Tag Archives: quantum mechanics

Explaining topological insulators with dance

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This must have been some high school physics class. A November 5, 2024 news item on ScienceDaily explains how physics topological insulators and dance intersected for three classes,

Science can be difficult to explain to the public. In fact, any subfield of science can be difficult to explain to another scientist who studies in a different area. Explaining a theoretical science concept to high school students requires a new way of thinking altogether.

This is precisely what researchers at the University of California San Diego did when they orchestrated a dance with high school students at Orange Glen High School in Escondido as a way to explain topological insulators.

The experiment, led by former graduate student Matthew Du and UC San Diego Associate Professor of Chemistry and Biochemistry Joel Yuen-Zhou, was published in Science Advances.

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A November 5, 2024 University of California at San Diego (UC San Diego) news release (also on EurekAlert), which originated the news item, provides more detail about how the researchers employed dance to teach physics concepts, Note: A link has been removed,

“I think the concept is simple,” stated Yuen-Zhou. “But the math is much harder. We wanted to show that these complex ideas in theoretical and experimental physics and chemistry are actually not as impossible to understand as you might initially think.”

Topological insulators are a relatively new type of quantum material that has insulating properties on the inside, but have conductive properties on the outside. To use a Southern California staple, if a topological insulator was a burrito, the filling would be insulating and the tortilla would be conducting.

Since topological insulators are able to withstand some disorder and deformation, they can be synthesized and used under conditions where imperfections can arise. For this reason, they hold promise in the areas of quantum computing and lasers, and in creating more efficient electronics.

To bring these quantum materials to life, the researchers made a dance floor (topological insulator) by creating a grid with pieces of blue and red tape. Then to choreograph the dance, Du created a series of rules that governed how individual dancers moved.

These rules are based on what is known as a Hamiltonian in quantum mechanics. Electrons obey rules given by a Hamiltonian, which represents the total energy of a quantum system, including kinetic and potential energy. The Hamiltonian encodes the interactions of the electron in the potential energy of the material.

Each dancer (electron) had a pair of flags and was given a number that corresponded to a movement:

  •  1 = wave flags with arms pointing up
  •  0 = stand still
  • -1 = wave flags with arms pointing down

Subsequent moves were based on what a neighboring dancer did and the color of the tape on the floor. A dancer would mimic a neighbor with blue tape, but do the opposite of a neighbor with red tape. Individual mistakes or dancers leaving the floor didn’t disrupt the overall dance, exhibiting the robustness of topological insulators.

In addition to topology, Yuen-Zhou’s lab also studies chemical processes and photonics, and it was in thinking of light waves that they realized the movement of a group of people also resembled a wave. This gave Yuen-Zhou the idea of using dance to explain a complex topic like topological insulators. Implementing this idea seemed like a fun challenge to Du, who is currently a postdoctoral scholar at the University of Chicago and takes salsa lessons in his free time.

Du, who comes from a family of educators and is committed to scientific outreach, says the project gave him an appreciation for being able to distill science into its simplest elements.

“We wanted to demystify these concepts in a way that was unconventional and fun,” he stated. “Hopefully, the students were able to see that science can be made understandable and enjoyable by relating it to everyday life.”   

Full list of authors: Matthew Du, Juan B. Pérez-Sánchez, Jorge A. Campos-Gonzalez-Angulo, Arghadip Koner, Federico Mellini, Sindhana Pannir-Sivajothi, Yong Rui Poh, Kai Schwennicke, Kunyang Sun, Stephan van den Wildenberg, Alec Barron and Joel Yuen-Zhou (all UC San Diego); and Dylan Karzen (Orange Glen High School).

This research was supported by an National Science Foundation CAREER grant (CHE 1654732).

