Article
Physics, Multidisciplinary
Niklas Hornedal, Nicoletta Carabba, Apollonas S. Matsoukas-Roubeas, Adolfo del Campo
Summary: This study introduces a bound on the growth of Krylov complexity in quantum isolated systems by using the uncertainty principle. The authors show the conditions for this bound to be saturated and demonstrate that quantum chaos is not strictly necessary for the saturation of the bound.
COMMUNICATIONS PHYSICS
(2022)
Article
Multidisciplinary Sciences
Meng Wang, Songlin Shi, Jay Fineberg
Summary: Brittle materials were conventionally believed to have crack propagation speeds limited by the Rayleigh wave speed. However, our experimental study on brittle neo-hookean materials shows the existence of supershear tensile cracks, which can surpass the shear wave speed and even approach the dilatation wave speed. The dynamics of supershear cracks are controlled by different principles compared to classical cracks and this nonclassical fracture mode occurs at critical strain levels specific to the material, representing a fundamental shift in our understanding of fracture processes.
Article
Physics, Multidisciplinary
Maxwell Aifer, Sebastian Deffner
Summary: This article studies the energetically optimal implementation of quantum operations. By using the framework of quantum speed limits, we find the universally optimal solutions for single and N-qubit operations.
NEW JOURNAL OF PHYSICS
(2022)
Article
Quantum Science & Technology
Katarzyna Bolonek-Lason, Joanna Gonera, Piotr Kosinski
Summary: The new bound on quantum speed limit, calculated in terms of relative purity, is derived by applying the original Mandelstam-Tamm method to the evolution in the space of Hilbert-Schmidt operators acting in the initial space of states. It is shown to be the quantum counterpart of the classical speed limit derived in Phys. Rev. Lett. 120 (2018), 070402, with the limit of h approaching 0 yielding the latter. The existence of a classical limit is found to be related to the degree of mixing of the quantum state.
Article
Physics, Multidisciplinary
Luis Pedro Garcia-Pintos, Schuyler B. Nicholson, Jason R. Green, Adolfo del Campo, Alexey Gorshkov
Summary: The presence of noise or interaction with the environment can significantly impact the dynamics of a isolated quantum system. In this study, we establish a limit on the speed at which observables of open quantum systems can evolve. We consider both the time-energy uncertainty relation and the time-information uncertainty relation, which have been previously derived for classical systems, and extend them to open quantum systems. By separating the coherent and incoherent contributions to system dynamics, we determine lower and upper bounds on the evolution speed. Our findings show that the upper bounds provide tighter limits on the speed of observables compared to known quantum speed limits. Additionally, we identify a preferred basis of speed operators that fully characterizes the observables that reach the speed limits. Furthermore, we use this framework to limit the impact of incoherent dynamics on observable evolution and identify the Hamiltonian that maximizes coherent speedup.
Article
Physics, Multidisciplinary
Brij Mohan, Siddhartha Das, Arun Kumar Pati
Summary: This study determines the speed limits on the evolution of informational measures in quantum systems, such as von Neumann entropy, maximal information, and coherence. These limits provide crucial insights into the minimal time required for erasing quantum information, which is essential for future quantum computing devices.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Francesco Campaioli, Chang-shui Yu, Felix A. Pollock, Kavan Modi
Summary: Recent advances in quantum resource theories address the issue of how quickly a resource can be generated or degraded. Using the toolkit of quantum speed limits, bounds on the minimum time required for a given resource to change are constructed, and examples are provided to demonstrate the tightness of the derived bounds. The results have applications in thermodynamics, computation rate, and more.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Satoshi Nakajima, Yasuhiro Utsumi
Summary: We investigate the speed limit of state transformation in open quantum systems described by the Lindblad type quantum master equation. Our results provide universal bounds for the total entropy production using the trace distance between the initial and final states in the interaction picture. Our bounds are tighter than the previous bound proposed by Vu and Hasegawa, which measures the distance using the eigenvalues of the initial and final states. Furthermore, we show that the trace distance in the Schrodinger picture is bounded by a sum of the trace distance in the interaction picture and the trace distance for unitary dynamics described by only the Hamiltonian in the quantum master equation.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Jiaozi Wang, Barbara Dietz, Dario Rosa, Giuliano Benenti
Summary: We investigate the generation of entanglement in a two-body interacting system starting from a separable coherent state. By analyzing the system's classical dynamics, we find that the entanglement growth rate in the quasiclassical regime can be simply computed. This rate is determined by the Kolmogorov-Sinai entropy, indicating a connection between the generation of entanglement and classical complexity.
