Article
Computer Science, Interdisciplinary Applications
Yulong Shen, Nengji Zhou
Summary: With the use of a generalized trial wave function, this study accurately determines the transition points and critical exponents in the sub-Ohmic spin-boson model and confirms the quantum-to-classical correspondence. Mean-field and non-mean-field critical behaviors are found in deep and shallow sub-Ohmic regimes, respectively.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Leonardo da Silva Souza, Luis Fernando dos Prazeres, Fernando Iemini
Summary: We discuss a condition for gapless excitations in the Lindbladian master equation for collective spin-boson systems and permutationally invariant systems. This condition relates a nonzero macroscopic cumulant correlation in the steady state to the presence of gapless modes in the Lindbladian. In phases arising from competing coherent and dissipative Lindbladian terms, such gapless modes can lead to persistent dynamics in the spin observables and the formation of dissipative time crystals. We study different models within this perspective and provide a simple analytical proof for the exactness of the mean-field semiclassical approach in such systems based on a cumulant expansion.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Xiaohui Qian, Congzhi Zeng, Nengji Zhou
Summary: This study conducts large-scale numerical simulations based on the variational principle to accurately study dissipative quantum phase transitions in the Ohmic spin-boson model. The validity of variational calculations, spontaneous breakdown of symmetries, and quantum fluctuations are carefully analyzed, while quantum criticality of the Ohmic bath is uncovered both in the delocalized phase and at the transition point.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Physics, Multidisciplinary
Manuel Weber, David J. Luitz, Fakher F. Assad
Summary: In this study, we use quantum Monte Carlo simulations to stabilize long-range antiferromagnetic order in the Heisenberg chain by coupling it to an independent bosonic bath. Unlike the isolated Heisenberg chain, the coupled chain retains the global SO(3) spin symmetry. It is experimentally challenging to observe long-range order at small coupling due to the requirement for exponentially large system sizes.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Xiaohui Qian, Zhe Sun, Nengji Zhou
Summary: This study numerically investigates quantum entanglement and correlation of sub-Ohmic and Ohmic baths for dissipative quantum phase transitions by employing the spin-boson model in a dense limit of environmental modes based on the variational principle. Three different types of singularities are found for the first-order, second-order, and Kosterlitz-Thouless phase transitions, respectively, and the values of transition points and critical exponents are accurately determined. Furthermore, the scaling form of the quantum discord in the Ohmic case is identified, which is quite different from that in the sub-Ohmic regime. In a two-spin model, two distinct behaviors of the quantum discord are uncovered: one is related to the quantum entanglement between two spins and the other is decided by the correlation function in the position space rather than the entanglement.
Article
Materials Science, Multidisciplinary
Ji Zou, Shu Zhang, Yaroslav Tserkovnyak
Summary: We theoretically investigate the dynamics of two spin qubits interacting with a magnetic medium. We show that a sizable long-lived entanglement can be established between the spin qubits via the magnetic environment, in the absence of any coherent coupling. Moreover, we demonstrate that maximally entangled two-qubit states can be achieved in this scheme when complemented by proper postselection.
Article
Optics
Alvaro Rubio-Garcia, Angel L. Corps, Armando Relano, Rafael A. Molina, Francisco Perez-Bernal, Jose Enrique Garcia-Ramos, Jorge Dukelsky
Summary: This article studies a model of a quantum spin weakly coupled to a spin-polarized Markovian environment, and discovers a special Liouvillian spectral phase. The exceptional phase is composed of second-order exceptional points, and it leads to a slower evolution that cannot be described by exponential decay. This phase is separated from the normal phase by a critical line.
Article
Quantum Science & Technology
S. Hernandez-Gomez, S. Gherardini, N. Staudenmaier, F. Poggiali, M. Campisi, A. Trombettoni, F. S. Cataliotti, P. Cappellaro, N. Fabbri
Summary: Engineered dynamical maps have shown technological applications and potential in quantum thermodynamic processes. In this study, we experimentally realized an autonomous feedback process with tunable dissipative strength by controlling the nitrogen-vacancy center. The efficacy of the feedback process was quantified using a generalized Sagawa-Ueda-Tasaki relation for dissipative dynamics.
Article
Physics, Multidisciplinary
Venelin P. Pavlov, Diego Porras, Peter A. Ivanov
Summary: We propose two critical dissipative quantum metrology schemes based on a quantum probe consisting of a coherently driven ensemble of N spin-1/2 particles under collective spin decay. The dissipative phase transition between thermal and ferromagnetic phases in the collective spin system enhances the sensitivity of parameter estimation. Additionally, the steady state is a spin squeezed state, enabling parameter estimation with sub shot-noise limited measurement uncertainty.
Article
Materials Science, Multidisciplinary
Tomohiro Hata, Eiji Nakano, Kei Iida, Hiroyuki Tajima, Junichi Takahashi
Summary: In this study, the interaction between spin relaxation and momentum dissipation in an open system of a single spin-1/2 particle with Rashba-type SOC is elucidated. The spin relaxation mechanism is largely controlled by the Rashba coupling strength.
Article
Materials Science, Multidisciplinary
Gehad Sadiek, Maryam AlQasimi
Summary: In this study, a finite two-dimensional Heisenberg triangular spin lattice coupled to a dissipative Markovian environment at finite temperature in the presence of an external uniform magnetic field is considered. It is shown that inserting a magnetic impurity in the spin system can effectively control the dynamics and asymptotic state of the system. A strong impurity, at a border or central site, enhances its entanglement with other spins and their thermal robustness to the dissipative environment, leading to an asymptotic state independent of the initial state. However, it reduces the entanglement among other spins in the lattice and their thermal robustness, potentially diminishing them depending on its strength and the environment temperature. Moreover, the effect of the impurity increases significantly as the degree of anisotropy of the spin system increases. Therefore, the entanglement distribution over the different sites of the lattice can be modulated by tuning the impurity strength, system anisotropy, and environment temperature. The impurity can be used as a switch that simultaneously turns on entanglement among specific spins and turns it off among others.
RESULTS IN PHYSICS
(2022)
Article
Physics, Multidisciplinary
Ke Yang, Ning-Hua Tong
Summary: Using the full-density matrix numerical renormalization group method, we calculated the equilibrium dynamical correlation function of the sub-ohmic spin-boson model at finite temperature. A peak was observed at a frequency similar to the temperature. The curve gradually merges with the zero-temperature curve as the frequency increases.
Article
Physics, Multidisciplinary
Arif Ullah, Pavlo O. Dral
Summary: This article demonstrates the use of machine learning algorithms to study quantum dissipative dynamics in the spin-boson (SB) model, showing that the ML model performs well in both symmetric and asymmetric SB models and can be extended to complex systems.
NEW JOURNAL OF PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yan Qin, Sheng-Chang Li
Summary: We investigate the quantum phase transition in an ultracold atom-molecule conversion system involving molecule-molecule interaction using a modified spin-boson model. The properties of ground state, entanglement entropy, and many-body dynamics confirm a second-order phase transition from a pure atom phase to a mixed atom-molecule phase when the energy detuning is below a critical value. We obtain scaling laws and critical exponents to characterize the phase transition, and discuss the effects of ground-state dynamical evolution speed and molecular interaction strength. Our results show that molecular interaction can reduce the upper bound of the adiabatic condition, facilitating the observation of the phase transition in experiments.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Physics, Multidisciplinary
Gehad Sadiek, Samaher Almalki
Summary: The study demonstrates that applying varying magnetic field gradients at different levels of anisotropy can significantly impact spin states and entanglement properties, leading to distinct steady states for spins in different system configurations.
