Article
Optics
Simon Kochsiek, Federico Carollo, Igor Lesanovsky
Summary: In this study, we consider open quantum systems governed by a time-independent Markovian Lindblad master equation, and demonstrate a phenomenon of accelerating the approach to stationarity by performing a unitary transformation.
Article
Multidisciplinary Sciences
Leonardo S. Lima
Summary: Transport in non-Hermitian quantum systems is investigated, specifically focusing on the Lieb lattice and the integrable Ising chain. The study aims to understand the influence of non-Hermitian parameters on spin conductivity and transport coefficients. The results show that the non-Hermitian parameters have minimal impact on conductivity in both the Ising model and noninteracting fermion models, with the opening of a gap in the spectrum also affecting longitudinal conductivity.
SCIENTIFIC REPORTS
(2023)
Article
Computer Science, Interdisciplinary Applications
Zhiqiang Liao, Kaijie Ma, Siyi Tang, Hiroyasu Yamahara, Munetoshi Seki, Hitoshi Tabata
Summary: In this study, a new perspective is provided and the potential design range of GIMs is broadened by constructing a nonbistable rectified linear unit-based gain-dissipative Ising spin network (RISN). It is found that RISN is nonbistable in the uncoupled state, and it can effectively solve combinatorial optimization problems with high noise levels.
JOURNAL OF COMPUTATIONAL SCIENCE
(2022)
Article
Physics, Multidisciplinary
Federico Roccati, Archak Purkayastha, G. Massimo Palma, Francesco Ciccarello
Summary: We investigate the dynamics of correlations in a dissipative gain-loss system. By using a setup with two coupled oscillators, one subject to local gain, we can implement parity-time (PT) symmetry in a more realistic way. We find that quantum correlations are reduced while total correlations are enhanced. Furthermore, we observe different behaviors across an exceptional point (EP) outside the PT symmetric regime, indicating the relevance of PT symmetry in the long-time dynamics.
EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS
(2023)
Article
Optics
Xinglei Yu, Chengjie Zhang
Summary: In this study, we investigate quantum parameter estimation for general non-Hermitian Hamiltonians and derive an intuitive expression of quantum Fisher information for pure states. We also propose a condition for optimal measurements that is applicable to both Hermitian and non-Hermitian Hamiltonians. To demonstrate these findings, we analyze the quantum Fisher information and optimal measurement of a specific parity-time (PT) symmetric non-Hermitian Hamiltonian, revealing interesting properties such as mutations in the quantum Fisher information at exceptional points. Furthermore, we compare the variance of estimation generated by the optimal measurement with the theoretical precision bound to verify our proposed condition for optimal measurements.
Article
Materials Science, Multidisciplinary
Maxime Charlebois, Jean-Baptiste Moree, Kazuma Nakamura, Yusuke Nomura, Terumasa Tadano, Yoshihide Yoshimoto, Youhei Yamaji, Takumi Hasegawa, Kazuyuki Matsuhira, Masatoshi Imada
Summary: An ab initio derivation method for effective low-energy Hamiltonians of materials with strong spin-orbit interactions is presented in this study, and successfully applied to Ca5Ir3O12 material. The material is classified as a strongly correlated electron system, where the spin-orbit interaction physics competes with Hund physics.
Article
Physics, Multidisciplinary
Ken Funo, Neill Lambert, Franco Nori
Summary: Counter-diabatic driving (CD) is a technique in quantum control theory that can counteract nonadiabatic excitations and guide the system to follow its instantaneous energy eigenstates, with applications in state preparation, quantum annealing, and quantum thermodynamics. In practical situations, the performance of CD may degrade due to the effect of the environment. By optimizing the external driving protocol of the system, the error can be systematically reduced and unit fidelity can be achieved by allowing a time-dependent system-bath coupling angle.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Jayson G. Cosme, Jim Skulte, Ludwig Mathey
Summary: We investigate the impact of dissipation in a bosonic channel on the prevalence and stability of time crystals (TCs) in a periodically driven spin-boson system described by the Dicke model. By mapping out the phase diagrams for varying dissipation strengths, we find that the region where a TC exists expands with increasing dissipation strength but only up to a certain point, beyond which most TCs become unstable. We demonstrate that dissipative TCs are more robust against random noise in the drive and are only weakly affected by the choice of initial state.
