page can be found here.

Does it mean anything?

Since I only skim the top layer of information (disparagingly described as ‘high level’ by the technology types I used to work with), all I can say is there’s a remarkable level of interest from various groups who are self-organizing. (The interest is international as well. I found the International Society for Quantum Gravity [ISQG], which had its first meeting in 2021.)

I don’t know what the purpose is other than it seems the Canadian focus seems to be on money. The board of trade and business council have no interest in primary research and the federal government’s national quantum strategy is part of Innovation, Science and Economic Development (ISED) Canada’s mandate. You’ll notice ‘science’ is sandwiched between ‘innovation’, which is often code for business, and economic development.

The Bank of Canada’s monetary interests are quite obvious.

The Perimeter Institute mentioned earlier was founded by Mike Lazaridis (from his Wikipedia entry) Note: Links have been removed,

… a Canadian businessman [emphasis mine], investor in quantum computing technologies, and founder of BlackBerry, which created and manufactured the BlackBerry wireless handheld device. With an estimated net worth of US$800 million (as of June 2011), Lazaridis was ranked by Forbes as the 17th wealthiest Canadian and 651st in the world.[4]

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In 2000, Lazaridis founded and donated more than $170 million to the Perimeter Institute for Theoretical Physics.[11][12] He and his wife Ophelia founded and donated more than $100 million to the Institute for Quantum Computing at the University of Waterloo in 2002.[8]

That Institute for Quantum Computing? There’s an interesting connection. Raymond Laflamme, the chair for the CCA expert panel, was its director for a number of years and he’s closely affiliated with the Perimeter Institute. (I’m not suggesting anything nefarious or dodgy. It’s a small community in Canada and relationships tend to be tightly interlaced.) I’m surprised he’s not part of the quantum mechanics and gravity conference but that could have something to do with scheduling.

One last interesting bit about Laflamme, from his Wikipedia entry, Note: Links have been removed)

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As Stephen Hawking’s PhD student, he first became famous for convincing Hawking that time does not reverse in a contracting universe, along with Don Page. Hawking told the story of how this happened in his famous book A Brief History of Time in the chapter The Arrow of Time.[3] Later on Laflamme made a name for himself in quantum computing and quantum information theory, which is what he is famous for today.

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Getting back to the Quantum Mechanics & Gravity: Marrying Theory & Experiment, the public day looks pretty interesting and when is the next time you’ll have a chance to hobnob with all those Nobel Laureates?

Loop quantum cosmology connects the tiniest with the biggest in a cosmic tango

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Caption: Tiny quantum fluctuations in the early universe explain two major mysteries about the large-scale structure of the universe, in a cosmic tango of the very small and the very large. A new study by researchers at Penn State used the theory of quantum loop gravity to account for these mysteries, which Einstein’s theory of general relativity considers anomalous.. Credit: Dani Zemba, Penn State

A July 29, 2020 news item on ScienceDaily announces a study showing that quantum loop cosmology can account for some large-scale mysteries,

While [1] Einstein’s theory of general relativity can explain a large array of fascinating astrophysical and cosmological phenomena, some aspects of the properties of the universe at the largest-scales remain a mystery. A new study using loop quantum cosmology — a theory that uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity — accounts for two major mysteries. While the differences in the theories occur at the tiniest of scales — much smaller than even a proton — they have consequences at the largest of accessible scales in the universe. The study, which appears online July 29 [2020] in the journal Physical Review Letters, also provides new predictions about the universe that future satellite missions could test.

A July 29, 2020 Pennsylvania State University (Penn State) news release (also on EurekAlert) by Gail McCormick, which originated the news item, describes how this work helped us avoid a crisis in cosmology,

While [2] a zoomed-out picture of the universe looks fairly uniform, it does have a large-scale structure, for example because galaxies and dark matter are not uniformly distributed throughout the universe. The origin of this structure has been traced back to the tiny inhomogeneities observed in the Cosmic Microwave Background (CMB)–radiation that was emitted when the universe was 380 thousand years young that we can still see today. But the CMB itself has three puzzling features that are considered anomalies because they are difficult to explain using known physics.