Here’s what it looked like,

series of overhead images of dancers on dance floor grid
Snapshots showing dancers on the edge of the topological insulator moving in a clockwise direction. Courtesy of University of California at San Diego

You may find this helps you to understand what’s happening in the pictures,

Before getting to a link and citation for the paper, here’s the paper’s abstract,

Topological insulators are insulators in the bulk but feature chiral energy propagation along the boundary. This property is topological in nature and therefore robust to disorder. Originally discovered in electronic materials, topologically protected boundary transport has since been observed in many other physical systems. Thus, it is natural to ask whether this phenomenon finds relevance in a broader context. We choreograph a dance in which a group of humans, arranged on a square grid, behave as a topological insulator. The dance features unidirectional flow of movement through dancers on the lattice edge. This effect persists when people are removed from the dance floor. Our work extends the applicability of wave physics to dance. [emphasis mine]

I wonder if we’re going to see some ‘wave physics’ inspired dance performances.

Finally, here’s a link to and a citation for the paper,

Chiral edge waves in a dance-based human topological insulator by Matthew Du, Juan B. Pérez-Sánchez, Jorge A. Campos-Gonzalez-Angulo, Arghadip Koner, Federico Mellini, Sindhana Pannir-Sivajothi, Yong Rui Poh, Kai Schwennicke, Kunyang Sun, Stephan van den Wildenberg, Dylan Karzen, Alec Barron, and Joel Yuen-Zhou. Science Advances 28 Aug 2024 Vol 10, Issue 35 DOI: 10.1126/sciadv.adh7810

This paper is open access.

I think this is the first year I’ve stumbled across two stories about physics and dance in one year. Here’s the other one, “Happy Canada Day! Breakdancing at the 2024 Paris Summer Olympics: physics in action + heat, mosquitoes, and sports” in a July 1, 2024 posting.

World’s smallest disco party features nanoscale disco ball

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I haven’t featured one of these ‘fun’ (world’s smallest xxx) announcements in a long time. An August 14, 2024 news item on phys.org announces the world’s smallest disco party and a step towards exploring quantum gravity, Note: Links have been removed,

Physicists at Purdue [Purdue University, Indiana, US] are throwing the world’s smallest disco party. The disco ball itself is a fluorescent nanodiamond, which they have levitated and spun at incredibly high speeds. The fluorescent diamond emits and scatters multicolor lights in different directions as it rotates. The party continues as they study the effects of fast rotation on the spin qubits within their system and are able to observe the Berry phase.

The team, led by Tongcang Li, professor of Physics and Astronomy and Electrical and Computer Engineering at Purdue University, published their results in Nature Communications. Reviewers of the publication described this work as “arguably a groundbreaking moment for the study of rotating quantum systems and levitodynamics” and “a new milestone for the levitated optomechanics community.”

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This graph illustrates a diamond particle levitated above a surface ion trap. The fluorescent diamond nanoparticle is driven to rotate at a high speed (up to 1.2 billion rpm) by alternating voltages applied to the four corner electrodes. This rapid rotation induces a phase in the nitrogen-vacancy electron spins inside the diamond. The diagram in the top left corner depicts the atomic structure of a nitrogen-vacancy spin defect inside the diamond. Graphic provided by Kunhong Shen.

An August 13, 2024 Purdue University news release (also on EurekAlert but published August 14, 2024) by Cheryl Pierce, which originated the news item, explains what makes this work so exciting (!), Note: Links have been removed,

“Imagine tiny diamonds floating in an empty space or vacuum. Inside these diamonds, there are spin qubits that scientists can use to make precise measurements and explore the mysterious relationship between quantum mechanics and gravity,” explains Li, who is also a member of the Purdue Quantum Science and Engineering Institute.  “In the past, experiments with these floating diamonds had trouble in preventing their loss in vacuum and reading out the spin qubits. However, in our work, we successfully levitated a diamond in a high vacuum using a special ion trap. For the first time, we could observe and control the behavior of the spin qubits inside the levitated diamond in high vacuum.”

The team made the diamonds rotate incredibly fast—up to 1.2 billion times per minute! By doing this, they were able to observe how the rotation affected the spin qubits in a unique way known as the Berry phase.

