Article
Physics, Multidisciplinary
Stefan Richter, Matthew Thornton, Imran Khan, Hamish Scott, Kevin Jaksch, Ulrich Vogl, Birgit Stiller, Gerd Leuchs, Christoph Marquardt, Natalia Korolkova
Summary: This paper explores the application of agile and versatile cryptography principles to quantum cryptography, demonstrating quantum digital signatures (QDS) and quantum secret sharing (QSS) protocols. The system is compatible with quantum key distribution and uses standard encoding and detection methods. Improvements in protocol performance are achieved by implementing postselection at the receiver for QDS protocols.
Article
Multidisciplinary Sciences
Renata Turkes, Jannes Nys, Tim Verdonck, Steven Latre
Summary: Topological data analysis using techniques from algebraic topology, with persistent homology as the main tool, has seen significant growth in applications. Research shows that the sensitivity of persistent homology to noise is influenced by the choice of filtrations and persistence signatures, and it is often not robust in classification tasks.
Article
Physics, Multidisciplinary
Samgeeth Puliyil, Manik Banik, Mir Alimuddin
Summary: This Letter extends the connection between the theory of bipartite entanglement and thermodynamics to multipartite quantum systems. Thermodynamic quantities that capture the genuineness of multipartite entangled states are proposed, defined in terms of energy. These quantities can serve as faithful measures of genuineness and distinguish different classes of genuinely entangled states.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Tal Mor, Roman Shapira, Guy Shemesh
Summary: In this paper, the qandy model is used to describe three QDS protocols, providing an important example of using superpositionless quantum information processing for individuals without background knowledge in the field.
Article
Computer Science, Artificial Intelligence
Maxwell T. West, Shu-Lok Tsang, Jia S. Low, Charles D. Hill, Christopher Leckie, Lloyd C. L. Hollenberg, Sarah M. Erfani, Muhammad Usman
Summary: Machine learning algorithms are powerful but vulnerable to adversarial attacks. Integrating quantum computing with machine learning can improve accuracy and provide better defense against such attacks.
NATURE MACHINE INTELLIGENCE
(2023)
Article
Physics, Multidisciplinary
Oliver Hahn, Alessandro Ferraro, Lina Hultquist, Giulia Ferrini, Laura Garcia-Alvarez
Summary: Quantum resource theories offer a powerful framework for understanding and quantifying quantum phenomena. This paper introduces a resource measure, based on bosonic codes, for the sought-after property of "magic" in fault-tolerant quantum computers. By utilizing the Gottesman-Kitaev-Preskill code and considering the Wigner negativity, the authors provide analytical expressions that extend the current analysis to systems of up to 12 qubits.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Deepesh Giri, Logan Williams, Arpan Mukherjee, Krishna Rajan
Summary: This paper describes a new data-driven framework for computational screening and discovery of metavalent solids, introducing the use of Hirshfeld surface analysis for rapid identification of potential metavalent solids with novel properties.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Simon A. Haine
Summary: This study explores the quantum nature of the gravitational field using an ensemble of ultra-cold atoms and employs multi-parameter estimation techniques to compare different schemes. The research finds that interactions mediated via a quantum-valued gravitational field provide a distinct signature from classical gravitational interactions, but definitive demonstration of quantum gravitational interaction is limited by uncertainty in residual electromagnetic interactions between atoms, which may be overcome with improvements in experimental techniques.
NEW JOURNAL OF PHYSICS
(2021)
Article
Optics
Carlo Marconi, Andreu Riera-Campeny, Anna Sanpera, Albert Aloy
Summary: Nonlocality refers to the existence of nonclassical correlations between local measurements. Previous studies primarily focused on isolated quantum systems. This study demonstrates the presence and detectability of nonlocal correlations in many-body open quantum systems, both in steady-state and transient regimes, suggesting their robustness against noise. Additionally, the robustness of nonlocal correlations under repeated measurements in open quantum systems, which is relevant to quantum cryptography, is also discussed.
