Physicists have developed a new theoretical framework which unifies a wide array of seemingly unrelated “Mpemba effects”: counterintuitive cases where systems driven further from equilibrium relax faster than those closer to it. Reporting their results in Physical Review X, researchers led by John Goold at Trinity College Dublin show that both classical and quantum versions of the effect can be understood using the same underlying logic—resolving a long-standing conceptual puzzle.
In 1963, 13-year-old Tanzanian student Erasto Mpemba noticed that when he placed an ice cream mixture in the freezer while it was still hot, it froze faster than the other, initially cooler mixtures in the freezer. His observation was later confirmed in 1969 through a study involving Mpemba, together with physicist Denis Osborne.
Since then, effects analogous to the Mpemba effect have been observed in transitions ranging from crystallizing polymers to transitions in magnetic materials. Yet despite close experimental scrutiny, the mechanisms underlying the effect remained elusive.
A research team led by Professor Jiwoong Yang of the Department of Energy Science and Engineering at DGIST has developed next-generation optical sensor technology capable of precisely detecting not only the intensity and wavelength of light but also its rotational direction—the spin information of photons. The team successfully implemented a quantum-dot-based optical sensor that can detect circularly polarized light (CPL) across an ultra-wide spectral range—from ultraviolet to short-wave infrared—demonstrating photodetection performance comparable to that of commercial silicon optical sensors. The paper is published in Advanced Materials.
CPL refers to light in which the electric field rotates helically as it propagates. This is directly linked to the spin information of photons—the fundamental particles of light. This polarization information serves as a crucial signal in next-generation security and communication technologies, such as quantum communication, quantum cryptography, and photonic quantum information processing, which is why related optical sensor technologies are attracting significant worldwide attention.
Conventional circularly polarized light sensors typically require the light-absorbing material itself to possess a specific helical orientation, known as a chiral structure. This approach not only limits the range of usable materials but also confines detection to narrow spectral regions, such as ultraviolet or visible light. Extending this technology into the infrared region, which is essential for quantum communication and optical sensing, has previously posed a major technical challenge.
Scientists in the Riccio College of Engineering at the University of Massachusetts Amherst and the University of California Santa Barbara have demonstrated key laser and ion trap components necessary to help drastically shrink the size of quantum computers, an achievement aligned with the shrinking of integrated microprocessors in the 1970s, 80s and 90s that allowed computers to move from room-sized behemoths to today’s ultrathin smartphones.
The current state-of-the-art technology for quantum computing is too large and complex to scale and too sensitive and bulky to be portable. The largest and most sensitive components of these quantum systems are the optics, which include multiple lasers and vibration-isolated, temperature-controlled vacuum chambers that contain ultrastable optical cavities. These cavities stabilize the lasers to extremely high precision in order to control trapped ions for quantum computing and optical clocks.
When lasers were invented in the 1960s, they opened new avenues for scientific discovery and everyday applications, from scanners at the grocery store to corrective eye surgery. Conventional lasers control photons—individual particles of light—but over the past 20 years, scientists have invented lasers that control other fundamental particles, including phonons—individual particles of vibration or sound. Controlling phonons could open even more possibilities with lasers, such as taking advantage of unique quantum properties like entanglement.
A new squeezed phonon laser developed by researchers at the University of Rochester and Rochester Institute of Technology provides precise control over phonons at the nanoscale level. This could give new insights into the nature of gravity, particle acceleration, and quantum physics.
In a paper in Nature Communications, the researchers describe how they coax these individual particles of mechanical motion to behave like a laser.
In quantum technologies, everything depends on the ability to detect the properties carried by a single photon. But in the real world, that photon of interest is often buried in a sea of unwanted light—a true “needle in a haystack” challenge that currently limits the deployment of many applications, including secure quantum communication, quantum sensors used in telescope networks, as well as the interconnection of quantum computers to accelerate the development of new drugs and materials.
At the Institut national de la recherche scientifique (INRS), the team of Professor José Azaña, in collaboration with Professor Roberto Morandotti’s group, has developed a surprisingly simple and energy-efficient way to overcome this obstacle. The work was carried out by Benjamin Crockett during his Ph.D. at the INRS Énergie Matériaux Télécommunications Research Centre. He recently completed his degree and is now a Banting postdoctoral fellow at the University of British Columbia (UBC).
