Category Archives: Quantum Physics

Were learning theres a lot more to learn about nothing than we thought, said Isabel Garcia Garcia, a particle physicist at the Kavli Institute for Theoretical Physicsin California. How much more are we missing?

So far, such studies have led to a dramatic conclusion: Our universe may sit on a platform of shoddy construction, a metastable vacuum that is doomed in the distant future to transform into another sort of nothing, destroying everything in the process.

Nothing started to seem like something in the 20th century, as physicists came to view reality as a collection of fields: objects that fill space with a value at each point (the electric field, for instance, tells you how much force an electron will feel in different places). In classical physics, a fields value can be zero everywhere so that it has no influence and contains no energy. Classically, the vacuum is boring, said Daniel Harlow, a theoretical physicist at the Massachusetts Institute of Technology. Nothing is happening.

But physicists learned that the universes fields are quantum, not classical, which means they are inherently uncertain. Youll never catch a quantum field with exactly zero energy. Harlow likens a quantum field to an array of pendulums one at each point in space whose angles represent the fields values. Each pendulum hangs nearly straight down but jitters back and forth.

Left alone, a quantum field will stay in its minimum-energy configuration, known as its true vacuum or ground state. (Elementary particles are ripples in these fields.) When we talk about the vacuum of a system, we have in mind in some loose way the preferred state of the system, said Garcia Garcia.

Most of the quantum fields that fill our universe have one, and only one, preferred state, in which theyll remain for eternity. Most, but not all.

In the 1970s, physicists came to appreciate the significance of a different class of quantum fields whose values prefer not to be zero, even on average. Such a scalar field is like a collection of pendulums all hovering at, say, a 10-degree angle. This configuration can be the ground state: The pendulums prefer that angle and are stable.

In 2012, experimentalists at the Large Hadron Collider proved that a scalar field known as the Higgs field permeates the universe. At first, in the hot, early universe, its pendulums pointed down. But as the cosmos cooled, the Higgs field changed state, much as water can freeze into ice, and its pendulums all rose to the same angle. (This nonzero Higgs value is what gives many elementary particles the property known as mass.)

With scalar fields around, the stability of the vacuum is not necessarily absolute. A fields pendulums might have multiple semi-stable angles and a proclivity for switching from one configuration to another. Theorists arent certain whether the Higgs field, for instance, has found its absolute favorite configuration the true vacuum. Some have argued that the fields current state, despite having persisted for 13.8 billion years, is only temporarily stable, or metastable.

If so, the good times wont last forever. In the 1980s, the physicists Sidney Coleman and Frank De Luccia described how a false vacuum of a scalar field could decay. At any moment, if enough pendulums in some location jitter their way into a more favorable angle, theyll drag their neighbors to meet them, and a bubble of true vacuum will fly outward at nearly light speed. It will rewrite physics as it goes, busting up the atoms and molecules in its path. (Dont panic. Even if our vacuum is only metastable, given its staying power so far, it will probably last for billions of years more.)

In the potential mutability of the Higgs field, physicists identified the first of a practically infinite number of ways that nothingness could kill us all.

As physicists have attempted to fit natures confirmed laws into a larger set (filling in giant gaps in our understanding in the process), they have cooked up candidate theories of nature with additional fields and other ingredients.

When fields pile up, they interact, influencing each others pendulums and establishing new mutual configurations in which they like to get stuck. Physicists visualize these vacuums as valleys in a rolling energy landscape. Different pendulum angles correspond to different amounts of energy, or altitudes in the energy landscape, and a field seeks to lower its energy just as a stone seeks to roll downhill. The deepest valley is the ground state, but the stone could come to rest for a time, anyway in a higher valley.

A couple of decades ago, the landscape exploded in scale. The physicists Joseph Polchinski and Raphael Bousso were studying certain aspects of string theory, the leading mathematical framework for describing gravitys quantum side. String theory works only if the universe has some 10 dimensions, with the extra ones curled up into shapes too tiny to detect. Polchinski and Bousso calculated in 2000 that such extra dimensions could fold up in a tremendous number of ways. Each way of folding would form a distinct vacuum with its own physical laws.

The discovery that string theory allows nearly countless vacuums jibed with another discovery from nearly two decades earlier.

Cosmologists in the early 1980s developed a hypothesis known as cosmic inflation that has become the leading theory of the universes birth. The theory holds that the universe began with a quick burst of exponential expansion, which handily explains the universes smoothness and hugeness. But inflations successes come at a price.

The researchers found that once cosmic inflation started, it would continue. Most of the vacuum would violently explode outward forever. Only finite regions of space would stop inflating, becoming bubbles of relative stability separated from each other by inflating space in between. Inflationary cosmologists believe we call one of these bubbles home.

To some, the notion that we live in a multiverse an endless landscape of vacuum bubbles is disturbing. It makes the nature of any one vacuum (such as ours) seem random and unpredictable, curbing our ability to understand our universe. Polchinski, who died in 2018, told the physicist and author Sabine Hossenfelder that discovering string theorys landscape of vacuums initially made him so miserable it led him to seek therapy. If string theory predicts every imaginable variety of nothing, has it predicted anything?

To others, the plethora of vacuums is not a problem; in fact, its a virtue, said Andrei Linde, a prominent cosmologist at Stanford University and one of the developers of cosmic inflation. Thats because the multiverse potentially solves a great mystery: the ultra-low energy of our particular vacuum.