“This breakthrough helps us better understand and study the fascinating world of quantum physics,” he says.

The fluorescent nanodiamonds, with an average diameter of about 750 nm, were produced through high-pressure, high-temperature synthesis. These diamonds were irradiated with high-energy electrons to create nitrogen-vacancy color centers, which host electron spin qubits. When illuminated by a green laser, they emitted red light, which was used to read out their electron spin states. An additional infrared laser was shone at the levitated nanodiamond to monitor its rotation. Like a disco ball, as the nanodiamond rotated, the direction of the scattered infrared light changed, carrying the rotation information of the nanodiamond.

The authors of this paper were mostly from Purdue University and are members of Li’s research group: Yuanbin Jin (postdoc), Kunhong Shen (PhD student), Xingyu Gao (PhD student) and Peng Ju (recent PhD graduate). Li, Jin, Shen, and Ju conceived and designed the project and Jin and Shen built the setup. Jin subsequently performed measurements and calculations and the team collectively discussed the results. Two non-Purdue authors are Alejandro Grine, principal member of technical staff at Sandia National Laboratories, and Chong Zu, assistant professor at Washington University in St. Louis. Li’s team discussed the experiment results with Grine and Zu who provided suggestions for improvement of the experiment and manuscript.

“For the design of our integrated surface ion trap,” explains Jin, “we used a commercial software, COMSOL Multiphysics, to perform 3D simulations. We calculate the trapping position and the microwave transmittance using different parameters to optimize the design. We added extra electrodes to conveniently control the motion of a levitated diamond. And for fabrication, the surface ion trap is fabricated on a sapphire wafer using photolithography. A 300-nm-thick gold layer is deposited on the sapphire wafer to create the electrodes of the surface ion trap.”

So which way are the diamonds spinning and can they be speed or direction manipulated? Shen says yes, they can adjust the spin direction and levitation.

“We can adjust the driving voltage to change the spinning direction,” he explains. “The levitated diamond can rotate around the z-axis (which is perpendicular to the surface of the ion trap), shown in the schematic, either clockwise or counterclockwise, depending on our driving signal. If we don’t apply the driving signal, the diamond will spin omnidirectionally, like a ball of yarn.”

Levitated nanodiamonds with embedded spin qubits have been proposed for precision measurements and creating large quantum superpositions to test the limit of quantum mechanics and the quantum nature of gravity.

“General relativity and quantum mechanics are two of the most important scientific breakthroughs in the 20th century. However, we still do not know how gravity might be quantized,” says Li. “Achieving the ability to study quantum gravity experimentally would be a tremendous breakthrough. In addition, rotating diamonds with embedded spin qubits provide a platform to study the coupling between mechanical motion and quantum spins.”

This discovery could have a ripple effect in industrial applications. Li says that levitated micro and nano-scale particles in vacuum can serve as excellent accelerometers and electric field sensors. For example, the US Air Force Research Laboratory (AFRL) are using optically-levitated nanoparticles to develop solutions for critical problems in navigation and communication.

“At Purdue University, we have state-of-the-art facilities for our research in levitated optomechanics,” says Li. “We have two specialized, home-built systems dedicated to this area of study. Additionally, we have access to the shared facilities at the Birck Nanotechnology Center, which enables us to fabricate and characterize the integrated surface ion trap on campus. We are also fortunate to have talented students and postdocs capable of conducting cutting-edge research. Furthermore, my group has been working in this field for ten years, and our extensive experience has allowed us to make rapid progress.”

Quantum research is one of four key pillars of the Purdue Computes initiative, which emphasizes the university’s extensive technological and computational environment.

This research was supported by the National Science Foundation (grant number PHY-2110591), the Office of Naval Research (grant number N00014-18-1-2371), and the Gordon and Betty Moore Foundation (grant DOI 10.37807/gbmf12259). The project is also partially supported by the Laboratory Directed Research and Development program at Sandia National Laboratories.