Article
Physics, Multidisciplinary
C. Campbell, J. Li, Th Busch, T. Fogarty
Summary: Supersymmetry allows for the construction of a hierarchy of Hamiltonians with common spectral properties and connected through super-potentials. The iso-spectral properties of these Hamiltonians connect the dynamics and control of different eigenstates through supersymmetric intertwining relations. In this work, we explore how this property enables the study of general dynamics, shortcuts to adiabaticity, and quantum speed limits for different states of distinct supersymmetric partner potentials using the infinite box as an example.
NEW JOURNAL OF PHYSICS
(2022)
Article
Quantum Science & Technology
Ryusuke Hamazaki
Summary: This study develops a general framework for deriving qualitatively tighter speed limits for macroscopic systems by utilizing the local conservation law of probability. The speed of the expectation value of an observable is found to be bounded by the gradient of the observable, leading to a new trade-off relation between time and quantum phase difference. The newly obtained bounds provide fundamental limits to various types of nonequilibrium quantum macroscopic phenomena.
Article
Physics, Multidisciplinary
Kang Lan, Shijie Xie, Xiangji Cai
Summary: We theoretically study the geometric quantum speed limits (QSLs) of open quantum systems under Markovian dynamical evolution. We introduce three types of QSL time bounds based on the geometric inequality associated with the dynamical evolution from an initial state to a final state. By illustrating these bounds in different scenarios, we reveal the significant role of the system Hamiltonian in driving the Markovian evolution and its impact on the unsaturation of QSL bounds.
NEW JOURNAL OF PHYSICS
(2022)
Article
Optics
Sahel Ashhab, Fumiki Yoshihara, Tomoko Fuse, Naoki Yamamoto, Adrian Lupascu, Kouichi Semba
Summary: This study examines the implementation of two-qubit gates in the presence of additional quantum states in the accessible energy range. The results show that the coupling between higher energy levels can increase the gate speed, while weak anharmonicity constrains the system's control speed. By modifying the pulse optimization algorithm, the impact of higher levels can be minimized. Furthermore, the optimal-control gate speeds are compared with those obtained using other protocols.
Review
Physics, Applied
Miguel Gallego
Summary: This research shows that, in the macroscopic limit, the Hilbert space structure of quantum theory can be preserved, leading to a violation of the principle of macroscopic locality.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2022)
Article
Physics, Multidisciplinary
Michael Zwolak
Summary: Our everyday reality is made up of objective information selected and amplified by the environment interacting with quantum systems. Observers can indirectly infer this information by measuring fragments of the environment. The correlations between a system and a fragment of the environment can be quantified by the quantum mutual information, or the Holevo quantity, which bounds the classical information about the system transmitted through a quantum channel. Recent research has discovered a different Holevo quantity that provides a tighter bound on the accessible classical information about the system. This research is important for understanding the correlations and information transmission between systems and their environments.
