Open Quantum System Response from the Hierarchy of Pure States

Hartmann, Richard; Strunz, Walter T.

doi:10.1021/acs.jpca.1c03339

Cited by 8 publications

(2 citation statements)

References 50 publications

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“…Following the introduction of the pure state decomposition by Hartmann et al 45 and the subsequent work of Chen et al, 41 the dipole autocorrelation function that defines the linear absorption spectrum can be written as…”

Section: Dyadic Hopsmentioning

confidence: 99%

Simulating optical linear absorption for mesoscale molecular aggregates: an adaptive hierarchy of pure states approach

Gera¹,

Chen²,

Eisfeld³

et al. 2023

Preprint

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In this paper, we present a new method for calculating linear absorption spectra for large molecular aggregates, called dyadic adaptive HOPS (DadHOPS). This method combines the adaptive HOPS (adHOPS) framework, which uses locality to improve computational scaling, with the dyadic HOPS method previously developed to calculate linear and non-linear spectroscopic signals. To construct a local representation of dyadic HOPS, we introduce an initial state decomposition which reconstructs the linear absorption spectra from a sum over locally excited initial conditions. We demonstrate the sum over initial conditions can be efficiently Monte Carlo sampled, that the corresponding calculations achieve size-invariant (i.e. O(1)) scaling for sufficiently large aggregates, and that it allows for the trivial inclusion of static disorder in the Hamiltonian. We present calculations on the photosystem I core complex to explore the behavior of the initial state decomposition in complex molecular aggregates, and proof-of-concept DadHOPS calculations on an artificial molecular aggregate inspired by perylene bis-imide.

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Section: Dyadic Hopsmentioning

confidence: 99%

Simulating optical linear absorption for mesoscale molecular aggregates: an adaptive hierarchy of pure states approach

Gera¹,

Chen²,

Eisfeld³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Such wavefunction-based approaches have also been developed based on an explicit treatment of noise, including the stochastic hierarchy of pure states, [58][59][60][61][62] the stochastic Schrödinger equation, 63 the stochastic Schrödinger equation with a diagonalized influence functional along the contour in the complex time plane, 64 and a hierarchy of stochastic Schrödinger equations. [65][66][67][68][69][70] Although the formulation of the stochastic approaches is considerably simpler than the HSEOM approach, it is not suitable for studying a system with slow relaxation or a system subjected to a slowly varying time-dependent external force, because the convergence of the trajectories is slow in the stochastic approaches.…”

Section: B Hierarchical Schrödinger Equations Of Motionmentioning

confidence: 99%

Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath

Nakamura,

Tanimura

2021

Preprint

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Complex environments, such as molecular matrices and biological material, play a fundamental role in many important dynamic processes in condensed phases. Because it is extremely difficult to conduct full quantum dynamics simulations on such environments due to their many degrees of freedom, here we treat in detail the environment only around the main system of interest (the subenvironment), while the other degrees of freedom needed to maintain the equilibrium temperature are described by a simple harmonic bath, which we call a quantum thermostat. The noise generated by the subenvironment is spatially non-local and non-Gaussian and cannot be characterized by the fluctuation-dissipation theorem. We describe this model by simulating the dynamics of a two-level system (TLS) that interacts with a subenvironment consisting of a one-dimensional XXZ spin chain. The hierarchical Schrödinger equations of motion are employed to describe the quantum thermostat, allowing time-irreversible simulations of the dynamics at arbitrary temperature. To see the effects of a quantum phase transition of the subenvironment, we investigate the decoherence and relaxation processes of the TLS at zero and finite temperatures for various values of the spin anisotropy. We observed the decoherence of the TLS at finite temperature, even when the anisotropy of the XXZ model is enormous. We also found that the population relaxation dynamics of the TLS changed in a complex manner with the change of the anisotropy and the ferromagnetic or antiferromagnetic orders of the spins.

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Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath

Nakamura

Tanimura

2021

The Journal of Chemical Physics

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Complex environments, such as molecular matrices and biological material, play a fundamental role in many important dynamic processes in condensed phases. Because it is extremely difficult to conduct full quantum dynamics simulations on such environments due to their many degrees of freedom, here, we treat in detail the environment only around the main system of interest (the subenvironment), while the other degrees of freedom needed to maintain the equilibrium temperature are described by a simple harmonic bath, which we call a quantum thermostat. The noise generated by the subenvironment is spatially non-local and non-Gaussian and cannot be characterized by the fluctuation–dissipation theorem. We describe this model by simulating the dynamics of a two-level system (TLS) that interacts with a subenvironment consisting of a one-dimensional XXZ spin chain. The hierarchical Schrödinger equations of motion are employed to describe the quantum thermostat, allowing for time-irreversible simulations of the dynamics at arbitrary temperature. To see the effects of a quantum phase transition of the subenvironment, we investigate the decoherence and relaxation processes of the TLS at zero and finite temperatures for various values of the spin anisotropy. We observed the decoherence of the TLS at finite temperature even when the anisotropy of the XXZ model is enormous. We also found that the population-relaxation dynamics of the TLS changed in a complex manner with the change in the anisotropy and the ferromagnetic or antiferromagnetic orders of spins.

show abstract

Open Quantum System Response from the Hierarchy of Pure States

Cited by 8 publications

References 50 publications

Simulating optical linear absorption for mesoscale molecular aggregates: an adaptive hierarchy of pure states approach

Simulating optical linear absorption for mesoscale molecular aggregates: an adaptive hierarchy of pure states approach

Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath

Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath

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