Posts Tagged ‘quantum computing’
“We couldn’t build quantum computers unless the universe were quantum and computing… We’re hacking into the universe.”*…
… in the process of which, as Ben Brubaker explains, we learn some fascinating things…
If you want to tile a bathroom floor, square tiles are the simplest option — they fit together without any gaps in a grid pattern that can continue indefinitely. That square grid has a property shared by many other tilings: Shift the whole grid over by a fixed amount, and the resulting pattern is indistinguishable from the original. But to many mathematicians, such “periodic” tilings are boring. If you’ve seen one small patch, you’ve seen it all.
In the 1960s, mathematicians began to study “aperiodic” tile sets with far richer behavior. Perhaps the most famous is a pair of diamond-shaped tiles discovered in the 1970s by the polymathic physicist and future Nobel laureate Roger Penrose. Copies of these two tiles can form infinitely many different patterns that go on forever, called Penrose tilings. Yet no matter how you arrange the tiles, you’ll never get a periodic repeating pattern.
“These are tilings that shouldn’t really exist,” said Nikolas Breuckmann, a physicist at the University of Bristol.
For over half a century, aperiodic tilings have fascinated mathematicians, hobbyists and researchers in many other fields. Now, two physicists have discovered a connection between aperiodic tilings and a seemingly unrelated branch of computer science: the study of how future quantum computers can encode information to shield it from errors. In a paper posted to the preprint server arxiv.org in November, the researchers showed how to transform Penrose tilings into an entirely new type of quantum error-correcting code. They also constructed similar codes based on two other kinds of aperiodic tiling.
At the heart of the correspondence is a simple observation: In both aperiodic tilings and quantum error-correcting codes, learning about a small part of a large system reveals nothing about the system as a whole…
Fascinating: “Never-Repeating Tiles Can Safeguard Quantum Information,” from @benbenbrubaker in @QuantaMagazine.
Plus- bonus background on tiling.
* “We couldn’t build quantum computers unless the universe were quantum and computing. We can build such machines because the universe is storing and processing information in the quantum realm. When we build quantum computers, we’re hijacking that underlying computation in order to make it do things we want: little and/or/not calculations. We’re hacking into the universe.” –Seth Lloyd
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As we care for qubits, we might send carefully-calculated birthday greetings to Herman Hollerith; he was born on this date in 1860. A statistician and inventor, he was a seminal figure in the development of data processing: he invented (for the 1890 U.S. Census) an electromechanical tabulating machine for punched cards to assist in summarizing information (and, later, for use in accounting). His invention of the punched card tabulating machine, which he patented in 1884, marked the beginning of the era of mechanized binary code and semiautomatic data processing systems– and his approach dominated that landscape for nearly a century.
The company that Hollerith founded to exploit his invention was merged in 1911 with several other companies to form the Computing-Tabulating-Recording Company. In 1924, the company was renamed “International Business Machines” (or, as we know it, IBM).
“You must not fool yourself, and you are the easiest person to fool”*…
The quest for room-temperature superconducting seems a bit like the hunt for the Holy Grail. A superconductor is a material that will transmit electricity with no resistance– thus very quickly and with no loss. (Estimates of loss in the U.S. electric grid, most of it due to heat loss from resistance in transmission, range from 5-10%; at the low end, that’s enough to power all seven Central American countries four times over.) Beyond that (already extraordinary) benefit, superconductivity could enable high-efficiency electric motors, maglev trains, low-cost magnets for MRI and nuclear fusion, a promising form of quantum computing (superconducting qubits), and much, much more.
Superconductivity was discovered in 1911, and has been the subject of fervent study ever since; indeed, four Nobel prizes have gone to scientists working on it, most recently in 2003. But while both understanding and application have advanced, it has remained the case that superconductivity can only be achieved at very low temperatures (or very high pressures). Until the mid-80s, it was believed that it could be established only below 30 Kelvin (-405.67 degrees Farenheit); by 2015, scientists had gotten that up to 80 K (-316 degrees Farenheit)… that’s to say, still requiring way too much cooling to be widely practical.