Article
Physics, Multidisciplinary
Julien Cornelius, Zhenyu Xu, Avadh Saxena, Aurelia Chenu, Adolfo del Campo
Summary: The study finds that balanced gain and loss in non-Hermitian evolution can enhance the manifestation of quantum chaos and provide a feasible experimental mechanism for spectral filtering.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Jing Yang, Shengshi Pang, Zekai Chen, Andrew N. Jordan, Adolfo del Campo
Summary: A variational principle was developed to optimize the quantum Fisher information for quantum controls and initial state. It was found that for time-independent Hamiltonians with restricted controls, the optimal initial state and controls may depend on probe time. However, the problem can be approximately reduced to the unconstrained case by Floquet engineering, showing that Heisenberg scaling can still be achieved even with limited controls.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Luis Pedro Garcia-Pintos, Schuyler B. Nicholson, Jason R. Green, Adolfo del Campo, Alexey Gorshkov
Summary: The presence of noise or interaction with the environment can significantly impact the dynamics of a isolated quantum system. In this study, we establish a limit on the speed at which observables of open quantum systems can evolve. We consider both the time-energy uncertainty relation and the time-information uncertainty relation, which have been previously derived for classical systems, and extend them to open quantum systems. By separating the coherent and incoherent contributions to system dynamics, we determine lower and upper bounds on the evolution speed. Our findings show that the upper bounds provide tighter limits on the speed of observables compared to known quantum speed limits. Additionally, we identify a preferred basis of speed operators that fully characterizes the observables that reach the speed limits. Furthermore, we use this framework to limit the impact of incoherent dynamics on observable evolution and identify the Hamiltonian that maximizes coherent speedup.
Article
Physics, Particles & Fields
Apollonas S. Matsoukas-Roubeas, Federico Roccati, Julien Cornelius, Zhenyu Xu, Aurelia Chenu, Adolfo del Campo
Summary: This research considers a broad class of non-Hermitian Hamiltonian deformations in a nonrelativistic setting, which can describe a large class of open quantum systems, including arbitrary Markovian evolutions conditioned to the absence of quantum jumps. The time evolution operator and time-evolving density matrix in the undeformed and deformed theories are related through integral transforms with a specific kernel. Non-Hermitian Hamiltonian deformations naturally arise in the description of energy diffusion due to time-keeping errors in a real clock used for time evolution tracking. The spectral properties of the dynamical generators associated with the deformed theories are also studied.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Chemistry, Physical
Ali Saffar Shamshirgar, Maria Fernandez Alvarez, Adolfo del Campo, Jose Francisco Fernandez, Rocio E. Rojas Hernandez, Roman Ivanov, Johanna Rosen, Irina Hussainova
Summary: This study incorporates graphene-augmented alumina nanofibers into epoxy resin to fabricate a tunable absorption multilayer structure for electromagnetic interference shielding and RF absorption. Highly aligned graphene augmented alumina nanofibers were produced using a hot wall one-step catalyst-free chemical vapor deposition method. The highest loss tangent of 0.4 was achieved in a composite containing 1 vol% of randomly oriented nanofibers. A superposed three-layer structure was fabricated, offering an absorption of >90% in the entire X-band and an absorption peak of -25 dB at around 11 GHz. The hybrid nanofibers with a dual loss function show potential for versatile design options in RF absorption.
Article
Physics, Multidisciplinary
Hua-Bi Zeng, Chuan-Yin Xia, Adolfo del Campo
Summary: The crossing of a continuous phase transition leads to the formation of topological defects, which is described by the Kibble-Zurek mechanism (KZM) in slow quenches. KZM predicts a universal power-law scaling for the defect density and the quench time. Deviations from KZM in rapid quenches have been experimentally observed and their universality has been established. The defect density and freeze-out time become independent of the quench rate and show a universal power-law scaling with the final value of the control parameter.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Pablo Martinez-Azcona, Aritra Kundu, Adolfo del Campo, Aurelia Chenu
Summary: Noise is prevalent in nature and understanding its impact is crucial. In this study, we introduce a measurable quantity, the stochastic operator variance (SOV), which characterizes the spread of different stochastic trajectories in the space of operators. The dynamics of the SOV is shown to be intimately connected to that of out-of-time-order correlators, defining the quantum Lyapunov exponent. Our findings are validated analytically and numerically in a stochastic Lipkin-Meshkov-Glick Hamiltonian experiencing energy dephasing.