When theorists navely estimate the collective jittering of all the universes quantum fields, the energy is huge enough to rapidly accelerate the expansion of space and, in short order, rip the cosmos apart. But the observed acceleration of space is extremely mild in comparison, suggesting that much of the collective jittering cancels out and our vacuum has an extraordinarily low positive value for its energy.

In a solitary universe, the tiny energy of the one and only vacuum looks like a profound puzzle. But in a multiverse, its just dumb luck. If different bubbles of space have different energies and expand at different rates, galaxies and planets will form only in the most lethargic bubbles. Our calm vacuum, then, is no more mysterious than the Goldilocks orbit of our planet: We find ourselves here because most everywhere else is inhospitable to life.

Love it or hate it, the multiverse hypothesis as currently understood has a problem. Despite string theorys seemingly infinite menu of vacuums, so far no one has found a specific folding of tiny extra dimensions that corresponds to a vacuum like ours, with its barely positive energy. String theory seems to yield negative-energy vacuums much more easily.

Perhaps string theory is untrue, or the flaw could lie with researchers immature understanding of it. Physicists may not have hit on the right way to handle positive vacuum energy within string theory. Thats perfectly possible, said Nathan Seiberg, a physicist at the Institute for Advanced Study in Princeton, New Jersey. This is a hot topic.

Or our vacuum could just be inherently sketchy. The prevailing view is that [positively energized] space is not stable, Seiberg said. It could decay to something else, so that could be one of the reasons why it is so hard to understand the physics of it.

These researchers suspect that our vacuum is not one of realitys preferred states, and that it will someday jitter itself into a deeper, more stable valley. In doing so, our vacuum could lose the field that generates electrons or pick up a new palette of particles. The tightly folded dimensions could come unfurled. Or the vacuum could even give up on existence entirely.

Thats another one of the options, Harlow said. A true nothing.

The physicist Edward Witten first discovered the bubble of nothing in 1982. While studying a vacuum with one extra dimension curled up into a tiny circle at each point, he found that quantum jitters inevitably jiggled the extra dimension, sometimes shrinking the circle to a point. As the dimension vanished into nothingness, Witten found, it took everything else with it. The instability would spawn a rapidly expanding bubble with no interior, its mirrorlike surface marking the end of space-time itself.

This instability of tiny dimensions has long plagued string theory, and various ingredients have been devised to stiffen them. In December, Garcia Garcia, together with Draper and Benjamin Lillard of Illinois, calculated the lifetime of a vacuum with a single extra curled-up dimension. They considered various stabilizing bells and whistles, but they found that most mechanisms failed to stop the bubbles. Their conclusions aligned with Wittens: When the size of the extra dimension fell below a certain threshold, the vacuum collapsed at once. A similar calculation one extended to more sophisticated models could rule out vacuums in string theory with dimensions below that size.

With a large enough hidden dimension, however, the vacuum could survive for many billions of years. This means that theories producing bubbles of nothing could plausibly match our universe. If so, Aristotle may have been more right than he knew. Nature may not be a big fan of the vacuum. In the extremely long run, it may prefer nothing at all.

Correction: August 10, 2022

Otto von Guerickes vacuum-filled copper sphere was the size of a watermelon, rather than the size of a grapefruit as initially stated.

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How the Physics of Nothing Underlies Everything - Quanta Magazine

Car co-invented the approach to using underlying quantum mechanical laws to predict the physical movements of atoms and molecules. Quantum mechanical laws dictate how atoms bind to each other to form molecules, and how molecules join with each other to form everyday objects.

Car and Michele Parrinello, a physicist now at the Istituto Italiano di Tecnologia in Italy, published their approach, known as ab initio (Latin for from the beginning) molecular dynamics, in a groundbreaking paper in 1985.

But quantum mechanical calculations are complex and take tremendous amounts of computing power. In the 1980s, computers could simulate just a hundred atoms over spans of a few trillionths of a second. Subsequent advances in computing and the advent of modern supercomputers boosted the number of atoms and timespan of the simulation, but the result fell far short of the number of atoms needed to observe complex processes such as ice nucleation.

AI provided an attractive potential solution. Researchers train a neural network, named for its similarities to the workings of the human brain, to recognize a comparatively small number of selected quantum calculations. Once trained, the neural network can calculate the forces between atoms that it has never seen before with quantum mechanical accuracy. This machine learning approach is already in use in everyday applications such as voice recognition and self-driving automobiles.

In the case of AI applied to molecular modeling, a major contribution came in 2018 when Princeton graduate student Linfeng Zhang, working with Car and Princeton professor of mathematics Weinan E, found a way to apply deep neural networks to modeling quantum-mechanical interatomic forces. Zhang, who earned his Ph.D. in 2020 and is now a research scientist at the Beijing Institute of Big Data Research, called the approach deep potential molecular dynamics.

In the current paper, Car and postdoctoral researcher Pablo Piaggi along with colleagues applied these techniques to the challenge of simulating ice nucleation. Using deep potential molecular dynamics, they were able to run simulations of up to 300,000 atoms using significantly less computing power, for much longer timespans than were previously possible. They carried out the simulations on Summit, one of the worlds fastest supercomputers, located at Oak Ridge National Laboratory.