Their method not only reduces noise but, more importantly, recovers essential quantum properties that would otherwise be lost in bright environments where current technologies fail.
Waterloo scientists have developed a new way to understand how the universe began, and it could change what we know about the Big Bang and the earliest moments of cosmic history. Their work suggests that the universe’s rapid early expansion could have arisen naturally from a deeper, more complete theory of quantum gravity. The paper, “Ultraviolet completion of the Big Bang in quadratic gravity,” appears in Physical Review Letters.
Dr. Niayesh Afshordi, professor of physics and astronomy at the University of Waterloo and Perimeter Institute (PI), led the research team that explored a novel method of combining gravity with quantum physics, the rules that govern how the smallest particles in the universe behave. While general relativity has been successful for more than a century, it breaks down at the extreme conditions that existed at the birth of the universe. To address this problem, the team used Quadratic Quantum Gravity, which remains mathematically consistent even at extremely high energies—similar to the kind present during the Big Bang.
Most existing explanations for the Big Bang rely on Einstein’s theory of gravity, plus additional components added by hand. This new approach offers a more unified picture that connects the earliest moments of the universe to the well-tested cosmology scientists observe today.
Quantum technologies, devices that can process, store, or detect information leveraging quantum mechanical effects, could outperform classical devices in some tasks or scenarios. Despite their potential, verifying that these devices work correctly and truly realize desired quantum states can be challenging, particularly when they cannot be fully examined or inspected.
One approach to verify quantum states or measurements is known as self-testing. This is a technique that allows quantum scientists to confirm the properties of a quantum system solely by analyzing its outputs, instead of examining how it operates internally.
Researchers at Université libre de Bruxelles (ULB), the University of Gdansk, and the Polish Academy of Sciences recently introduced a new universal scheme that could be used to self-test any quantum state or measurement. Their protocol, introduced in a paper published in Nature Physics, works by placing a device within a simple star-shaped quantum network and assessing the correlations between measurements obtained from different outputs that share entangled quantum states, to determine whether they are aligned with theoretical predictions.
Quantum computers, systems that process information leveraging quantum mechanical effects, could outperform classical computers on some computationally demanding tasks. Despite their potential, as the size of quantum computers increases, reliably describing and measuring the states driving their functioning becomes increasingly difficult.
One mathematical approach to simplify the description of quantum systems entails the use of matrix-product operators (MPOs). These are mathematical representations that allow researchers to break down very large systems into a long chain of connected smaller pieces.
Researchers at Université Grenoble Alpes, Technical University of Munich, Max Planck Institute of Quantum Optics, University of Innsbruck and University of Bologna recently developed a new protocol that could be used to learn the MPO representations of quantum states in real, large-scale quantum experiments. Their protocol, presented in a paper published in Physical Review Letters, has so far been found to reliably reconstruct states in quantum systems including up to 96 qubits.
Civilizations at the end of time—how intelligence could survive heat death, cosmic isolation, entropy, and the universe’s longest future eras. Take back your personal data with Incogni! Use code isaacarthur at the link below and get 60% off annual plans: https://incogni.com/isaacarthur.
