Quantum Sensing & Metrology: Atomic Clocks & Quantum Sensors
Quantum sensing news: quantum metrology, atomic clocks, quantum gravimetry, magnetometers. Quantum imaging & positioning applications.
Quantum sensing exploits quantum superposition and entanglement to achieve measurement precision beyond classical limits, offering orders-of-magnitude improvements in timing, navigation, magnetic field detection, and gravitational sensing.
Core technologies include atomic clocks achieving precision of 10^-18 (losing 1 second over 30 billion years); quantum magnetometers detecting femtotesla magnetic fields; and quantum gravimeters measuring gravitational acceleration for underground infrastructure mapping.
India's Quantum Sensing and Metrology Initiatives
India's National Quantum Mission includes quantum sensing and metrology as one of four verticals with dedicated funding. The Qmet Tech Foundation at IIT Bombay serves as the Thematic Hub on Quantum Sensing, Imaging, and Metrology under NQM. Established as a Section-8 not-for-profit company, Qmet brings together 16 premier institutions and 40+ researchers across India.
Key Qmet technologies include the portable magnetometer and quantum diamond microscope developed at IIT Bombay's Photonics and Quantum Sensing Technology Lab (P-Quest Lab). The quantum diamond microscope uses nitrogen-vacancy (NV) centers in diamond as ultra-sensitive magnetic field sensors for applications including non-destructive testing of semiconductor chips and biological sensing of neuronal cultures.
The Physical Research Laboratory (PRL) in Ahmedabad develops atomic clocks for ISRO's navigation satellites (NavIC). The Defence Research and Development Organisation (DRDO) develops quantum sensors for defense applications including submarine detection and navigation in GPS-denied environments.
The NQM targets developing magnetometers with high sensitivity in atomic systems and atomic clocks for precision timing, communications, and navigation. The ₹720 crore quantum fabrication facility investment includes quantum sensing infrastructure at IIT Bombay and IIT Kanpur.
quantum-computingIonQ Selected to Support Missile Defense Agency SHIELD IDIQ Contract
Insider Brief IonQ was awarded a position on the U.S. Missile Defense Agency’s SHIELD indefinite-delivery/indefinite-quantity (IDIQ) contract, which has a ceiling value of $151 billion. IonQ is one of more than 2,400 companies eligible to compete for future task orders under the SHIELD contract framework. The company said its portfolio spans quantum computing, networking, sensing, and security, alongside subsidiary capabilities in space-based imaging, optical communications, and precision timing. PRESS RELEASE — IonQ (NYSE: IONQ) is pleased to announce it was awarded a contract under the Missile Defense Agency Scalable Homeland Innovative Enterprise Layered Defense (SHIELD) indefinite-delivery/indefinite-quantity (IDIQ) contract with a ceiling of $151 billion. This contract encompasses a broad range of work areas that allows for the rapid delivery of innovative capabilities to the warfighter with increased speed and agility. IonQ is among more than 2,400 companies eligible to compete for future task orders issued under the SHIELD IDIQ contract framework. IonQ delivers a full portfolio of quantum technologies spanning quantum computing, quantum networking, quantum sensing, and quantum security. The company also includes subsidiaries with established capabilities across space-based intelligence, secure communications, and precision timing technologies. IonQ’s subsidiary companies include Capella Space, which provides on-demand, all-weather synthetic aperture radar imagery from space to support data-driven decision-making for operational and security missions; Skyloom, which delivers high-capacity optical communications technologies designed to enable secure, high-speed data transfer between space and ground systems; and Vector Atomic, which develops precision timing and navigation technologies designed to support system performance in GPS-degraded or denied environments. “IonQ brings together a broad set of quantum technologies and supporting capabiliti
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quantum-computingTime uncertainty and fundamental sensitivity limits in quantum sensing: application to optomechanical gravimetry
--> Quantum Physics arXiv:2602.18524 (quant-ph) [Submitted on 20 Feb 2026] Title:Time uncertainty and fundamental sensitivity limits in quantum sensing: application to optomechanical gravimetry Authors:Salman Sajad Wani, Saif Al-Kuwari, Arshid Shabir, Paolo Vezio, Francesco Marino, Mir Faizal View a PDF of the paper titled Time uncertainty and fundamental sensitivity limits in quantum sensing: application to optomechanical gravimetry, by Salman Sajad Wani and Saif Al-Kuwari and Arshid Shabir and Paolo Vezio and Francesco Marino and Mir Faizal View PDF HTML (experimental) Abstract:High-sensitivity accelerometers and gravimeters, achieving the ultimate limits of measurement sensitivity are key tools for advancing both fundamental and applied physics. While numerous platforms have been proposed to achieve this goal, from atom interferometers to optomechanical systems, all of these studies neglect the effects of intrinsic quantum uncertainty in