Article
Optics
Namrata Shukla, Ranjan Modak, Bhabani Prasad Mandal
Summary: We establish an uncertainty relation for PT-invariant non-Hermitian quantum systems of arbitrary finite dimensions using a specific inner product framework. This construction is motivated by good observables, which are a broader class of operators. We demonstrate that the cumulative gain in quantum Fisher information obtained by measuring two good observables in these non-Hermitian systems surpasses that in their Hermitian counterparts. The preference for minimum uncertainty states near the exceptional point confirms the effectiveness of intelligent or simultaneous non-Hermitian quantum sensors.
Article
Physics, Applied
Yaroslav Tserkovnyak, Eran Maniv, James G. Analytis
Summary: Current-induced spin torques in layered magnetic heterostructures have similarities across different magnetic materials, but their consequences depend on the nature of the order and whether there is a net magnetic moment. The presence of a net magnetic moment allows for unipolar switching capability in the system, while magnetically compensated materials tend to evolve into limit cycles with chirality dependent on the torque sign under large torques.
APPLIED PHYSICS LETTERS
(2021)
Article
Astronomy & Astrophysics
David Montenegro, Giorgio Torrieri
Summary: We develop a Lagrangian hydrodynamics model that incorporates shear and bulk viscosity in the presence of spin density and investigate it using linear response functional formalism. Our findings demonstrate the mixing of sound waves and vortices via polarization in the shear mode, extending previous observations in the ideal fluid limit. We also analyze the phenomenological implications of these results.
Article
Astronomy & Astrophysics
Dong-Lin Wang, Shuo Fang, Shi Pu
Summary: By studying analytically the longitudinally boost-invariant motion of a relativistic dissipative fluid with spin, we have derived analytic solutions for spin density and spin chemical potential as functions of proper time tau, showing that they decay at rates similar to tau-1 and tau-1/3, respectively. These solutions provide insights into spin polarization dynamics in relativistic heavy-ion collisions and serve as test beds for further numerical simulations.
Article
Physics, Mathematical
Yoshiko Ogata
Summary: This paper focuses on the classification of SPT phases using Z(2) indices, introducing an index for unique gapped ground state phases with reflection symmetry and completing the generalization problem of the index by Pollmann et al. It is shown that the index is an invariant of the C-1 classification.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2021)
Article
Astronomy & Astrophysics
Samapan Bhadury, Wojciech Florkowski, Amaresh Jaiswal, Avdhesh Kumar, Radoslaw Ryblewski
Summary: This study extends the recent formulation of perfect-fluid hydrodynamics for spin-polarized fluids to include dissipation, using the classical description of spin degrees of freedom. The analysis is based on classical kinetic equations for massive particles with spin 1/2, treating collision terms in the relaxation time approximation. The kinetic-theory framework allows for the calculation of a complete set of new kinetic coefficients characterizing dissipative spin dynamics.
Article
Physics, Multidisciplinary
Pieter W. Claeys, Austen Lamacraft
Summary: In specific open systems with collective dissipation, the Liouvillian can be mapped to a non-Hermitian Hamiltonian. This study considers such a system and presents the exact Bethe ansatz solution. As the strength of the coupling to the environment increases, the system's spectrum in a fixed symmetry sector transitions from a broken pseudo-Hermitian phase with complex conjugate eigenvalues to a pseudo-Hermitian phase with real eigenvalues, passing through a series of exceptional points and associated dissipative quantum phase transitions.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Nanoscience & Nanotechnology
Kirill P. Kalinin, Alberto Amo, Jacqueline Bloch, Natalia G. Berloff
Article
Optics
Samuel N. Alperin, Natalia G. Berloff
Summary: Researchers have found that the intrinsic particle flux in a photonic Bose-Einstein condensate can stabilize multiply charged vortex states and spontaneously form through dynamic symmetry breaking mechanisms during condensate formation. The vortex states are found to radiate acoustically at topologically quantized frequencies and are limited by a quantum Kelvin-Helmholtz instability. This represents a fundamental result in fluid dynamics for quantum photonic fluids.
