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Category: quantum physics – Page 35

Quantum error correction that suppresses errors below a critical threshold needed for achieving future practical quantum computing applications is demonstrated on the newest generation quantum chips from Google Quantum AI, reports a paper in Nature this week. The device performance, if scaled, could facilitate the operational requirements of large-scale fault-tolerant quantum computing.

Quantum computing has the potential to speed up computing and exceed the capabilities of classical computers at certain tasks. However, quantum computers are prone to errors, making current prototypes unable to run long enough to achieve practical outputs.

The strategy devised by researchers to address this relies on quantum error correction, where information is spread over many qubits (units of quantum information, similar to classical computer bits) allowing the identification and compensation of errors without damaging the computation. The overhead in required by quantum error correction potentially introduces more errors than it corrects.

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The authors demonstrate electrically pumped continuous-wave operation of a SiGeSn/GeSn lasers. The devices are based on a multi-quantum-well design in a small footprint micro-disk cavity resulting in driving parameters compatible with on-chip operation.

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A new study by Rice University physicist Qimiao Si unravels the enigmatic behaviors of quantum critical metals—materials that defy conventional physics at low temperatures. Published in Nature Physics Dec. 9, the research examines quantum critical points (QCPs), where materials teeter on the edge between two distinct phases, such as magnetism and nonmagnetism. The findings illuminate the peculiarities of these metals and provide a deeper understanding of high-temperature superconductors, which conduct electricity without resistance at relatively high temperatures.

Key to this study is , a delicate state where the material becomes ultrasensitive to quantum fluctuations—microscopic disturbances that alter electron behavior. While ordinary metals obey well-established principles, quantum critical metals defy these norms, exhibiting strange and collective properties that have long puzzled scientists. Physicists call such systems “strange metals.”

“Our work dives into how quasiparticles lose their identity in strange metals at these quantum critical points, which leads to unique properties that defy traditional theories,” said Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy and director of Rice’s Extreme Quantum Materials Alliance.

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A team of researchers from the University of Cologne, Hasselt University (Belgium) and the University of St Andrews (Scotland) has succeeded in using the quantum mechanical principle of strong light-matter coupling for an optical technology that overcomes the long-standing problem of angular dependence in optical systems.

The study, “Breaking the angular dispersion limit in thin film optics by ultra-strong light-matter coupling,” published in Nature Communications presents ultra-stable thin-film polariton filters that open new avenues in photonics, sensor technology, optical imaging and display technology.

The study at the University of Cologne was led by Professor Dr. Malte Gather, director of the Humboldt Center for Nano-and Biophotonics at the Department of Chemistry and Biochemistry of the Faculty of Mathematics and Natural Sciences.

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Science and Technology: Google said its quantum computer, based on a computer chip called Willow, needed less than five minutes to perform a mathematical calculation that one of the world’s most powerful supercomputers could not complete in 10 septillion years, a length of time that exceeds the age of the known universe.

Electronic skins (e-skins) are flexible sensing materials designed to mimic the human skin’s ability to pick up tactile information when touching objects and surfaces. Highly performing e-skins could be used to enhance the capabilities of robots, to create new haptic interfaces and to develop more advanced prosthetics.

In recent years, researchers and engineers have been trying to develop e-skins with individual tactile units (i.e., taxels) that can accurately sense both normal (i.e., perpendicular) and shear (i.e., lateral) forces. While some of these attempts were successful, most existing multi-axis sensors are based on intricate designs or require complex fabrication and calibration processes, which limits their widespread deployment.

Researchers at CNRS-University of Montpellier have introduced a new soft e-skin that leverages magnetic fields to independently detect forces on three axes. This e-skin, described in a paper published in Nature Machine Intelligence, has a simple design that could be easy to reproduce on a large scale.

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Currently, dark matter detection requires specialized laboratories with costly equipment. ODIN has the potential to overcome this limitation.

“ODIN’s sensitivity is primarily dependent on phonon density rather than target volume, in contrast to existing systems. This feature may enable compact, low-cost detectors, with the ability to perform lock-in dark matter detection by periodically depopulating the phonon mode,” the study authors explain.

Moreover, the proposed device design features only one optomechanical cavity. Instruments with multiple cavities could result in more exciting results.

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Researchers at Google have built a chip that has enabled them to demonstrate the first ‘below threshold’ quantum calculations — a key milestone in the quest to build quantum computers that are accurate enough to be useful.

The experiment, described on 9 December in Nature1, shows that with the right error-correction techniques, quantum computers can perform calculations with increasing accuracy as they are scaled up — with the rate of this improvement exceeding a crucial threshold. Current quantum computers are too small and too error-prone for most commercial or scientific applications.

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