Quantum physics articles within Nature Communications

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  • 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

  • Article
    | Open Access

    Highly polarized nuclear spins can supress decoherence of electron spin qubits, but this requires near-unity polarization. Here the authors implement a protocol combining optical excitation and fast carrier tunnelling to achieve nuclear spin polarizations above 95% in GaAs quantum dots on a timescale of 1 minute.

    • Peter Millington-Hotze
    • , Harry E. Dyte
    •  & Evgeny A. Chekhovich

  • Article
    | Open Access

    Recent work proposed a machine learning algorithm for predicting ground state properties of quantum many-body systems that outperforms any non-learning classical algorithm but requires extensive training data. Lewis et al. present an improved algorithm with exponentially reduced training data requirements.

    • Laura Lewis
    • , Hsin-Yuan Huang
    •  & John Preskill

  • Article
    | Open Access

    The use of NISQ devices for useful quantum simulations of materials and chemistry is still mainly limited by the necessary circuit depth. Here, the authors propose to combine classically-generated effective Hamiltonians, hybrid fermion-to-qubit mapping and circuit optimisations to bring this requirement closer to experimental feasibility.

    • Laura Clinton
    • , Toby Cubitt
    •  & Evan Sheridan

  • Article
    | Open Access

    Thermal fluctuations can induce ordering in frustrated magnetic systems, yet the impact of quantum fluctuations is less explored. Here, in the controlled environment of a quantum annealer composed of superconducting qubits, the authors study a frustrated magnetic system finding that quantum fluctuations enhance magnetic correlations.

    • Alejandro Lopez-Bezanilla
    • , Andrew D. King
    •  & Avadh Saxena

  • Article
    | Open Access

    Light-matter interfaces implementing arbitrary conditional operations on incoming photons would have several applications in quantum computation and communications. Here, the authors demonstrate conditional polarization rotation induced by a single quantum dot spin embedded in an electrically contacted micropillar, spanning up to a pi flip.

    • E. Mehdi
    • , M. Gundín
    •  & L. Lanco

  • Article
    | Open Access

    Enhanced sensitivity is a key parameter in quantum metrology. Here the authors demonstrate a distributed quantum phase sensing method that uses fewer photons than the number of parameters needed, and an enhanced quantum sensitivity is achieved.

    • Dong-Hyun Kim
    • , Seongjin Hong
    •  & Hyang-Tag Lim

  • Article
    | Open Access

    The authors demonstrate a method controlling the lattice filling of doped 1D Bose-Hubbard system of Rb atoms composed of chains of 3 to 6 sites in an optical lattice. The control is achieved by changing of the light potential and interaction strength.

    • Andrea Di Carli
    • , Christopher Parsonage
    •  & Stefan Kuhr

  • Article
    | Open Access

    It is still unclear whether and how quantum computing might prove useful in solving known large-scale classical machine learning problems. Here, the authors show that variants of known quantum algorithms for solving differential equations can provide an advantage in solving some instances of stochastic gradient descent dynamics.

    • Junyu Liu
    • , Minzhao Liu
    •  & Liang Jiang

  • Article
    | Open Access

    Efficient characterisation of quantum many-body Hamiltonians has important applications for benchmarking NISQ devices. Here, the authors propose a method employing Chebyshev regression to learn the full Hamiltonian of a quantum system, with a sample complexity that scales efficiently with the system size.

    • Andi Gu
    • , Lukasz Cincio
    •  & Patrick J. Coles

  • Article
    | Open Access

    Learning Hamiltonians or Lindbladians of quantum systems from experimental data is important for characterization of interactions and noise processes in quantum devices. Here the authors propose an efficient protocol based on estimating time derivatives using multiple temporal sampling points and robust polynomial interpolation.

    • Daniel Stilck França
    • , Liubov A. Markovich
    •  & Johannes Borregaard

  • Article
    | Open Access

    Periodically driven quantum systems have been extensively studied but with a predominant focus on long-time dynamics. Here, the authors study short-to-intermediate-time dynamics of an isolated many-body system, showing that its response to driving is supressed for the initial state close to thermal equilibrium.

    • Lennart Dabelow
    •  & Peter Reimann

  • Article
    | Open Access

    Isotope engineering can enhance spin coherence of solid-state defects, such as NV centers in diamond but progress for defects in hBN has been limited. Gong et al. report the optimization of isotopes in hBN and demonstrate improved coherence and relaxation times for the negatively charged boron vacancy centers.