PHYSICAL REVIEW LETTERS
(2023)
Article
Quantum Science & Technology
Kai-Siang Chen, Gelo Noel M. Tabia, Chellasamy Jebarathinam, Shiladitya Mal, Jun-Yi Wu, Yeong-Cherng Liang
Summary: In device-independent quantum information, the correlation between local measurement outcomes observed by separate parties in a Bell test is important, but many questions remain unanswered. The problem of when the boundary of the quantum set coincides with the no-signaling set in the simplest Bell scenario is revisited, and various quantum strategies that realize these correlations are provided. Self-testing is possible in certain classes, and evidence supports the robustness of the results. The set of quantum correlations arising from maximally entangled states is also characterized.
Article
Physics, Multidisciplinary
Tangyou Huang, Yongcheng Ding, Leonce Dupays, Yue Ban, Man Hong-Yung, Adolfo del Campo, Xi Chen
Summary: The simulation of quantum dynamics on a digital quantum computer with parametrized circuits is widely used in fundamental and applied physics and chemistry. The hybrid quantum-classical algorithm, combining classical optimizers and quantum computers, is a competitive strategy for solving specific problems. We propose its use for optimal quantum control. We simulate the wave-packet expansion of a trapped quantum particle on a quantum device with a finite number of qubits, and use circuit learning based on gradient descent to find the connection between control phase transition and quantum speed limit. We discuss the robustness of our method against errors and demonstrate the absence of barren plateaus in the circuit. The combination of digital quantum simulation and hybrid circuit learning opens up new prospects for quantum optimal control.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Leonce Dupays, Jing Yang, Adolfo del Campo
Summary: In one spatial dimension, the expansion dynamics of a Tonks-Girardeau gas is characterized by dynamical fermionization (DF), which can be controlled and reversed using a generalization of delta-kick cooling (DKC). This provides a simple protocol for rescaling the initial momentum distribution and can be applied to both expansions and compressions, as well as for the microscopy of quantum correlations.
Article
Optics
S. Alipour, A. T. Rezakhani, A. Chenu, A. del Campo, T. Ala-Nissila
Summary: This study presents a method to separate the internal energy change of an open quantum system into entropy-related and entropy-free contributions, identified as heat and work. It demonstrates that heat and work have geometric and dynamical descriptions and introduces a universal dynamical equation for the system's trajectory. The study also defines an expression for irreversible entropy production, independent of internal energy change and environmental properties, based on the system's observables excluding its Hamiltonian.
Article
Optics
M. Beau, A. del Campo, D. J. Frantzeskakis, T. P. Horikis, P. G. Kevrekidis
Summary: This article investigates the interplay of repulsive short-range and same-sign long-range interactions in the dynamics of dark solitons in a trapped one-dimensional Bose gas. The study shows that single- and multiple-dark-soliton states can exist and are generically robust in the presence of long-range interactions. The frequencies of the soliton oscillations are significantly upshifted as the strength of the long-range interactions is increased.
Article
Physics, Multidisciplinary
P. Chandarana, N. N. Hegade, K. Paul, F. Albarran-Arriagada, E. Solano, A. del Campo, Xi Chen
Summary: A digitized version of the QAOA enhanced via the use of counterdiabatic driving term is proposed, demonstrating better performance in Ising models, classical optimization problems, and the P-spin model compared to the standard QAOA.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Aurelia Chenu, Shiue-Yuan Shiau, Ching-Hang Chien, Monique Combescot
Summary: In this study, we investigate the strong coupling between photons and excitonic excitations in a coupled quantum well under the presence of an electric field. We demonstrate the transition from a hybrid polariton, composed of a photon coupled to hybrid carriers in two wells, to a dipolariton, composed of a photon coupled to direct and indirect excitons, with an increase in the field strength. We also explore how the cavity photon lifetime and the coherence time of the carrier wave vectors affect these polaritonic states through non-hermitian Hamiltonians. While the hybrid polaritons exhibit a spectral singularity known as an exceptional point, depending on detuning and lifetimes, we find that the three dipolaritonic states display an anticrossing without an exceptional point due to the interaction among photons, direct, and indirect excitons.