This work provides one of the best studies of ice nucleation, said Pablo Debenedetti, Princetons dean for research and the Class of 1950 Professor of Engineering and Applied Science, and a co-author of the new study.

Ice nucleation is one of the major unknown quantities in weather prediction models, Debenedetti said. This is a quite significant step forward because we see very good agreement with experiments. Weve been able to simulate very large systems, which was previously unthinkable for quantum calculations.

Currently, climate models obtain estimates of how fast ice nucleates primarily from observations made in laboratory experiments, but these correlations are descriptive, not predictive, and are valid over a limited range of experimental conditions. In contrast, molecular simulations of the type done in this study can produce simulations that are predictive of future situations, and can estimate ice formation under extreme conditions of temperature and pressure, such as on other planets.

The deep potential methodology used in our study will help realize the promise of ab initio molecular dynamics to produce valuable predictions of complex phenomena, such as chemical reactions and the design of new materials, said Athanassios Panagiotopoulos, the Susan Dod Brown Professor of Chemical and Biological Engineering and a co-author of the study.

The fact that we are studying very complex phenomena from the fundamental laws of nature, to me that is very exciting, said Piaggi, the studys first author and a postdoctoral research associate in chemistry at Princeton. Piaggi earned his Ph.D. working with Parrinello on the development of new techniques to study rare events, such as nucleation, using computer simulation. Rare events take place over timescales that are longer than the simulation times that can be afforded, even with the help of AI, and specialized techniques are needed to accelerate them.

Jack Weis, a graduate student in chemical and biological engineering, helped increase the likelihood of observing nucleation by seeding tiny ice crystals into the simulation. The goal of seeding is to increase the likelihood that water will form ice crystals during the simulation, allowing us to measure the nucleation rate, said Weis, who is advised by Debenedetti and Panagiotopoulos.

Water molecules consist of two hydrogen atoms and an oxygen atom. The electrons around each atom determine how atoms can bond with each other to form molecules.

We start with the equation that describes how electrons behave, Piaggi said. Electrons determine how atoms interact, how they form chemical bonds, and virtually the whole of chemistry.

The atoms can exist in literally millions of different arrangements, said Car, who is director of the Chemistry in Solution and at Interfaces center, funded by the U.S. Department of Energy Office of Science and including regional universities.

The magic is that because of some physical principles, the machine is able to extrapolate what happens in a relatively small number of configurations of a small collection of atoms to the countless arrangements of a much bigger system, Car said.

Although AI approaches have been available for some years, researchers have been cautious about applying them to calculations of physical systems, Piaggi said. When machine learning algorithms started to become popular, a big part of the scientific community was skeptical, because these algorithms are a black box. Machine learning algorithms dont know anything about the physics, so why would we use them?

In the last couple of years, however, there has been a significant change in this attitude, Piaggi said, not only because the algorithms work but also because researchers are using their knowledge of physics to inform the machine learning models.

For Car, it is satisfying to see the work started three decades ago come to fruition. The development came via something that was developed in a different field, that of data science and applied mathematics, Car said. Having this kind of cross interaction between different fields is very important.

This work was supported by the U.S. Department of Energy (grant DE-731 SC0019394) and used resources of the Oak Ridge Leadership Computing Facility (grant DE-AC05-00OR22725) at the Oak Ridge National Laboratory. Simulations were substantially performed using the Princeton Research Computing resources at Princeton University. Pablo Piaggi was supported by an Early Postdoc.Mobility fellowship from the Swiss National Science Foundation.

The study, Homogeneous ice nucleation in an ab initio machine learning model of water, by Pablo M. Piaggi, Jack Weis, Athanassios Z. Panagiotopoulos, Pablo G. Debenedetti, and Roberto Car, was published in the journal Proceedings of the National Academy of Sciences the week of August 8, 2022. DOI: /10.1073/pnas.2207294119.

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Researchers Simulate Ice Formation by Combining AI and Quantum Mechanics - HPCwire

D-Wave completed a planned merger on Monday with DPCM Capital (the latter of which was already listed on the New York Stock Exchange), making the Canada-basedfirm the third quantum player to go public via a SPACthat is, a special purpose acquisition companywithin the last year. (The other companies? Rigetti and IonQ.)

Its an interesting trend, but perhaps not a surprising one: According to D-Wave CEO Alan Baratz, the until-recently-obscure financial quirk offers his companyone thats in a still-budding sectorfaster access to capital.

In some sense SPACs are ideal for a company that has huge potential but is going to take some time to mature,he tells Fast Company. With a SPAC, youre able to tap into the funding sources in the public markets to accelerate your growth and do it based on the future potential.

A traditional IPO, on the other hand, is all about today, he adds.

SPACs can also save companies money (though this point is subject to some debate). I dont think all SPACs should be discounted, says Patrick Moorhead of Moor Insights & Strategy, a consulting firm. Its a much less expensive way to go public and takes less time and effort.

So far, D-Waves post-SPAC stock is holding its own. It opened at $9.98 Monday and closed at $11.86 on Thursday. But Rigetti and IonQ havent fared as well. Rigetti has seen its shares drop in value by roughly half since its listing on the NASDAQ in March. IonQs shares have lost about 40% of their value since its listing in October 2021.

In the young field of quantum computing, D-Wave has emerged as a major character. Back in 2011, the company became the first to actually sell a quantum computer; it now counts NASA, Google, and Lockheed Martin as customers.