    • Ruotian Gong
    • , Xinyi Du
    •  & Chong Zu

  • Article
    | Open Access

    Photonic waveguide lattices implementing continuous quantum walks have a wide range of applications yet remain based on static devices. Here, the authors demonstrated a fully programmable waveguide array by implementing various Hamiltonians.

    • Yang Yang
    • , Robert J. Chapman
    •  & Alberto Peruzzo

  • Article
    | Open Access

    Several solid-state defect platforms have been proposed for application as a spin-photon interface in quantum communication networks. Here the authors report spin-selective optical transitions and narrow inhomogeneous spectral distribution of V centers in isotopically-enriched SiC emitting in the telecom O-band.

    • Pasquale Cilibrizzi
    • , Muhammad Junaid Arshad
    •  & Cristian Bonato

  • Article
    | Open Access

    Developing quantum networks would require reliable sources of coherent quantum light at telecom wavelengths. Here, the authors employ elastic scattering of excitation laser photons on InAs/InP quantum dots to demonstrate the emission of telecom photons with coherence times longer than the Fourier limit.

    • L. Wells
    • , T. Müller
    •  & A. J. Shields

  • Article
    | Open Access

    Scalable training of parametrised quantum circuit approaches is usually hindered by the barren plateau issue. Here, the authors show how initializing parametrised quantum circuits starting from scalable tensor-network based algorithms could ameliorate the problem.

    • Manuel S. Rudolph
    • , Jacob Miller
    •  & Alejandro Perdomo-Ortiz

  • Article
    | Open Access

    Remote transport of high-dimensional-encoded photonic states could in principle be achieved via quantum teleportation, but with considerable experimental effort. Here, instead, the authors exploit spatial-mode engineered frequency conversion between a coherent wave packet and a single photon to remotely transfer the HD OAM states, also providing a strategy for quantum imaging.

    • Xiaodong Qiu
    • , Haoxu Guo
    •  & Lixiang Chen

  • Article
    | Open Access

    Consistent theories have been proposed in which spacetime is treated classically while matter remains quantum. Here, the authors prove that such theories are constrained by a trade-off between the decoherence induced in the quantum system, and stochasticity in the classical one, providing a way to experimentally test the quantum nature of gravity.

    • Jonathan Oppenheim
    • , Carlo Sparaciari
    •  & Zachary Weller-Davies

  • Article
    | Open Access

    Standard techniques for Fluorescence Lifetime Imaging Microscopy are limited by the electronics to 100’s of picoseconds time resolution. Here, the authors show how to use two-photon interference to perform fluorescence lifetime sensing with picosecond-scale resolution.

    • Ashley Lyons
    • , Vytautas Zickus
    •  & Daniele Faccio

  • Article
    | Open Access

    Graphene quantum dots promise applications for spin and valley qubits; however a demonstration of phase coherent oscillations has been lacking. Here the authors report coherent charge oscillations and measurements of coherence times in highly tuneable double quantum dots in bilayer graphene.

    • K. Hecker
    • , L. Banszerus
    •  & C. Stampfer

  • Article
    | Open Access

    It has been conjectured that an alternative model of quantum computation—in which one only applies two-qubit singlet-vs-triplet measurements to almost any source of input qubits—is as powerful as the usual gate-based model. Here, the authors prove this conjecture, ending up with a model where computations are independent from the way in which one picks the axes of the Bloch sphere.

    • Terry Rudolph
    •  & Shashank Soyuz Virmani

  • Article
    | Open Access

    Multi-client demonstrations of blind quantum computation are still missing, due to their high resource overhead. Here, the authors fill this gap, by proposing a more scalable solution based on a recently introduced linear quantum network structure with high modularity, and demonstrating it in the two-client case.

    • Beatrice Polacchi
    • , Dominik Leichtle
    •  & Elham Kashefi

  • Article
    | Open Access

    Bringing atom-interferometric quantum sensors out of the lab requires the mitigation of several sources of noise. Here, the authors experimentally demonstrate a software-based mitigation method based on tailored error-robust Bragg light-pulse beamsplitters and mirrors.