time estimation. Starting from the Hamiltonian of a generic linear quantum sensor, we derive the two-parameter quantum Fisher information matrix and establish the corresponding Cram'er-Rao bound, treating time as an uncertain (nuisance) parameter. Our analysis reveals a fundamental coupling between time and signal estimation that inherently degrades measurement sensitivity, with the standard single-parameter quantum limit recovered only at specific interrogation times or under special decoupling conditions. We then apply these results to an optomechanical gravimeter and explicitly derive an optimal decoupling condition under which the effects of time uncertainty are averaged out in a continuous measurement scheme. Our approach is general and can be readily extended to a broad class of quantum sensors. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.18524 [quant-ph] (or arXiv:2602.18524v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.18524 Focus to learn more arXiv-issued DOI via
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quantum-computingExceptional Point Superradiant Lasing with Ultranarrow Linewidth
--> Quantum Physics arXiv:2602.19030 (quant-ph) [Submitted on 22 Feb 2026] Title:Exceptional Point Superradiant Lasing with Ultranarrow Linewidth Authors:Min Du, Qian Bin, Qing-Yang Qiu, Franco Nori, Xin-You Lü View a PDF of the paper titled Exceptional Point Superradiant Lasing with Ultranarrow Linewidth, by Min Du and 4 other authors View PDF Abstract:Achieving superradiant lasing with an ultranarrow linewidth is crucial for enhancing atomic clock stability in quantum precision measurement. By employing the exceptional point (EP) property of the system, we demonstrate theoretically superradiant lasing with linewidths in the $\mu$Hz range, sustained at the high-power level. This is achieved by incoherently pumping optical lattice clock transitions with ultracold alkaline-earth strontium-87 atoms in the EP of a $\mathcal{PT}$-symmetric system. Physically, the atomic coherence reaches a maximum in the EP, significantly amplifying the superradiance effect and resulting in superradiant lasing with an ultranarrow linewidth. This linewidth is even three orders of magnitude smaller than that of superradiant lasing in the systems without EP. Our work extends the realm of superradiant lasing by introducing the EP property, and offers promising applications for developing atomic clocks with exceptional stability and accuracy. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.19030 [quant-ph] (or arXiv:2602.19030v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.19030 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Journal reference: Phys. Rev. Lett. 136, 063602 (2026) Related DOI: https://doi.org/10.1103/sbbk-xdvs Focus to learn more DOI(s) linking to related resources Submission history From: Xinyou Lu Prof. [view email] [v1] Sun, 22 Feb 2026 03:36:50 UTC (1,804 KB) Full-text links: Access Paper: View a PDF of the paper titled Exceptional Point Superradiant Lasing with Ultranarrow Linewidth, by Mi
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quantum-computingQuantum superresolution and noise spectroscopy with quantum computing
--> Quantum Physics arXiv:2602.17862 (quant-ph) [Submitted on 19 Feb 2026] Title:Quantum superresolution and noise spectroscopy with quantum computing Authors:James W. Gardner, Federico Belliardo, Gideon Lee, Tuvia Gefen, Liang Jiang View a PDF of the paper titled Quantum superresolution and noise spectroscopy with quantum computing, by James W. Gardner and 4 other authors View PDF HTML (experimental) Abstract:Quantum metrology of an incoherent signal is a canonical sensing problem related to superresolution and noise spectroscopy. We show that quantum computing can accelerate searches for a weak incoherent signal when the signal and noise are not precisely known. In particular, we consider weak Schur sampling, density matrix exponentiation, and quantum signal processing for testing the rank, purity, and spectral gap of the unknown quantum state to detect the incoherent signal. We show that these algorithms are faster than full-state tomography, which scales with the dimension of the Hilbert space. We apply our results to detecting exoplanets, stochastic gravitational waves, ultralight dark matter, geontropic quantum gravity, and Pauli noise. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.17862 [quant-ph] (or arXiv:2602.17862v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.17862 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: James Gardner [view email] [v1] Thu, 19 Feb 2026 21:56:06 UTC (100 KB) Full-text links: Access Paper: View a PDF of the paper titled Quantum superresolution and noise spectroscopy with quantum computing, by James W. Gardner and 4 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev | next > new | recent | 2026-02 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... D
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quantum-computingMeasuring and correcting nanosecond pulse distortions in quantum-dot spin qubits
