Quantum information articles within Nature Communications

Featured

  • Article
    | Open Access

    Aumann’s agreement theorem states that observers of classical systems can’t “agree to disagree." Here, the authors show that the same epistemic consistency holds for observers of quantum states, but not for observers of post-quantum no-signalling boxes, hinting at its potential status as a physical principle.

    • Patricia Contreras-Tejada
    • , Giannicola Scarpa
    •  & Pierfrancesco La Mura

  • Article
    | Open Access

    Variational quantum algorithms (VQAs) are a leading candidate for useful applications of near-term quantum computing, but limitations due to unavoidable noise have not been clearly characterized. Here, the authors prove that local Pauli noise can cause vanishing gradients rendering VQAs untrainable.

    • Samson Wang
    • , Enrico Fontana
    •  & Patrick J. Coles

  • Article
    | Open Access

    The combination of superconducting nanowire single photon detectors and electro-optically reconfigurable circuits in a cryogenic environment is notoriously difficult to reach. Here, the authors realise this on a Lithium-Niobate-On-Insulator platform, reaching high speed modulation at a frequency up to 1 GHz.

    • Emma Lomonte
    • , Martin A. Wolff
    •  & Francesco Lenzini

  • Article
    | Open Access

    When trying to characterise a bath coupled to a sensor qubit, one should consider that quantum environments change their properties in response to external perturbations. Here, the authors show how back-action of the qubit on the bath leads to a quench, which can be used to infer the bath spectral function.

    • Yu-Xin Wang
    •  & Aashish A. Clerk

  • Article
    | Open Access

    Understanding the mechanism of formation of solid-state spin defects underpins their future applications in quantum technologies. Here, the authors use a combination of ab initio molecular dynamics, enhanced sampling, and density functional theory to clarify the formation process of spin defects in silicon carbide.

    • Elizabeth M. Y. Lee
    • , Alvin Yu
    •  & Giulia Galli

  • Article
    | Open Access

    Reliable and fast active reset protocols are key to the functioning of quantum computing systems. Here, the authors use parametric driving to swap an excitation from a transmon qubit to its readout resonator within 34 ns, with negligible effects on neighboring qubits.

    • Yu Zhou
    • , Zhenxing Zhang
    •  & Shengyu Zhang

  • Article
    | Open Access

    Non-additivity of the quantum channel coherent information is known to occur in some very noisy channels, but its fundamental origin is unclear. Here, the author explains its link with log singularity of quantum entropy, and shows that it can also come up for low-noise channels.

    • Vikesh Siddhu

  • Article
    | Open Access

    N00N states are a key resource in quantum metrology, but the use of their multi-mode extension for multiparameter estimation has been elusive so far. Here, the authors use multi-mode N00N states - with N=2 photons in 4 modes - for multiple-phase estimation saturating the quantum Cramer-Rao bound.

    • Seongjin Hong
    • , Junaid ur Rehman
    •  & Hyang-Tag Lim

  • Article
    | Open Access

    The question whether a given isolated quantum many-body system would thermalize has currently no general answer. Here, Shiraishi and Matsumoto demonstrate the computational universality of thermalization phenomena already for simplified 1D systems, thus proving that the thermalization problem is undecidable.

    • Naoto Shiraishi
    •  & Keiji Matsumoto

  • Article
    | Open Access

    The way quantum simulation algorithms are translated into specific hardware implementations often translates into additional overhead. Here, the authors improve the efficiency of Hamiltonian simulation using a method that allows efficient synthesis of multi-qubit evolutions from two-qubit interactions.

    • Laura Clinton
    • , Johannes Bausch
    •  & Toby Cubitt

  • Article
    | Open Access

    In quantum mechanics, counterfactual behaviours are generally associated with particles being affected by events taking place where they can’t be found. Here, the authors consider extended quantum Cheshire cat scenarios where a particle can be influenced in regions where only its disembodied property has entered.

    • Yakir Aharonov
    • , Eliahu Cohen
    •  & Sandu Popescu

  • Article
    | Open Access

    Microcavity exciton-polaritons in atomically thin semiconductors are a promising platform for valley manipulation. Here, the authors show valley-selective control of polariton energies in monolayer WS2 using the optical Stark effect, thereby extending coherent valley manipulation to a hybrid light-matter regime

    • Trevor LaMountain
    • , Jovan Nelson
    •  & Nathaniel P. Stern

  • Article
    | Open Access

    Nuclear spins in diamond are promising for applications in quantum technologies due to their long coherence times. Here, the authors demonstrate a scalable electrical readout of individual intrinsic 14N nuclear spins in diamond, mediated by hyperfine coupling to electron spin of the NV center, as a step towards room-temperature nanoscale diamond quantum devices.

    • Michal Gulka
    • , Daniel Wirtitsch
    •  & Milos Nesladek

  • Article
    | Open Access

    Several key tasks in quantum information processing can be regarded as channel manipulation. Here, focusing on the class of distillation protocols, the authors derive general bounds on resource overhead and incurred errors, showing application to magic state distillation and quantum channel capacities.