So imagine the excitement earlier this month, when…
In a packed talk on Tuesday afternoon at the American Physical Society’s annual March meeting in Las Vegas, Ranga Dias, a physicist at the University of Rochester, announced that he and his team had achieved a century-old dream of the field: a superconductor that works at room temperature and near-room pressure. Interest was so intense in the presentation that security personnel stopped entry to the overflowing room more than fifteen minutes before the talk. They could be overheard shooing curious onlookers away shortly before Dias began speaking.
The results, published in Nature, appear to show that a conventional conductor — a solid composed of hydrogen, nitrogen and the rare-earth metal lutetium — was transformed into a flawless material capable of conducting electricity with perfect efficiency.
While the announcement has been greeted with enthusiasm by some scientists, others are far more cautious, pointing to the research group’s controversial history of alleged research malfeasance. (Dias strongly denies the accusations.) Reactions by 10 independent experts contacted by Quanta ranged from unbridled excitement to outright dismissal…
Interesting if true– a paper in Nature divides the research community: “Room-Temperature Superconductor Discovery Meets With Resistance,” from @QuantaMagazine.
* Richard Feynman
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As we review research, we might pause, on Pi Day, for a piece of pi(e)…
… in celebration of Albert Einstein’s birthday; he was born on this date in 1879.
“Everything should be made as simple as possible, but not simpler.”
“The ‘paradox’ is only a conflict between reality and your feeling of what reality ‘ought to be’”*…
Elegant experiments with entangled light have laid bare a profound mystery at the heart of reality. Daniel Garisto explains the importance of the work done by this year’s Nobel laureates in Physics…
One of the more unsettling discoveries in the past half century is that the universe is not locally real. “Real,” meaning that objects have definite properties independent of observation—an apple can be red even when no one is looking; “local” means objects can only be influenced by their surroundings, and that any influence cannot travel faster than light. Investigations at the frontiers of quantum physics have found that these things cannot both be true. Instead, the evidence shows objects are not influenced solely by their surroundings and they may also lack definite properties prior to measurement. As Albert Einstein famously bemoaned to a friend, “Do you really believe the moon is not there when you are not looking at it?”
This is, of course, deeply contrary to our everyday experiences. To paraphrase Douglas Adams, the demise of local realism has made a lot of people very angry and been widely regarded as a bad move.
Blame for this achievement has now been laid squarely on the shoulders of three physicists: John Clauser, Alain Aspect and Anton Zeilinger. They equally split the 2022 Nobel Prize in Physics “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science.” (“Bell inequalities” refers to the pioneering work of the Northern Irish physicist John Stewart Bell, who laid the foundations for this year’s Physics Nobel in the early 1960s.) Colleagues agreed that the trio had it coming, deserving this reckoning for overthrowing reality as we know it. “It is fantastic news. It was long overdue,” says Sandu Popescu, a quantum physicist at the University of Bristol. “Without any doubt, the prize is well-deserved.”
“The experiments beginning with the earliest one of Clauser and continuing along, show that this stuff isn’t just philosophical, it’s real—and like other real things, potentially useful,” says Charles Bennett, an eminent quantum researcher at IBM…
Quantum foundations’ journey from fringe to favor was a long one. From about 1940 until as late as 1990, the topic was often treated as philosophy at best and crackpottery at worst. Many scientific journals refused to publish papers in quantum foundations, and academic positions indulging such investigations were nearly impossible to come by…
Today, quantum information science is among the most vibrant and impactful subfields in all of physics. It links Einstein’s general theory of relativity with quantum mechanics via the still-mysterious behavior of black holes. It dictates the design and function of quantum sensors, which are increasingly being used to study everything from earthquakes to dark matter. And it clarifies the often-confusing nature of quantum entanglement, a phenomenon that is pivotal to modern materials science and that lies at the heart of quantum computing…
Eminently worth reading in full: “The Universe Is Not Locally Real, and the Physics Nobel Prize Winners Proved It,” from @dangaristo in @sciam.