Building and operating a quantum computer is an extraordinary feat of science and engineering. Instead of the bits used in traditional computers (which can be set to zero or one), quantum computers use subatomic particles called qubits, which can represent many values between zero and one, as well as zero and one at the same time (a superposition). Qubits can also entangle to represent values in extremely complex problems. In order to take advantage of these properties, the computer has to control the state of the qubits, whose erratic behavior is governed by quantum physics, not regular physics. This is very hard, and usually involves supercooling the qubits to slow their constant spin, then using lasers or electricity to control their state.

D-Wave was able to get to market with a quantum computer because it adopted a unique approach to working with the qubitsone that asks far less of them. What its looking for is the minimum energy level within a qubit, and by finding the minimum energy level, then theyre able to find the most optimized solution to a problem, says Heather West, research manager at research firm IDC. And thats why D-Wave is able to say they have 5,000 to 7,000 qubits in their system versus an IBM, which is still down around 127.

Even though that approach, called quantum annealing, doesnt try to exert a lot of control over the states of the qubits, its still very useful for solving optimization problemsthat is, problems where the goal is to find the best solution among a huge number of possibles. An optimization problem might be finding the optimal routes and cargos for a large fleet of delivery trucks, or finding the optimal number of employees to schedule on a given day. Its a common type of business puzzle, and annealers are especially good at solving them.

Some of these industries really gravitated toward D-Wave because of those optimization problems, and being able to pull in all sorts of data to find these optimized solutions and solving problems faster was really appealing, West says.

That application is a good example of the way companies are using quantum services like D-Wave today. Theyre looking for problem types where classical computers struggle and quantum computers excel.

They [D-Wave] are really more of an accelerator, says Ashish Nadkarni, group VP and general manager at IDC. We are not at the point where you can completely run all kinds of jobs on a quantum computer.

But D-Waves annealer may eventually be seen as a forerunner to a more robust kind of quantum computing, called gate model, in which the quantum computer takes full advantage of the quantum properties of the qubitstheir many possible states, their capacity for superposition, and the compute power enabled by multiple qubits entangling with each other.

Controlling and leveraging these properties opens the possibility of solving problems that are far beyond the reach of classical supercomputers (and annealers). These are large probabilistic problems where the qubits are asked to model huge and complex data sets. It could be modeling all the receptors in the brain to explore how theyll react to a drug, or a huge array of stock market conditions to predict their effect on the price of a certain commodity.

Realizing that much of the upside and excitement around quantum computing is coming from the possibility to solve such problems, D-Wave announced last year that it had begun building gate-model quantum computers more like the ones built by Google, IBM, and IonQ. D-Wave will need years to develop its gate-model quantum, but Baratz believes offering both annealers and gate-model quantum computing will eventually put his company at an advantage.

By doing both and being the only company thats doing both, were the only company in the world that will be able to address the full market for quantum, and the full set of use cases, he says. D-Waves customers typically tap into these computing services via a dedicated cloud service.

Because quantum is considered a nascent technology, many potential customers (such as companies in the financial services and pharmaceutical industries) are experimenting with running certain types of algorithms on quantum systems to look for some advantage over classical computing. But theyre not necessarily paying customers.

Baratz says that its the gate-model quantum services that are nascent technology, not D-Waves annealers, which he says are ready to deliver real value today. He believes the gate-model quantum computers are still as many as seven years away from being able to run general business applications in a way that beats classical computers.

Baratz believes that D-Wave is now challenged to make sure customers differentiate between gate-model computingwhich he says could be as many as seven years away from running real business applicationsand D-Waves quantum annealing service, which is mature and ready to deliver value today. While his gate-model competitors are out telling customers its okay to dip their toes into the water and experiment, D-Wave must counter that narrative in the marketplace with the message that customers can be doing real optimization work using quantum annealing now.

We truly are commercial, so when our competitors talk about revenue, they talk about government research grants as revenue, and they talk about national labs and academic institutions as customers, Baratz says. When we talk about our customers, we talk about our recently announced deal with MasterCard, or Deloitte or Johnson & Johnson or Volkswagen.

Baratz says over 65% of D-Waves quantum cloud revenue last year came from more than 50 commercial customers, which include over two dozen members of the Forbes Global 2000.

Baratz says D-Wave is now entering a phase in which it can leverage its annealers to start customer relationships.

We do have a significant head start, but we think now is the time to really make the investment to grow that loyal customer base and get the market share, Baratz says.And then, as we bring new generations of annealing to market, its just an upsell to more complex applications as we bring gate [model] to market.

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D-Wave is the third quantum startup to SPAC in less than a year - Fast Company

Worried about your aging brain? One solution might be on a shelf in the refrigerator aisle of your grocery store, according to new research conducted by scientists at the University of Kansas Medical Center.

The KU Medical Center research team found that older adults who drink three cups of dairy milk a day can increase their brains level of glutathione (GSH), a powerful antioxidant that helps protect the brain from some of the damage that accompanies aging and aging-related diseases. (The typical American adult over age 60 drinks less than two cups of milk per day, according to data from the Centers for Disease Control and Prevention.)