Article
Physics, Multidisciplinary
Nikita Stroev, Natalia G. Berloff
Summary: This study introduces a new computational method based on gain-dissipative simulators, utilizing complex coupling switching to solve higher-order optimization problems, and demonstrates its efficiency on sets of complex problems.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Kirill P. Kalinin, Natalia G. Berloff
Summary: The advantage of unconventional computing architectures is demonstrated by solving different instances of problems, and a criterion for optimization simplicity is proposed to classify the complexity of these instances. Different neuromorphic architectures can optimize instances according to this criterion, and the Ising model on the Mobius ladder graph is shown to be easy for Ising machines. By studying various graphs, it is found that the computational complexity lies between P and NP-hard classes and there are a significant number of polynomially simple instances.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Multidisciplinary
Samuel N. Alperin, Natalia G. Berloff
Summary: This paper investigates a generic mechanism of breather formation by simultaneously driving a polariton condensate with both nonresonant and nth order resonant pump frequencies. It constructs a family of exotic breathers with nontrivial discrete order of rotational symmetry for the second order resonance. Furthermore, it demonstrates the spontaneous emergence of crystalline and glassy orderings of lattices of polygonal breathers, depending on the degree of polygonal excitations at the lattice sites.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Marvin Syed, Natalia G. Berloff
Summary: Many physical systems with dynamical evolution have been proposed and realized as promising alternatives to conventional computing, as they can solve optimization problems at their steady state. Systems of oscillators such as coherent Ising and XY machines based on lasers, optical parametric oscillators, memristors, polariton and photon condensates are particularly promising due to their scalability, low power consumption, and room temperature operation. Our work shows that the canonical Andronov-Hopf networks can capture the bifurcation behavior of physical optimizers, and by transforming any physical optimizer into the canonical network, the success of the physical XY-Ising machine depends on the control of network parameters. This allows for the hybridization of ideas across different physical platforms.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2023)
Article
Physics, Multidisciplinary
L. Q. English, A. V. Zampetaki, K. P. Kalinin, N. G. Berloff, P. G. Kevrekidis
Summary: This paper explores the application of networks of nonlinear electronic oscillators in solving combinatorial optimization problems. Experimental results show that by driving the oscillator networks into subharmonic response, energy minimization can be achieved on specific graphs. Theoretical modeling accurately predicts experimental results and extends them to larger graphs.
COMMUNICATIONS PHYSICS
(2022)
Review
Quantum Science & Technology
Nikita Stroev, Natalia G. Berloff
Summary: This review provides an overview of photonics computing, which utilizes photons, photons coupled with matter, and optics-related technologies for efficient computational purposes. It covers the history and development of photonics computing, focusing on optimization tasks and neural network implementations. The authors examine special-purpose optimizers, mathematical descriptions of photonics optimizers, and discuss various applications such as logistics, finance, machine learning, and image processing. The paper also explores the technological advancements and challenges in photonics computing, as well as the prospects and potential applications of optical quantum computing.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Materials Science, Multidisciplinary
Nikita Stroev, Natalia G. Berloff
Summary: The classical XY model in statistical mechanics is known for its universality across various physical systems. Researchers have demonstrated how to build complex structures for machine learning based on the model's nonlinear blocks, aiming to reproduce the capabilities of deep learning architectures in tasks like speech recognition and visual processing. They have developed a robust and transparent approach with universal applicability and potential for extensions, while maintaining simplicity in methodology.
Article
Materials Science, Multidisciplinary
Alexander Johnston, Kirill P. Kalinin, Natalia G. Berloff
Summary: This study demonstrates that geometrically coupled polariton condensates in semiconductor devices can simulate molecules with specific characteristics. By varying the number and geometry of condensates, the spectral weights and separation of oscillatory states can be controlled, reflecting the coupling strengths. Asymmetric stationary states combine discrete and continuous degrees of freedom, potentially paving the way for manufacturing controllable artificial molecules.
Article
Quantum Science & Technology
Kirill P. Kalinin, Natalia G. Berloff
ADVANCED QUANTUM TECHNOLOGIES
(2020)
Article
Materials Science, Multidisciplinary
Kirill P. Kalinin, Natalia G. Berloff
Article
Materials Science, Multidisciplinary
Kirill P. Kalinin, Pavlos G. Lagoudakis, Natalia G. Berloff
Article
Materials Science, Multidisciplinary
Kirill P. Kalinin, Pavlos G. Lagoudakis, Natalia G. Berloff
Article
Physics, Multidisciplinary
L. Pickup, K. Kalinin, A. Askitopoulos, Z. Hatzopoulos, P. G. Savvidis, N. G. Berloff, P. G. Lagoudakis
PHYSICAL REVIEW LETTERS
(2018)
