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Category: quantum physics – Page 5

Researchers have demonstrated a new quantum sensing technique that widely surpasses conventional methods, potentially accelerating advances in fields ranging from medical imaging to foundational physics research, as shown in a study published in Nature Communications.

For decades, the performance of quantum sensors has been limited by decoherence, which is unpredictable behavior caused by environmental noise.

“Decoherence causes the state of a quantum system to become randomly scrambled, erasing any quantum sensing signal,” said Eli Levenson-Falk, senior author of the study, associate professor of physics and astronomy at the USC Dornsife College of Letters, Arts and Sciences and associate professor of electrical and computer engineering at the USC Viterbi School of Engineering.

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It’s easy to solve a 3×3 Rubik’s cube, says Shantanu Chakrabartty, the Clifford W. Murphy Professor and vice dean for research and graduate education in the McKelvey School of Engineering at Washington University in St. Louis. Just learn and memorize the steps then execute them to arrive at the solution.

Computers are already good at this kind of procedural problem solving. Now, Chakrabartty and his collaborators have developed a tool that can go beyond procedure to discover new solutions to complex in logistics to .

Chakrabartty and his collaborators introduced NeuroSA, a problem-solving neuromorphic architecture modeled on how human neurobiology functions, but that leverages quantum mechanical behavior to find optimal solutions—guaranteed—and find those solutions more reliably than state-of-the-art methods.

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An atomic clock research team from the National Time Service Center of the Chinese Academy of Sciences has proposed and implemented a compact optical clock based on quantum interference enhanced absorption spectroscopy, which is expected to play an important role in micro-positioning, navigation, timing (μPNT) and other systems.

Inspired by the successful history of the coherent population trapping (CPT)-based chip-scale microwave atomic clock and the booming of optical microcombs, a chip-scale optical clock was also proposed and demonstrated with better frequency stability and accuracy, which is mainly based on two-photon transition of Rubidium atom ensemble.

However, the typically required high cell temperatures (~100 ℃) and laser powers (~10 mW) in such a configuration are not compliant with the advent of a fully miniaturized and optical clock.

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He Qinglin’s group at the Center for Quantum Materials Science, School of Physics, has reported the first observation of non-reciprocal Coulomb drag in Chern insulators. This breakthrough opens new pathways for exploring Coulomb interactions in magnetic topological systems and enhances our understanding of quantum states in such materials. The work was published in Nature Communications.

Coulomb arises when a current in one conductor induces a measurable voltage in a nearby, electrically insulated conductor via long-range Coulomb interactions.

Chern insulators are magnetic topological materials that show a quantized Hall effect without , due to intrinsic magnetization and chiral edge states.

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Many atomic nuclei have a magnetic field similar to that of Earth. However, directly at the surface of a heavy nucleus such as lead or bismuth, it is trillions of times stronger than Earth’s field and more comparable to that of a neutron star. Whether we understand the behavior of an electron in such strong fields is still an open question.

A research team led by TU Darmstadt at the GSI Helmholtz Center for Heavy Ion Research has now taken an important step toward clarifying this question. Their findings have been published in Nature Physics. The results confirm the .

Hydrogen-like ions, i.e., to which only a is bound, are theoretically particularly easy to describe. In the case of heavy nuclei with a high proton number—bismuth, for example, has 83 positively charged protons in its nucleus—the strong electrical attraction binds the electron close to the nucleus and thus within this extreme . There, the electron aligns its own magnetic field with that of the nucleus like a compass needle.

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It would be difficult to understand the inner workings of a complex machine without ever opening it up, but this is the challenge scientists face when exploring quantum systems. Traditional methods of looking into these systems often require immense resources, making them impractical for large-scale applications.

Researchers at UC San Diego, in collaboration with colleagues from IBM Quantum, Harvard and UC Berkeley, have developed a novel approach to this problem called “robust shallow shadows.” This technique allows scientists to extract essential information from more efficiently and accurately, even in the presence of real-world noise and imperfections. The research is published in the journal Nature Communications.

Imagine casting shadows of an object from various angles and then using those shadows to reconstruct the object. By using algorithms, researchers can enhance sample efficiency and incorporate noise-mitigation techniques to produce clearer, more detailed “shadows” to characterize quantum states.

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