“While [3] seeing one of these anomalies may not be that statistically remarkable, seeing two or more together suggests we live in an exceptional universe,” said Donghui Jeong, associate professor of astronomy and astrophysics at Penn State and an author of the paper. “A recent study in the journal Nature Astronomy proposed an explanation for one of these anomalies that raised so many additional concerns, they flagged a ‘possible crisis in cosmology‘ [emphasis mine].’ Using quantum loop cosmology, however, we have resolved two of these anomalies naturally, avoiding that potential crisis.”

Research over the last three decades has greatly improved our understanding of the early universe, including how the inhomogeneities in the CMB were produced in the first place. These inhomogeneities are a result of inevitable quantum fluctuations in the early universe. During a highly accelerated phase of expansion at very early times–known as inflation–these primordial, miniscule fluctuations were stretched under gravity’s influence and seeded the observed inhomogeneities in the CMB.

“To understand how primordial seeds arose, we need a closer look at the early universe, where Einstein’s theory of general relativity breaks down,” said Abhay Ashtekar, Evan Pugh Professor of Physics, holder of the Eberly Family Chair in Physics, and director of the Penn State Institute for Gravitation and the Cosmos. “The standard inflationary paradigm based on general relativity treats space time as a smooth continuum. Consider a shirt that appears like a two-dimensional surface, but on closer inspection you can see that it is woven by densely packed one-dimensional threads. In this way, the fabric of space time is really woven by quantum threads. In accounting for these threads, loop quantum cosmology allows us to go beyond the continuum described by general relativity where Einstein’s physics breaks down–for example beyond the Big Bang.”

The researchers’ previous investigation into the early universe replaced the idea of a Big Bang singularity, where the universe emerged from nothing, with the Big Bounce, where the current expanding universe emerged from a super-compressed mass that was created when the universe contracted in its preceding phase. They found that all of the large-scale structures of the universe accounted for by general relativity are equally explained by inflation after this Big Bounce using equations of loop quantum cosmology.

In the new study, the researchers determined that inflation under loop quantum cosmology also resolves two of the major anomalies that appear under general relativity.

“The primordial fluctuations we are talking about occur at the incredibly small Planck scale,” said Brajesh Gupt, a postdoctoral researcher at Penn State at the time of the research and currently at the Texas Advanced Computing Center of the University of Texas at Austin. “A Planck length is about 20 orders of magnitude smaller than the radius of a proton. But corrections to inflation at this unimaginably small scale simultaneously explain two of the anomalies at the largest scales in the universe, in a cosmic tango of the very small and the very large.”

The researchers also produced new predictions about a fundamental cosmological parameter and primordial gravitational waves that could be tested during future satellite missions, including LiteBird and Cosmic Origins Explorer, which will continue improve our understanding of the early universe.

That’s a lot of ‘while’. I’ve done this sort of thing, too, and whenever I come across it later; it’s painful.

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

Alleviating the Tension in the Cosmic Microwave Background Using Planck-Scale Physics by Abhay Ashtekar, Brajesh Gupt, Donghui Jeong, and V. Sreenath. Phys. Rev. Lett. 125, 051302 DOI: https://doi.org/10.1103/PhysRevLett.125.051302 Published 29 July 2020 © 2020 American Physical Society

This paper is behind a paywall.

You need a quantum mechanic for an atom-sized machine

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This news comes from the National University of Singapore’s Centre for Quantum Technologies according to a May 4, 2020 news item on Nanowerk (Note: A link has been removed),

Here’s a new chapter in the story of the miniaturisation of machines: researchers in a laboratory in Singapore have shown that a single atom can function as either an engine or a fridge. Such a device could be engineered into future computers and fuel cells to control energy flows.

“Think about how your computer or laptop has a lot of things inside it that heat up. Today you cool that with a fan that blows air. In nanomachines or quantum computers, small devices that do cooling could be something useful,” says Dario Poletti from the Singapore University of Technology and Design (SUTD).

This work gives new insight into the mechanics of such devices. The work is a collaboration involving researchers at the Centre for Quantum Technologies (CQT) and Department of Physics at the National University of Singapore (NUS), SUTD and at the University of Augsburg in Germany. The results were published in the peer-reviewed journal npj Quantum Information (“Single-atom energy-conversion device with a quantum load”).