Article
Materials Science, Multidisciplinary
Balazs Gulacsi, Guido Burkard
Summary: We describe temporally correlated noise processes that influence the idle evolution of a superconducting transmon qubit. Based on quantum circuit theory, we model the composite qubit-environment system and derive a circuit Hamiltonian for transverse noise affecting the qubit. Using the time-convolutionless projection operator method, we construct a time-local master equation that exhibits eternally non-Markovian dynamics. By expressing the solution of the master equation in the Kraus representation, we identify two crucial non-Markovian phenomena: periodic revivals of coherence and the appearance of additional frequencies far from the qubit frequency.
Article
Materials Science, Multidisciplinary
Yu-Guo Liu, Shu Chen
Summary: In this study, the effects of the Liouvillian flat band on the relaxation dynamics of open quantum systems were investigated using the Lindblad master equation scheme. Three types of Liouvillian band dispersion were observed: a flat band, a dispersionless band in the real part, and a dispersionless band in the imaginary part, and their respective dynamical signatures were captured. It was found that when the Liouvillian rapidity spectrum is flat, the particle numbers in different sites relax to their steady-state value with the same decay rate, while a dispersionless real or imaginary part of the rapidity spectrum leads to oscillating or forked relaxation behaviors. Furthermore, the Liouvillian flat band was shown to induce dynamical localization, characterized by a halt in the propagation of local perturbation in the steady state.
Article
Physics, Multidisciplinary
Yuzuru Kato, Hiroya Nakao
Summary: Synchronization of quantum nonlinear oscillators has been recently studied. A fully quantum-mechanical definition of the asymptotic phase was proposed to characterize the quantum oscillatory dynamics. Multiple asymptotic phases were introduced using the eigenoperators of the adjoint Liouville superoperator of the quantum nonlinear oscillator. The phase locking of the system with a harmonic drive at multiple different frequencies can be interpreted as synchronization on a torus rather than a simple limit cycle, which is a distinct quantum signature observed only in the strong quantum regime.
NEW JOURNAL OF PHYSICS
(2023)
Article
Quantum Science & Technology
Maurice Weber, Nana Liu, Bo Li, Ce Zhang, Zhikuan Zhao
Summary: Quantum machine learning models have the potential to be faster and more accurate than classical models, but they are also vulnerable to input perturbations. A fundamental link between binary quantum hypothesis testing and provably robust quantum classification has been formalized, leading to a tight robustness condition that puts constraints on the amount of noise a classifier can tolerate. This robustness condition against worst-case noise scenarios extends to known noise sources, providing a framework to study the reliability of quantum classification protocols beyond adversarial attacks.
NPJ QUANTUM INFORMATION
(2021)
Article
Physics, Multidisciplinary
Yoann Pelet, Ittoop Vergheese Puthoor, Natarajan Venkatachalam, Soren Wengerowsky, Martin Loncaric, Sebastian Philipp Neumann, Bo Liu, Zeljko Samec, Mario Stipcevic, Rupert Ursin, Erika Andersson, John G. Rarity, Djeylan Aktas, Siddarth Koduru Joshi
Summary: This article presents an experimental demonstration of an unconditionally secure digital signature protocol implemented on a fully connected quantum network. The protocol ensures the authenticity and non-repudiation of signatures.
NEW JOURNAL OF PHYSICS
(2022)
Article
Optics
Tanjung Krisnanda, Huawen Xu, Sanjib Ghosh, Timothy C. H. Liew
Summary: Quantum reservoir processing provides a method for performing quantum tomography of input objects by postprocessing quantities obtained from local measurements of a quantum reservoir network. We have developed a method to evaluate the tomographic completeness criterion for any quantum reservoir architecture and proposed a figure of merit to assess their robustness against imperfections. Our general method provides guidance in optimizing implementations of quantum reservoir processing.