--> Quantum Physics arXiv:2602.17899 (quant-ph) [Submitted on 19 Feb 2026] Title:Measuring and correcting nanosecond pulse distortions in quantum-dot spin qubits Authors:Jiheng Duan, Fernando Torres-Leal, John M. Nichol View a PDF of the paper titled Measuring and correcting nanosecond pulse distortions in quantum-dot spin qubits, by Jiheng Duan and 2 other authors View PDF HTML (experimental) Abstract:Gate-defined semiconductor quantum dots utilize fast electrical control to manipulate spin and charge states of individual electrons. Electrical pulse distortions can limit control fidelities but are difficult to measure at the device level. Here, we use detuning-axis pulsed spectroscopy to characterize baseband pulse distortions in a silicon double quantum-dot. We extract the gate-voltage impulse response and apply a digital pre-distortion filter to eliminate pulse distortions on timescales longer than 1~ns. With the pre-distortion, we reduce the frequency chirp of coherent exchange oscillations in a singlet-triplet qubit. Our results suggest a scalable and tuning-efficient method for characterizing pulse distortions in quantum-dot spin qubits. Comments: Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Cite as: arXiv:2602.17899 [quant-ph] (or arXiv:2602.17899v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.17899 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Jiheng Duan [view email] [v1] Thu, 19 Feb 2026 23:33:44 UTC (2,164 KB) Full-text links: Access Paper: View a PDF of the paper titled Measuring and correcting nanosecond pulse distortions in quantum-dot spin qubits, by Jiheng Duan and 2 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph < prev | next > new | recent | 2026-02 Change to browse by: cond-mat cond-mat.mes-hall References & Citations INSPIRE HEP NASA A
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quantum-computingPolariton-polariton coherent coupling in a molecular spin-superconductor chip
--> Quantum Physics arXiv:2602.18103 (quant-ph) [Submitted on 20 Feb 2026] Title:Polariton-polariton coherent coupling in a molecular spin-superconductor chip Authors:Carolina del Río (1), Marcos Rubín-Osanz (1), David Rodriguez (2), Sebastián Roca-Jerat (1), María Carmen Pallarés (1 and 3), J. Alejandro de Sousa (4), Paweł Pakulski (5), José Luis García Palacios (1), Daniel Granados (6), Dawid Pinkowicz (5), Núria Crivillers (4), Anabel Lostao (1 and 3 and 7), David Zueco (1), Alicia Gomez (2), Fernando Luis (1) ((1) Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Spain, (2) Centro de Astrobiología (CAB), CSIC-INTA, Torrejón de Ardoz, Spain, (3) Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, Spain, (4) Instituto de Ciencia de Materiales de Barcelona (ICMAB), CSIC, Barcelona, Spain, (5) Jagiellonian University, Faculty of Chemistry, Krakow, Poland, (6) IMDEA-Nanoscience, Madrid, Spain, (7) Fundación ARAID, Zaragoza, Spain) View a PDF of the paper titled Polariton-polariton coherent coupling in a molecular spin-superconductor chip, by Carolina del R\'io (1) and 37 other authors View PDF HTML (experimental) Abstract:The ability to establish coherent communication channels is key for scaling up quantum devices. Here, we engineer interactions between distant polaritons, hybrid spin-photon excitations formed at different lumped-element superconducting resonators within a chip. The chip consists of several resonator pairs, slightly detuned in frequency to make them addressable, capacitively coupled within each pair and inductively coupled to a common readout line. They interact locally with samples of PTMr and Tripak$^{-}$ organic free radicals, deposited onto their inductors, which provide model $S = 1/2$, $g \simeq 2$ spin ensembles. Frequency-dependent microwave transmission experiments, performed at very low temperatures, measure polariton frequencies as a function of magnetic field in different scenarios. W
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quantum-computingSensing with discrete time crystals
MainNon-equilibrium matter has emerged as a frontier in modern many-body physics, displaying novel phenomena beyond restrictions imposed by thermal equilibrium. A milestone is the demonstration1,2,3,4,5,6,7,8,9,10,11,12,13 of discrete time crystals (DTCs)14,15,16,17,18,19,20,21,22, a new form of non-equilibrium matter that breaks time-translation symmetry, akin to ordinary crystals breaking spatial symmetry. A hallmark of DTCs is their robust period-doubling response, stabilized by many-body interactions of mean strength J, making them resilient to errors in the protocol creating them. Most observed time-crystalline states rely on Floquet prethermalization23,24,25,26,27,28, where periodically driven quantum states are preserved for durations parametrically controlled by the drive frequency, resulting in lifetimes \({T}_{2}^{{\prime} }\) far exceeding the system’s interaction-dominated intrinsic decay time \({T}_{2}^{* }\) (∝J−1).The robustness and long lifetimes of DTCs in the presence of interactions make them promising for quantum technologies, such as simulating complex systems29, topologically protected quantum computation30 and robust generation of entangled states31. Experimental work has demonstrated the use of continuous time crystals as a d.c. field sensor32. Separately, theoretical proposals have suggested using DTCs for enhanced quantum sensing33,34,35,36,37. However, experimental realizations using DTCs as quantum sensors have been challenging due to the necessity of using strongly correlated states33 or fine-tuned systems34,35,36.In this work, we develop a new approach for using DTCs to construct highly frequency-selective quantum sensors for time-varying (a.c.) magnetic fields, and demonstrate it experimentally in an ensemble of randomly positioned, hyperpolarized 13C nuclear spins in diamond. The sensor operates in the 0.5–50-kHz range—typically a challenging frequency regime for sensors based on atomic vapour38 or electronic spins39—and achieves comp