Apposite: entangled particles and wormholes could be manifestations of the same phenomenon, and resolve paradoxes like information escaping a black hole: “Black Holes May Hide a Mind-Bending Secret About Our Universe.”
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As we rethink reality, we might spare a thought for Walter Brattain; he died on this date in 1987. A physicist (at Bell Labs at the time), he worked with John Bardeen and William Shockley to invent the point-contact transistor in 1947, the birth of the semiconductor– work for which the trio shared the Nobel Prize in Physics in 1956.
At college, Brattain said, he majored in physics and math because they were the only subjects he was good at. He became a solid physicist with a good understanding of theory, but his strength was in physically constructing experiments. Working with the ideas of Shockley and Bardeen, Brattain’s hands built the first transistor. Shortly, the transistor replaced the bulkier vacuum tube for many uses and was the forerunner of microminiature electronic parts.
As semiconductor technology has advanced, it has begun to incorporate quantum effects.
“If you are confused by the underlying principles of quantum technology – you get it!”*…
A tour through the map above– a helpful primer on the origins, development, and possible futures of quantum computing…
From Dominic Walliman (@DominicWalliman) on @DomainOfScience.
* Kevin Coleman
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As we embrace uncertainty, we might spare a thought for
Alan Turing; he died on this date in 1954. A British mathematician, he was a foundational computer science pioneer (inventor of the Turing Machine, creator of the “Turing Test” (perhaps to b made more relevant by quantum computing :), and inspiration for “The Turing Award“) and cryptographer (leading member of the team that cracked the Enigma code during WWII).
“If you are not completely confused by quantum mechanics, you do not understand it”*…
If we can harness it, quantum technology promises fantastic new possibilities. But first, scientists need to coax quantum systems to stay yoked for longer than a few millionths of a second.
A team of scientists at the University of Chicago’s Pritzker School of Molecular Engineering announced the discovery of a simple modification that allows quantum systems to stay operational—or “coherent”—10,000 times longer than before. Though the scientists tested their technique on a particular class of quantum systems called solid-state qubits, they think it should be applicable to many other kinds of quantum systems and could thus revolutionize quantum communication, computing and sensing…
Down at the level of atoms, the world operates according to the rules of quantum mechanics—very different from what we see around us in our daily lives. These different rules could translate into technology like virtually unhackable networks or extremely powerful computers; the U.S. Department of Energy released a blueprint for the future quantum internet in an event at UChicago on July 23. But fundamental engineering challenges remain: Quantum states need an extremely quiet, stable space to operate, as they are easily disturbed by background noise coming from vibrations, temperature changes or stray electromagnetic fields.
Thus, scientists try to find ways to keep the system coherent as long as possible…
“This breakthrough lays the groundwork for exciting new avenues of research in quantum science,” said study lead author David Awschalom, the Liew Family Professor in Molecular Engineering, senior scientist at Argonne National Laboratory and director of the Chicago Quantum Exchange. “The broad applicability of this discovery, coupled with a remarkably simple implementation, allows this robust coherence to impact many aspects of quantum engineering. It enables new research opportunities previously thought impractical.”…
Very big news at a very small scale: “Scientists discover way to make quantum states last 10,000 times longer.”
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As we strive for stability, we might send calculated birthday greetings to Brook Taylor; he was born on this date in 1685. A mathematician, he is best known for his work in describing and understanding oscillation. In 1708, Taylor produced a solution to the problem of the center of oscillation. His Methodus incrementorum directa et inversa (“Direct and Indirect Methods of Incrementation,” 1715) introduced what is now called the calculus of finite differences. Using this, he was the first to express mathematically the movement of a vibrating string on the basis of mechanical principles. Methodus also contained Taylor’s theorem, later recognized by Joseph Lagrange as the basis of differential calculus.
A gifted artist, Taylor also wrote on the basic principles of perspective, including the first general treatment of the principle of vanishing points.
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