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Category: quantum physics – Page 6
True single-photon source boosts secure key rates in quantum key distribution systems
Quantum key distribution (QKD), a cryptographic technique rooted in quantum physics principles, has shown significant potential for enhancing the security of communications. This technique enables the transmission of encryption keys using quantum states of photons or other particles, which cannot be copied or measured without altering them, making it significantly harder for malicious parties to intercept conversations between two parties while avoiding detection.
As true single-photon sources (SPS) are difficult to produce, most QKD systems developed to date rely on attenuated light sources that mimic single photons, such as low-intensity laser pulses. As these laser pulses can also contain no photons or more than one photon, only approximately 37% of pulses employed by the systems can be used to generate secure keys.
Researchers at the University of Science and Technology of China (USTC) were recently able to overcome this limitation of previously proposed QKD systems, using a true SPS (i.e., a system that can emit only one photon on demand). Their newly proposed QKD system, outlined in a paper published in Physical Review Letters, was found to outperform techniques introduced in the past, achieving a substantially higher secure key rate (SKR).
Scientists demonstrate unconditional exponential quantum scaling advantage using two 127-qubit computers
Quantum computers have the potential to speed up computation, help design new medicines, break codes, and discover exotic new materials—but that’s only when they are truly functional.
One key thing that gets in the way: noise or the errors that are produced during computations on a quantum machine—which in fact makes them less powerful than classical computers —until recently.
Daniel Lidar, holder of the Viterbi Professorship in Engineering and Professor of Electrical & Computer Engineering at the USC Viterbi School of Engineering, has been iterating on quantum error correction, and in a new study along with collaborators at USC and Johns Hopkins, has been able to demonstrate a quantum exponential scaling advantage, using two 127-qubit IBM Quantum Eagle processor-powered quantum computers, over the cloud.
Magically reducing errors in quantum computers: Researchers invent technique to decrease overhead
For decades, quantum computers that perform calculations millions of times faster than conventional computers have remained a tantalizing yet distant goal. However, a new breakthrough in quantum physics may have just sped up the timeline.
In an article titled “Efficient Magic State Distillation by Zero-Level Distillation” published in PRX Quantum, researchers from the Graduate School of Engineering Science and the Center for Quantum Information and Quantum Biology at the University of Osaka devised a method that can be used to prepare high-fidelity “magic states” for use in quantum computers with dramatically less overhead and unprecedented accuracy.
Quantum computers harness the fantastic properties of quantum mechanics such as entanglement and superposition to perform calculations much more efficiently than classical computers can. Such machines could catalyze innovations in fields as diverse as engineering, finance, and biotechnology. But before this can happen, there is a significant obstacle that must be overcome.
Phonon-mediated heat transport across materials visualized at the atomic level
Gao Peng’s research group at the International Center for Quantum Materials, School of Physics, Peking University, has developed a breakthrough method for visualizing interfacial phonon transport with sub-nanometer resolution. Leveraging fast electron inelastic scattering in electron microscopy, the team directly measured temperature fields and thermal resistance across interfaces, unveiling the microscopic mechanism of phonon-mediated heat transport at the nanoscale.
The study is published in Nature under the title “Probing phonon transport dynamics across an interface by electron microscopy.”
Phonons are central to heat conduction, electrical transport, and light interactions. In modern semiconductor devices, phonon mismatches at material interfaces create significant thermal resistance, limiting performance. Yet, existing methods lack the spatial resolution needed for today’s sub-10 nm technologies.
50 Years Later, a Quantum Mystery Has Finally Been Solved
The quantum physics community is buzzing with excitement after researchers at Rice University finally observed a phenomenon that had eluded scientists for over 70 years. This breakthrough, recently published in Science Advances is known as the superradiant phase transition (SRPT), represents a significant milestone in quantum mechanics and opens extraordinary possibilities for future technological applications.
In 1954, physicist Robert H. Dicke proposed an intriguing theory suggesting that under specific conditions, large groups of excited atoms could emit light in perfect synchronization rather than independently. This collective behavior, termed superradiance, was predicted to potentially create an entirely new phase of matter through a complete phase transition.
For over seven decades, this theoretical concept remained largely confined to equations and speculation. The primary obstacle was the infamous “no-go theorem,” which seemingly prohibited such transitions in conventional light-based systems. This theoretical barrier frustrated generations of quantum physicists attempting to observe this elusive phenomenon.
A framework for realizing a microscopic, highly precise and energy-efficient quantum clock
Over the past decades, physicists have been trying to develop increasingly sophisticated and precise clocks to reliably measure the duration of physical processes that unfold over very short periods of time, helping to validate various theoretical predictions. These include so-called quantum clocks, timekeeping systems that leverage the principles of quantum mechanics to measure time with extremely high precision.
New breakthrough enables precise activation of quantum features in diamond
A new study led by researchers at the Universities of Oxford, Cambridge and Manchester has achieved a major advance in quantum materials, developing a method to precisely engineer single quantum defects in diamond—an essential step toward scalable quantum technologies. The results have been published in the journal Nature Communications.