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quantum-computingGuest Post — Helium-Free Magnetic Refrigeration Supports Continuous Milli-Kelvin Temperatures For Quantum Research
Guest Post by by Jim McMahon Cryogenic characterization is a must to accelerate and enable breakthrough science and quantum technologies. Quantum sensors, quantum communication devices and future quantum computers will rely on scalable and efficient cooling for their operation. Quantum computers rely on qubits, which can exist in multiple states simultaneously. These quantum states are extremely […]
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quantum-computingFastest Change in Physics Limited by Planck Time
Scientists have long sought to understand the minimum time required for a system to reach local thermal equilibrium. Marvin Qi from the Leinweber Institute for Theoretical Physics & James Franck Institute, University of Chicago, and Alexey Milekhin from the Department of Physics and Astronomy, University of Kentucky, alongside Luca Delacr etaz from the Leinweber Institute for Theoretical Physics & James Franck Institute, University of Chicago, demonstrate a rigorous lower bound on this ‘equilibration time’, conjecturing it is fundamentally limited by the Planckian time. Their research establishes this bound by analysing the emergence of hydrodynamic behaviour in conserved densities, revealing a dimensionless coefficient dependent only on dimensionality and the type of behaviour, irrespective of the underlying thermalisation mechanism. This universally applicable result, achieved through careful consideration of real-time thermal correlators, offers significant insight into the foundations of statistical mechanics and applies to a broad range of physical systems, even those lacking a quasiparticle description or exhibiting inelastic scattering. Within a cryostat chilled to near absolute zero, delicate measurements track how quickly order arises from chaos. This pursuit reveals a fundamental limit to how rapidly any physical system can reach stability. The universal timescale, linked to the very fabric of spacetime, governs the emergence of predictable behaviour in everything from fluids to quantum materials. Scientists have long recognised the importance of the Planckian timescale, ħ/T, in quantum statistical physics — recent attention focuses on a compelling conjecture: that this timescale fundamentally limits how quickly quantum many-body systems reach local equilibrium. With a local equilibration time τeq greater than or equal to the Planckian time, and scientists have now moved beyond theoretical motivation to formally establish this bound. Defining τeq a
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quantum-computingAI Spots New Electron Crystal Within Graphene Layers
Scientists have uncovered a novel ground state of matter within artificial graphene, revealing a paired Wigner crystal formed through an unexpected self-assembly process. Conor Smith from the Center for Computational Quantum Physics at the Flatiron Institute and the Department of Electrical and Computer Engineering at the University of New Mexico, alongside Yubo Yang from the Center for Computational Quantum Physics, Flatiron Institute and the Department of Physics and Astronomy at Hofstra University, Zhou-Quan Wan, Yixiao Chen from ByteDance, Miguel A. Morales from the Center for Computational Quantum Physics, Flatiron Institute and the Department of Physics at the University of Toronto, and Shiwei Zhang utilised a neural-network-based Monte Carlo approach to identify this state in a two-dimensional electron gas subjected to a honeycomb moiré potential. This research demonstrates the spontaneous formation of molecules comprising paired electrons, which then organise into a Wigner crystal without any external guiding potential or attractive forces, offering a compelling example of emergent collective behaviour and opening avenues for the design of materials with unique electronic characteristics. For decades, physicists have sought to understand how electrons arrange themselves in complex materials. Now, an artificial graphene system reveals an unexpected, self-organised pattern where electrons pair up and form crystalline structures, offering a fresh perspective on collective electron behaviour and potential control over material properties. Scientists are increasingly focused on moiré systems as tunable platforms for investigating quantum matter — these artificially created structures, arising from the interference of two overlaid lattices, have already exhibited a range of exotic states. Prompting considerable research across experimental and theoretical physics. This new state emerges at a specific filling factor, where one electron occupies every four minima wi