Just like an old car that rusts, the human brain becomes corroded over time by free radicals and other oxidants that are released as the brain converts nutrients into energy. This oxidative stress, as its called, is believed to be a major mechanism of brain aging as well as many neurodegenerative diseases including Alzheimers and Parkinsons. GSH helps stave off oxidative stress and the damage it causes. But as people age, brain levels of GSH tend to fall.

It's exciting that something as simple as drinking milk can increase GSH because its not a drug, its just a simple food, said Debra Sullivan, Ph.D., RD, professor and chair of the Department of Dietetics and Nutrition in the School of Health Professions at KU Medical Center and an author on the study, which was published August 15 in Frontiers in Nutrition. And the three cups a day is actually what is recommended by the U.S. Dietary Guidelines.

The study builds on work that Sullivan began over a decade ago with In-Young Choi, Ph.D., lead author on the study and director of the Metabolic Imaging Unit and the Magnetic Resonance Science Program at the Hoglund Biomedical Imaging Center at KU Medical Center. Choi, who focuses on brain aging and neurodegeneration, had collaborated with Phil Lee, Ph.D., a professor of the Department of Radiology, to develop a novel magnetic resonance imaging technique that can measure the level of antioxidants in the brain. These unique scans use special imaging techniques based on a multiple quantum physics concept and can selectively detect GSH in different parts of the brain simultaneously, Choi said.

Sullivan approached Choi about collaborating and using her brain antioxidant scanning technique to measure how what people eat affects their brain. When they completed their first exploratory study, they were surprised by the results.

I was thinking fruits and vegetables would be highly correlated with antioxidants in the brain, remembered Choi. But instead it was dairy, and among the dairy foods, it was milk. That was really surprising.

The researchers then applied for and were awarded a grant from the National Dairy Council, which along with a National Institutes of Health (NIH) grant that funds the Hoglund Biomedical Imaging Center, supports their work. These funders have no input on the study design, data, the interpretation of the data or the writing the manuscript, Sullivan said.

In 2015, Choi and Sullivan and their team published an observational study in the American Journal of Clinical Nutrition that again found that milk was highly correlated with concentrations of GSH in the brain of older adults. The next step, the current study, was designed to see what would happen to someones brain if that person increased their milk consumption.

In this study, 73 adults aged between the ages of 60 and 89 who typically consumed less than 1.5 servings of dairy per day were randomly assigned into a control group, which did not alter its usual milk intake, and into an intervention group, which increased their milk intake to three cups per day for three months. The study provided the participants in the intervention group with low-fat 1% milk from regional Kansas City area grocery stores weekly. For both groups, brain antioxidant imaging scans were conducted at baseline and after three months.

While there was no change in the levels of GSH in the brains of the participants in the control group, the group that drank three cups of dairy milk a day saw their brain GSH levels increase by an average of nearly 5% overall and by more than 7% in the parietal region of the brain.

Choi noted that earlier findings have shown that GSH levels are lower in older adults about 10%. So, by drinking milk, it looks like you can catch up some, she said.

What remains to be discovered is the specific mechanisms by which milk increases levels of GSH in the brain. The researchers know this much: The GSH molecule is made of three amino acidsglycine, glutamate, and cysteineand milk is a source of all three. Compared with other foods, the whey protein in milk has particularly high levels of cysteine, which is especially important for the body to make more GSH. Milk is also rich in riboflavin and calcium, which are required for GSH maintenance.

More research is needed to determine which of these factors are behind the increase in brain GSH levels. The researchers also plan to conduct a larger study as well as studies including cognitive tests to measure if milk is leading to measurable changes in brain function. They also want to determine if there is an optimal dose of milk and if the amount of milk fat matters.

In the meantime, Sullivan sees no reason to wait to make sure youre getting your three cups of milk each day. Its important for your brain health, your bone health, your muscle health, all of those things, she said. Thats the takeaway.

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Drinking more dairy milk may improve brain health in older adults, KU Medical Center researchers find - University of Kansas Medical Center

About Centre for Quantum Technologies (CQT)

The Centre for Quantum Technologies (CQT) is a research centre of excellence in Singapore. It brings together physicists, computer scientists and engineers to do basic research on quantum physics and to build devices based on quantum phenomena. Experts in this new discipline of quantum technologies are applying their discoveries in computing, communications, and sensing. CQT is hosted by the National University of Singapore and also has staff at Nanyang Technological University. With some 180 researchers and students, it offers a friendly and international work environment. Learn more about CQT at http://www.quantumlah.org

Job Description

The key job purpose is to extend our previous studies of artificial gauge field in SU(2) to SU(3) symmetry. We are using an ultracold gas of Strontium atoms and simple generalization to our tripod system. SU(3) symmetry appears in the Yang-Mills theory for high energy physics and more recently in specific problems in condensed-matter physics where three-fold band structure are engineered (Weyl semimetal, spintronics). One important aspect of SU(3) with respect to SU(2) is its higher dimensionality which allow for richer topological properties. For example, SU(3) transformations naturally break the time invariance symmetry leading to singularities of the Berry curvature and related magnetic monopoles.

KEY RESPONSIBILITIES

Job Requirements

More Information

Location: [[NTU]]Organization: [[NUS]]Department: [[David Wilkowski's group]]Job requisition ID: [[16651]]

Covid-19 Message

At NUS, the health and safety of our staff and students are one of our utmost priorities, and COVID-vaccination supports our commitment to ensure the safety of our community and to make NUS as safe and welcoming as possible. Many of our roles require a significant amount of physical interactions with students/staff/public members. Even for job roles that may be performed remotely, there will be instances where on-campus presence is required.