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The researchers have included an exceptionally pretty illustration with the press release,

Caption: Experiments with a single-atom device help researchers understand what quantum effects come into play when machinery shrinks to the atomic scale. Credit: Aki Honda / Centre for Quantum Technologies, National University of Singapore

A May 4, 2020 National University of Singapore press release (also on EurekAlert), which originated the news item, delves further into the work,

Engines and refrigerators are both machines described by thermodynamics, a branch of science that tells us how energy moves within a system and how we can extract useful work. A classical engine turns energy into useful work. A refrigerator does work to transfer heat, reducing the local temperature. They are, in some sense, opposites.

People have made small heat engines before using a single atom, a single molecule and defects in diamond. A key difference about this device is that it shows quantumness in its action. “We want to understand how we can build thermodynamic devices with just a few atoms. The physics is not well understood so our work is important to know what is possible,” says Manas Mukherjee, a Principal Investigator at CQT, NUS, who led the experimental work.

The researchers studied the thermodynamics of a single barium atom. They devised a scheme in which lasers move one of the atom’s electrons between two energy levels as part of a cycle, causing some energy to be pushed into the atom’s vibrations. Like a car engine consumes petrol to both move pistons and charge up its battery, the atom uses energy from lasers as fuel to increase its vibrating motion. The atom’s vibrations act like a battery, storing energy that can be extracted later. Rearrange the cycle and the atom acts like a fridge, removing energy from the vibrations.

In either mode of operation, quantum effects show up in correlations between the atom’s electronic states and vibrations. “At this scale, the energy transfer between the engine and the load is a bit fuzzy. It is no longer possible to simply do work on the load, you are bound to transfer some heat,” says Poletti. He worked out the theory with collaborators Jiangbin Gong at NUS Physics and Peter Hänggi in Augsburg. The fuzziness makes the process less efficient, but the experimentalists could still make it work.

Mukherjee and colleagues Noah Van Horne, Dahyun Yum and Tarun Dutta used a barium atom from which an electron (a negative charge) is removed. This makes the atom positively charged, so it can be more easily held still inside a metal chamber by electrical fields. All other air is removed from around it. The atom is then zapped with lasers to move it through a four-stage cycle.

The researchers measured the atom’s vibration after applying 2 to 15 cycles. They repeated a given number of cycles up to 150 times, measuring on average how much vibrational energy was present at the end. They could see the vibrational energy increasing when the atom was zapped with an engine cycle, and decreasing when the zaps followed the fridge cycle.

Understanding the atom-sized machine involved both complicated calculations and observations. The team needed to track two thermodynamic quantities known as ergotropy, which is the energy that can be converted to useful work, and entropy, which is related to disorder in the system. Both ergotropy and entropy increase as the atom-machine runs. There’s still a simple way of looking at it, says first author and PhD student Van Horne, “Loosely speaking, we’ve designed a little machine that creates entropy as it is filled up with free energy, much like kids when they are given too much sugar.”

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

Single-atom energy-conversion device with a quantum load by Noah Van Horne, Dahyun Yum, Tarun Dutta, Peter Hänggi, Jiangbin Gong, Dario Poletti & Manas Mukherjee. npj Quantum Information volume 6, Article number: 37 (2020) Published: 01 May 2020

This paper is open access.

A mathematical sculptor, a live webcast (May 6, 2020) with theoretical cosmologist and author Katie Mack, & uniting quantum theory with Einstein’s Theory of General Relativity in a drawing

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I’ve bookended information about the talk with physicist Katie Mack at Canada’s Perimeter Institute on May 6, 2020 with two items on visual art and mathematics and the sciences.

Mathematical sculpting

Robert Fathauer’s Three-Fold Hyperbolic Form exhibits negative curvature, a concept in geometry and topology that describes a surface curving in two directions at every point. Hemp crochet by Marla Peterson. Image courtesy of Robert Fathauer. [downloaded from https://www.pnas.org/content/114/26/6643.full]

You’ll find this image and a few more in a fascinating 2017 paper (see link and citation below) about mathematical sculpture,

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Ferguson [Helaman Ferguson], who holds a doctorate in mathematics, never chose between art and science: now nearly 77 years old, he’s a mathematical sculptor. Working in stone and bronze, Ferguson creates sculptures, often placed on college campuses, that turn deep mathematical ideas into solid objects that anyone—seasoned professors, curious children, wayward mathophobes—can experience for themselves.