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quantum-computingAtomic Vapour Cells Enable Scalable Entanglement Swapping
Researchers demonstrate a crucial advancement in quantum networking by achieving high-rate, scalable entanglement swapping between remote sources utilising existing New York City fibre infrastructure. Alexander N. Craddock and Tyler Cowan, working at Qunnect Inc. and the Center for Quantum Information Physics at New York University respectively, led the study in collaboration with Niccolò Bigagli, Suresh Yekasiri, Dylan Robinson, Gabriel Bello Portmann, Ziyu Guo, Michael Kilzer, Jiapeng Zhao, Mael Flament, Javad Shabani, Reza Nejabati and Mehdi Namazi from Qunnect Inc. and Cisco Quantum Labs. This work overcomes significant hurdles in maintaining photon indistinguishability and entanglement fidelity over deployed fibres, achieving a swapping rate of nearly 500 pairs per second with a CHSH parameter exceeding 2 on a 17.6-km network. The successful demonstration utilising standard components like commercially available detectors and time synchronisation techniques represents a substantial step towards building practical, large-scale quantum networks for applications ranging from secure communication to distributed sensing. The demonstration overcomes a key hurdle in scaling up quantum communication by using simple, widely available components, promising secure data transmission and distributed computing power beyond the reach of conventional technology. Researchers have achieved a significant advance in quantum networking, demonstrating a scalable entanglement swapping experiment exceeding 470 entangled photon pairs per second. This breakthrough relies on a new architecture utilising warm atomic vapor cells as naturally indistinguishable entanglement sources, a departure from methods requiring precise laser synchronization or pulsed sources. The work addresses a long-standing challenge in building quantum repeaters, blind quantum computing systems, and distributed quantum sensors, efficiently connecting quantum devices over existing telecommunication infrastructure. P
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quantum-computingNew Method Reveals Hidden Order in Complex Systems
Scientists have developed a novel spectroscopic technique, termed dissipative spectroscopy, to extract spectral information from complex systems by harnessing controlled dissipation. Xudong He and Yu Chen, from the University of Science and Technology of China, present this framework, establishing a general dissipative response applicable to both Markovian and non-Markovian environments. Their research details a protocol to access the dissipative spectrum through driven oscillation-dissipation resonance, revealing previously hidden signatures of critical behaviour and macroscopic order. This work is significant because it identifies two-particle soft modes near critical points and predicts power-law growth following a dissipation quench, even in quasiparticle-dominant regimes often dismissed as trivial. By introducing extended dissipative susceptibilities and demonstrating their utility in a fermionic model, the authors offer a versatile tool for probing both equilibrium properties and predicting non-equilibrium dissipative dynamics. Scientists have devised a novel technique for understanding complex materials by carefully controlling how energy fades away within them. This method reveals hidden details about a material’s behaviour, even when traditional approaches fail to detect changes, and promises a fresh perspective on predicting how systems evolve and respond to external stimuli. This work introduces dissipative spectroscopy, a technique that extracts spectral information from quantum materials through controlled dissipation, opening avenues to study phenomena previously hidden from view. The research details how this approach can identify subtle changes within materials near critical points, moments of dramatic transformation, and even predict the emergence of order in seemingly disordered systems. Probing quantum dynamics often requires distinguishing between external influences and inherent noise. Equipped with recent advances in dissipation engineering, re
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quantum-computingMachine Learning Clarifies Elusive Quantum States in Material
Scientists continue to pursue the definitive identification of Majorana zero modes (MZMs) within topological superconductors, a pursuit complicated by overlapping spectral features that mimic genuine MZM signals. Jewook Park and Hoyeon Jeon, both from the Center for Nanophase Materials Science at Oak Ridge National Laboratory, alongside Dongwon Shin from the Materials Sciences and Technology Division at the same institution, have led a study employing a novel machine-learning approach to address this challenge. Working with colleagues including Guannan Zhang from the Computer Science and Mathematics Division, Michael A McGuire and Brian C Sales from the Materials Sciences and Technology Division, and An-Ping Li, the team developed a data-driven workflow for analysing tunneling spectroscopy data from the intrinsic topological superconductor FeTe0.55Se0.45. This research is significant because it introduces an objective and reproducible method for distinguishing