Taking into consideration the health and well-being of our staff and students and to better protect everyone in the campus, applicants are strongly encouraged to have themselves fully COVID-19 vaccinated to secure successful employment with NUS.

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Research Fellow (David Wilkowski 's Group), Centre for Quantum Technologies job with NATIONAL UNIVERSITY OF SINGAPORE | 304528 - Times Higher...

Consciousness researcher Robert Prentner and cognitive psychologist will tell a prestigious music and philosophy festival in London next month that great physicist Donald Hoffman, quantum physicist Erwin Schrdinger (18871961) believed that The total number of minds in the universe is one. That is, a universal Mind accounts for everything.

In a world where many scientists strive mightily to explain how the human mind can arise from non-living matter, Prentner and Hoffman will tell the HowtheLightGetsIn festival in London (September 1718, 2022) that the author of the famous Cat paradox was hardly a materialist:

In 1925, just a few months before Schrdinger discovered the most basic equation of quantum mechanics, he wrote down the first sketches of the ideas that he would later develop more thoroughly in Mind and Matter. Already then, his thoughts on technical matters were inspired by what he took to be greater metaphysical (religious) questions. Early on, Schrdinger expressed the conviction that metaphysics does not come after physics, but inevitably precedes it. Metaphysics is not a deductive affair but a speculative one.

Inspired by Indian philosophy, Schrdinger had a mind-first, not matter-first, view of the universe. But he was a non-materialist of a rather special kind. He believed that there is only one mind in the universe; our individual minds are like the scattered light from prisms:

A metaphor that Schrdinger liked to invoke to illustrate this idea is the one of a crystal that creates a multitude of colors (individual selves) by refracting light (standing for the cosmic self that is equal to the essence of the universe). We are all but aspects of one single mind that forms the essence of reality. He also referred to this as the doctrine of identity. Accordingly, a non-dual form of consciousness, which must not be conflated with any of its single aspects, grounds the refutation of the (merely apparent) distinction into separate selves that inhabit a single world.

But in Mind and Matter (1958), Schrdinger, we are told, took this view one step further:

Schrdinger drew remarkable consequences from this. For example, he believed that any man is the same as any other man that lived before him. In his early essay Seek for the Road, he writes about looking into the mountains before him. Thousands of years ago, other men similarly enjoyed this view. But why should one assume that oneself is distinct from these previous men? Is there any scientific fact that could distinguish your experience from another mans? What makes you you and not someone else? Similarly as John Wheeler once assumed that there is really only one electron in the universe, Schrdinger assumed that there really is only one mind. Schrdinger thought this is supported by the empirical fact that consciousness is never experienced in the plural, only in the singular. Not only has none of us ever experienced more than one consciousness, but there is also no trace of circumstantial evidence of this ever happening anywhere in the world.

Most non-materialists will wish they had gotten off two stops ago. We started with Mind first, which when accounting for why there is something rather than nothing has been considered a reasonable assumption throughout history across the world (except among materialists). But the assumption that no finite mind could experience or act independently of the Mind behind the universe is a limitation on the power of that Mind. Why so?

Its not logically clear and logic is our only available instrument here why the original Mind could not grant to dogs, chimpanzees, and humans the power to apprehend and act as minds in their own right in their natural spheres not simply as seamless extensions of the universal Mind.

With humans, the underlying assumptions of Schrdingers view are especially problematic. Humans address issues of good and evil. If Schrdinger is right, for example, Dr. Martin Luther King, and Comrade Josef Stalin are really only one mind because each experienced only his own consciousness. But wait. As a coherent human being, each could only have experienced his own consciousness and not the other mans.

However, that doesnt mean that they were mere prisms displaying different parts of the spectrum of broken light. The prism analogy fails to take into account that humans can act for good or ill. Alternatively, it is saying that good and evil, as we perceive them, are merely different colors in a spectrum. As noted earlier, many of us should have got off two stops ago

In any event, Schrdingers views are certain to be an interesting discussion at HowLightGetsIn.

Schrdinger was hardly the only modern physicist or mathematician to dissent from materialism. Mathematician Kurt Gdel (19061978), to take one example, destroyed a popular form of atheism (logical positivism) via his Incompleteness Theorems.

The two thinkers held very different views, of course. But both saw the fatal limitations of materialism (naturalism) and they addressed these limitations quite differently. In an age when Stephen Hawkings disdain for philosophy is taken to be representative of great scientists, its a good thing if festivals like HowLightGetsIn offer a broader perspective and corrective.

You may also wish to read: Why panpsychism is starting to push out naturalism. A key goal of naturalism/materialism has been to explain human consciousness away as nothing but a pack of neurons. That cant work. Panpsychism is not a form of dualism. But, by including consciousness especially human consciousness as a bedrock fact of nature, it avoids naturalisms dead end.

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Schrdinger Believed That There Was Only One Mind in the Universe - Walter Bradley Center for Natural and Artificial Intelligence

About the Centre for Quantum Technologies

The Centre for Quantum Technologies (CQT) is a research centre of excellence in Singapore. It brings together physicists, computer scientists and engineers to do basic research on quantum physics and to build devices based on quantum phenomena. Experts in this new discipline of quantum technologies are applying their discoveries in computing, communications, and sensing.

