Theoretical physics articles within Nature Communications

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  • Article |

    In quantum information, the phase-flip error of a logical qubit protected by Z2 topological order is the vison, an elementary excitation of the Z2 phase, which is predicted to condense at zero temperature. Here, Hao et al.study a vison-induced transition in a quantum dimer model on the kagome lattice.

    • Zhihao Hao
    • , Stephen Inglis
    •  & Roger Melko

  • Article |

    While most quantum optical techniques reveal either the wave or particle nature of light, weak-field homodyne detection combines wave- and particle-like descriptions. Here, Donati et al.employ this hybrid detection scheme to study the coherence between photon number states across two-mode entangled states.

    • Gaia Donati
    • , Tim J. Bartley
    •  & Ian A. Walmsley

  • Article
    | Open Access

    Coherently coupling microwave photons to quantum electronic conductors could provide a useful platform for quantum information processing. Souquet et al. now theoretically demonstrate that such systems can also act as sensitive probes of the quantum properties of non-classical microwave radiation.

    • J. -R. Souquet
    • , M. J. Woolley
    •  & A. A. Clerk

  • Article |

    The conversion of quantum states between single photons and single atoms is an essential ingredient for the implementation of quantum memories. Here, Kurz et al. demonstrate a photon-to-atom quantum state conversion protocol characterized by mapping fidelities as high as 95%.

    • Christoph Kurz
    • , Michael Schug
    •  & Jürgen Eschner

  • Article
    | Open Access

    Network controllability has numerous applications in natural and technological systems. Here, Gao et al.develop a theoretical approach and a greedy algorithm to study target control—the ability to efficiently control a preselected subset of nodes—in complex networks.

    • Jianxi Gao
    • , Yang-Yu Liu
    •  & Albert-László Barabási

  • Article |

    Spin–orbit coupling gives rise to a plethora of rich phenomena in many condensed matter and atomic systems. Syzranov et al.study the role of dipole–dipole interactions in ultracold polar molecule gases and show that they produce an effective spin–orbit coupling that generates chiral excitations.

    • Sergey V. Syzranov
    • , Michael L. Wall
    •  & Ana Maria Rey

  • Article |

    A longstanding question in quantum information is the validity of the disputed Peres conjecture stating that bound entangled state can never lead to Bell inequality violation. Here Vértesi and Brunner prove that the Peres conjecture is false by providing an explicit counter example.

    • Tamás Vértesi
    •  & Nicolas Brunner

  • Article |

    A problem in the treatment of 1D quantum magnetic systems is the shortage of theoretical models applicable for general confinement. Here, Volosniev et al.introduce an energy-functional technique to solve 1D fermionic and bosonic systems with strong short-range interaction in arbitrary geometry.

    • A. G. Volosniev
    • , D. V. Fedorov
    •  & N. T. Zinner

  • Article
    | Open Access

    Semiconductor quantum dots embedded in nanowires are good candidates for the realization of a nearly ideal entangled photons source. Here, Versteegh et al.demonstrate emission of single-photon pairs from a position-controlled nanowire quantum dot without the need for temporal post-selection.

    • Marijn A. M. Versteegh
    • , Michael E. Reimer
    •  & Val Zwiller

  • Article
    | Open Access

    Contact parameterises two-body correlations at short distances in dilute systems like ultracold atomic gases. Using a fundamental thermodynamic relation, Chen et al.study the contact near a continuous classical or quantum phase transition and find that it displays a number of critical behaviours.

    • Y.-Y. Chen
    • , Y.-Z. Jiang
    •  & Qi Zhou

  • Article |

    An open question in quantum key distribution (QKD) is whether there exist protocols avoiding the exponential decay of the secret key generation rate with distance. Takeoka et al.show a fundamental tradeoff between the secret-key generation rate and the channel loss for optical repeater-less QKD protocols.

    • Masahiro Takeoka
    • , Saikat Guha
    •  & Mark M. Wilde

  • Article |

    Long quantum coherence time is a fundamental requirement for the realization of any quantum-mechanically operating machine. Here, Bader et al.demonstrate a coherence time as long as 68 μs at low temperature and of 1 μs at room temperature for a transition metal complex.

    • Katharina Bader
    • , Dominik Dengler
    •  & Joris van Slageren

  • Article |

    Unlike metals, Weyl and Dirac semimetals possess open discontinuous Fermi surfaces. Here, Potter et al.show how such materials may still exhibit characteristic electronic oscillations under applied magnetic fields via bulk tunnelling between Fermi arcs and predict their experimental signatures.

    • Andrew C. Potter
    • , Itamar Kimchi
    •  & Ashvin Vishwanath

  • Review Article |

    Neutrinos are ghost-like particles that interact only very weakly with other particles. As ongoing experiments to measure their properties improve, Ohlsson and Zhou review neutrino mass models and the renormalization group running of neutrino parameters that aim to understand the origin of neutrino mass.

    • Tommy Ohlsson
    •  & Shun Zhou

  • Article |

    The manipulation of magnetic skyrmions in thin films has presented new possibilities for emerging devices and technology. Here, Koshibae et al.use numerical simulations to show how localized nanoscale heating can generate such chiral topological spin textures in both dipolar and chiral magnets.

