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Category: quantum physics – Page 229

In 1960, Luttinger proposed a universal principle connecting the total capacity of a system for particles with its response to low-energy excitations. Although easily confirmed in systems with independent particles, this theorem remains applicable in correlated quantum systems characterized by intense inter-particle interactions.

However, and quite surprisingly, Luttinger’s theorem has been shown to fail in very specific and exotic instances of strongly correlated phases of matter. The failure of Luttinger’s theorem and its consequences on the behavior of quantum matter are at the core of intense research in condensed matter physics.

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An international collaboration, led by Macquarie University scientists, has introduced a new quantum optics technique that can provide unprecedented access to the fundamental properties of light-matter interactions in semiconductors.

The research, published Jan. 15 in the journal Nature Physics, uses a novel spectroscopic technique to explore interactions between photons and electrons at the .

Professor Thomas Volz, co-author of the study and research group leader at Macquarie University’s School of Mathematical and Physical Sciences, says the work has the potential to drive a breakthrough in the global quest for accessible quantum photonic technologies.

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The Hilbert space of a physical qubit typically features more than two energy levels. Using states outside the qubit subspace can provide advantages in quantum computation. To benefit from these advantages, individual states of the $d$-dimensional qudit Hilbert space have to be discriminated during readout. We propose and analyze two measurement strategies that improve the distinguishability of transmon qudit states. Based on a model describing the readout of a transmon qudit coupled to a resonator, we identify the regime in hardware parameter space where each strategy is optimal. We discuss these strategies in the context of a practical implementation of the default measurement of a ququart on IBM Quantum hardware whose states are prepared by employing higher-order $X$ gates that make use of two-photon transitions.

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A significant breakthrough has been achieved by quantum physicists from Dresden and Würzburg. They’ve created a semiconductor device where exceptional robustness and sensitivity are ensured by a quantum phenomenon. This topological skin effect shields the functionality of the device from external perturbations, allowing for measurements of unprecedented precision.

This remarkable advance results from the clever arrangement of contacts on the aluminum-gallium-arsenide material. It unlocks potential for high-precision quantum modules in topological physics, bringing these materials into the industry’s focus. These results, published in Nature Physics, mark a major milestone.

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Quasicrystals are intermetallic materials that have garnered significant attention from researchers aiming to advance condensed matter physics understanding. Unlike normal crystals, in which atoms are arranged in an ordered repeating pattern, quasicrystals have non-repeating ordered patterns of atoms.

Their unique structure leads to many exotic and interesting properties, which are particularly useful for practical applications in spintronics and magnetic refrigeration.

A unique quasicrystal variant, known as the Tsai-type icosahedral quasicrystal (iQC) and their cubic approximant crystals (ACs), display intriguing characteristics. These include long-range ferromagnetic (FM) and anti-ferromagnetic (AFM) orders, as well as unconventional quantum critical phenomenon, to name a few.

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It is widely accepted that consciousness or, more generally, mental activity is in some way correlated to the behavior of the material brain. Since quantum theory is the most fundamental theory of matter that is currently available, it is a legitimate question to ask whether quantum theory can help us to understand consciousness. Several approaches answering this question affirmatively, proposed in recent decades, will be surveyed. There are three basic types of corresponding approaches: consciousness is a manifestation of quantum processes in the brain, quantum concepts are used to understand consciousness without referring to brain activity, and matter and consciousness are regarded as dual aspects of one underlying reality. Major contemporary variants of these quantum-inspired approaches will be discussed.

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Scientists at Heriot-Watt University in Edinburgh, Scotland, have found a powerful new way to program optical circuits that are critical to the delivery of future technologies such as unhackable communications networks and ultrafast quantum computers.

“Light can carry a lot of information, and optical circuits that compute with light—instead of electricity—are seen as the next big leap in computing technology,” explains Professor Mehul Malik, an experimental physicist and Professor of Physics at Heriot-Watt’s School of Engineering and Physical Sciences.

“But as optical circuits get bigger and more complex, they’re harder to control and make—and this can affect their performance. Our research shows an alternative—and more versatile—way of engineering optical circuits, using a process that occurs naturally in nature.”

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“In recent years, the clinical development of liquid biopsies for cancer, a revolutionary screening tool, has created great optimism,” write Liz Kwo and Jenna Aronson in the American Journal of Managed Care.

At present, liquid biopsies can detect more than 50 different types of cancer. A standard visit to the doctor may eventually be able to detect cancers years before they become lethal.

In the future, even the toilet in your bathroom may be sensitive enough to detect the signs of cancer cells, enzymes and genes circulating in your bodily fluids, so that cancer becomes no more lethal than the common cold. Every time you go to the bathroom, you might be tested for cancer. The “smart toilet” might become our first line of defense.

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We all mark days with clocks and calendars, but perhaps no timepiece is more immediate than a mirror. The changes we notice over the years vividly illustrate science’s “arrow of time”—the likely progression from order to disorder. We cannot reverse this arrow any more than we can erase all our wrinkles or restore a shattered teacup to its original form.

Or can we?

An international team of scientists led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory explored this question in a first-of-its-kind experiment, managing to return a computer briefly to the past. The results, published March 13 in the journal Scientific Reports, suggest new paths for exploring the backward flow of time in . They also open new possibilities for quantum computer program testing and .

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