Non-adiabatic quantum dynamics simulation using classical baths

Control of the dynamics of an open quantum system is crucial in quantum information processing. Basically there are two ways: one is the control on the system and the other is tuning the bath parameters. In this paper, we use the latter to analyze the non-Markovian dynamics of the open system. The model is that the system is immersed in non-Markovian squeezed baths. For the dynamics, a non-Markovian master eqation is obtained using the quantum state diffusion (QSD) equation technique for the weak system-bath couplings. We use the adiabatic evolution or quantum state transmission as examples to analyze the effects of the bath parameters: non-Markovianity $γ$ , the squeezed direction $θ$ and squeezed strength $r$ . For the adiabatic or state transmission fidelity, the calculation results show that they both can be enhanced by a smaller $γ$ or bigger $p$ -quadrature. Interestingly, when $0<θ<π/2$ , the squeezed quadrature is determined by the combination of $r$ and $θ$ , and by numerical simulation we find that the fidelity peak occurs at $r=1-2θ/π$ . The fidelities increase with increasing $r$ when $r\in (0,1-2θ/π]$ . When $θ\geπ/2$ , lower fidelities are obtained due to the squeezed bath. Our results show that the dynamics of the open systems can be effectively controlled by reservoir enginerring.Control of the dynamics of an open quantum system is crucial in quantum information processing. Basically there are two ways: one is the control on the system and the other is tuning the bath parameters. In this paper, we use the latter to analyze the non-Markovian dynamics of the open system. The model is that the system is immersed in non-Markovian squeezed baths. For the dynamics, a non-Markovian master eqation is obtained using the quantum state diffusion (QSD) equation technique for the weak system-bath couplings. We use the adiabatic evolution or quantum state transmission as examples to analyze the effects of the bath parameters: non-Markovianity $γ$, the squeezed direction $θ$ and squeezed strength $r$. For the adiabatic or state transmission fidelity, the calculation results show that they both can be enhanced by a smaller $γ$ or bigger $p$-quadrature. Interestingly, when $0<θ<π/2$, the squeezed quadrature is determined by the combination of $r$ and $θ$, and by numerical simulation we find that the fidelity peak occurs at $r=1-2θ/π$. The fidelities increase with increasing $r$ when $r\in (0,1-2θ/π]$. When $θ\geπ/2$, lower fidelities are obtained due to the squeezed bath. Our results show that the dynamics of the open systems can be effectively controlled by reservoir enginerring.

arXiv:2304.04223Apr 9, 20231 citation

Quantum dynamics in classical thermal baths

Nkosinathi Dlamini, Alessandro Sergi

Computer Physics CommunicationsJun 26, 20133 citations

Deterministic constant-temperature dynamics for dissipative quantum systems

Alessandro Sergi

A novel method is introduced in order to treat the dissipative dynamics of quantum systems interacting with a bath of classical degrees of freedom. The method is based upon an extension of the Nosè–Hoover chain (constant temperature) dynamics to quantum-classical systems. Both adiabatic and nonadiabatic numerical calculations on the relaxation dynamics of the spin-boson model show that the quantum-classical Nosè–Hoover chain dynamics represents the thermal noise of the bath in an accurate and simple way. Numerical comparisons, both with the constant-energy calculation and with the quantum-classical Brownian motion treatment of the bath, show that the quantum-classical Nosè–Hoover chain dynamics can be used to introduce dissipation in the evolution of a quantum subsystem even with just one degree of freedom for the bath. The algorithm can be computationally advantageous in modelling, within computer simulation, the dynamics of a quantum subsystem interacting with complex molecular environments.A novel method is introduced in order to treat the dissipative dynamics of quantum systems interacting with a bath of classical degrees of freedom. The method is based upon an extension of the Nosè–Hoover chain (constant temperature) dynamics to quantum-classical systems. Both adiabatic and nonadiabatic numerical calculations on the relaxation dynamics of the spin-boson model show that the quantum-classical Nosè–Hoover chain dynamics represents the thermal noise of the bath in an accurate and simple way. Numerical comparisons, both with the constant-energy calculation and with the quantum-classical Brownian motion treatment of the bath, show that the quantum-classical Nosè–Hoover chain dynamics can be used to introduce dissipation in the evolution of a quantum subsystem even with just one degree of freedom for the bath. The algorithm can be computationally advantageous in modelling, within computer simulation, the dynamics of a quantum subsystem interacting with complex molecular environments.

arXiv:quant-ph/0701242Journal of Physics A Mathematical and TheoreticalApr 11, 200729 citations

Quantum Simulation of Nonlinear Classical Dynamics

Ilon Joseph, Alessandro R. Castelli, Jonathan L. DuBois +6 more

Bulletin of the American Physical SocietyMar 3, 20200 citations

Two Approaches to Quantum Simulation of Classical Dynamics

Ilon Joseph, Alessandro R. Castelli, Vasily Geyko +6 more

Bulletin of the American Physical SocietyMar 19, 20210 citations

Ensemble Variational Quantum Algorithm for Non-Markovian Quantum Dynamics

Peter Walters, Joachim Tsakanikas, Fei Wang

Many physical and chemical processes in the condensed phase environment exhibit non-Markovian quantum dynamics. As such simulations are challenging on classical computers, we developed a variational quantum algorithm that is capable of simulating non-Markovian dynamics on NISQ devices. We used a quantum system linearly coupled to its harmonic bath as the model Hamiltonian. The non-Markovianity is captured by introducing auxiliary variables from the bath trajectories. With Monte Carlo sampling of the bath degrees of freedom, finite temperature dynamics is produced. We validated the algorithm on the simulator and demonstrated its performance on the IBM quantum device. The framework developed is naturally adapted to any anharmonic bath with non-linear coupling to the system, and is also well suited for simulating spin chain dynamics in a dissipative environment.Many physical and chemical processes in the condensed phase environment exhibit non-Markovian quantum dynamics. As such simulations are challenging on classical computers, we developed a variational quantum algorithm that is capable of simulating non-Markovian dynamics on NISQ devices. We used a quantum system linearly coupled to its harmonic bath as the model Hamiltonian. The non-Markovianity is captured by introducing auxiliary variables from the bath trajectories. With Monte Carlo sampling of the bath degrees of freedom, finite temperature dynamics is produced. We validated the algorithm on the simulator and demonstrated its performance on the IBM quantum device. The framework developed is naturally adapted to any anharmonic bath with non-linear coupling to the system, and is also well suited for simulating spin chain dynamics in a dissipative environment.

arXiv:2403.04885Mar 7, 20240 citations

γ

, the squeezed direction

θ

and squeezed strength

r

. For the adiabatic or state transmission fidelity, the calculation results show that they both can be enhanced by a smaller

γ

or bigger

p

-quadrature. Interestingly, when

0<θ<π/2

, the squeezed quadrature is determined by the combination of

r

and

θ

, and by numerical simulation we find that the fidelity peak occurs at

r=1-2θ/π

. The fidelities increase with increasing

r

when

r\in (0,1-2θ/π]

. When

θ\geπ/2

, lower fidelities are obtained due to the squeezed bath. Our results show that the dynamics of the open systems can be effectively controlled by reservoir enginerring.