Mathematics has an intrinsic aesthetic—proofs are often described as “beautiful” or “elegant”—that can be difficult for mathematicians to communicate to outsiders, says Ferguson. “It isn’t something you can tell somebody about on the street,” he says. “But if I hand them a sculpture, they’re immediately relating to it.” Sculpture, he says, can tell a story about math in an accessible language.

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

Science and Culture: Armed with a knack for patterns and symmetry, mathematical sculptors create compelling forms by Stephen Ornes. PNAS [Proceedings of the National Academy of Sciences] June 27, 2017 114 (26) 6643-6645; https://doi.org/10.1073/pnas.1706987114

This paper appears to be open access.

Live webcast: theoretical cosmologist & science communicator Katie Mack

The live webcast will take place at 4 pm PT (1600 hours) on Wednesday, May 6, 2020. Here’s more about Katie Mack and the webcast from the event webpage (click through to the event page to get to the webcast) on the Perimeter Institute of Theoretical Physics (PI) website,

In a special live webcast on May 6 [2020] at 7 pm ET [4 pm PT], theoretical cosmologist and science communicator Katie Mack — known to her many Twitter followers as @astrokatie — will answer questions about her favourite subject: the end of the universe.

Mack, who holds a Simons Emmy Noether Visiting Fellowship at Perimeter, will give viewers a sneak peek at her upcoming book, The End of Everything (Astrophysically Speaking). She will then participate in a live “ask me anything” session, answering questions submitted via social media using the hashtag #piLIVE.

Mack is an Assistant Professor at North Carolina State University whose research investigates dark matter, vacuum decay, and the epoch of reionization. Mack is a popular science communicator on social media, and has contributed to Scientific American, Slate, Sky & Telescope, Time, and Cosmos.

PI is located in Waterloo, Ontario, Canada.

Uniting quantum theory with Einstein’s Theory of General Relativity with a drawing about light

The article by Stephon Alexander was originally published March 16, 2017 for Nautilus. My excerpts are from a getpocket.com selection,

LIGHT IN THE GARDEN: This drawing by the Oakes brothers, Irwin Gardens at the Getty in Winter, inspired the author to think anew about quantum mechanics and general relativity. The meticulous drawing, done on curved paper, allows viewers to reflect on the act of perception. Credit: Ryan and Trevor Oakes [downloaded from http://nautil.us/issue/46/balance/what-this-drawing-taught-me-about-four_dimensional-spacetime]

My aim as a theoretical physicist is to unite quantum theory with Einstein’s Theory of General Relativity. While there are a few proposals for this unification, such as string theory and loop quantum gravity, many roadblocks to a complete unification remain.

Einstein’s theory tells us the gravitational force is a direct manifestation of space and time bending. The sun bends the fabric of space, much like a sleeping person bends a mattress. Planetary orbits, including Earth’s, are motion along the contours of the bent space created by the sun. This theory provides some critical insights into the nature of light.

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… one summer, I had the most unexpected breakthrough. Beth Jacobs, a member of the New York Academy of Sciences’ Board of Governors, invited me and some friends to her New York City apartment to meet the Oakes twins, artists who have gained attention in recent years for their drawings as well as the innovative technique and inventions they deploy to create them. An Oakes work, Irwin Gardens at the Getty in Winter (2011), an intricate drawing of the famous gardens designed by Robert Irwin at The Getty Museum in Los Angeles, was displayed on the balcony of Jacobs’ apartment overlooking Central Park, with the backdrop of the New York City skyline lit with a warm orange sky moments before sunset.

