Quantum physics articles within Nature Communications

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  • 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

  • Article
    | Open Access

    Electron holography and microscopy have long been used to map static electric and magnetic fields. Here, authors establish Lorentz Microscopy of Optical Fields, a new technique that uses the deflection and interference of an electron beam to obtain phase-resolved images of nanoscale optical fields.

    • John H. Gaida
    • , Hugo Lourenço-Martins
    •  & Claus Ropers

  • Article
    | Open Access

    The authors propose an implementation of Floquet non-Abelian topological insulators in a 1D three-band system with parity-time symmetry. Furthermore, they demonstrate that the bulk-edge correspondence is multifold and follows the multiplication rule of a quaternion group.

    • Tianyu Li
    •  & Haiping Hu

  • Article
    | Open Access

    Realising a quantum-backaction-limited oscillator in the acoustic frequency range would have applications in sensing and metrology. Here, the authors reach this goal by demonstrating destructive interference between quantum back-action noise and shot noise down to sub-kHz range in a warm atomic vapor cell.

    • Jun Jia
    • , Valeriy Novikov
    •  & Eugene S. Polzik

  • Article
    | Open Access

    Schrodinger’s cat states constitute an important resource for quantum information processing, but present challenges in terms of scalabilty and controllability. Here, the authors exploit fast Kerr nonlinearity modulation to generate and store cat states in superconducting circuits in a more scalable way.

    • X. L. He
    • , Yong Lu
    •  & Z. R. Lin

  • Article
    | Open Access

    Circuit QED with strongly driven cavities is a powerful framework for quantum technologies, but often undesired effects on the qubit are introduced. Here, by using an external tone tailored to destructively interfere with the cavity field, the authors show how a transmon can be protected from these unwanted effects.

    • Cristóbal Lledó
    • , Rémy Dassonneville
    •  & Alexandre Blais

  • Article
    | Open Access

    Nanodiamonds containing NV centers are promising electron paramagnetic resonance sensors, however applications are hindered by their random orientation. Qin et al. propose a new protocol that makes the technique insensitive to the sensor’s orientation and present a proof-of-principle in situ demonstration.

    • Zhuoyang Qin
    • , Zhecheng Wang
    •  & Jiangfeng Du

  • Article
    | Open Access

    Multiparameter sensors in quantum optics are often complex due to use of external fields. Here the authors demonstrate a simple single-shot all-optical vector atomic magnetometer based on machine learning for the correspondence of the measured signals and the magnetic field.

    • Xin Meng
    • , Youwei Zhang
    •  & Yanhong Xiao

  • Article
    | Open Access

    Our current understanding of the computational abilities of near-intermediate scale quantum (NISQ) computing devices is limited, in part due to the absence of a precise definition for this regime. Here, the authors formally define the NISQ realm and provide rigorous evidence that its capabilities are situated between the complexity classes BPP and BQP.

    • Sitan Chen
    • , Jordan Cotler
    •  & Jerry Li

  • Article
    | Open Access

    Performing quantum computing in the NISQ era requires reliable information on the gate noise characteristics and their performance benchmarks. Here, the authors show how to estimate the individual noise properties of any quantum process from the noisy eigenvalues of its corresponding quantum channel.

    • Yanwu Gu
    • , Wei-Feng Zhuang
    •  & Dong E. Liu

  • Article
    | Open Access

    Quantum theory allows for indefinite causal order, but experimental demonstrations of such scenarios have so far required trust in the internal functioning of the apparatus. Here, the authors point out a scenario where indefinite causal order could be certified in a device-independent way, if one excludes superluminal and retrocausal influences.

    • Tein van der Lugt
    • , Jonathan Barrett
    •  & Giulio Chiribella

  • Article
    | Open Access

    The beamsplitter operation is a key component for quantum information processing, but implementations in superconducting circuit-QED usually introduce additional decoherence. Here, the authors exploit the symmetry within a SQUID, driven in a purely differential manner, to realise clean BS operations between two SC cavity modes.

    • Yao Lu
    • , Aniket Maiti
    •  & Robert J. Schoelkopf

  • Article
    | Open Access

    Axions are hypothetical particles that constitute leading candidates for the identity of dark matter. Here, the authors improve previous exclusion bounds on axion-like particles in the range of 1.4–200 peV, and report direct terrestrial limits on the coupling of protons and neutrons with axion-like dark matter.

    • Itay M. Bloch
    • , Roy Shaham
    •  & Or Katz

  • Article
    | Open Access

    Quantum simulations of topological matter with superconducting qubits have been attracting attention recently. Xiang et al. realize 2D and bilayer Chern insulators with synthetic dimensions on a programmable 30-qubit-ladder superconducting processor, showing bulk-boundary correspondence.

    • Zhong-Cheng Xiang
    • , Kaixuan Huang
    •  & Heng Fan

  • Article
    | Open Access

    Rydberg atom arrays are a promising platform for simulating many-body systems. The authors introduce a tensor-network method to compute phase diagrams of infinite arrays with long-range interactions and experimental-scale finite arrays, unveiling a new entangled phase and offering a guide for experiments.

    • Matthew J. O’Rourke
    •  & Garnet Kin-Lic Chan

  • Article
    | Open Access

    By carefully inducing twists or lattice stacking offsets between two adjacent van der Waals crystals, a superlattice potential can be introduced. This Moire lattice offers an incredibly rich physics, ranging from superconductivity to exotic magnetism, depending on van der Waals materials in question. Here, Du et al. study the magnetic domains in twisted CrI3, and show that despite this domain structure, spin fluctuations are spatially homogenous.

    • Mengqi Huang
    • , Zeliang Sun
    •  & Chunhui Rita Du

  • Article
    | Open Access

    Security proofs against general attacks are the ultimate goal of QKD. Here, the authors show how the Generalised Entropy Accumulation Theorem can be used, for some classes of QKD scenarios, to translate security proofs against collective attacks in the asymptotic regime into proofs against general attacks in the finite-size regime.

    • Tony Metger
    •  & Renato Renner

  • Article
    | Open Access

    Negatively-charged boron vacancy centers in hBN have short coherence times, hindering their potential as quantum sensors. By employing dynamical decoupling, the authors achieve an ensemble coherence time approaching the fundamental relaxation limit, enabling sensitive detection of MHz range electromagnetic fields.

    • Roberto Rizzato
    • , Martin Schalk
    •  & Dominik B. Bucher

  • Article
    | Open Access

    In order to be practical, schemes for characterizing quantum operations should require the simplest possible gate sequences and measurements. Here, the authors show how random gate sequences and native measurements (followed by classical post-processing) are sufficient for estimating several gate set properties.

    • J. Helsen
    • , M. Ioannou
    •  & I. Roth

  • Article
    | Open Access

    Machine learning methods in condensed matter physics are an emerging tool for providing powerful analytical methods. Here, the authors demonstrate that convolutional neural networks can identify nematic electronic order from STM data of twisted double-layer graphene—even in the presence of heterostrain.

    • João Augusto Sobral
    • , Stefan Obernauer
    •  & Mathias S. Scheurer

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