Effective Hamiltonian in the Problem of a "Central Spin" Coupled to a Spin Environment

Tupitsyn, I. S.; Prokof’ev, Nikolay; Stamp, P. C. E.

doi:10.1142/s0217979297001416

Cited by 31 publications

(64 citation statements)

References 23 publications

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“…Further, it is important to consider more-involved models for the reservoirs and mimic complex and realistic environments [27,28,30]: to consider baths with both harmonic and anharmonic components [56], and allow for interactions between sub-units in the bath [26,57].…”

Section: Discussionmentioning

confidence: 99%

Two-level system in spin baths: Non-adiabatic dynamics and heat transport

Segal

2014

The Journal of Chemical Physics

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We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, corresponding to the harmonic bath with an effective, temperature-dependent, spectral density function. We then proceed and study the heat current characteristics in the out-of-equilibrium spin-spin-bath model, with a two-state subsystem bridging two thermal spin-baths of different temperatures. We compare the behavior of this model to the case of a spin connecting boson baths, and demonstrate pronounced qualitative differences between the two models. Specifically, we focus on the development of the thermal diode effect, and show that the spin-spin-bath model cannot support it at weak (subsystem-bath) coupling, while in the intermediate-strong coupling regime its rectifying performance outplays the spin-boson model.

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Section: Discussionmentioning

confidence: 99%

Two-level system in spin baths: Non-adiabatic dynamics and heat transport

Segal

2014

The Journal of Chemical Physics

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“…1), where Ω o ∼ K. First, let's cheat and look at the final answer! One finds for the general problem of a giant spin coupled to a spin bath that [14,16,35] …”

Section: ∼ 10mentioning

confidence: 99%

QUANTUM ENVIRONMENTS: SPINS BATHS, OSCILLATOR BATHS, and applications to QUANTUM MAGNETISM

Stamp

1998

Proceedings From the Institute for Nuclear Theory

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The low-energy physics of systems coupled to their surroundings is understood by truncating to effective Hamiltonians; these tend to reduce to a few canonical forms, involving coupling to "baths' of oscillators or spins. The method for doing this is demonstrated using examples from magnetism, superconductivity, and measurement theory, as is the way one then solves for the low-energy dynamics. Finally, detailed application is given to the exciting recent Quantum Relaxation and tunneling work in nanomagnets.

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“…Applications for various physical systems have been reported. 12,13,14,15,16,17,18 Fermionic heat bath has also been considered. 19 We note that a true heat bath should cause a microscopic system interacting with it to thermalize.…”

Section: Introductionmentioning

confidence: 99%

<title>Decoherence and measurement in open quantum systems</title>

Privman

2000

Quantum Computing

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We review results of a recently developed model of a microscopic quantum system interacting with the macroscopic world components which are modeled by collections of bosonic modes. The interaction is via a general operator Λ of the system, coupled to the creation and annihilation operators of the environment modes. We assume that in the process of a nearly instantaneous quantum measurement, the function of the environment involves two distinct parts: the pointer and the bath. Interaction of the system with the bath leads to decoherence such that the system and the pointer both evolve into a statistical mixture state described by the density matrix such that the system is in one of the eigenstates of Λ with the correct quantum mechanical probability, whereas the expectation values of pointer operators retain amplified information on that eigenstate. We argue that this process represents the initial step of a quantum measurement. Calculation of the elements of the reduced density matrix of the system and pointer is carried out exactly, and time dependence of decoherence is identified. We discuss general implications of our model of energy-conserving coupling to a heat bath for processes of adiabatic quantum decoherence. We also evaluate changes in the expectation values of certain pointer operators and suggest that these can be interpreted as macroscopic indicators of the measurement outcome.

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Effective Hamiltonian in the Problem of a "Central Spin" Coupled to a Spin Environment

Cited by 31 publications

References 23 publications

Two-level system in spin baths: Non-adiabatic dynamics and heat transport

Two-level system in spin baths: Non-adiabatic dynamics and heat transport

QUANTUM ENVIRONMENTS: SPINS BATHS, OSCILLATOR BATHS, and applications to QUANTUM MAGNETISM

<title>Decoherence and measurement in open quantum systems</title>

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