Article
Physics, Condensed Matter
Elisabeth Wybo, Michael Knap, Frank Pollmann
Summary: The dynamics of entanglement in a Wannier-Stark many-body localized system coupled to a dephasing environment is investigated, using the third Renyi negativity as an accessible entanglement proxy. This measure captures the characteristic logarithmic growth of interacting localized phases up to intermediate time-scales, providing a tool to distinguish Wannier-Stark MBL from noninteracting Wannier-Stark localization and quantify quantum correlations in mixed-state dynamics.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Physics, Multidisciplinary
J. Knoerzer, T. Shi, E. Demler, J. Cirac
Summary: By studying trapped-ion quantum systems, we can gain insights into generalized Holstein models and benchmark expensive numerical calculations. Our focus is on simulating many-electron systems and examining the competition between charge-density wave order, fermion pairing, and phase separation.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
M. K. Joshi, F. Kranzl, A. Schuckert, I Lovas, C. Maier, R. Blatt, M. Knap, C. F. Roos
Summary: Identifying universal properties of nonequilibrium quantum states is a major challenge in modern physics. In this study, researchers experimentally observed a family of hydrodynamic universality classes in a long-range interacting spin chain system, ranging from normal diffusion to anomalous superdiffusion, and extracted the transport coefficients of the hydrodynamic theory, reflecting the microscopic properties of the system.
Article
Physics, Multidisciplinary
Clemens Kuhlenkamp, Michael Knap, Marcel Wagner, Richard Schmidt, Atac Imamoglu
Summary: In this paper, we theoretically analyze a solid-state analog of Feshbach resonances in two-dimensional semiconductor heterostructures. By tuning the applied electric field, the scattering of excitons and electrons occupying different layers can be resonantly enhanced, leading to the formation of an interlayer Feshbach molecule. This discovery has potential implications for the realization of correlated Bose-Fermi mixtures in bilayer semiconductors.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Alex Gomez Salvador, Clemens Kuhlenkamp, Livio Ciorciaro, Michael Knap, Atac Imamoglu
Summary: This study analyzes the exciton band structure arising from the periodic modulation of the valley Zeeman effect and proposes detection schemes for magnetic order in quantum moire magnets and semiclassical moire magnets.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
A. von Hoegen, M. Fechner, M. Foerst, N. Taherian, E. Rowe, A. Ribak, J. Porras, B. Keimer, M. Michael, E. Demler, A. Cavalleri
Summary: In this study, it is shown that certain lattice vibrations in cuprate high-T-c superconductors can induce transient terahertz reflectivity features suggestive of nonequilibrium superconductivity above the critical temperature. Time-resolved measurements reveal a three-order-of-magnitude amplification of a 2.5-THz electronic mode in driven YBa2Cu3O6+x. Theoretical analysis explains these observations by proposing an amplification mechanism for finite-momentum Josephson plasma polaritons. The study also emphasizes the significance of nonlinear mode mixing in amplifying fluctuating modes above the transition temperature in a wide range of materials.
Article
Physics, Multidisciplinary
N. Darkwah Oppong, G. Pasqualetti, O. Bettermann, P. Zechmann, M. Knap, I Bloch, S. Foelling
Summary: This study observes constrained dynamics in a one-dimensional mass-imbalanced Fermi-Hubbard model. By displacing the trap potential and monitoring the dynamical response of the system, suppressed transport and slow relaxation are identified, with a strong dependence on mass imbalance and interspecies interaction strength.
Article
Materials Science, Multidisciplinary
Johannes Feldmeier, William Witczak-Krempa, Michael Knap
Summary: In this study, we demonstrate how the tracer motion of tagged particles can effectively describe transport in quantum many-body systems with constraints. The conservation of spin patterns in the systems leads to specific dynamical behaviors, such as subdiffusive dynamics and intriguing coexistence phenomena. Our findings provide new insights into the dynamics of constrained lattice models and offer a common framework to understand the behavior of different systems.