true MZMs from trivial in-gap states, offering a crucial step towards reliable detection and eventual manipulation of these exotic states for potential quantum computation applications. Scientists are edging closer to realising the potential of quantum computing with a new technique for identifying elusive quantum particles. The method overcomes a major hurdle in materials science by reliably distinguishing genuine quantum signals from misleading background noise, promising to accelerate the development of stable and scalable quantum technologies. Researchers are developing a new method to reliably identify Majorana zero modes within topological superconductors, a critical step towards building more stable quantum computers. Identifying these quasiparticles has proven difficult because their signatures, zero-bias conductance peaks, can be mimicked by other, non-topological phenomena within the material. The team demonstrated a data-driven workflow integrating detailed spectral analysis with machine learning to
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quantum-computingTwisted Material Hosts Topological Superconductivity and Vortices
Researchers are increasingly focused on understanding the interplay between superconductivity and the fractional quantum anomalous Hall (FQAH) effect in twisted materials. Daniele Guerci, Ahmed Abouelkomsan, and Liang Fu, all from the Department of Physics at the Massachusetts Institute of Technology, demonstrate that the superconducting state observed in twisted MoTe₂ is a chiral p-wave superconductor hosting an array of vortices. These vortices are induced by an emergent magnetic field within the moiré superlattice, resulting in a topological superconducting vortex lattice state with a Chern number of one. This work offers a unified understanding of both FQAH and topological superconductivity, potentially paving the way for novel electronic devices and a deeper comprehension of correlated electron systems. Recent observations in twisted molybdenum ditelluride (MoTe₂) revealed the simultaneous presence of superconductivity and the fractional quantum anomalous Hall effect (FQAH), prompting a detailed theoretical investigation into their underlying connection. The arrangement of electrons within the material creates a unique, ordered structure with implications for future electronic devices. Scientists have uncovered a surprising link between these two distinct quantum phenomena. This work demonstrates that the superconducting state emerging in these materials is not conventional, but a chiral f-wave superconductor hosting a unique array of vortices, each carrying twice the usual quantum of magnetic flux. These vortices, induced by an emergent magnetic field arising from the material’s layered structure, form a topological vortex lattice with a Chern number of -1/2, directly resulting in a half-integer thermal Hall conductance. The research establishes a unified framework explaining both phenomena, controlled by the spatial variation of this emergent magnetic field. Unlike traditional superconductivity induced by external magnetic fields, this system’s superconductiv
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quantum-computingSuperconductor Effect Lost in Stages, Not All at Once
Researchers are investigating the behaviour of superconductivity in bilayer materials, revealing a surprising sequence of events leading to the loss of key quantum properties. F. Yang, C. Y. Dong, and Joshua A. Robinson from the Department of Materials Science and Engineering and Materials Research Institute at The Pennsylvania State University, working with L. Q. Chen, demonstrate that the Josephson diode effect, a form of nonreciprocal current flow, disappears at a lower temperature than complete superconducting coherence. This challenges the established understanding that both effects vanish simultaneously. Their self-consistent microscopic theory, incorporating phase fluctuations, shows a hierarchy of thermal crossovers, progressing from a nonreciprocal to a reciprocal and finally an incoherent Josephson regime before the superconducting gap closes. Significantly, this research highlights the sensitivity of these transitions to factors like interlayer coupling, in-plane disorder, and carrier density, offering insights relevant to layered superconductors such as cuprates and nickelates, and potentially advancing the development of superconducting devices. Imagine building a delicate house of cards, where even the slightest tremor can cause it to collapse. Similarly, maintaining the flow of supercurrent in advanced materials requires shielding it from disruptive thermal vibrations. New work reveals how this delicate balance breaks down in layered superconductors, with specific components failing at different temperatures before complete loss of conductivity. Scientists have long understood that superconductivity, the lossless flow of electricity, relies on the delicate coherence of electrons forming Cooper pairs. Recent investigations into superconducting diodes, devices exhibiting a directional preference for current flow, have revealed a surprising complexity in how this coherence breaks down within layered superconductors. Contrary to expectations of a simultan