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As I gazed at the drawing, I could feel the artists challenging me to reconsider the nature of light. I began to realize I should consider not only the physics of light, but also how light information is perceived by observers, when theorizing and conceiving new principles to unify quantum mechanics and general relativity. …

Ryan and Trevor Oakes, 35, have been exploring the impact and intersection of visual perception and the physics of light since they were kids. After attending The Cooper Union for the Advancement of Science and Art in New York City, and years of experimentation and inventing new techniques, the twins exploited the notion that light information is better described when originating from a spherical surface.

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Fascinating stuff. BTW, you can find the original article here on Nautilus.

Quantum supremacy

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This supremacy, refers to an engineering milestone and a October 23, 2019 news item on ScienceDaily announces the milestone has been reached,

Researchers in UC [University of California] Santa Barbara/Google scientist John Martinis’ group have made good on their claim to quantum supremacy. Using 53 entangled quantum bits (“qubits”), their Sycamore computer has taken on — and solved — a problem considered intractable for classical computers.

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An October 23, 2019 UC Santa Barbara news release (also on EurekAlert) by Sonia Fernandez, which originated the news item, delves further into the work,

“A computation that would take 10,000 years on a classical supercomputer took 200 seconds on our quantum computer,” said Brooks Foxen, a graduate student researcher in the Martinis Group. “It is likely that the classical simulation time, currently estimated at 10,000 years, will be reduced by improved classical hardware and algorithms, but, since we are currently 1.5 trillion times faster, we feel comfortable laying claim to this achievement.”

The feat is outlined in a paper in the journal Nature.

The milestone comes after roughly two decades of quantum computing research conducted by Martinis and his group, from the development of a single superconducting qubit to systems including architectures of 72 and, with Sycamore, 54 qubits (one didn’t perform) that take advantage of the both awe-inspiring and bizarre properties of quantum mechanics.

“The algorithm was chosen to emphasize the strengths of the quantum computer by leveraging the natural dynamics of the device,” said Ben Chiaro, another graduate student researcher in the Martinis Group. That is, the researchers wanted to test the computer’s ability to hold and rapidly manipulate a vast amount of complex, unstructured data.

“We basically wanted to produce an entangled state involving all of our qubits as quickly as we can,” Foxen said, “and so we settled on a sequence of operations that produced a complicated superposition state that, when measured, returns bitstring with a probability determined by the specific sequence of operations used to prepare that particular superposition. The exercise, which was to verify that the circuit’s output correspond to the equence used to prepare the state, sampled the quantum circuit a million times in just a few minutes, exploring all possibilities — before the system could lose its quantum coherence.

‘A complex superposition state’

“We performed a fixed set of operations that entangles 53 qubits into a complex superposition state,” Chiaro explained. “This superposition state encodes the probability distribution. For the quantum computer, preparing this superposition state is accomplished by applying a sequence of tens of control pulses to each qubit in a matter of microseconds. We can prepare and then sample from this distribution by measuring the qubits a million times in 200 seconds.”

“For classical computers, it is much more difficult to compute the outcome of these operations because it requires computing the probability of being in any one of the 2^53 possible states, where the 53 comes from the number of qubits — the exponential scaling is why people are interested in quantum computing to begin with,” Foxen said. “This is done by matrix multiplication, which is expensive for classical computers as the matrices become large.”

According to the new paper, the researchers used a method called cross-entropy benchmarking to compare the quantum circuit’s output (a “bitstring”) to its “corresponding ideal probability computed via simulation on a classical computer” to ascertain that the quantum computer was working correctly.

“We made a lot of design choices in the development of our processor that are really advantageous,” said Chiaro. Among these advantages, he said, are the ability to experimentally tune the parameters of the individual qubits as well as their interactions.

While the experiment was chosen as a proof-of-concept for the computer, the research has resulted in a very real and valuable tool: a certified random number generator. Useful in a variety of fields, random numbers can ensure that encrypted keys can’t be guessed, or that a sample from a larger population is truly representative, leading to optimal solutions for complex problems and more robust machine learning applications. The speed with which the quantum circuit can produce its randomized bit string is so great that there is no time to analyze and “cheat” the system.