CQT is hosted by the National University of Singapore and also has staff at Nanyang Technological University. With some 180 researchers and students, it offers a friendly and international work environment.

Learn more about CQT atwww.quantumlah.org

Job Description

A postdoctoral research fellow opening is available in the group of Loh Huanqian at the Centre for Quantum Technologies.

Our research is centered on the quantum control of singly trapped ultracold atoms using arrays of reconfigurable tweezers. These atom arrays offer exquisite control over the internal quantum states, motional states, array dimensionality, array geometry, doping, and interactions. The postdoctoral research fellow will work with a team of students to set up an experiment to induce and manipulate tunable interactions between the single atoms. The postdoctoral position is funded by the Singapore Quantum Engineering Programme.

Job Requirements

The candidate should have a PhD degree in physics and a proven track record in experimental atomic physics. At least 4 years of laboratory experience with quantum gases (Bose-Einstein condensates or degenerate Fermi gases) is strongly preferred.

More Information

Department : [[Centre for Quantum Technologies]]

Job requisition ID : [[16710]]

Covid-19 Message

At NUS, the health and safety of our staff and students are one of our utmost priorities, and COVID-vaccination supports our commitment to ensure the safety of our community and to make NUS as safe and welcoming as possible. Many of our roles require a significant amount of physical interactions with students/staff/public members. Even for job roles that may be performed remotely, there will be instances where on-campus presence is required.

Taking into consideration the health and well-being of our staff and students and to better protect everyone in the campus, applicants are strongly encouraged to have themselves fully COVID-19 vaccinated to secure successful employment with NUS.

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Research Fellow (Loh Huanqian's group ), Centre for Quantum Technologies job with NATIONAL UNIVERSITY OF SINGAPORE | 303038 - Times Higher Education

The worlds top physicists will gather in Vancouver this August to launch a Quantum Gravity Institute that could significantly advance our understanding of physics and gravity.

The goal is to discover the theory of quantum gravity, one of sciences greatest mysteries.

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, a professor at the University of British Columbia.

The conference will take place between Aug. 15-19, and will welcome two dozen of the worlds top physicists, including Nobel Laureates Jim Peebles, Sir Roger Penrose and Kip Thorne who is well known for developing the original idea for the 2014 film Interstellar.

For roughly 100 years, physics has been based on Einsteins theory of relativity and quantum mechanics.

The theory of relativity has helped us understand the cosmos, leading to space travel and technology like atomic clocks, which govern GPS systems. Quantum mechanics is responsible for the electronics, lasers, computers, cell phones and plastics that support modern transportation, communications, medicine, agriculture and energy systems.

The two theories have provided countless breakthroughs but are seemingly contradictory the theory of quantum gravity is meant to be the bridge between these two theories.

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 todays technology would have seemed to people living 100 years ago, Stamp said.

The conference will be open to the public on Aug. 17 and provide a once-in-a-lifetime opportunity to learn from the worlds pre-eminent physicists.

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Science

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World's top physicists to be in B.C. this summer to bring down science's greatest mystery - Surrey Now Leader

When studying a complex system, scientists identify smaller pieces called subsystems that they can make sense of. By studying subsystems and the correlations between them, they reconstruct an understanding of the whole.

This approach has been used with great success to explain phenomena and develop applications in computing, cryptography and sensing based on quantum mechanicsthe physics of matter and energy at the scale of the atom or smaller. But this approach is limited to systems that operate in a world where time is absolute.

This description of subsystems falls short when describing scenarios that involve Einsteins theory of general relativity, where time is relative to an observers motion and tightly interwoven with space into a four-dimensional spacetime.

Now, a theoretical study co-authored byAlexander Smith, assistant professor of physics at Saint Anselm College and adjunct assistant professor at Dartmouth, and Shadi Ali Ahmad 22, proposes a new way to identify subsystems and correlations compatible with general relativity.

Theoretical physicists have long been striving to combine quantum mechanics and general relativity into a unified theory of quantum gravity. It is hoped that this work may be applied in developing a quantum description of spacetime, says Smith.

The results, published in April inPhysical Review Letters, build on previous work on a generalized notion of subsystems by the James Frank Family Professor of Physics Lorenza Violaand her collaborators. Instead of having composite building parts that are glued together into a larger system, subsystems should be thought of as directly arising from the observable properties one can measure, says Viola.

Quantum mechanics allows for correlations that are not consistent with our classical understanding of the world, says Smith, Viola and her collaborators gave us a new way to think about these unintuitive quantum correlations.

Smith, Ali Ahmad and their collaborators apply this idea to build a framework for identifying subsystems, which is consistent with relativity, and find that the notion of the subsystem is no longer rigid.

The way we partition a system is also relative. It depends on who is looking at it, says Smith. While their method currently applies to simple systems of several particles, the authors are working to generalize the framework to quantum field theory, which constitutes our most fundamental description of nature.

Several theoretical concepts that are driving the emerging understanding of quantum gravity have their origin in quantum information theorya relatively new field that studies how information in a quantum system can be analyzed and manipulated. Quantum information science has given us this whole new way to think about quantum mechanics itself, says Smith.

