Quantum physics articles within Nature Communications

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  • Article
    | Open Access

    Standard ways of characterising quantum states incur exponential overhead. Here, the authors consider the task of reconstructing density matrices of multimode continuous variable systems, and demonstrate a method which scales polynomially with the system size, provided the state lies in a polynomial dimensional subspace.

    • Kevin He
    • , Ming Yuan
    •  & David I. Schuster

  • Article
    | Open Access

    The authors demonstrated an unprecedented level of polarization squeezing of light generated by an atomic ensemble, and a new regime of continuous quantum measurements on a macroscopic material oscillator.

    • Christian Bærentsen
    • , Sergey A. Fedorov
    •  & Eugene S. Polzik

  • Article
    | Open Access

    Color centers in diamond have been proposed as a link between remote superconducting units in hybrid quantum systems, where their orbital degree of freedom is utilized. Here the authors report coherent electric-field control of the orbital state of a neutral NV center in diamond.

    • Hodaka Kurokawa
    • , Keidai Wakamatsu
    •  & Hideo Kosaka

  • Article
    | Open Access

    Carbon nanotube-based single photon emitters allow for room-temperature operation, but suffer from vanishing indistinguishability due to strong dephasing. Following a theoretical proposal, the authors tackle the problem experimentally by using a cavity to enhance the photon coherence time and the emission spectral density in the regime of incoherent good cavity-coupling.

    • Lukas Husel
    • , Julian Trapp
    •  & Alexander Högele

  • Article
    | Open Access

    Given that entangled states can store more information than unentangled ones, it would be natural to assume that highly-entangled data would always enhance capabilities of quantum machine learning models. Here, the authors show that this is not the case, in particular when the allowed number of measurements to incoherently learn quantum dynamics is low

    • Xinbiao Wang
    • , Yuxuan Du
    •  & Dacheng Tao

  • Article
    | Open Access

    A promising strategy for scaling trapped-ion-based quantum technologies is to use fully integrated optical waveguides to deliver light to numerous ions at multiple sites. Here, the authors. optically address three ions using on-chip waveguides to deliver three distinct wavelengths per ion, and perform Rabi flopping on each ion simultaneously.

    • Joonhyuk Kwon
    • , William J. Setzer
    •  & Hayden J. McGuinness

  • Article
    | Open Access

    Understanding loss mechanisms in superconducting circuits is crucial for improving qubit coherence. Here the authors use a multimode resonator to study loss mechanisms in thin-film superconducting circuits and demonstrate on-chip quantum memories with lifetimes exceeding 1ms, using Ta thin-films and high-temperature substrate annealing

    • Suhas Ganjam
    • , Yanhao Wang
    •  & Robert J. Schoelkopf

  • Article
    | Open Access

    In most materials, the hall conductivity has a scaling to the longitudinal resistance that varies between linear and quadratic. Here, Zhang et al demonstrate a hall conductivity proportional to the fifth power of the longitudinal conductivity in Mn3Si2Te6, which they attribute to enhanced force on charge carriers due to chiral orbital currents.

    • Yu Zhang
    • , Yifei Ni
    •  & Gang Cao

  • Article
    | Open Access

    Confining atoms to lattices can modify their interaction and collision. Here the authors show suppression of dipolar relaxation in the form of reduced decay rate of dysprosium atoms in quasi-2D regime.

    • Pierre Barral
    • , Michael Cantara
    •  & Wolfgang Ketterle

  • Article
    | Open Access

    Point defects in 2D semiconductors have potential for quantum computing applications, but their controlled design and synthesis remains challenging. Here, the authors identify and fabricate a promising quantum defect in 2D WS2 via high-throughput computational screening and scanning tunnelling microscopy.

    • John C. Thomas
    • , Wei Chen
    •  & Geoffroy Hautier

  • Article
    | Open Access

    Quantum annealing is usually discussed as a means of finding an optimal solution for a problem where there are many local minima, such as the travelling salesman. Here, Zhao et al present an intriguing example of quantum annealing in the case of the frustrated magnet α-CoV2O6, where a transverse magnetic field triggers the quantum annealing process.

    • Yuqian Zhao
    • , Zhaohua Ma
    •  & Yuesheng Li

  • Article
    | Open Access

    The authors experimentally study a chain of superconducting islands (SI) and quantum dots (QD), where a Bogoliubov quasiparticle occupies each SI. They demonstrate correlations between the quasiparticles in each SI mediated by a single spin on the QD, known as an “over-screened" doublet state of the QD.

    • Juan Carlos Estrada Saldaña
    • , Alexandros Vekris
    •  & Jesper Nygård

  • Article
    | Open Access

    Measuring quantum entanglement remains a demanding task. The authors introduce two functions to quantify entanglement induced by fermionic or bosonic statistics, in transport experiments. Both functions, in theory and experiment, are remarkably resilient against the nonuniversal effects of interactions.