“Quantum mechanical states do things that go beyond our day-to-day experience and so have the potential to provide capabilities and application that would otherwise be unattainable,” commented Joe Incandela, UC Santa Barbara’s vice chancellor for research. “The team has demonstrated the ability to reliably create and repeatedly sample complicated quantum states involving 53 entangled elements to carry out an exercise that would take millennia to do with a classical supercomputer. This is a major accomplishment. We are at the threshold of a new era of knowledge acquisition.”

Looking ahead

With an achievement like “quantum supremacy,” it’s tempting to think that the UC Santa Barbara/Google researchers will plant their flag and rest easy. But for Foxen, Chiaro, Martinis and the rest of the UCSB/Google AI Quantum group, this is just the beginning.

“It’s kind of a continuous improvement mindset,” Foxen said. “There are always projects in the works.” In the near term, further improvements to these “noisy” qubits may enable the simulation of interesting phenomena in quantum mechanics, such as thermalization, or the vast amount of possibility in the realms of materials and chemistry.

In the long term, however, the scientists are always looking to improve coherence times, or, at the other end, to detect and fix errors, which would take many additional qubits per qubit being checked. These efforts have been running parallel to the design and build of the quantum computer itself, and ensure the researchers have a lot of work before hitting their next milestone.

“It’s been an honor and a pleasure to be associated with this team,” Chiaro said. “It’s a great collection of strong technical contributors with great leadership and the whole team really synergizes well.”

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

Quantum supremacy using a programmable superconducting processor by Frank Arute, Kunal Arya, Ryan Babbush, Dave Bacon, Joseph C. Bardin, Rami Barends, Rupak Biswas, Sergio Boixo, Fernando G. S. L. Brandao, David A. Buell, Brian Burkett, Yu Chen, Zijun Chen, Ben Chiaro, Roberto Collins, William Courtney, Andrew Dunsworth, Edward Farhi, Brooks Foxen, Austin Fowler, Craig Gidney, Marissa Giustina, Rob Graff, Keith Guerin, Steve Habegger, Matthew P. Harrigan, Michael J. Hartmann, Alan Ho, Markus Hoffmann, Trent Huang, Travis S. Humble, Sergei V. Isakov, Evan Jeffrey, Zhang Jiang, Dvir Kafri, Kostyantyn Kechedzhi, Julian Kelly, Paul V. Klimov, Sergey Knysh, Alexander Korotkov, Fedor Kostritsa, David Landhuis, Mike Lindmark, Erik Lucero, Dmitry Lyakh, Salvatore Mandrà, Jarrod R. McClean, Matthew McEwen, Anthony Megrant, Xiao Mi, Kristel Michielsen, Masoud Mohseni, Josh Mutus, Ofer Naaman, Matthew Neeley, Charles Neill, Murphy Yuezhen Niu, Eric Ostby, Andre Petukhov, John C. Platt, Chris Quintana, Eleanor G. Rieffel, Pedram Roushan, Nicholas C. Rubin, Daniel Sank, Kevin J. Satzinger, Vadim Smelyanskiy, Kevin J. Sung, Matthew D. Trevithick, Amit Vainsencher, Benjamin Villalonga, Theodore White, Z. Jamie Yao, Ping Yeh, Adam Zalcman, Hartmut Neven & John M. Martinis. Nature volume 574, pages505–510 (2019) DOI: https://doi.org/10.1038/s41586-019-1666-5 Issue Date 24 October 2019

This paper appears to be open access.

Quantum back action and devil’s play

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I always appreciate a reference to James Clerk Maxwell’s demon thought experiment (you can find out about it in the Maxwell’s demon Wikipedia entry). This time it comes from physicist  Kater Murch in a July 23, 2018 Washington University in St. Louis (WUSTL) news release (published July 25, 2018 on EurekAlert) written by Brandie Jefferson (offering a good explanation of the thought experiment and more),

Thermodynamics is one of the most human of scientific enterprises, according to Kater Murch, associate professor of physics in Arts & Sciences at Washington University in St. Louis.

“It has to do with our fascination of fire and our laziness,” he said. “How can we get fire” — or heat — “to do work for us?”

Now, Murch and colleagues have taken that most human enterprise down to the intangible quantum scale — that of ultra low temperatures and microscopic systems — and discovered that, as in the macroscopic world, it is possible to use information to extract work.