Article
Materials Science, Multidisciplinary
Wilhelm Kadow, Laurens Vanderstraeten, Michael Knap
Summary: Quantum spin liquids are fascinating phases of matter with fractionalized spin excitations and unconventional long-range quantum entanglement. This study numerically computes the spectral function of a single hole doped into the half-filled Hubbard model on the triangular lattice, revealing distinct signatures of different phases and providing insights into their low-energy features. The hole spectral function, as measured by angle-resolved photoemission spectroscopy, is suggested as a useful tool for characterizing quantum spin liquids.
Article
Materials Science, Multidisciplinary
Izabella Lovas, Robert Citro, Eugene Demler, Thierry Giamarchi, Michael Knap, Edmond Orignac
Summary: We study a quantum many-body variant of the parametric oscillator using a semiclassical truncated Wigner approximation (TWA) to investigate the driven sine-Gordon model with a modulated tunnel coupling. By comparing different methods, we find that TWA can be used to explore the mode-resolved energy density dynamics and higher-order correlations between modes in the prethermal heating regime.
Article
Materials Science, Multidisciplinary
Elisabeth Wybo, Michael Knap, Alvise Bastianello
Summary: The researchers aim to realize quantum simulators of the sine-Gordon model by interfering two weakly coupled one-dimensional cold atomic gases. They use matrix-product state techniques to numerically characterize the low-energy sector of the system and compare it with the exact field-theory predictions, obtaining quantitative boundaries for the validity of the sine-Gordon description. They provide comprehensive evidence for the emergent field theory by probing its rich spectrum and observing the signatures of integrable dynamics in scattering events.
Article
Materials Science, Multidisciplinary
Stefan Birnkammer, Annabelle Bohrdt, Fabian Grusdt, Michael Knap
Summary: In this study, we propose a Floquet protocol to realize and characterize interacting topological phases in synthetic quantum systems, and provide experimental and numerical evidence for its effectiveness.
Article
Materials Science, Multidisciplinary
Ansgar G. Burchards, Johannes Feldmeier, Alexander Schuckert, Michael Knap
Summary: The study investigates the coupled dynamics of charge and energy in interacting lattice models with dipole conservation, formulating a generic hydrodynamic theory for this combination of fractonic constraints. By developing a microscopic nonequilibrium quantum field theory, the applicability to the late-time dynamics of a specific bosonic quantum system is numerically verified. Extracting all entries of a generalized diffusion matrix using a self-consistent 1/N approximation, the study determines their dependence on microscopic model parameters and discusses the relation of the results to experiments in ultracold atom quantum simulators.
Article
Materials Science, Multidisciplinary
Julian Boesl, Rohit Dilip, Frank Pollmann, Michael Knap
Summary: In this study, we investigate the Bose-Hubbard model under an effective magnetic field and discover various gapped phases connected to quantum Hall states by using the density matrix renormalization group method. Through the calculation of Hall conductance and extraction of topological entanglement entropy, we identify features compatible with different topological orders and further analyze the entanglement spectrum of topological states at different interaction strengths.
Article
Materials Science, Multidisciplinary
Joaquin F. Rodriguez-Nieva, Alexander Schuckert, Dries Sels, Michael Knap, Eugene Demler
Summary: In this study, we analyze the intrinsic stability of spin spiral states in the two-dimensional Heisenberg model. We find that the SU(2) symmetric point exhibits a dynamic instability caused by energetically favorable transverse deformations in both real and spin space of the spiral order. This instability is universal and applies to systems with any spin number, spiral wave vector, and spiral amplitude. Unlike traditional Landau or modulational instabilities, this instability can be triggered solely by quantum fluctuations. By introducing an easy-plane exchange coupling, we show that the stability boundary continuously interpolates between the modulational instability and the transverse instability.