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

Quantum control and Berry phase of electron spins in rotating levitated diamonds in high vacuum by Yuanbin Jin, Kunhong Shen, Peng Ju, Xingyu Gao, Chong Zu, Alejandro J. Grine & Tongcang Li. Nature Communications volume 15, Article number: 5063 (2024) DOI: https://doi.org/10.1038/s41467-024-49175-3 Published online: 13 June 2024

This paper is open access.

Using measurements to generate quantum entanglement and teleportation

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Caption: The researchers at Google Quantum AI and Stanford University explored how measurements can fundamentally change the structure of quantum information in space-time. Credit: Google Quantum AI, designed by Sayo-Art

interesting approach to illustrating a complex scientific concept! This October 18, 2023 news item on phys.org describes the measurement problem,

Quantum mechanics is full of weird phenomena, but perhaps none as weird as the role measurement plays in the theory. Since a measurement tends to destroy the “quantumness” of a system, it seems to be the mysterious link between the quantum and classical world. And in a large system of quantum bits of information, known as “qubits,” the effect of measurements can induce dramatically new behavior, even driving the emergence of entirely new phases of quantum information.

This happens when two competing effects come to a head: interactions and measurement. In a quantum system, when the qubits interact with one another, their information becomes shared nonlocally in an “entangled state.” But if you measure the system, the entanglement is destroyed. The battle between measurement and interactions leads to two distinct phases: one where interactions dominate and entanglement is widespread, and one where measurements dominate, and entanglement is suppressed.

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An October 18, 2023 Google Quantum AI news release, which originated the news item, on EurekAlert provides more information about a research collaboration between Google and Stanford University,

As reported today [October 18, 2023] in the journal Nature, researchers at Google Quantum AI and Stanford University have observed the crossover between these two regimes — known as a “measurement-induced phase transition” — in a system of up to 70 qubits. This is by far the largest system in which measurement-induced effects have been explored. The researchers also saw signatures of a novel form of “quantum teleportation” — in which an unknown quantum state is transferred from one set of qubits to another — that emerges as a result of these measurements. These studies could help inspire new techniques useful for quantum computing.

One can visualize the entanglement in a system of qubits as an intricate web of connections. When we measure an entangled system, the impact it has on the web depends on the strength of the measurement. It could destroy the web completely, or it could snip and prune selected strands of the web, but leave others intact. 

To actually see this web of entanglement in an experiment is notoriously challenging. The web itself is invisible, so researchers can only infer its existence by seeing statistical correlations between the measurement outcomes of qubits. Many, many runs of the same experiment are needed to infer the pattern of the web. This and other challenges have plagued past experiments and limited the study of measurement-induced phase transitions to very small system sizes. 

To address these challenges, the researchers used a few experimental sleights of hand. First, they rearranged the order of operations so that all the measurements could be made at the end of the experiment, rather than interleaved throughout, thus reducing the complexity of the experiment. Second, they developed a new way to measure certain features of the web with a single “probe” qubit. In this way, they could learn more about the entanglement web from fewer runs of the experiment than had been previously required. Finally, the probe, like all qubits, was susceptible to unwanted noise in the environment. This is normally seen as a bad thing, as noise can disrupt quantum calculations, but the researchers turned this bug into a feature by noting that the probe’s sensitivity to noise depended on the nature of the entanglement web around it. They could therefore use the probe’s noise sensitivity to infer the entanglement of the whole system.

The team first looked at this difference in sensitivity to noise in the two entanglement regimes and found distinctly different behaviors. When measurements dominated over interactions (the “disentangling phase”), the strands of the web remained relatively short. The probe qubit was only sensitive to the noise of its nearest qubits. In contrast, when the measurements were weaker and entanglement was more widespread (the “entangling phase”) the probe was sensitive to noise throughout the entire system. The crossover between these two sharply contrasting behaviors is a signature of the sought-after measurement-induced phase transition.

