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Category: quantum physics – Page 6

Prototype sets record for optical quantum information technology

Chinese scientists have developed a programmable quantum computing prototype called Jiuzhang 4.0 that has set a new world record for optical quantum information technology, according to a study published May 13 in the journal Nature.

Led by the University of Science and Technology of China (USTC), the team used the prototype to solve the Gaussian boson sampling problem at a speed more than 1054 times that of the world’s most powerful supercomputer, the study said.

The researchers said they manipulated and detected quantum states of up to 3,050 photons —a significant leap from the 255 photons achieved with the previous Jiuzhang 3.0.

Roadmap charts three paths to room-temperature quantum materials for cooler computing

Imagine a laptop that never gets hot, a phone that holds its charge for days, or a computer memory chip designed to permanently retain data, even when the power goes out. This is the possibility sitting inside a remarkable family of materials that a team of researchers from the University of Ottawa and the Massachusetts Institute of Technology (MIT) has spent years trying to understand, and they just published a comprehensive roadmap of the field to date in the journal Newton.

Magnetic topological materials sit at the crossroads of magnetism and topology in modern physics. Topology is the mathematical study of shapes that cannot be continuously deformed into one another. In these materials, that idea protects the flow of electrons in a way that normal materials simply cannot.

“Magnetic topological materials offer a unique platform where magnetism and quantum physics work together in ways we are only beginning to fully understand,” explains Hang Chi, Canada Research Chair in Quantum Electronic Devices and Circuits and Assistant Professor at uOttawa’s Department of Physics. “This review brings together the field’s most significant advances and gives researchers a shared foundation to build on.”

Jacob Barandes — “A New Formulation of Quantum Theory”

Talk by Jacob Barandes (Harvard University)
Seminar Website: https://harvardfop.jacobbarandes.com/
YouTube Channel: / @foundationsofphysicsharvard.
Foundations of Physics @Harvard Seminar Series.
April 12, 2023.

Abstract: In this talk, I will present a novel, exact correspondence between stochastic-process theory and quantum theory. On the one hand, this stochastic-quantum correspondence means that one can use the Hilbert-space tools of quantum theory to model real-world stochastic processes beyond the usual Markov approximation, generalizing previous stochastic approaches to quantum theory as well as potentially opening up new applications for quantum simulators and quantum computers. On the other hand, the stochastic-quantum correspondence implies that one can replace the instrumentalist textbook axioms of quantum theory with much more physically transparent axioms. The result is a clearer physical picture underlying quantum theory that is consistent with the standard no-go theorems, helps clarify the meaning of signature features of quantum theory like interference and entanglement, and has potential implications for addressing the measurement problem.

Designing better quantum circuits with AI

Researchers from the group of theoretical physicist Hans Briegel have collaborated with NVIDIA to develop an AI method that automatically generates efficient quantum circuits, a key bottleneck in making quantum computers practically useful.

The work was published in Machine Learning: Science and Technology, in a paper titled “Synthesis of discrete–continuous quantum circuits with multimodal diffusion models.”

Before a quantum computer can perform any useful task, a quantum algorithm needs to be translated into a sequence of elementary quantum operations, known as quantum gates. Writing these quantum circuits efficiently is one of the hardest open problems in the field.

Dr. Stuart Hameroff: Consciousness is More than Computation!

13 years ago, I walked into Dr. Stuart Hameroff’s operating room with a camera, a microphone, and a single stubborn question:

Is consciousness computation?

Hameroff, an anesthesiologist and professor at the University of Arizona, and co-author with Sir Roger Penrose of the Orch OR theory, said no.

Emphatically. Unfashionably. Against the entire weight of mainstream neuroscience and Silicon Valley orthodoxy.

At the GF2045 conference, where I first met him, Ray Kurzweil went out of his way to declare Orch OR “totally wrong.” Others called it speculative. Untestable. Unscientific.

Today, in the age of large language models, that argument is no longer a niche dispute among philosophers and physicists. It is the decisive question of our century.

Continue reading “Dr. Stuart Hameroff: Consciousness is More than Computation!” | >

Scientists found a way to cool quantum computers using noise

Quantum computers only work when they are kept extremely cold. The problem is that today’s cooling systems also create noise, which can interfere with the fragile quantum information they are supposed to protect. Researchers at Chalmers University of Technology in Sweden have now introduced a new type of minimal quantum “refrigerator” that turns this challenge into an advantage. Instead of fighting noise, the device partially relies on it to operate. The result is highly precise control over heat and energy flow, which could help make large scale quantum technology possible.

Quantum technology is widely expected to reshape major areas of society. Potential applications include drug discovery, artificial intelligence, logistics optimization, and secure communications. Despite this promise, serious technical barriers still stand in the way of real world use. One of the most difficult challenges is maintaining and controlling the delicate quantum states that make these systems work.

Sunlight-powered generation of correlated photon pairs

Pairs of correlated or entangled photons are a foundational resource in quantum optics. They are most commonly produced through spontaneous parametric down-conversion (SPDC), a nonlinear optical process that typically relies on a stable, coherent laser to pump a nonlinear crystal. Because of this requirement, SPDC has long been viewed as impractical without laboratory-grade laser systems.

Recent studies have shown that fully coherent light is not strictly necessary: Partially coherent sources can also drive SPDC, with their coherence properties transferred to the generated photon pairs. This insight raises a natural and intriguing question—can sunlight, the most abundant natural light source, be used to generate correlated photon pairs?

Using sunlight for SPDC presents clear challenges. Sunlight collected from the ground is inherently unstable, with continuous changes in intensity, angle, and position that interfere with the precise illumination and photon detection required for SPDC experiments. At the same time, sunlight offers a compelling advantage: it removes dependence on lasers and external power sources, opening possibilities for photon-pair generation in remote or extreme environments.

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