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Category: quantum physics – Page 69

Scientists have long known that light can sometimes appear to exit a material before entering it—an effect dismissed as an illusion caused by how waves are distorted by matter.

Now, researchers at the University of Toronto, through innovative quantum experiments, say they have demonstrated that “negative time” isn’t just a theoretical idea—it exists in a tangible, physical sense, deserving closer scrutiny.

The findings, posted on the preprint server arXiv but not yet published in a peer-reviewed journal, have attracted both global attention and skepticism.

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Researchers at Rice University have made a meaningful advance in the simulation of molecular electron transfer—a fundamental process underpinning countless physical, chemical and biological processes. The study, published in Science Advances, details the use of a trapped-ion quantum simulator to model electron transfer dynamics with unprecedented tunability, unlocking new opportunities for scientific exploration in fields ranging from molecular electronics to photosynthesis.

Electron transfer, critical to processes such as cellular respiration and energy harvesting in plants, has long posed challenges to scientists due to the complex quantum interactions involved. Current computational techniques often fall short of capturing the full scope of these processes. The multidisciplinary team at Rice, including physicists, chemists and biologists, addressed these challenges by creating a programmable quantum system capable of independently controlling the key factors in : donor-acceptor energy gaps, electronic and vibronic couplings and environmental dissipation.

Using an ion crystal trapped in a vacuum system and manipulated by , the researchers demonstrated the ability to simulate real-time spin dynamics and measure transfer rates across a range of conditions. The findings not only validate key theories of quantum mechanics but also pave the way for novel insights into light-harvesting systems and molecular devices.

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Northwestern University engineers are the first to successfully demonstrate quantum teleportation over a fiberoptic cable already carrying internet traffic.

The discovery introduces the new possibility of combining quantum communication with existing internet cables—greatly simplifying the infrastructure required for distributed quantum sensing or computing applications.

The study is published on the arXiv preprint server and is due to appear in the journal Optica.

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Quantum walks are a powerful theoretical model using quantum effects such as superposition, interference and entanglement to achieve computing power beyond classical methods.

A research team at the National Innovation Institute of Defense Technology from the Academy of Military Sciences (China) recently published a review article that thoroughly summarizes the theories and characteristics, physical implementations, applications and challenges of quantum walks and quantum walk computing. The review was published Nov. 13 in Intelligent Computing in an article titled “Quantum Walk Computing: Theory, Implementation, and Application.”

As quantum mechanical equivalents of classical random walks, quantum walks use quantum phenomena to design advanced algorithms for applications such as database search, network analysis and navigation, and . Different types of quantum walks include discrete-time quantum walks, continuous-time quantum walks, discontinuous quantum walks, and nonunitary quantum walks. Each model presents unique features and computational advantages.

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UC Santa Barbara researchers developed a compact, low-cost laser that matches the performance of lab-scale systems. Using rubidium atoms and advanced chip integration, it enables applications like quantum computing, timekeeping, and environmental sensing, including satellite-based gravitational mapping.

For experiments requiring ultra-precise atomic measurements and control—such as two-photon atomic clocks, cold-atom interferometer sensors, and quantum gates—lasers are indispensable. The key to their effectiveness lies in their spectral purity, meaning they emit light at a single color or frequency. Today, achieving the ultra-low-noise, stable light necessary for these applications relies on bulky and expensive tabletop laser systems designed to generate and manage photons within a narrow spectral range.

But what if these atomic applications could break free from the confines of labs and benchtops? This is the vision driving research in UC Santa Barbara engineering professor Daniel Blumenthal’s lab, where his team is working to replicate the performance of these high-precision lasers in lightweight, handheld devices.

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Scientists have found evidence of a strange state of matter called a quantum spin liquid in a material known as pyrochlore cerium stannate.

In this mysterious state, magnetic particles don’t settle into a fixed pattern but stay in constant motion, even at extremely low temperatures. Researchers used advanced tools like neutron scattering and theoretical models to detect unusual magnetic behavior that behaves like waves of light. This breakthrough could lead to new discoveries in physics and future technologies like quantum computing.

Quantum Spin Liquids

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Patreon: https://www.patreon.com/seanmcarroll.
Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2024/03/04/267-…f-reality/

In the 1860s, James Clerk Maxwell argued that light was a wave of electric and magnetic fields. But it took over four decades for physicists to put together the theory of special relativity, which correctly describes the symmetries underlying Maxwell’s theory. The delay came in part from the difficulty in accepting that light was a wave, but not a wave in any underlying “aether.” Today our most basic view of fundamental physics is found in quantum field theory, which posits that everything around us is a quantum version of a relativistic wave. I talk with physicist Matt Strassler about how we go from these interesting-but-intimidating concepts to the everyday world of tables, chairs, and ourselves.

Matt Strassler received his Ph.D. in physics from Stanford University. He is currently a writer and a visiting researcher in physics at Harvard University. His research has ranged over a number of topics in theoretical high-energy physics, from the phenomenology of dark matter and the Higgs boson to dualities in gauge theory and string theory. He blogs at Of Particular Significance, and his new book is Waves in an Impossible Sea: How Everyday Life Emerges from the Cosmic Ocean.

Mindscape Podcast playlist: https://www.youtube.com/playlist?list=PLrxfgDEc2NxY_fRExpDXr87tzRbPCaA5x.
Sean Carroll channel: https://www.youtube.com/c/seancarroll.

#podcast #ideas #science #philosophy #culture

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Quantum technologies are radically transforming our understanding of the universe. One emerging technology is macroscopic mechanical oscillators, devices that are vital in quartz watches, mobile phones, and lasers used in telecommunications. In the quantum realm, macroscopic oscillators could enable ultra-sensitive sensors and components for quantum computing, opening new possibilities for innovation in various industries.

Controlling mechanical oscillators at the quantum level is essential for developing future technologies in and ultra-precise sensing. But controlling them collectively is challenging, as it requires near-perfect units, i.e., identical.

Most research in quantum optomechanics has centered on single oscillators, demonstrating like ground-state cooling and quantum squeezing. But this hasn’t been the case for collective quantum behavior, where many oscillators act as one. Although these collective dynamics are key to creating more powerful quantum systems, they demand exceptionally over multiple oscillators with nearly identical properties.

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UNSW engineers have developed and built a special maser system that boosts microwave signals—such as those from deep space—but does not need to be super-cooled.

They say that diamonds are a girl’s best friend—but that might also soon be true for astronomers and astrophysicists following the new research. The team of quantum experts have developed a device known as a which uses a specially created purple diamond to amplify weak microwave signals, such as those which can come from .

Most importantly, their maser works at room temperature, whereas previous such devices needed to be super-cooled, at great expense, down to about minus 269°C.

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Queen Mary University of London physicist Professor Chris White, along with his twin brother Professor Martin White from the University of Adelaide, have discovered a surprising connection between the Large Hadron Collider (LHC) and the future of quantum computing.

For decades, scientists have been striving to build quantum computers that leverage the bizarre laws of quantum mechanics to achieve far greater processing power than traditional computers. A recently identified property—amusingly called “magic”—is critical for building these machines, but its generation and enhancement remain a mystery.

For any given quantum system, magic is a measure that tells us how hard it is to calculate on a non-quantum computer. The higher the magic, the more we need quantum computers to describe the behavior. Studying the magic properties of quantum systems generates profound insights into the development and use of quantum computers.

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