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quantum-computingEnhanced States Boost Sensitivity to Tiny Displacements
Scientists are increasingly focused on exploiting quantum states exhibiting sub-Planck features to enhance the precision of measurements. Naeem Akhtar from the School of Physics, Anhui University, Jia-Xin Peng from the School of Physics and Technology, Nantong University, and Tariq Aziz, also of the School of Physics, Anhui University, working with Xiaosen Yang from the Department of Physics, Jiangsu University, and Dong Wang from the School of Physics, Anhui University, demonstrate a novel approach to constructing such states with improved characteristics. Their research details the creation of multi-component SU(1,1) circular states, built through the superposition of coherent states, which exhibit isotropic sub-Planck features and uniform sensitivity to phase-space displacements. This represents a significant advance over previous designs, offering a pathway towards more balanced and effective enhancement of measurement precision, and the principles established are applicable to superpositions containing an arbitrarily large number of components. Scientists have devised a method to sharpen the sensitivity of quantum measurements beyond conventional limits. These specially constructed quantum states respond to even the smallest disturbances with greater uniformity than previously possible, promising improvements in precision sensing and benefiting technologies reliant on detecting faint signals. Scientists have engineered a new method for creating quantum states with remarkably refined sub-Planck features, enhancing their sensitivity to even the smallest changes in phase space. Improved phase-space sensitivity directly translates to more precise measurements in quantum metrology, the science of ultra-precise measurement. Applications range from gravitational wave detection to biological imaging and advanced sensing technologies. The research details a specific configuration utilising sixteen coherent states to verify the creation of these isotropic sub-Planck feat
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quantum-computingAtoms Entangled with Enhanced Control for Experiments
Researchers are continually seeking methods to enhance spin squeezing, a crucial resource for precision measurement. Zhiwei Hu from Fudan University, Youwei Zhang from Fudan University, and Junlei Duan from Fudan University, working with Mingfeng Wang from Wenzhou University and Yanhong Xiao from Fudan University, demonstrate a novel coherent control scheme to simultaneously boost collective spin squeezing and simplify the resulting atom-atom entanglement. This collaborative effort presents a protocol utilising a one-axis twisting echo sequence, effectively leveraging internal atomic states to optimise entanglement and encode it within two readily accessible magnetic sublevels. The significance of this work lies in offering a straightforward and efficient strategy for generating highly entangled states in multilevel atomic systems, circumventing the complexities of previous methods and paving the way for more practical applications in quantum technologies. Scientists have devised a clever technique to improve the entanglement of atoms, bringing practical quantum technologies closer to reality. The method simplifies state control, overcoming limitations of previous approaches to generate more useful quantum states. This advancement promises more precise sensors and accelerates progress in harnessing the power of quantum mechanics. Researchers have devised a new method for generating highly entangled states within atomic systems, potentially revolutionizing the precision of quantum sensors and accelerating the development of quantum technologies. This work addresses a longstanding challenge in quantum metrology, enhancing the sensitivity of measurements beyond the limitations imposed by standard quantum mechanics. Existing techniques for boosting entanglement often rely on complex internal atomic states, hindering practical implementation and limiting the accessibility of these states for subsequent experiments. A coherent control scheme simultaneously amplifies colle
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quantum-computingLight Squeezed at Band-Gap Frequency in New States
Researchers are increasingly investigating high-harmonic generation (HHG) through the lens of strong-field quantum optics, demonstrating that generated radiation often exhibits nonclassical light characteristics. However, a comprehensive quantum optical understanding of HHG originating from topological insulators remains elusive. Christian Saugbjerg Lange and Lars Bojer Madsen, both from the Department of Physics and Astronomy at Aarhus University, have addressed this knowledge gap by examining HHG responses within the Su-Schrieffer-Heeger model, a finite atomic chain exhibiting both trivial and nontrivial insulating phases supporting edge states. Their findings reveal squeezed light generation at the band-gap frequency for both phases, with harmonic spectra differentiating the phases, although this distinction weakens with increasing chain length due to increased overlap between bulk and edge states. This work elucidates the role of dipole coupling strength in governing