A 10-µm-wide microchip can generate light with any desired direction, polarization, and intensity, which will be handy for future quantum technologies.
Emerging technologies for quantum computing and cryptography require small components capable of emitting photons whose properties are precisely controlled. Researchers have been developing such components, and now a team has demonstrated a technique that provides control of direction, polarization, and intensity simultaneously [1]. Like previous experiments, the technique uses microscopic structures on a semiconductor surface to convert wave-like surface excitations to light waves. But the new demonstration uses shapes for these structures that allow more precise control over the outgoing light. The team expects the new technique to find wide use in efforts to build quantum technologies in miniature solid-state devices.
Solid-state miniaturization is one of the few realistic routes toward making quantum technologies practical, scalable, and easily manufacturable, says Fei Ding of the University of Southern Denmark. But there are not many good compact photon sources. “The technology really requires a compact and flexible solid-state photon source that gives us full control over how light is emitted—its direction, polarization, and spatial profile,” Ding says. “This is crucial for building scalable quantum and nanophotonic technologies, where single photons are used as the fundamental carriers of information.”
A research team has provided the first experimental proof that flat electronic bands in a kagome superconductor are active and directly shape electronic and magnetic behaviors.
Researchers from Rice University, working with international partners, have found the first clear evidence of active flat electronic bands within a kagome superconductor. The discovery marks an important step toward creating new strategies for designing quantum materials, including superconductors, topological insulators, and spin-based electronics, which could play a central role in advancing future electronics and computing.
The findings, published on August 14 in Nature Communications.
This tool provides scanning cryogenic thermal sensing that is 4 orders of magnitude more sensitive than previous devices allowing the detection of a sub 1 μK temperature difference. Furthermore, it is non-contact and non-invasive and allows thermal imaging of very low intensity, nanoscale energy dissipation down to the fundamental Landauer limit of 40 femtowatts for continuous readout of a single qubit at one gigahertz at 4.2 kelvin.
In a new study, physicists at the University of Colorado Boulder have used a cloud of atoms chilled down to incredibly cold temperatures to simultaneously measure acceleration in three dimensions—a feat that many scientists didn’t think was possible.
The device, a new type of atom “interferometer,” could one day help people navigate submarines, spacecraft, cars and other vehicles more precisely.
“Traditional atom interferometers can only measure acceleration in a single dimension, but we live within a three-dimensional world,” said Kendall Mehling, a co-author of the new study and a graduate student in the Department of Physics at CU Boulder. “To know where I’m going, and to know where I’ve been, I need to track my acceleration in all three dimensions.”
The researchers published their paper, titled “Vector atom accelerometry in an optical lattice,” this month in the journal Science Advances. The team included Mehling; Catie LeDesma, a postdoctoral researcher in physics; and Murray Holland, professor of physics and fellow of JILA, a joint research institutebetween CU Boulder and the National Institute of Standards and Technology (NIST) (More information about the new quantum GPS)
A new quantum device could one day help spacecraft travel beyond Earth’s orbit or aid submarines as they navigate deep under the ocean with more precision than.
It has been widely recognized that whoever controls the development of novel materials controls technologies that evolve from them. The science and technology of materials synthesis are at the heart of the discovery, design, and realization of novel quantum materials that underpin quantum technologies. From a fundamental point of view, there is a current lack of clear-cut material realizations of recently proposed quantum states that promise revolutionary advances in novel technologies, including quantum spin liquids, accessible topological superconductors, room-temperature superconductors, controllable anyonic states, etc. The current mismatch between theory and experiment strongly suggests that daunting materials challenges will hinder advances in the development of quantum technologies, such as realistic quantum computers in future decades. Indeed, despite advances in quantum information processing in recent decades, major materials challenges have significantly limited progress in quantum computing hardware platforms. It requires collaborative efforts beyond the field of quantum computing to tackle these materials challenges. There is a clear indication that existing synthesis techniques are inadequate. New synthesis technologies capable of producing new phases and structures are urgently needed.
