Exact quantum dynamics in structured environments

Gribben, Dominic; Strathearn, Aidan; Iles-Smith, Jake; Kilda, Dainius; Nazir, Ahsan; Lovett, Brendon W.; Kirton, Peter

doi:10.1103/physrevresearch.2.013265

Cited by 28 publications

(22 citation statements)

References 51 publications

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“…Spurred by the growing interest in quantum information science, there have been many investigations of non-Markovian open quantum systems, e.g., single atom(s) in front of a mirror [30][31][32][33][34] or distant atoms coupled locally to the same environment [35][36][37][38][39][40][41][42][43]. The physical origin of the non-Markovianity is typically the coupling to a structured bath causing information backflow from the environment [44][45][46]. These systems can exhibit nonexponential relaxation [47,48] and bound states [34,[49][50][51][52][53][54][55][56][57][58][59][60], which can be harnessed for quantum simulations [61,62].…”

Section: Introductionmentioning

confidence: 99%

Oscillating bound states for a giant atom

Guo

Kockum

Marquardt

et al. 2020

Phys. Rev. Research

141

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We investigate the relaxation dynamics of a single artificial atom interacting, via multiple coupling points, with a continuum of bosonic modes (photons or phonons) in a one-dimensional waveguide. In the non-Markovian regime, where the traveling time of a photon or phonon between the coupling points is sufficiently large compared to the inverse of the bare relaxation rate of the atom, we find that a boson can be trapped and form a stable bound state. As a key discovery, we further find that a persistently oscillating bound state can appear inside the continuous spectrum of the waveguide if the number of coupling points is more than two since such a setup enables multiple bound modes to coexist. This opens up prospects for storing and manipulating quantum information in larger Hilbert spaces than available in previously known bound states.

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Section: Introductionmentioning

confidence: 99%

Oscillating bound states for a giant atom

Guo

Kockum

Marquardt

et al. 2020

Phys. Rev. Research

141

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show abstract

“…The only information kept about the environment is its correlation function, or equivalently its spectral density. The evolution of the system's density matrix can then be described, for example, by an approximate weak-coupling master equation [1] or exactly using a process tensor [17] or a tensor network representation of the influence functional as in the time-evolving matrix product operator (TEMPO) method [18,19]. Indeed, a process tensor can be extracted from the TEMPO method [20] and this can lead to still more efficient calculations [21].…”

Section: Etmentioning

confidence: 99%

Unveiling non-Markovian spacetime signaling in open quantum systems with long-range tensor network dynamics

et al. 2021

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Nanoscale devices, either biological or artificial, operate in a regime where the usual assumptions of a structureless Markovian bath do not hold. Being able to predict and study the dynamics of such systems is crucial and is usually done by tracing out the bath degrees of freedom, which implies losing information about the environment. To go beyond these approaches we use a numerically exact method relying on a matrix product state representation of the quantum state of a system and its environment to keep track of the bath explicitly. This method is applied to a specific example of interaction that depends on the spatial structure of a system made of two sites. The result is that we predict a non-Markovian dynamics where long-range couplings induce correlations into the environment. The environment dynamics can be naturally extracted from our method and shine a light on long-time feedback effects that are responsible for the observed non-Markovian recurrences in the eigenpopulations of the system.

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“…The remaining environmental degrees of freedom are then captured through a residual environment, which can be treated to second order using a Born-Markov master equation [32,64]. This treatment allows one to access strong coupling and highly non-Markovian regimes with the conceptual simplicity of a master equation, and little computational cost [65]. In this section we shall give an outline of the RC mapping and the subsequent derivation of the master equation.…”

Section: B Reaction Coordinatementioning

confidence: 99%

Exact dynamics of non-additive environments in non-Markovian open quantum systems

Gribben,

Rouse,

Iles-Smith

et al. 2021

Preprint

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When a quantum system couples strongly to multiple baths then it is generally no longer possible to describe the resulting system dynamics by simply adding the individual effects of each bath. However, capturing such multi-bath system dynamics has up to now required approximations that can obscure some of the non-additive effects. Here we present a numerically-exact and efficient technique for tackling this problem that builds on the time-evolving matrix product operator (TEMPO) representation. We test the method by applying it to a simple model system that exhibits nonadditive behaviour: a two-level dipole coupled to both a vibrational and an optical bath. Although not directly coupled, there is an effective interaction between the baths mediated by the system that can lead to population inversion in the matter system when the vibrational coupling is strong. We benchmark and validate multi-bath TEMPO against two approximate methods -one based on a polaron transformation, the other on an identification of a reaction coordinate -before exploring the regime of simultaneously strong vibrational and optical coupling where the approximate techniques break down. Here we uncover a new regime where the quantum Zeno effect leads to a fully mixed state of the electronic system.

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Exact quantum dynamics in structured environments

Cited by 28 publications

References 51 publications

Oscillating bound states for a giant atom

Oscillating bound states for a giant atom

Unveiling non-Markovian spacetime signaling in open quantum systems with long-range tensor network dynamics

Exact dynamics of non-additive environments in non-Markovian open quantum systems

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