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Category: quantum physics – Page 226

A research team led by Professor Jong-min Choi of the Department of Energy Engineering has developed a technology that can significantly improve the efficiency of quantum dot photovoltaic cells by introducing organic solvent dispersible MXene.

The findings were published in Advanced Energy Materials (“Organic solvent dispersible MXene integrated colloidal quantum dot photovoltaics”).

Comparison of the dispersibility of quantum dot solar cell ink organic solvent according to surface modification of MXene. (Image: DGIST)

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A team led by researchers at Osaka University and University of California, San Diego has conducted simulations of creating matter solely from collisions of light particles. Their method circumvents what would otherwise be the intensity limitations of modern lasers and can be readily implemented by using presently available technology. This work might help experimentally test long-standing theories such as the Standard Model of particle physics, and possibly the need to revise them.

One of the most striking predictions of quantum physics is that matter can be generated solely from light (i.e., photons), and in fact, the astronomical bodies known as pulsars achieve this feat. Directly generating matter in this manner has not been achieved in a laboratory, but it would enable further testing of the theories of basic quantum physics and the fundamental composition of the universe.

In a study published in Physical Review Letters, a team led by researchers at Osaka University has simulated conditions that enable photon–photon collisions, solely by using lasers. The simplicity of the setup and ease of implementation at presently available laser intensities make it a promising candidate for near-future experimental implementation.

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A recent study published in the journal Physical Review D marks a significant advancement in cosmology. A team of researchers has analyzed over one million galaxies to delve into the origins of the universe’s current cosmic structures.

This study contributes to the understanding of the ΛCDM model, the standard framework for the universe, which posits the significance of cold dark matter (CDM) and dark energy (the cosmological constant, Λ).

The model theorizes that primordial fluctuations, originating at the universe’s inception, acted as catalysts for the formation of all celestial objects, including stars, galaxies, and galaxy clusters.

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Harvard’s breakthrough in quantum computing features a new logical quantum processor with 48 logical qubits, enabling large-scale algorithm execution on an error-corrected system. This development, led by Mikhail Lukin, represents a major advance towards practical, fault-tolerant quantum computers.

In quantum computing, a quantum bit or “qubit” is one unit of information, just like a binary bit in classical computing. For more than two decades, physicists and engineers have shown the world that quantum computing is, in principle, possible by manipulating quantum particles ­– be they atoms, ions or photons – to create physical qubits.

But successfully exploiting the weirdness of quantum mechanics for computation is more complicated than simply amassing a large-enough number of physical qubits, which are inherently unstable and prone to collapse out of their quantum states.

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Quantum computing is often hailed as the next frontier of technology, promising to solve some of the most complex and challenging problems in science, engineering, and business. But how close are we to achieving this quantum dream, and what are the limitations of this emerging field?

As IEEE Spectrum shares in its detailed report, some of the leading voices in quantum computing have recently expressed doubts and concerns about the technology’s current state and prospects. They argue that quantum computers are far from being ready for practical use and that their applications are more restricted than commonly assumed.

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Purdue quantum researchers twist double bilayers of an antiferromagnet to demonstrate tunable moiré magnetism.

Twistronics isn’t a new dance move, exercise equipment, or new music fad. No, it’s much cooler than any of that. It is an exciting new development in quantum physics and material science where van der Waals materials are stacked on top of each other in layers, like sheets of paper in a ream that can easily twist and rotate while remaining flat, and quantum physicists have used these stacks to discover intriguing quantum phenomena.

Adding the concept of quantum spin with twisted double bilayers of an antiferromagnet, it is possible to have tunable moiré magnetism. This suggests a new class of material platform for the next step in twistronics: spintronics. This new science could lead to promising memory and spin-logic devices, opening the world of physics up to a whole new avenue with spintronic applications.

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In a typical battery, charged ions zip one way through a sea of other particles as the battery recharges, before racing back in the other direction to release the stored energy on cue.

Back and forth the ions go, some getting diverted along the way, until the capacity of the battery is drained, and it loses energy too quickly to be of any use.

But physicists, good on them, are imagining new ways of storing energy in handy portable devices by drawing on a strange quantum phenomenon that twists time, amongst other unusual happenings.

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Major technical improvements to a quantum computer based on trapped ions could bring a large-scale version closer to reality.

Scientists are exploring various platforms for future large-scale quantum computation. Among the leading contenders, those in which the quantum bits (qubits) are trapped ions stand out for their low-error operation. However, scaling up such platforms to the millions of qubits needed for utility-scale quantum computing is a daunting task. Now Steven Moses at Quantinuum in Colorado and colleagues describe an impressive new trapped-ion quantum computer, the Quantinuum System Model H2, in which they have been able to increase the number of qubits (from 20 to 32) without increasing the error rate [1]. The researchers have put this system through its paces with full component-level testing, a suite of industry-standard benchmark tests, and a set of diverse applications.

In a typical trapped-ion quantum computer, a linear chain of ions is confined by an electric potential using direct-current (dc) and radio-frequency (rf) fields. Whereas the ion-trap apparatus can be at any temperature, the ions themselves need to be laser cooled to near their ground state. Their motion can then be quantized, and the resulting motional modes can be used to entangle any pair of ions in the chain—a requirement for performing quantum operations. However, controlling individual ions in a long chain comes with its own technical difficulties, and it is unlikely that a million qubits—as needed to build a universal, fault-tolerant quantum computer [2]—could be trapped in a single potential.

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