Working with Smith and other researchers, Ali Ahmad, a physics and mathematics major from Beirut, has used quantum information theory to study a number of different theoretical problems. Inprevious work, they were the first to examine how gravitational wavesripples in spacetime produced when massive astronomical objects (e.g. black holes) speed up to extreme levelsaffect entanglement between systems.Another projecttackled the question of how workthe measure of how much energy is transferred when a force acts on an objectcan be defined operationally at the quantum scale.

Smith says Ali Ahmad is one of the most driven to learn, hardworking and productive students he has encountered. Seeing Shadi develop his ability in theoretical physics over the past four years has been very rewarding, he says.

Ali Ahmad won the 2022 Gazzaniga Family Science Award, which recognizes scientific accomplishment of a graduating senior in the sciences. He is also the recipient of the Physics and Astronomy Chairs Prize.

Quantum information theory is a toolbox that I like to borrow from and use broadly, says Ali Ahmad. The promise of access to undergraduate research opportunities and funding was what drew him to Dartmouth, he says. Now a research fellow at Dartmouth, Ali Ahmad is wrapping up ongoing projects as he prepares to apply to graduate programs.

With classes as a springboard, he sought out research mentors in the physics and mathematics departments, collaborating with them on a wide range of research topics. Talking about science with people shapes the way you think, says Ali Ahmad, who already has three publications under his belt. I think it really sharpens your interests.

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Physics Major Works on a New Theory of Quantum Subsystems - Dartmouth News

The supermarket checkout scanner, the printer in your office, the pointer used in yesterdays meeting lasers are pretty much a part of everyday life now. You think about them very little, even as they do amazing things like instantly read barcodes or correct your nearsightedness via LASIK surgery.

But what is a laser, really? What makes them so special and so useful? Indeed, what makes a laser different from a simple lightbulb? The answers rest in the remarkable weirdness of quantum physics. Lasers are a quintessential quantum phenomenon.

The key question we have to deal with here is the interaction of light and matter. In classical physics, light is made of waves of electromagnetic energy traveling through space. These waves can be emitted or absorbed by accelerating electrically charged particles of matter. This is what happens in a radio tower: Electrical charges are accelerated up and down the tower to create the electromagnetic waves that travel through space to your car and let you listen to your station of choice.

At the turn of the century, scientists wanted to apply this classical idea to create models of atoms. They imagined an atom as a little solar system, with the positively charged protons at the center and the negatively charged electrons orbiting around them. If an electron emitted or absorbed some light, i.e. electromagnetic energy, it would speed up or slow down. But this model didnt hold. For one thing, there is always an acceleration happening when one thing orbits another this is called centripetal acceleration. So the electron in this classical model of the atom must always be emitting radiation as it orbits and thereby losing energy. That makes the orbit unstable. The electron would quickly fall onto the proton.

Niels Bohr got around this problem with a new model of the atom. In the Bohr model, an electron can only occupy a set of discrete orbits around the proton. These orbits were visualized like circular train tracks that the electrons rode as they circled about the proton. The farther out an orbit was from the proton, the more excited it was, and the more energy it held.

In the Bohr model, the emission and absorption of light was all about electrons jumping between these orbits. To emit light, an electron jumped from a higher orbit down to a lower orbit, emitting a packet of light energy called a photon. An electron could also jump from a lower orbit to a higher one if it absorbed one of these light packets. The wavelength of the light emitted or absorbed was directly related to the energy difference between the orbits.

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There was much quantum weirdness in all of this. If the electron was bound to these orbits, that meant it was never between them. It jumped from one location to the other without ever occupying the intervening space. Also, light was both a particle a photon that had a packet of energy and a wave spread out through space. How do you imagine that? While the Bohr model was only a first step, modern versions of the theory still feature discrete energy levels and photon wave-particle duality.

How does this relate to lasers? LASER stands for Light Amplification Through Stimulated Emission of Radiation. The ideas of amplification and stimulated emission in a laser are based on those specific energy levels of electrons in atoms.

To make a laser, you take some material and exploit its quantum energy levels.

The first step is to invert the population of the levels. Usually, most electrons will reside in the atoms lowest energy levels that is where they like to rest. But lasers rely on boosting most of the electrons to a higher, excited level also called an excited state. This is done using a pump that pushes the electrons up to a specific excited state. Then, as some of these electrons begin spontaneously falling down again, they emit a specific wavelength of light. These photons travel through the material and tickle other electrons in the excited state, stimulating them to jump down, and causing more photons of the same wavelength to be emitted. By placing mirrors at either end of the material, this process builds up until there is a nice, steady beam of photons that are all the same wavelength. Some fraction of synchronized photons then escapes through a hole in one of the mirrors. That is the beam you see coming from your laser pointer.

This is exactly what does not happen in a light bulb, where atoms in the heated filament have electrons jumping up and down chaotically between different levels. The photons they emit have a wide range of wavelengths, which causes their light to look white. It is only by exploiting the weird quantum levels of electrons in an atom, the weird quantum jumps between those levels, and finally, the weird wave-particle duality of light itself, that those amazing and very useful lasers come into being.

There is, of course, a lot more to this story. But the basic idea you want to remember next time youre at the grocery store check-out is simple. A world beyond your perception the nanoworld of atoms is incredibly different from the one you live in. Somehow, we humans have peered into that tiny realm and come back with a deep enough understanding to reshape the macroworld we inhabit.

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Lasers are weird and amazing - Big Think