    • Wataru Koshibae
    •  & Naoto Nagaosa

  • Article |

    Quantum simulators offer a test bed to emulate physical phenomena that are difficult to reproduce numerically. Using a multi-element superconducting quantum circuit, Chen et al.emulate weak localization for a mesoscopic system using a control sequence that lets them continuously tune the level of disorder.

    • Yu Chen
    • , P. Roushan
    •  & John M. Martinis

  • Article
    | Open Access

    It is an old adage in quantum physics that the observation of a system changes its properties, as exemplified by the quantum Zeno effect. Now, Burgarth et al.show that such repeated measurement of a quantum system actually enriches its dynamics, letting it explore a much larger algebra than it did before.

    • Daniel Klaus Burgarth
    • , Paolo Facchi
    •  & Kazuya Yuasa

  • Article |

    Chiral spin liquids, a topological phase in frustrated quantum spin systems, have been recently very sought-after. Here, Bauer et al.present a model for a Mott insulator on the Kagome lattice with broken time-reversal symmetry exhibiting such a topological phase.

    • B. Bauer
    • , L. Cincio
    •  & A.W.W. Ludwig

  • Article
    | Open Access

    Decoherence is anathema to quantum systems, as it reduces their performance and stability. Shulman et al.show that real-time Hamiltonian parameter estimation can significantly increase the coherence time of a qubit by enabling continuous adjustment of its control parameters.

    • M. D. Shulman
    • , S. P. Harvey
    •  & A. Yacoby

  • Article |

    In condensed matter physics, p-wave chiral superfluidity is an unconventional topological many-body quantum state. Here, Liu et al. report a new mechanism to achieve a centre-of-mass p-wave chiral superfluid state in a spin imbalanced atomic Fermi gas with s-wave interaction.

    • Bo Liu
    • , Xiaopeng Li
    •  & W Vincent Liu

  • Article |

    Arguably, the most counterintuitive aspects of quantum mechanics are indeterminacy of physical quantities and ambiguity of wave/particle behaviour prior to measurement. Terno et al.propose an experiment to test hidden-variable models that aim to restore objectivity and determinism in quantum theory.

    • Radu Ionicioiu
    • , Thomas Jennewein
    •  & Daniel R. Terno

  • Article |

    In complex networks, non-Markovianity is an important mechanism affecting causality and the dynamics of a process. Here, Scholtes et al.introduce an analytical approach to study non-Markovian temporal networks, allowing to predict causality-driven changes of diffusion speed.

    • Ingo Scholtes
    • , Nicolas Wider
    •  & Frank Schweitzer

  • Article
    | Open Access

    Quantum gates based on geometric phase shifts offer a promising approach for the realization of fault-tolerant quantum computing. Using nitrogen-vacancy centre qubits in diamond, this study experimentally realises a high-fidelty, non-adiabatic, non-Abelian holonomic single-qubit gate at room temperature.

    • Silvia Arroyo-Camejo
    • , Andrii Lazariev
    •  & Gopalakrishnan Balasubramanian

  • Article |

    The device resistance of organic spin valves is closely related to their large magnetoresistance, but the origin of this phenomenon is still unclear. Here, Yu provides an explanation in terms of electrons tunneling into a broad impurity band located between occupied and unoccupied molecular orbitals.

    • Z. G. Yu

  • Article |

    Testing the validity of the quantum superposition principle with increasingly large particles may shed light on the quantum to classical transition for macroscopic objects. Here, Bateman et al. propose a near-field interference scheme based on the single-source Talbot effect for 106 amu silicon particles.

    • James Bateman
    • , Stefan Nimmrichter
    •  & Hendrik Ulbricht

  • Article
    | Open Access

    A quantum system that super-radiates must also exhibit enhanced absorption, but the former always dominates in natural systems. However, by invoking environmental quantum control techniques, Higgins et al.demonstrate that a system can exhibit quantum-enhanced light absorption.

    • K. D. B. Higgins
    • , S. C. Benjamin
    •  & E. M. Gauger

  • Article |

    In quantum mechanics, the uncertainty principle is considered a limiting factor forbidding a system from being in a state where all possible measurements have perfectly predictable outcomes. Here, Dahlsten et al. show its positive role as the enabler of non-classical dynamics in an interferometer.

    • Oscar C. O. Dahlsten
    • , Andrew J. P. Garner
    •  & Vlatko Vedral

  • Article
    | Open Access

    Dynamic force spectroscopy is widely applied to probe molecular interactions by forcible bond breaking, but it currently lacks an analytical theory that spans the divide between experiment and simulation. Here, such a unified framework is developed and shown to be accurate for slow and fast loading.

    • Jakob T. Bullerjahn
    • , Sebastian Sturm
    •  & Klaus Kroy

  • Article
    | Open Access

    One of the paradoxical phenomena of quantum mechanics is the quantum Cheshire Cat, consisting of the apparent spatial separation of a particle and one of its properties. Denkmayr et al.use neutron interferometry to prepare and evaluate the Cheshire Cat state of a neutron and its magnetic moment.

