Nonequilibrium dynamics of a system with quantum frustration

Kohler, Heiner; Hackl, Andreas; Kehrein, Stefan

doi:10.1103/physrevb.88.205122

Cited by 16 publications

(24 citation statements)

References 35 publications

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“…Moreover, the decay dynamics of decoherence and relaxation can be always underdamped despite the fact that the strength of the dissipative interaction increases. This state of affairs was termed 'quantum frustration' and was analysed for an open quantum system realized by a harmonic oscillator [23][24][25][26] or a single spin [27][28][29][30][31]. These findings can be understood by considering the two baths as two detectors continuously coupled to the system and measuring simultaneously two non-commutating observables.…”

Section: Introductionmentioning

confidence: 99%

Dissipation-induced enhancement of quantum fluctuations

Rastelli

2016

New J. Phys.

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We study a quantum harmonic oscillator linearly coupled through the position operatorq to a first bath and through the momentum operatorp to a second bath yielding an Ohmic-Drude dissipation. We analyse the oscillator's fluctuations as a function of the ratio between the strength of the two couplings, focusing in particular on the situation in which the two dissipative interactions are comparable. Analytic formulas are derived in the relevant regimes corresponding to the low temperature limit and when the Drude high frequency cutoff is much larger than all other frequencies.At low temperature, each bath operates to suppress the oscillator's ground state quantum fluctuations áD ñ q 2 0 or áD ñ p 2 0 appearing in the corresponding interaction. When one of the two dissipative interactions dominates over the other, the fluctuations for the coupling operator are squeezed. When the two interactions are comparable, the two baths enter in competition as the two conjugate operators do not commute yielding quantum frustration. In this regime, remarkably, the fluctuations of both two quadratures can be enhanced by increasing the dissipative coupling.

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Section: Introductionmentioning

confidence: 99%

Dissipation-induced enhancement of quantum fluctuations

Rastelli

2016

New J. Phys.

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“…The oscillations rapidly attenuate on a time scale of less than one period of the Rabi oscillations. This rather surprising oscillatory behavior of the transverse purity was to my best knowledge rst reported in [17]. Fig.…”

Section: Non-equilibrium: Thermalization and Decoherencementioning

confidence: 83%

“…A more complete analysis reveals [17] that for arbitrary asymmetry angle 0 ≤ θ ≤ π/4 and for a more general initial state ρ S (0) = 1 2 1 2 + cos θ Ŝ z + sin θ Ŝ z the decay of P ⊥ depends crucially on both angles θ and θ and on details of the cuto function. Like for the quantum frustrated harmonic oscillator no universal features of quantum frustration can be identied.…”

Section: Non-equilibrium: Thermalization and Decoherencementioning

confidence: 99%

“…For overall couplings large than γ tot ≈ 2.5 the integration routine becomes ‡ Actually not all parameters ow to zero, but the diagonal terms σ The gure is taken from Ref. [17]. numerically unstable.…”

Section: Thus Thatmentioning

confidence: 99%

“…It is taken from Ref. [17]. The values for γtot are γtot = 0.1 √ 2n, 1 ≤ n ≤ 10, from top to bottom (online color: from dark-colored to light-colored).…”

Section: The 2 Bath Two Level System (2btls)mentioning

confidence: 99%

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Asymmetry Induced Localization

Kohler

2013

Acta Phys. Pol. A

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We consider a two-level system, which couples via non-commuting operators to two independent oscillator baths. When the coupling is symmetric, the renormalized hopping matrix element is nite even for innitely strong coupling strength. The two-level system is in a delocalized phase. For nite coupling strength a localization transition occurs for a critical asymmetry angle, which separates the localized from the delocalized phase. Using the method of ow equations we are able to monitor real time dynamics.

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Unusual Transport Properties with Noncommutative System–Bath Coupling Operators

Duan

Hsieh

Liu

et al. 2020

J. Phys. Chem. Lett.

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Understanding nonequilibrium transport is crucial for controlling energy flow in nanoscale systems. We study thermal energy transfer in a generalized nonequilibrium spin-boson model (NESB) with noncommutative system−bath coupling operators and discover its unusual transport properties. Compared to the conventional NESB, the energy current is greatly enhanced by rotating the system−bath coupling operators. Constructive contribution to thermal rectification can be optimized when two sources of asymmetry, system−bath coupling strength and coupling operators, coexist. At the weak coupling and the adiabatic limit, the scaling dependence of energy current on the coupling strength and the system energy gap changes drastically when the coupling operators become noncommutative. These scaling relations can further be explained analytically by the nonequilibrium polaron-transformed Redfield equation (NE-PTRE). These novel transport properties, arising from the pure quantum effect of noncommutative coupling operators, suggest an unvisited dimension of controlling transport in nanoscale systems and should generally appear in other nonequilibrium set-ups and driven systems.

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Nonequilibrium dynamics of a system with quantum frustration

Cited by 16 publications

References 35 publications

Dissipation-induced enhancement of quantum fluctuations

Dissipation-induced enhancement of quantum fluctuations

Asymmetry Induced Localization

Unusual Transport Properties with Noncommutative System–Bath Coupling Operators

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