    • Gu Zhang
    • , Changki Hong
    •  & Yuval Gefen

  • Article
    | Open Access

    Nearly a century after dark matter was proposed, yet its nature remains elusive. Here, authors present their dark photon dark matter search results using two atomic magnetometer arrays 1700 km apart in large magnetic shields and offer the strongest terrestrial constraint in this mass range to date.

    • Min Jiang
    • , Taizhou Hong
    •  & Jiangfeng Du

  • Article
    | Open Access

    The problem of reversibility within general quantum resource theories is still an open one. Here, the authors prove that a reversible entanglement manipulation framework (and, consequently, the concept of entanglement entropy) can be formally established by adjusting the setting to allow for probabilistic operations

    • Bartosz Regula
    •  & Ludovico Lami

  • Comment
    | Open Access

    Can many-body systems be beneficial to designing quantum technologies? We address this question by examining quantum engines, where recent studies indicate potential benefits through the harnessing of many-body effects, such as divergences close to phase transitions. However, open questions remain regarding their real-world applications.

    • Victor Mukherjee
    •  & Uma Divakaran

  • Article
    | Open Access

    Entangled local states can be made capable of violating Bell inequalities via nonlocality activation. Typical theoretical approaches require processing many copies of the original state and performing joint measurements on the ensemble. Here, instead, the authors experimentally demonstrate how to do so using a single copy of the state, broadcasting it to two spatially separated parties within a three-node network.

    • Luis Villegas-Aguilar
    • , Emanuele Polino
    •  & Geoff J. Pryde

  • Article
    | Open Access

    Interesting non-Hermitian quantum dynamics can be accessed in analogue quantum simulators consisting of Hermitian bosonic systems with squeezing and antisqueezing terms. Here, the authors use a coplanar waveguide resonator connected to a SQUID to simulate the bosonic version of the Kitaev chain.

    • Jamal H. Busnaina
    • , Zheng Shi
    •  & Christopher M. Wilson

  • Article
    | Open Access

    Parity detection is essential in quantum error correction. Here, authors propose a reliable joint parity measurement (JPM) scheme inspired by stimulated emission and experimentally implement the weight-2(4) JPM scheme in a tunable coupling superconducting circuit, which shows comparable performance to the standard CNOT-gate based scheme.

    • Sainan Huai
    • , Kunliang Bu
    •  & Yicong Zheng

  • Article
    | Open Access

    Solving combinatorial optimization problems using quantum or quantum-inspired machine learning models would benefit from strategies able to work with arbitrary objective functions. Here, the authors use the power of generative models to realise such a black-box solver, and show promising performances on some portfolio optimization examples.

    • Javier Alcazar
    • , Mohammad Ghazi Vakili
    •  & Alejandro Perdomo-Ortiz

  • Article
    | Open Access

    Usual multiqubit entangled states can be described using the graph formalism, where each edge connects only two qubits. Here, instead, the authors use a reprogrammable silicon photonics chip to showcase preparation, verification and processing of arbitrary four-qubit hypergraph states, where hyperedges describe entanglement within a subset of many qubits.

    • Jieshan Huang
    • , Xudong Li
    •  & Jianwei Wang

  • Article
    | Open Access

    Studying bounds on the speed of information propagation across interacting boson systems is notoriously difficult. Here, the authors find tight bounds for both the transport of boson particles and information propagation, for arbitrary time-dependent Bose-Hubbard-type Hamiltonians in arbitrary dimensions.

    • Tomotaka Kuwahara
    • , Tan Van Vu
    •  & Keiji Saito

  • Article
    | Open Access

    Manipulating quantum information encoded in a bosonic mode requires sizeable and controllable nonlinearities, but superconducting devices’ strong nonlinearities are normally static. Here, the authors use a SNAIL to suppress static nonlinearities and use drive-dependent ones to reach universal control of a bosonic mode.

    • Axel M. Eriksson
    • , Théo Sépulcre
    •  & Simone Gasparinetti

  • Article
    | Open Access

    Ensuring high-fidelity quantum gates while increasing the number of qubits poses a great challenge. Here the authors present a scalable strategy for optimizing frequency trajectories as a form of error mitigation on a 68-qubit superconducting quantum processor, demonstrating high single- and two-qubit gate fidelities.

    • Paul V. Klimov
    • , Andreas Bengtsson
    •  & Hartmut Neven

  • Article
    | Open Access

    Topological properties of a photonic environment are crucial to engineer robust photon-mediated interactions between quantum emitters. Here, the authors find general theorems on the topology of photon-mediated interactions, unveiling the phenomena of topological preservation and reversal.

    • Federico Roccati
    • , Miguel Bello
    •  & Angelo Carollo

  • Article
    | Open Access

    T centers in silicon are promising candidates for quantum applications yet suffer from weak optical transitions. Here, by integrating with a silicon nanocavity, the authors demonstrate an enhancement of the photon emission rate for a single T center.