The team also demonstrated a novel form of quantum teleportation that emerged naturally from the measurements: by measuring all but two distant qubits in a weakly entangled state, stronger entanglement was generated between those two distant qubits. The ability to generate measurement-induced entanglement across long distances enables the teleportation observed in the experiment.

The stability of entanglement against measurements in the entangling phase could inspire new schemes to make quantum computing more robust to noise. The role that measurements play in driving new phases and physical phenomena is also of fundamental interest to physicists. Stanford professor and co-author of the study, Vedika Khemani, says, “Incorporating measurements into dynamics introduces a whole new playground for many-body physics where many fascinating and new types of non-equilibrium phases could be found. We explore a few of these striking and counter-intuitive measurement induced phenomena in this work, but there is much more richness to be discovered in the future.” 

Before getting to the citation for and link to the paper, I have an interview with some of the researchers that was written up by Holly Alyssa MacCormick (Associate Director of Public Relations. Science writer and news editor for Stanford School of Humanities and Sciences) in an October 18, 2023 article for Stanford University, Note 1: Some of this will be redundant; Note 2: Links have been removed,

Harnessing the “weirdness” of quantum mechanics to solve practical problems is the long-standing promise of quantum computing. But much like the state of the cat in Erwin Schrödinger’s famous thought experiment, quantum mechanics is still a box of unknowns. Similar to the solid, liquid, and gas phases of matter, the organization of quantum information, too, can assume different phases. Yet unlike the phases of matter we are familiar with in everyday life, the phases of quantum information are much harder to formulate and observe and as a result have been only a theoretical dream until recently.

Measurements are arguably the weirdest facet of quantum mechanics. Intuition tells us that a state has some definite property and measurement reveals that property. However, measurements in quantum mechanics produce intrinsically random results, and the act of measurement irreversibly changes the state itself. Unlike laptops, smartphones, and other classical computers that rely on binary “bits” to code in the state of 0 (off) or 1 (on), quantum computers use “qubits” of information that can be in the state of 0, 1, or 0 and 1 at the same time, a concept known as superposition. The act of measurement doesn’t just extract information, but also changes the state, randomly “collapsing” a superposition into a specific value (0 or 1).

Moreover, this collapse affects not just the qubit that was measured, but also potentially the entire system—an effect described by Einstein as “spooky action at a distance.” This is due to “entanglement,” a quantum property that allows multiple particles in different places to jointly be in superposition, which is a key ingredient for quantum computing. The collapse of an entangled state can also enable spooky phenomena such as “teleportation,” thereby irretrievably altering the “arrow of time” (the concept that time moves in one forward direction) that governs our everyday experience.

In other words, measurements can be used to fundamentally reorganize the structure of quantum information in space and time.

Now, a new collaboration between Stanford and Google Quantum AI investigates the effect of measurements on quantum systems of many particles on Google’s quantum computer and has obtained the largest experimental demonstration of novel measurement-induced phases of quantum information to date. The study was co-led by Jesse Hoke, a physics graduate student and fellow at Stanford’s Quantum Science and Engineering initiative (Q-FARM), Matteo Ippoliti, a former postdoctoral scholar in the Department of Physics, and senior author Vedika Khemani, associate professor of physics at the Stanford School of Humanities and Sciences and Q-FARM. Their results were published Oct. 18 in the journal Nature.

Here, Hoke, Ippoliti, and Khemani discuss how they observed measurement-induced phases of quantum information—a feat once thought to be beyond the realm of what could be achieved in an experiment—and how their new insights could help pave the way for advancements in quantum science and engineering.

Question: What distinguishes the phases investigated in this study from one another, and what is teleportation?

Ippoliti: In the simplest case, there are two phases. In one phase, the structure of quantum information in the system forms a strongly connected web where qubits share a lot of entanglement, even at large spatial distances and/or temporal separations. In the other, the system is weakly connected, so correlations like entanglement decay quickly with distance or time. These are the two phases that we probed in our experiment. The strongly entangled phase enables teleportation, which occurs when the state of one qubit is instantly transmitted, or “teleported,” to another far away qubit by measuring all but those two qubits.