nonclassical HHG and opens new avenues for exploring the protected generation of quantum light in strong-field physics. Imagine building a complex electrical circuit where the very edges conduct power differently to the interior. New work explores how light emission from materials with unusual electronic properties, specifically those supporting edge states, exhibits a unique quantum character. This investigation demonstrates squeezed light at the material’s band-gap frequency, offering a pathway to control non-classical light generation. Scientists are increasingly applying quantum mechanical descriptions to the interaction between light and matter, a field known as strong-field quantum optics. Recent work has demonstrated that light generated through high-harmonic generation (HHG), a process where intense laser fields create new frequencies of light, often exhibits nonclassical properties. A complete quantum optical understanding of HHG originating from materials with unusual electronic structures
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quantum-computingSymmetry Breaking Develops Faster Than Charge Diffusion
Scientists investigate the breakdown of symmetry in open quantum systems, a phenomenon with implications for understanding non-equilibrium dynamics and the emergence of classical behaviour from quantum mechanics. Jacob Hauser, Kaixiang Su, and Hyunsoo Ha, working at the Department of Physics, University of California, Santa Barbara, alongside Jerome Lloyd and Romain Vasseur from the Department of Theoretical Physics, University of Geneva, and colleagues including Sarang Gopalakrishnan of Princeton University’s Department of Electrical and Computer Engineering, and Matthew P. A. Fisher from the Kavli Institute for Theoretical Physics and the Department of Physics at UC Santa Barbara, demonstrate how strong-to-weak symmetry breaking transitions occur, linking discrete particle behaviour to continuum hydrodynamic descriptions. Their research, conducted in collaboration across multiple institutions, reveals that this symmetry breaking manifests on timescales that define the limits of hydrodynamic approximations, offering new insights into the relationship between microscopic dynamics and macroscopic, classical phenomena. Can complex systems transition from behaving like distinct particles to flowing like a continuous fluid. This work demonstrates how such a change happens, revealing a precise timescale for when particle-like behaviour gives way to fluid-like dynamics. Understanding this shift unlocks new ways to model everything from quantum materials to biological systems. Scientists are increasingly focused on understanding transitions in systems interacting with external environments, moving beyond traditional equilibrium phase transitions. Recent investigations have uncovered a wider range of transitions occurring in systems coupled to external environments, including measurement-induced criticality, separability transitions, teleportation transitions, complexity transitions, and those driven by decoherence. Strong-to-weak spontaneous symmetry breaking (SW-SSB) is a
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quantum-computingGraphene Patterns Unlock Stacked Insulating Electron States
Researchers are increasingly focused on harnessing correlated insulating behaviour in graphene to unlock emergent phenomena such as superconductivity and magnetism. Xinyu Cai, Fengfan Ren, and Qiao Li, all from ShanghaiTech University, alongside Yanran Shi, Yifan Wang, Yifan Zhang, Zhenghang Zhi, Jiawei Luo, Yulin Chen, and Jianpeng Liu, also of ShanghaiTech University, working with Xufeng Kou and Zhongkai Liu, demonstrate a new method for achieving this using bilayer graphene. Their work details the creation of an artificial Kagome superlattice through nanopatterning of the substrate, offering a precisely defined and tunable periodic potential. This approach overcomes reproducibility and tunability issues associated with traditional moiré graphene superlattices, revealing a stack of correlated insulating states and establishing dielectric-patterned graphene superlattices as a robust platform for exploring flat-band-induced correlated phenomena. Imagine building a miniature city with perfectly arranged blocks, controlling how electrons flow through it. That level of precision is now possible with bilayer graphene, creating multiple, interacting layers of insulating behaviour. This new technique offers a reliable route to harnessing strong electron interactions for future electronic devices. Scientists have long sought to control the behaviour of electrons in materials to create new quantum phenomena. Graphene, a single-atom-thick sheet of carbon, presents a particularly promising platform due to its exceptional electronic properties. Recent work has focused on engineering ‘flat bands’ within graphene’s electronic structure, where electrons experience reduced kinetic energy and enhanced interactions, potentially leading to states like superconductivity and correlated insulation. Achieving these flat bands has traditionally relied on creating moiré superlattices, patterns arising from the slight misalignment of graphene layers, or utilising specific stacking arrangeme
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