    • Adam Johnston
    • , Ulises Felix-Rendon
    •  & Songtao Chen

  • Article
    | Open Access

    Strongly interacting interlayer excitons and the interplay between excitons and electronic states have recently been studied in moire superlattices. Here the authors study moire WS2/WSe2 heterobilayer with tuneable electron and exciton populations and find signatures of an excitonic Mott insulating state.

    • Beini Gao
    • , Daniel G. Suárez-Forero
    •  & Mohammad Hafezi

  • Article
    | Open Access

    Understanding machine learning models’ ability to extrapolate from training data to unseen data - known as generalisation - has recently undergone a paradigm shift, while a similar understanding for their quantum counterparts is still missing. Here, the authors show that uniform generalization bounds pessimistically estimate the performance of quantum machine learning models.

    • Elies Gil-Fuster
    • , Jens Eisert
    •  & Carlos Bravo-Prieto

  • Article
    | Open Access

    Interfacing single-photon emitters (SPEs) with high-finesse cavities can prevent decoherence processes, especially at elevated temperature, but its implementation remains challenging. Here, the authors report room-temperature strong coupling of SPEs in hexagonal boron nitride with a dielectric cavity based on bound states in the continuum, showing a Rabi splitting of ~ 4 meV.

    • T. Thu Ha Do
    • , Milad Nonahal
    •  & Son Tung Ha

  • Article
    | Open Access

    The ability to characterize large and complex nuclear-spin networks could enable quantum applications, such as quantum simulations of many-body physics. Here the authors develop a high-resolution quantum-sensing method and use it to image a network of 50 nuclear spins surrounding a single NV center in diamond.

    • G. L. van de Stolpe
    • , D. P. Kwiatkowski
    •  & T. H. Taminiau

  • Article
    | Open Access

    Studying out-of-equilibrium entanglement fluctuations is beyond the scope of current theories. Lim et al. present an analytical theory of fluctuations in long-time dynamics of entanglement in two classes of integrable lattice models, showing features reminiscent of universal mesoscopic fluctuations.

    • Lih-King Lim
    • , Cunzhong Lou
    •  & Chushun Tian

  • Article
    | Open Access

    Autonomous quantum error correction protects quantum systems against decoherence through engineered dissipation. Here the authors introduce the Star code, which actively corrects single-photon loss and passively suppresses low-frequency dephasing and implement it in a two-transmon device.

    • Ziqian Li
    • , Tanay Roy
    •  & David I. Schuster

  • Article
    | Open Access

    Real-time adaptive control of a qubit has been demonstrated but limited to single-axis Hamiltonian estimation. Here the authors implement two-axis control of a singlet-triplet spin qubit with two fluctuating Hamiltonian parameters, resulting in improved quality of coherent oscillations.

    • Fabrizio Berritta
    • , Torbjørn Rasmussen
    •  & Ferdinand Kuemmeth

  • Article
    | Open Access

    Detection of topological phases in experiments is challenging, especially in the presence of incoherent noise. Cong et al. introduce a novel method combining error correction and renormalization-group flow and apply it to characterization of quantum spin liquid phases realized in a Rydberg-atom simulator.

    • Iris Cong
    • , Nishad Maskara
    •  & Mikhail D. Lukin

  • Article
    | Open Access

    Qudits, higher-dimensional analogues of qubits, expand quantum state space for information processing using fewer physical units. Here the authors demonstrate control over a 16-dimensional Hilbert space, equivalent to four qubits, using combined electron-nuclear states of a single Sb donor atom in Si.

    • Irene Fernández de Fuentes
    • , Tim Botzem
    •  & Andrea Morello

  • Article
    | Open Access

    Electron charge and spin shuttling is a promising technique for connecting distant spin qubits. Here the authors use conveyor-mode shuttling to achieve high-fidelity transport of a single electron spin in Si/SiGe by separation and rejoining of two spin-entangled electrons across a shuttling distance of 560 nm.

    • Tom Struck
    • , Mats Volmer
    •  & Lars R. Schreiber

  • Article
    | Open Access

    R.-J. Slager et al. extend the theory of multigap topology from static to non-equilibrium systems. They identify Floquet-induced non-Abelian braiding, resulting in a phase characterized by anomalous Euler class, a multi-gap topological invariant. They also find a gapped anomalous Dirac string phase. Both phases have no static counterparts and exhibit distinct boundary signatures.

    • Robert-Jan Slager
    • , Adrien Bouhon
    •  & F. Nur Ünal

  • Article
    | Open Access

    By coupling a spin-qubit to a superconducting resonator, remote spin-entanglement becomes feasible. Here, Ungerer et al achieve strong coupling between a superconducting resonator and a singlet-triplet spin qubit, in an InAs nanowire.

    • J. H. Ungerer
    • , A. Pally
    •  & C. Schönenberger

  • Article
    | Open Access

    Trapped ion quantum systems based on sympathetic cooling use ions of different species. Here the authors demonstrate exchange cooling using two ions of the same species (40Ca+) by taking advantage of the exchange of energy when the ions are brought close together.

    • Spencer D. Fallek
    • , Vikram S. Sandhu
    •  & Kenton R. Brown

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