Question: How did you control when a phase transition occurred

Khemani: The competing forces at play are the interactions between qubits, which tend to build entanglement, and measurements of the qubits, which can destroy it. This is the famous “wave function collapse” of quantum mechanics—think of Schrödinger’s cat “collapsing” into one of two states (dead or alive) when we open the box. However, because of entanglement, the collapse is not restricted to the qubit we directly measure but affects the rest of the system too. By controlling the strength or frequency of measurements on the quantum computer, we can induce a phase transition between an entangled phase and a disentangled one.

Question: What were some of the challenges your team needed to overcome to measure quantum states, and how did you do it?

Ippoliti: Measurements in quantum mechanics are inherently random, which makes observing these phases notoriously challenging. This is because every repetition of our experiment produces a different, random-looking quantum state. This is a problem because detecting entanglement (the feature that sets our two phases apart) requires observations on many copies of the same state. To get around this difficulty, we developed a diagnostic that cross-correlates data from the quantum processor with the results of simulations on classical computers. This hybrid quantum-classical diagnostic allowed us to see evidence of the different phases on up to 70 qubits, making this one of the largest digital quantum simulations and experiments to date.

Hoke: Another challenge was that quantum experiments are currently limited by environmental noise. Entanglement is a delicate resource that is easily destroyed by interactions from the outside environment, which is the primary challenge in quantum computing. In our setup, we probe the entanglement structure between the system’s qubits, which is destroyed if the system is not perfectly isolated and instead gets entangled with the surrounding environment. We addressed this challenge by devising a diagnostic that uses noise as a feature rather than a bug—the two phases (weak and strong entanglement) respond to noise in different ways, and we used this as a probe of the phases.

Khemani: In addition, we used the fact that the “arrow of time” loses meaning with measurement-induced teleportation. This allowed us to reorganize the sequence of operations on the quantum computer in advantageous ways to mitigate the effects of noise and to devise new probes of the organization of quantum information in space-time.

Question: What do the findings mean?

Khemani: At the level of fundamental science, our experiments demonstrate new phenomena that extend our familiar concepts of “phase structure.” Instead of thinking of measurements merely as probes, we are now thinking of them as an intrinsic part of quantum dynamics, which can be used to create and manipulate novel quantum correlations. At the level of applications, using measurements to robustly generate structured entanglement is inspiring new ways to make quantum computing more robust against noise. More generally, our understanding of general phases of quantum information and dynamics is still nascent, and many exciting surprises await.

Acknowledgements

Hoke conducted research on this study while working as an intern at Google Quantum AI under the supervision of Xiao Mi and Pedram Roushan. Ippoliti is now an assistant professor of physics at the University of Texas at Austin. Additional co-authors on this study include the Google Quantum AI team and researchers from the University of Massachusetts, Amherst; Auburn University; University of Technology, Sydney; University of California, Riverside; and Columbia University. The full list of authors is available in the Nature paper.

Ippoliti was funded in part by the Gordon and Betty Moore Foundation’s EPiQS Initiative. Khemani was funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences; the Alfred P. Sloan Foundation; and the Packard Foundation.

Here’s a link to and a citation for the paper, Note: There are well over 100 contributors to the paper and I have not listed each one separately, You can find the list if you go to the Nature paper and click on Google Quantum AI and Collaborators in the author field,

Measurement-induced entanglement and teleportation on a noisy quantum processor by Google Quantum AI and Collaborators. Nature volume 622, pages 481–486 (2023) DOI: https://doi.org/10.1038/s41586-023-06505-7 Published online: 18 October 2023 Issue Date: 19 October 2023

This paper is open access.

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.

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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]

…

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)

…

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.

…

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”).

…

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.