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Category: quantum physics – Page 77

Quantum computers have the potential of outperforming classical computers on some optimization and computational tasks. Compared to classical systems, however, quantum systems are more prone to errors, as they are more sensitive to noise and prone to so-called decoherence.

Decoherence is a process via which a quantum system loses its quantum properties due to interactions with its surrounding environment, causing a loss of quantum information and errors. This loss of coherence can be caused by a range of external disturbances, including material defects, temperature fluctuations and .

In recent years, physicists and engineers worldwide have been trying to devise effective methods to reduce decoherence and thus improve the reliability of quantum computers. The sources of decoherence in include so-called two-level systems (TLSs), which are a class of material defects that arise from the random switching between two energy states, which can disrupt the stability of qubits.

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In an advance for quantum technologies, researchers at the Cavendish Laboratory, University of Cambridge, have created a functional quantum register using the atoms inside a semiconductor quantum dot.

Published in Nature Physics, the work demonstrates the introduction of a new type of optically connected qubits—a critical advance in the development of quantum networks, where stable, scalable, and versatile quantum nodes are essential.

Quantum dots are nanoscale objects with unique optical and electronic properties that come from quantum mechanical effects. These systems are already used in technologies like display screens and , and their adoption in quantum communication has been mostly due to their ability to operate as bright single-photon sources.

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An article published in the journal Optica describes the development of a new experimental device that explores the boundary between classical and quantum physics, allowing the simultaneous observation and investigation of phenomena from both worlds.

The instrument was developed in Florence and is the result of collaboration within the extended partnership of the National Quantum Science and Technology Institute (NQSTI), involving the Department of Physics and Astronomy at the University of Florence, the National Institute of Optics of the National Research Council (CNR-INO), as well as the European Laboratory for Nonlinear Spectroscopy (LENS) and the Florence branch of the National Institute for Nuclear Physics (INFN).

It is well known that the study of matter, as we progress to increasingly smaller scales, shows radically different behaviors from those observed at the macroscopic scale: this is where comes into play, helping to understand the properties of matter in the world of the infinitely small. While these phenomena have been studied separately until now, the instrument developed by CNR-INO researchers allows for the experimental exploration of matter’s behavior from both perspectives.

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To store ever more data in electronic devices of the same size, the manufacturing processes for these devices need to be studied in greater detail. By investigating new approaches to making digital memory at the atomic scale, researchers engaged in a public-private partnership are aiming to address the endless demand for denser data storage.

One such effort has focused on developing the ideal manufacturing process for a type of digital memory known as 3D NAND flash memory, which stacks data vertically to increase storage density.

The narrow, deep holes required for this type of memory can be etched twice as fast with the right and other key ingredients, according to a study published in the Journal of Vacuum Science & Technology A.

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It is one of the most important laws of nature that we know: The famous second law of thermodynamics says that the world gets more and more disordered when random chance is at play. Or, to put it more precisely: that entropy must increase in every closed system.

Ordered structures lose their order, regular ice crystals turn into water, porcelain vases are broken up into shards. At first glance, however, quantum physics does not really seem to adhere to this rule: Mathematically speaking, in always remains the same.

A research team at TU Wien has now taken a closer look at this apparent contradiction and has been able to show that it depends on what kind of entropy you look at. If you define the concept of entropy in a way that is compatible with the basic ideas of quantum physics, then there is no longer any contradiction between quantum physics and thermodynamics.

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However, a new study proves that hydrogen bonds can effectively link spin centers, enabling easier assembly of molecular spin qubits. This discovery could transform quantum material development by leveraging supramolecular chemistry.

A Light-Driven Approach to Spin Qubits

Qubits are the fundamental units of information in quantum technology. A key challenge in developing practical quantum applications is determining what materials these qubits should be made of. Molecular spin qubits are particularly promising for molecular spintronics, especially in quantum sensing. In these systems, light can stimulate certain materials, creating a second spin center and triggering a light-induced quartet state.

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How can the latest technology, such as solar cells, be improved? An international research team led by the University of Göttingen is helping to find answers to questions like this with a new technique. For the first time, the formation of tiny, difficult-to-detect particles—known as dark excitons—can be tracked precisely in time and space. These invisible carriers of energy will play a key role in future solar cells, LEDs and detectors. The results are published in Nature Photonics.

Dark excitons are tiny pairs made up of one electron together with the hole it leaves behind when it is excited. They carry energy but cannot emit light (hence the name “dark”). One way to visualize an is to imagine a balloon (representing the electron) that flies away and leaves behind an empty space (the hole) to which it remains connected by a force known as a Coulomb interaction. Researchers talk about “particle states” that are difficult to detect but are particularly important in atomically thin, two-dimensional structures in special semiconductor compounds.

In an earlier publication, the research group led by Professor Stefan Mathias from the Faculty of Physics at the University of Göttingen was able to show how these dark excitons are created in an unimaginably short time and describe their dynamics with the help of quantum mechanical theory.

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What if time didn’t just move forward? Scientists have uncovered something astonishing in a recent quantum physics experiment — the existence of ‘negative time.’ This mind-bending discovery defies conventional logic, suggesting that particles may not follow the rules we thought were unbreakable.

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In a monumental stride toward the realization of practical quantum computing and advanced quantum networks, researchers at the prestigious Cavendish Laboratory of the University of Cambridge have successfully crafted a fully operational quantum register utilizing the atomic properties within a semiconductor quantum dot. This innovative development could pave the way for pivotal advancements in quantum information technology, crucial for the anticipated future where quantum networking integrates into everyday digital communications.

This breakthrough is detailed in a publication in Nature Physics, where it reveals the introduction of an entirely new category of qubits that are optically interconnected. As the field of quantum networking progresses, the need for stable, scalable, and adaptable quantum nodes has become increasingly evident. The research team’s focus on quantum dots is particularly advantageous, as these nanoscale entities possess unique optical and electronic attributes intrinsic to quantum mechanical phenomena.

Quantum dots have demonstrated considerable potential in existing technologies, such as medical imaging and display screens, primarily due to their efficacy as bright single-photon sources. However, to create functional quantum networks, it is essential not only to emit single photons but also to establish reliable qubits that can effectively interact with these emitted photons. Moreover, these qubits must be capable of locally storing quantum information over extended periods. The researchers’ development enhances the inherent spins of the nuclear atoms within the quantum dots, optimizing them into a cohesive many-body quantum register.

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