🛒 SFIA Merchandise: https://isaac-arthur-shop.fourthwall… Visit our Website: http://www.isaacarthur.net ❤️ Support us on Patreon: / isaacarthur ⭐ Support us on Subscribestar: https://www.subscribestar.com/isaac-a… 👥 Facebook Group: / 1,583,992,725,237,264 📣 Reddit Community: / isaacarthur 🐦 Follow on Twitter / X: / isaac_a_arthur 💬 SFIA Discord Server: / discord Credits: Civilizations at the End of Time — How Intelligence Survives the Death of the Universe Written, Produced & Narrated by: Isaac Arthur Script Editors: Andy Popescu, Briana Brownell, Connor Hogan, Darius Said, David McFarlane, Edward Nardella, Eustratius Graham, Gregory Leal, Jefferson Eagley, Keith Blockus, Konstantin Sokerin, Luca de Rosa, Ludwig Luska, Lukas Konecny, Michael Gusevsky, Mitch Armstrong, MolbOrg, Naomi Kern, Philip Baldock, Sigmund Kopperud, Steve Cardon, Tiffany Penner, Yamagishi Graphics Courtesy of: Edward Nardella, Jakub Grygier, Jarred Eagley, Jeremy Jozwik, Justin Dixon, Katie Byrne, Ken York of YD Visual, LegionTech Studios, Mafic Studios, Misho Yordanov, Murat Mamkegh, Pierre Demet, Sergio Botero, Stefan Blandin, Udo Schroeter, and Select imagery/video supplied by Getty Images Music Courtesy of: AJ Prasad, Chris Zabriskie, Dan McLeod, NeptuneUK, Lombus, Markus Junnikkala, Miguel Johnson, Phase Shift, Stellardrone, Taras Harkavyi, and Epidemic Sound: http://nebula.tv/epidemic & Stellardrone Chapters 0:00 Intro 7:11 Eternal Intelligence 49:09 Incogni 50:30 Choosing the Long Night 55:24 The Last Planet 1:27:35 When Survival Stops Being Local 1:32:38 The Omega Point 2:05:18 Big Crunch Revisited — Uncertainty Returns 2:11:09 Iron Stars 2:51:05 The Big Slurp & Vacuum Decay 2:58:23 The Big Rip 3:32:13 After the End of Time — Quantum Resurrection & Poincare Recurrence 3:34:25 Galileo. 🌐 Visit our Website: http://www.isaacarthur.net. ❤️ Support us on Patreon: / isaacarthur. ⭐ Support us on Subscribestar: https://www.subscribestar.com/isaac-a… 👥 Facebook Group: / 1583992725237264 📣 Reddit Community: / isaacarthur. 🐦 Follow on Twitter / X: / isaac_a_arthur. 💬 SFIA Discord Server: / discord. Credits: Civilizations at the End of Time — How Intelligence Survives the Death of the Universe. Written, Produced & Narrated by: Isaac Arthur. Script Editors: Andy Popescu, Briana Brownell, Connor Hogan, Darius Said, David McFarlane, Edward Nardella, Eustratius Graham, Gregory Leal, Jefferson Eagley, Keith Blockus, Konstantin Sokerin, Luca de Rosa, Ludwig Luska, Lukas Konecny, Michael Gusevsky, Mitch Armstrong, MolbOrg, Naomi Kern, Philip Baldock, Sigmund Kopperud, Steve Cardon, Tiffany Penner, Yamagishi. Graphics Courtesy of: Edward Nardella, Jakub Grygier, Jarred Eagley, Jeremy Jozwik, Justin Dixon, Katie Byrne, Ken York of YD Visual, LegionTech Studios, Mafic Studios, Misho Yordanov, Murat Mamkegh, Pierre Demet, Sergio Botero, Stefan Blandin, Udo Schroeter, and Select imagery/video supplied by Getty Images. Music Courtesy of: AJ Prasad, Chris Zabriskie, Dan McLeod, NeptuneUK, Lombus, Markus Junnikkala, Miguel Johnson, Phase Shift, Stellardrone, Taras Harkavyi, and Epidemic Sound: http://nebula.tv/epidemic & Stellardrone.
Chapters. 0:00 Intro. 7:11 Eternal Intelligence. 49:09 Incogni. 50:30 Choosing the Long Night. 55:24 The Last Planet. 1:27:35 When Survival Stops Being Local. 1:32:38 The Omega Point. 2:05:18 Big Crunch Revisited — Uncertainty Returns. 2:11:09 Iron Stars. 2:51:05 The Big Slurp & Vacuum Decay. 2:58:23 The Big Rip. 3:32:13 After the End of Time — Quantum Resurrection & Poincare Recurrence. 3:34:25 Galileo
Quantum computers, systems that process information leveraging quantum mechanical effects, could outperform classical computers on some advanced tasks. These systems rely on qubits, the fundamental units of quantum information, that become linked via an effect known as quantum entanglement and share a unified quantum state.
Qubits are known to be highly sensitive to slight changes or disturbances in their surrounding environment, also referred to as noise. Noise can prompt them to lose quantum information via a process called decoherence, which in turn leads to errors.
In recent years, quantum scientists and engineers have introduced various approaches aimed at mitigating or correcting quantum errors, with the goal of realizing fault-tolerant quantum computing. Some of these approaches rely on so-called erasure qubits, qubits whose errors are easier to detect and locate in real time.