There is a catch, though: Some information may be lost in the process.

“We’ve experimentally confirmed the connection between information in the classical case and the quantum case,” Murch said, “and we’re seeing this new effect of information loss.”

The results were published in the July 20 [2018] issue of Physical Review Letters.

The international team included Eric Lutz of the University of Stuttgart; J. J. Alonzo of the University of Erlangen-Nuremberg; Alessandro Romito of Lancaster University; and Mahdi Naghiloo, a Washington University graduate research assistant in physics.

That we can get energy from information on a macroscopic scale was most famously illustrated in a thought experiment known as Maxwell’s Demon. [emphasis mine] The “demon” presides over a box filled with molecules. The box is divided in half by a wall with a door. If the demon knows the speed and direction of all of the molecules, it can open the door when a fast-moving molecule is moving from the left half of the box to the right side, allowing it to pass. It can do the same for slow particles moving in the opposite direction, opening the door when a slow-moving molecule is approaching from the right, headed left. ­

After a while, all of the quickly-moving molecules are on the right side of the box. Faster motion corresponds to higher temperature. In this way, the demon has created a temperature imbalance, where one side of the box is hotter. That temperature imbalance can be turned into work — to push on a piston as in a steam engine, for instance. At first the thought experiment seemed to show that it was possible create a temperature difference without doing any work, and since temperature differences allow you to extract work, one could build a perpetual motion machine — a violation of the second law of thermodynamics.

“Eventually, scientists realized that there’s something about the information that the demon has about the molecules,” Murch said. “It has a physical quality like heat and work and energy.”

His team wanted to know if it would be possible to use information to extract work in this way on a quantum scale, too, but not by sorting fast and slow molecules. If a particle is in an excited state, they could extract work by moving it to a ground state. (If it was in a ground state, they wouldn’t do anything and wouldn’t expend any work).

But they wanted to know what would happen if the quantum particles were in an excited state and a ground state at the same time, analogous to being fast and slow at the same time. In quantum physics, this is known as a superposition.

“Can you get work from information about a superposition of energy states?” Murch asked. “That’s what we wanted to find out.”

There’s a problem, though. On a quantum scale, getting information about particles can be a bit … tricky.

“Every time you measure the system, it changes that system,” Murch said. And if they measured the particle to find out exactly what state it was in, it would revert to one of two states: excited, or ground.

This effect is called quantum backaction. To get around it, when looking at the system, researchers (who were the “demons”) didn’t take a long, hard look at their particle. Instead, they took what was called a “weak observation.” It still influenced the state of the superposition, but not enough to move it all the way to an excited state or a ground state; it was still in a superposition of energy states. This observation was enough, though, to allow the researchers track with fairly high accuracy, exactly what superposition the particle was in — and this is important, because the way the work is extracted from the particle depends on what superposition state it is in.

To get information, even using the weak observation method, the researchers still had to take a peek at the particle, which meant they needed light. So they sent some photons in, and observed the photons that came back.

“But the demon misses some photons,” Murch said. “It only gets about half. The other half are lost.” But — and this is the key — even though the researchers didn’t see the other half of the photons, those photons still interacted with the system, which means they still had an effect on it. The researchers had no way of knowing what that effect was.

They took a weak measurement and got some information, but because of quantum backaction, they might end up knowing less than they did before the measurement. On the balance, that’s negative information.

And that’s weird.

“Do the rules of thermodynamics for a macroscopic, classical world still apply when we talk about quantum superposition?” Murch asked. “We found that yes, they hold, except there’s this weird thing. The information can be negative.

“I think this research highlights how difficult it is to build a quantum computer,” Murch said.

“For a normal computer, it just gets hot and we need to cool it. In the quantum computer you are always at risk of losing information.”

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

Information Gain and Loss for a Quantum Maxwell’s Demon by M. Naghiloo, J. J. Alonso, A. Romito, E. Lutz, and K. W. Murch. Phys. Rev. Lett. 121, 030604 (Vol. 121, Iss. 3 — 20 July 2018) DOI:https://doi.org/10.1103/PhysRevLett.121.030604 Published 17 July 2018

© 2018 American Physical Society

This paper is behind a paywall.