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Category: quantum physics

Attosecond interferometry meets quantum optics

Experimental attosecond science is built around the ability to generate and control light flashes lasting billionths of a billionth of a second. Such extreme pulses can be created through high harmonic generation (HHG), where an intense laser field drives electrons out of atoms or solids and then forces them back, releasing bursts of extreme ultraviolet radiation. Techniques like this have transformed our ability to observe electron motion on its natural timescale.

To extract information from such ultrafast processes, physicists often rely on attosecond interferometry. By combining a strong laser field with a weaker second colour, different electron trajectories are made to interfere, imprinting timing and phase information onto the emitted harmonics. Over recent years, these schemes have become standard tools for attosecond metrology and spectroscopy.

New buried-growth process enables 2D arrays of position- and orientation-controlled diamond qubits

Researchers at Kanazawa University, in collaboration with Diamond and Carbon Applications (Germany), have developed a buried-growth process for nitrogen–vacancy (NV) centers in diamond using microwave plasma chemical vapor deposition (MPCVD). By employing nitrogen-radical selective etching, which simultaneously enhances metal-mask durability through nitridation, the team enabled a continuous etching–growth sequence within a single MPCVD process.

The work is published in the journal Carbon.

Optical measurements confirmed highly aligned NV centers selectively buried in predefined regions. This integrated approach provides a stable and scalable platform for orientation-controlled diamond qubits and future room-temperature quantum technologies.

Physicists observe synchronized quantum dance of excitons and phonons

An international team of researchers has reported a major advance in understanding quantum dynamics in semiconductor materials. They directly observed how excitons and phonons evolve together in perovskite nanocrystals, revealing a fully coherent quantum dance between light-induced electronic excitations and crystal lattice vibrations. They published their findings in Nature Communications.

An exciton is created when light excites an electron inside a semiconductor. The electron absorbs energy and leaves behind a positively charged “hole”; the two bind together and move through the crystal as a single quantum object. A phonon is a different kind of quantum object, as it is a quantum of crystal lattice vibration. Though fundamentally different objects, in perovskites they are strongly linked and evolve together as a coupled quantum system.

Perovskite nanocrystals are miniature crystals only a few nanometers in size, a thousand times smaller than the thickness of a hair. Each crystal forms a nanoscale “box” that traps both excitons and phonons. This confinement makes the interaction between them especially strong: An exciton inside the nanocrystal is tightly coupled to vibrations of the surrounding crystal lattice.

Physicists harness potential of quantum phase transitions

Researchers at University College Dublin and international collaborators have just published a detailed and accessible guide that aims to translate theoretical ideas into practical devices for quantum enhanced sensing technologies.

Conventional sensors have enabled technologies from global positioning systems to satellite imaging. Quantum systems, however, provide the absolute best precision allowable by the laws of physics.

The challenge, however, is that quantum devices are often fragile. A promising theoretical avenue for designing quantum sensors not hindered by this fragility is called “critical quantum sensing.”

Quantum memory surpasses classical limits for storing unknown quantum operations

Quantum memories, systems that store and retrieve information leveraging quantum mechanical effects, can outperform classical storage systems on some existing tasks. Yet these promising memories could also complete operations that are very difficult or impossible for classical systems, including the storage and retrieval of so-called isometry channels.

Isometry channels are transformations that entail mapping a smaller quantum system onto a larger one while preserving quantum information.

In a paper published in Physical Review Letters, researchers at the University of Tokyo showed that quantum methods significantly outperform classical ones in the storage and retrieval of these transformations.

Scientists identify the origin of noise in spin qubit quantum processors

A spin qubit, in which quantum information is encoded in the spin state of an electron, is one of the most promising platforms for quantum computing. Spin qubits exhibit long coherence times and are compatible with advanced semiconductor manufacturing technologies. The leading implementation of spin qubits involves confined electrons inside quantum dots, a nanoscale semiconductor architecture that behaves like a controllable artificial atom. Recent advances have enabled high-fidelity operation of single- and two-qubit gates, exceeding the threshold required for certain surface code quantum error correction techniques.

Cloud-tested quantum noise model predicts superconducting qubit errors with sevenfold better accuracy

Researchers from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and Johns Hopkins University in Baltimore have developed a practical, comprehensive noise-modeling framework for a popular class of superconducting quantum processors. Their work, published in the journal PRX Quantum, offers a sevenfold improvement in predictive accuracy over existing approaches.

Quantum bits, or qubits, are intrinsically prone to noise—interference arising from environmental factors such as electrical and magnetic fields or temperature fluctuations—as a result of the extreme sensitivity that makes them so valuable for computing. Developing accurate noise models is key to creating the robust quantum algorithms and resilient error-correction protocols required to build truly fault-tolerant quantum computers.

“To really advance the field, we need models that can predict a wide range of behavior while utilizing a small number of parameters, rather than theoretical models that try to account for all of the fundamental physics at play in quantum interactions,” said project lead Gregory Quiroz, a senior physicist at APL and an associate research professor in the Department of Physics and Astronomy at the Johns Hopkins University Krieger School of Arts and Sciences. “The novelty of our approach lies in a unified and experimentally validated framework that connects multiple noise mechanisms and yields a coherent predictive methodology.”

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