    • Tobias Denkmayr
    • , Hermann Geppert
    •  & Yuji Hasegawa

  • Article |

    The observation of Majorana modes is one of the great challenges in the field of cold atomic gases. Here Bühler et al. propose an experimentally realistic setup for the realization of p-wave superfluids supporting Majorana fermions at lattice dislocations.

    • A. Bühler
    • , N. Lang
    •  & H.P. Büchler

  • Article
    | Open Access

    The successful realization of quantum information protocols relies on characterization of quantum states and measurements. Here, Cooper et al.experimentally demonstrate a technique enabling calibration of a detector with a sizeable number of outcomes using a limited amount of resources.

    • Merlin Cooper
    • , Michał Karpiński
    •  & Brian J. Smith

  • Article
    | Open Access

    Atoms experience large and typically undesirable forces near dielectric surfaces due to quantum fluctuations of the electromagnetic vacuum. The work of Chang et al.proposes a scheme in which these forces can be exploited to create strong atomic traps at nanoscale distances from surfaces.

    • D. E. Chang
    • , K. Sinha
    •  & H. J. Kimble

  • Article
    | Open Access

    Contradictory theories are used to describe radiation pressure at the interface between air and dielectric liquids. Here, Astrath et al. measure the surface deformation of water by laser excitation and conclude that both theories with different forms of electromagnetic momentum tensor may be correct.

    • Nelson G. C. Astrath
    • , Luis C. Malacarne
    •  & Stephen E. Bialkowski

  • Article |

    High-energy particle colliders are important for finding new particles, but huge volumes of data must be searched through to locate them. Here, the authors show the use of deep-learning methods on benchmark data sets as an approach to improving such new particle searches.

    • P. Baldi
    • , P. Sadowski
    •  & D. Whiteson

  • Article |

    Herbertsmithite is a kagome material presumed to host a spin liquid phase with fractionalized excitations. Here, Mazin et al.study the crystallographic and electronic properties of gallium-substituted herbertsmithite, finding that it has symmetry-protected Dirac points at the Fermi level.

    • I. I. Mazin
    • , Harald O. Jeschke
    •  & Roser Valentí

  • Article |

    Traditionally, thermodynamics deals with the study of macroscopic systems comprised of a large number of particles. Skrzypczyk et al. present a framework—including a thermal bath and work-storage device—to extract the optimal amount of work from individual quantum systems.

    • Paul Skrzypczyk
    • , Anthony J. Short
    •  & Sandu Popescu

  • Article |

    Quantum error correction protocols aim at protecting quantum information from corruption due to decoherence and imperfect control. Using three superconducting transmon qubits, Chow et al. demonstrate necessary elements for the implementation of the surface error correction code on a two-dimensional lattice.

    • Jerry M. Chow
    • , Jay M. Gambetta
    •  & M Steffen

  • Article |

    Closed timelike curves are solutions to the equations of general relativity that permit the possibility of time travel. Ringbauer et al.experimentally emulate the quantum equivalent of these solutions to explore the nature of such phenomena, their implications and relationship to quantum mechanics.

    • Martin Ringbauer
    • , Matthew A. Broome
    •  & Timothy C. Ralph

  • Article
    | Open Access

    Petawatt laser-matter interactions could open the way to fusion energy or compact particular accelerators, but predicting the amount of light absorbed in these interactions is challenging. New analysis by Levy et al.reveals the theoretical upper and lower limits of this absorption.

    • Matthew C. Levy
    • , Scott C. Wilks
    •  & Matthew G. Baring

  • Article |

    During photoionization, the recoil of the atom or molecule due to the ejected electron can subtly alter the observed photoelectron and Auger spectra from expectations. Here, the authors study Auger emission from isolated neon atoms and see a Doppler shift in the spectrum resulting from translation recoil.

    • Marc Simon
    • , Ralph Püttner
    •  & Denis Céolin

  • Article |

    Skyrmions—magnetic vortices that can behave like particles—have recently been observed in ultra-thin transition metal films. Dupé et al. show how the structure and composition of the interface influence the size and stability of the skyrmions.

    • Bertrand Dupé
    • , Markus Hoffmann
    •  & Stefan Heinze

  • Article
    | Open Access

    The Shannon limit describes the limit of error-free information transmission and thus the information that can be transmitted in telecommunications. Here, the authors derive the Shannon limit for nonlinear, regenerative systems, expanding on the classical linear case.

    • M. A. Sorokina
    •  & S. K. Turitsyn

  • Article |

    As electronic devices move towards higher frequencies, new quantum mechanical effects become accessible. Gaury and Waintal simulate ultra-fast voltage pulses in the quantum regime and study their ability to dynamically control the relative phases of the paths in an electronic interferometer.

    • Benoit Gaury
    •  & Xavier Waintal

  • Article |

    According to Noether’s theorem, every symmetry of a dynamical evolution implies a conservation law. Marvian and Spekkens show that this theorem is deficient for certain types of quantum dynamics, and they propose measures of the extent to which a quantum state breaks a symmetry.

    • Iman Marvian
    •  & Robert W Spekkens

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