    • Jack C. Saywell
    • , Max S. Carey
    •  & Michael J. Biercuk

  • Article
    | Open Access

    Nonlinear damping is a ubiquitous phenomenon in technological applications involving oscillators, but its origin is sometimes poorly understood. Here, the authors highlight how the interplay between quantum noise and Kerr anharmonicity introduces an effect resembling nonlinear damping.

    • Mario F. Gely
    • , Adrián Sanz Mora
    •  & Gary A. Steele

  • Article
    | Open Access

    Synthetic gauge field in ultracold atoms provides a controllable platform for the study of quantum many-body physics. Here the authors demonstrate frustrated chiral dynamics in synthetic triangular flux ladder under strong interaction using ultracold Cs atoms.

    • Yuqing Li
    • , Huiying Du
    •  & Suotang Jia

  • Article
    | Open Access

    The physics of confinement manifested in quantum spin chain models has been recently studied in quantum simulators. Here the authors report a numerical study of confinement of soliton excitations in a nonintegrable bosonic quantum field theory realized with a superconducting quantum electronic circuit.

    • Ananda Roy
    •  & Sergei L. Lukyanov

  • Article
    | Open Access

    The quantum error-correcting codes formed by tensor network models of holography have so far failed to produce the expected correlation functions in the boundary states. Here, the authors fill this gap by modifying a previously proposed model of hyperinvariant tensor networks.

    • Matthew Steinberg
    • , Sebastian Feld
    •  & Alexander Jahn

  • Article
    | Open Access

    Previous work on charge Kondo circuits, in which a spin is formed by two degenerate charge states of a metallic island, has been limited to transport measurements of multi-channel Kondo problems. Piquard et al. use thermodynamic measurements via a charge sensor to study the evolution of a single Kondo impurity.

    • C. Piquard
    • , P. Glidic
    •  & F. Pierre

  • Article
    | Open Access

    Real-time feedback control of quantum systems without relying on a description of the system itself is usually challenging. Here, the authors exploit deep reinforcement learning to realise feedback control for initialisation of a superconducting qubit on a submicrosecond timescale.

    • Kevin Reuer
    • , Jonas Landgraf
    •  & Christopher Eichler

  • Article
    | Open Access

    Ultracold atoms in arrays represent a useful platform to study quantum processes. Here the authors use Floquet frequency modulation to entangle neutral atoms beyond the usual Rydberg blockade range, protect entangled-state coherence, and realize Rydberg anti-blockade states for two atoms at close range.

    • Luheng Zhao
    • , Michael Dao Kang Lee
    •  & Huanqian Loh

  • Article
    | Open Access

    Feedback oscillators are a fundamental tool in science and engineering. Here, Loughlin and Sudhir provide a generalized Schawlow-Townes-like formula for quantum-limited feedback oscillators, thus giving a general model to study the fundamental output noise of these devices and techniques to reduce their noise further.

    • Hudson A. Loughlin
    •  & Vivishek Sudhir

  • Article
    | Open Access

    In order to be useful for future large-scale quantum computing, quantum error correction needs to allow for fast enough classical decoding time, while at the moment the slowdown is exponential in the size of the code. Here, the authors remove this roadblock, showing how to parallelize decoding and make the slowdown polynomial.

    • Luka Skoric
    • , Dan E. Browne
    •  & Earl T. Campbell

  • Article
    | Open Access

    Molecular electron spins are promising qubit candidates, however physical implementation of quantum gates is challenging. Little et al. explore the implementation of two-qubit entangling gates between nitroxide spin centres by pulsed electron paramagnetic resonance, building on NMR quantum computing protocols.

    • Edmund J. Little
    • , Jacob Mrozek
    •  & Richard E. P. Winpenny

  • Article
    | Open Access

    Storage of photon entanglement at telecommunication wavelength is an important milestone for the development of the quantum internet. Here, the authors demonstrate storage and retrieval of entangled telecom photons—generated through SWFM in a silicon nitride microring resonator—in an Erbium doped crystal.

    • Ming-Hao Jiang
    • , Wenyi Xue
    •  & Xiao-Song Ma

  • Article
    | Open Access

    Nuclear spins in solid-state systems present a promising platform for quantum information applications. Here the authors report evidence of the long-predicted entangled dark nuclear spin state via optical polarization of localized hole spins coupled to the nuclear bath in a lead halide perovskite semiconductor.

    • E. Kirstein
    • , D. S. Smirnov
    •  & M. Bayer

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