The central theme of this Special Collection is to communicate recent developments, identify new research areas, and collectively address urgent materials challenges faced by the community of quantum materials synthesis. It will serve as a renewed effort to improve the technical infrastructure available to researchers who require highly controlled sample materials for the conduct of fundamental materials investigations. This Collection presents invited articles written by leading scientists in this community and covers quantum materials synthesis of a range of forms of materials, such as bulk single crystals, thin films/heterostructures, and two-dimensional materials.
The pursuit of more efficient engines continually pushes the boundaries of thermodynamics, and recent work demonstrates that relativistic effects may offer a surprising pathway to surpass conventional limits. Tanmoy Pandit from the Leibniz Institute of Hannover, along with Tanmoy Pandit from TU Berlin and Pritam Chattopadhyay from the Weizmann Institute of Science, and colleagues, investigate a novel thermal machine that harnesses the principles of relativity to achieve efficiencies beyond those dictated by the Carnot cycle. Their research reveals that by incorporating relativistic motion into the system, specifically through the reshaping of energy spectra via the Doppler effect, it becomes possible to extract useful work even without a temperature difference, effectively establishing relativistic motion as a valuable resource for energy conversion. This discovery not only challenges established thermodynamic boundaries, but also opens exciting possibilities for designing future technologies that leverage the fundamental principles of relativity to enhance performance.
The appendices detail the Lindblad superoperator used to describe the system’s dynamics and the transformation to a rotating frame to simplify the analysis. They show how relativistic motion affects the average number of quanta in the reservoir and the superoperators, and present the detailed derivation of the steady-state density matrix elements for the three-level heat engine, providing equations for power output and efficiency. The document describes the Monte Carlo method used to estimate the generalized Carnot-like efficiency bound in relativistic quantum thermal machines, providing pseudocode for implementation and explaining how the efficiency bound is extracted from efficiency and power pairs. Overall, this is an excellent supplementary material document that provides a comprehensive and detailed explanation of the theoretical framework, calculations, and numerical methods used in the research paper. The clear organization, detailed derivations, and well-explained physical concepts make it a valuable resource for anyone interested in relativistic quantum thermal machines.
Relativistic Motion Boosts Heat Engine Efficiency
Researchers have demonstrated that relativistic motion can function as a genuine thermodynamic resource, enabling a heat engine to surpass the conventional limits of efficiency. The team investigated a three-level maser, where thermal reservoirs are in constant relativistic motion relative to the working medium, using a model that accurately captures the effects of relativistic motion on energy transfer. The results reveal that the engine’s performance is not solely dictated by temperature differences, but is significantly influenced by the velocity of the thermal reservoirs. Specifically, the engine can operate with greater efficiency than predicted by the Carnot limit, due to the reshaping of the energy spectrum caused by relativistic motion.
Encoding quantum information within bosonic modes offers a promising direction for hardware-efficient and fault-tolerant quantum information processing. However, achieving high-fidelity universal control over bosonic encodings using native photonic hardware remains a significant challenge. We establish a quantum control framework to prepare and perform universal logical operations on arbitrary multimode multi-photon states using a quantum photonic neural network. Central to our approach is the optical nonlinearity, which is realized through strong light-matter interaction with a three-level Λ atomic system. The dynamics of this passive interaction are asymptotically confined to the single-mode subspace, enabling the construction of deterministic entangling gates and overcoming limitations faced by many nonlinear optical mechanisms. Using this nonlinearity as the element-wise activation function, we show that the proposed architecture is able to deterministically prepare a wide array of multimode multi-photon states, including essential resource states. We demonstrate universal code-agnostic control of bosonic encodings by preparing and performing logical operations on symmetry-protected error-correcting codes. Our architecture is not constrained by symmetries imposed by evolution under a system Hamiltonian such as purely χ and χ processes, and is naturally suited to implement non-transversal gates on photonic logical qubits. Additionally, we propose an error-correction scheme based on non-demolition measurements that is facilitated by the optical nonlinearity as a building block. Our results pave the way for near-term quantum photonic processors that enable error-corrected quantum computation, and can be achieved using present-day integrated photonic hardware.
Basani, J.R., Niu, M.Y. & Waks, E. Universal logical quantum photonic neural network processor via cavity-assisted interactions. npj Quantum Inf 11, 142 (2025). https://doi.org/10.1038/s41534-025-01096-9