    • Bartosz Regula
    •  & Ryuji Takagi

  • Article
    | Open Access

    Photon echo techniques are difficult to implement in the quantum regime due to coherent and spontaneous emission noise. Here, the authors propose a low-noise photon-echo quantum memory approach based on all-optical control in a four-level system, and demonstrate it using a Eu3+:Y2SiO5 crystal.

    • You-Zhi Ma
    • , Ming Jin
    •  & Guang-Can Guo

  • Article
    | Open Access

    Hybrid devices based on electrons on helium may find application in quantum devices. Here the authors demonstrate surface acoustic wave driven acoustoelectric transport of electrons on superfluid helium.

    • H. Byeon
    • , K. Nasyedkin
    •  & J. Pollanen

  • Article
    | Open Access

    Long-range coherent spin-qubit transfer between semiconductor quantum dots requires understanding and control over associated errors. Here, the authors achieve high-fidelity coherent state transfer in a Si double quantum dot, underpinning the prospects of a large-scale quantum computer.

    • J. Yoneda
    • , W. Huang
    •  & A. S. Dzurak

  • Article
    | Open Access

    Control of quantum emitters is needed in order to enable many applications. Here, the authors demonstrate enhancement and dynamical control of the Purcell emission from erbium ions doped in a nanoparticle within a fiber-based microcavity.

    • Bernardo Casabone
    • , Chetan Deshmukh
    •  & Hugues de Riedmatten

  • Article
    | Open Access

    The use of optically addressable spins to control dark electron-spins is promising for multi-qubit platforms; however, control over darks spins has remained challenging. Here, the authors realize entanglement between individual dark spins associated with substitutional nitrogen defects in diamond.

    • M. J. Degen
    • , S. J. H. Loenen
    •  & T. H. Taminiau

  • Article
    | Open Access

    Optically detected magnetic resonance of defect spins typically relies on Stokes excitation, in which the excitation energy is larger than that of the emitted photon. Here, the authors use the opposite regime of anti-Stokes excitation to detect Si vacancy spins in SiC, with a threefold improvement in signal contrast.

    • Jun-Feng Wang
    • , Fei-Fei Yan
    •  & Guang-Can Guo

  • Article
    | Open Access

    Non-Abelian statistics plays a crucial role towards realizing topological quantum computation. Here, the authors discover new types of non-Abelian three-loop braiding statistics that can only be realized in 3D interacting fermionic systems.

    • Jing-Ren Zhou
    • , Qing-Rui Wang
    •  & Zheng-Cheng Gu

  • Article
    | Open Access

    Device-independent quantum key distribution aims at the ultimate quantum-based unconditional security, but current protocols’ rates are quite far from anything practical. The authors’ protocol narrows this gap by using two randomly chosen key generating bases instead of one.

    • René Schwonnek
    • , Koon Tong Goh
    •  & Charles C.-W. Lim

  • Article
    | Open Access

    Expectations for quantum machine learning are high, but there is currently a lack of rigorous results on which scenarios would actually exhibit a quantum advantage. Here, the authors show how to tell, for a given dataset, whether a quantum model would give any prediction advantage over a classical one.

    • Hsin-Yuan Huang
    • , Michael Broughton
    •  & Jarrod R. McClean

  • Article
    | Open Access

    Gamma photons used in positron emission tomography are predicted to be produced in an entangled state. Here, the authors simulate the effects of entanglement and test them through comparison with experimental data from a PET demonstrator apparatus, showing the potential gains in background suppression.

    • D. P. Watts
    • , J. Bordes
    •  & N. A. Zachariou

  • Article
    | Open Access

    Steering reflects the ability to predict measurement results on one side of a quantum-correlated system based on measurements on the other side, which can be phrased as a metrology problem. Here, the authors explore this connection, deriving a general steering criterion based on quantum Fisher information.

    • Benjamin Yadin
    • , Matteo Fadel
    •  & Manuel Gessner

  • Article
    | Open Access

    Quantum memories are key components for quantum communication, but current storage times are still too short. Here, the authors use the atomic frequency comb protocol in a zero-first-order-Zeeman field to coherently store an optical pulse for an hour in a cryogenically cooled rare-earth doped crystal.

    • Yu Ma
    • , You-Zhi Ma
    •  & Guang-Can Guo

  • Article
    | Open Access

    Integrated sources of nonclassical light are a key component for scalable quantum technologies. Here, the authors work with two coupled microring resonators and show how to detune the resonances involved in unwanted parametric fluorescence, without significantly affecting the pump power efficiency.

    • Y. Zhang
    • , M. Menotti
    •  & Z. Vernon

  • Article
    | Open Access

    The surface code is a keystone in quantum error correction, but it does not generally perform well against structured noise and suffers from large overheads. Here, the authors demonstrate that a variant of it has better performance and requires fewer resources, without additional hardware demands.

