Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect Henriet, Loıc Sclocchi, Antonio Orth, Peter Orth, Peter Le Hur, Karyn
dc.contributor.department Ames Laboratory
dc.contributor.department Physics and Astronomy 2018-06-09T04:38:22.000 2020-06-30T06:20:01Z 2020-06-30T06:20:01Z Sun Jan 01 00:00:00 UTC 2017 2017-02-01
dc.description.abstract <p>We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H = H(sin theta cos phi, sin theta sin phi cos theta) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for alpha < 1. We report a divergence of the Berry curvature at alpha(c) = 1 for magnetic fields aligned along the equator theta = pi/2. This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs at the localization Kosterlitz-Thouless quantum phase transition in this model. Recent experiments in quantum circuits have engineered nonequilibrium protocols to access topological properties from a measurement of a dynamical Chern number defined via the out-of-equilibrium spin expectation values. Applying a numerically exact stochastic Schrodinger approach we find that, for a fixed field sweep velocity theta(t) = vt, the bath induces a crossover from ( quasi) adiabatic to nonadiabatic dynamical behavior when the spin bath coupling a increases. We also investigate the particular regime H/omega(c) << v/H << 1 with large bath cutoff frequency.c, where the dynamical Chern number vanishes already at alpha = 1/2. In this regime, the mapping to an interacting resonance level model enables us to analytically describe the behavior of the dynamical Chern number in the vicinity of alpha = 1/2. We further provide an intuitive physical explanation of the bath-induced breakdown of adiabaticity in analogy to the Faraday effect in electromagnetism. We demonstrate that the driving of the spin leads to the production of a large number of bosonic excitations in the bath, which strongly affect the spin dynamics. Finally, we quantify the spin-bath entanglement and formulate an analogy with an effective model at thermal equilibrium.</p>
dc.description.comments <p>This article is published as Henriet, Loïc, Antonio Sclocchi, Peter P. Orth, and Karyn Le Hur. "Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect." <em>Physical Review B</em> 95, no. 5 (2017): 054307. DOI: <a href="" target="_blank">10.1103/PhysRevB.95.054307</a>. Posted with permission.</p>
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dc.identifier archive/
dc.identifier.articleid 1483
dc.identifier.contextkey 12283016
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath physastro_pubs/481
dc.language.iso en
dc.source.bitstream archive/|||Sat Jan 15 00:27:43 UTC 2022
dc.source.uri 10.1103/PhysRevB.95.054307
dc.subject.disciplines Condensed Matter Physics
dc.subject.disciplines Physics
dc.title Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect
dc.type article
dc.type.genre article
dspace.entity.type Publication
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relation.isOrgUnitOfPublication 4a05cd4d-8749-4cff-96b1-32eca381d930
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