    • J. Pablo Bonilla Ataides
    • , David K. Tuckett
    •  & Benjamin J. Brown

  • Article
    | Open Access

    Previous demonstrations of spin state transfer in quantum dot chains relied on physical motion of electrons or sequences of SWAP operations. Here, the authors implement an alternative method based on adiabatic evolution, offering advantages in terms of implementation and robustness to noise and errors.

    • Yadav P. Kandel
    • , Haifeng Qiao
    •  & John M. Nichol

  • Article
    | Open Access

    Establishing whether two quantum channels are compatible is a fundamental problem in quantum information. Here, the authors prove its equivalence to the quantum state marginal problem, introduce an efficient way to solve both, and draw further connection to the measurement compatibility problem.

    • Mark Girard
    • , Martin Plávala
    •  & Jamie Sikora

  • Article
    | Open Access

    Correlated errors coming from leakage out of the computational subspace are an obstacle to fault-tolerant superconducting circuits. Here, the authors use a multi-level reset protocol to improve the performances of a bit-flip error correcting code by reducing the magnitude of correlations.

    • M. McEwen
    • , D. Kafri
    •  & R. Barends

  • Article
    | Open Access

    Parametrised quantum circuits are a promising hybrid classical-quantum approach, but rigorous results on their effective capabilities are rare. Here, the authors explore the feasibility of training depending on the type of cost functions, showing that local ones are less prone to the barren plateau problem.

    • M. Cerezo
    • , Akira Sone
    •  & Patrick J. Coles

  • Article
    | Open Access

    Quantum computers based on superconducting transmon qubits are limited by single qubit lifetimes and coherence times, which are orders of magnitude shorter than limits imposed by bulk material properties. Here, the authors fabricate two-dimensional transmon qubits with both lifetimes and coherence times longer than 0.3 milliseconds by replacing niobium with tantalum in the device.

    • Alexander P. M. Place
    • , Lila V. H. Rodgers
    •  & Andrew A. Houck

  • Article
    | Open Access

    The Kondo effect can serve as a powerful paradigm to understand strongly correlated many-body processes in physics. Here, Guo et al. utilize single molecule transistor devices as a testbed to study multi-level Kondo correlation and show electrical gate evolution and the universality of the two-stage Kondo effect.

    • Xiao Guo
    • , Qiuhao Zhu
    •  & Wenjie Liang

  • Article
    | Open Access

    The Gibbs paradox stems from the entropy change upon mixing two gases. Here, by considering bosonic and fermionic statistics, the authors show that an observer unable to distinguish the particles’ spins assigns a greater entropy increase to the mixing process than is possible in classical physics.

    • Benjamin Yadin
    • , Benjamin Morris
    •  & Gerardo Adesso

  • Article
    | Open Access

    In quantum random number generation, one has generally to choose between high speed and strong security. Here, the authors show how to bound several adversarial imperfections on state preparation and measurement, generating 8192 secure random bits every 0.12 s in real time using a simple apparatus.

    • Yanbao Zhang
    • , Hsin-Pin Lo
    •  & William J. Munro

  • Article
    | Open Access

    The quantum marginal problem interrogates the existence of a global pure quantum state with some given marginals. Here, the authors reformulate it as an optimisation problem, and specifically as the existence of a two-party separable state with additional semidefinite constraints.

    • Xiao-Dong Yu
    • , Timo Simnacher
    •  & Otfried Gühne

  • Article
    | Open Access

    Engineering qubits with long coherence times requires the ability to distinguish multiple noise sources, which is not possible with typical two-level qubit sensors. Here the authors utilize the multiple level transitions of a superconducting qubit to characterize two common types of external noise.

    • Youngkyu Sung
    • , Antti Vepsäläinen
    •  & William D. Oliver

  • Article
    | Open Access

    While unusual processes allowing indefinite causal order are gaining attention in quantum physics, formalisms describing definite causal structures have so far been limited to acyclic ones. Here the authors extend to the cyclic case, offering a causal perspective on causally indefinite processes.

    • Jonathan Barrett
    • , Robin Lorenz
    •  & Ognyan Oreshkov

  • Article
    | Open Access

    Most demonstrations of quantum advantages with optics rely on single photons, and are thus difficult to scale up. Here, the authors use coherent states to demonstrate a quantum advantage for the task of verifying the solution to a NP-complete problem when only partial information on the solution is available.

    • Federico Centrone
    • , Niraj Kumar
    •  & Iordanis Kerenidis

  • Article
    | Open Access

    The advantages coming from involving quantum systems in machine learning are still not fully clear. Here, the authors propose a software/hardware co-design framework towards quantum-friendly neural networks showing quantum advantage, representing data as either random variables or numbers in unitary matrices.

    • Weiwen Jiang
    • , Jinjun Xiong
    •  & Yiyu Shi

Browse broader subjects

Browse Quantum information across other nature.com journals