Quantum sweeps, synchronization, and Kibble-Zurek physics in dissipative quantum spin systems

Henriet, Loïc; Hur, Karyn Le

doi:10.1103/physrevb.93.064411

Cited by 17 publications

(31 citation statements)

References 110 publications

(167 reference statements)

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“…For example, how charge and photonic dynamics behave when the critical point is passed nonadiabatically and if links to Kibble-Zurek or Landau-Zener like mechanisms can be established [51,52]. Further, the realization of microwave sources with tunable quantum/classical characteristics or current sources with tailored noise properties may be attractive in device applications.…”

Section: Discussionmentioning

confidence: 99%

Noise switching at a dynamical critical point in a cavity-conductor hybrid

2017

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.ukNoise switching at a dynamical critical point in a cavity-conductor hybrid Coupling a mesoscopic conductor to a microwave cavity can lead to fascinating feedback effects which generate strong correlations between the dynamics of photons and charges. We explore the connection between cavity dynamics and charge transport in a model system consisting of a voltagebiased Josephson junction embedded in a high-Q cavity, focussing on the behavior as the system is tuned through a dynamical critical point. On one side of the critical point the noise is strongly suppressed, signalling the existence of a novel regime of highly coherent transport, but on the other side it switches abruptly to a much larger value. Using a semiclassical approach we show that this behavior arises because of the strongly nonlinear cavity drive generated by the Cooper pairs. We also uncover an equivalence between charge and photonic current noise in the system which opens up a route to detecting the critical behavior through straightforward microwave measurements.

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Section: Discussionmentioning

confidence: 99%

Noise switching at a dynamical critical point in a cavity-conductor hybrid

2017

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“…This method is applicable in the regime α < 1/2 and becomes numerically exact in the universal regime of a large bath bandwidth ω c H . The SSE approach was successfully used to describe the dynamics of the Ohmic spin-boson model [29,44,47] as well as the dynamics of the Rabi model [46]. We present a summary of the most important technical details in Appendix D.…”

Section: B Spin Dynamics and Topology From Stochastic Schrödinger Eqmentioning

confidence: 99%

“…In the presence of an Ohmic bath, we calculate the spin dynamics using the numerically exact SSE approach, which was developed in Refs. [29,[44][45][46][47] (see also previous stochastic approaches to the spin-boson model [48][49][50][51]). This method is applicable in the regime α < 1/2 and becomes numerically exact in the universal regime of a large bath bandwidth ω c H .…”

Section: B Spin Dynamics and Topology From Stochastic Schrödinger Eqmentioning

confidence: 99%

Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

et al. 2017

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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. Disciplines Condensed Matter Physics | Physics CommentsThis 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." Physical Review B 95, no. 5 (2017) We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H = H (sin θ cos φ, sin θ sin φ, cos θ ) 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 α < 1. We report a divergence of the Berry curvature at α c = 1 for magnetic fields aligned along the equator θ = π/2. This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs a...

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“…If in addition the inter-level distance between level positions is maintained constant throughout the course of variation of a control parameter (time, chemical potential, flux, magnetic field, pressure, temperature etc), the relevant model leads to the so called SU (3) LZSM interferometry 6,7 . Such a system has stimulated active theoretical researches [5][6][7]9 and is currently attracting tremendous interests from both fundamental and experimental physics due to versatile applications in BoseJosephson junctions 10,11 (BJJ), quantum spectroscopy 12 , quantum metrology 13 , quantum information processing 14 etc. Quantum triangles are observed in various experimental protocols [15][16][17][18][19] (see also the triangle model in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…Other examples are triplet states energy levels of a linearly driven twospin-1/2 system 9, [17][18][19]21 . Indeed, if the triplets are coupled through Ising interactions and bath in a boson sea consisting of harmonic oscillators at room temperature, various types of quantum triangles form depending on the value of the Ising coupling 9 . Ultracold atoms in optical lattices with lattice sites converted into biased doublewell also depict a triangular geometry 22 .…”

Section: Introductionmentioning

confidence: 99%

SU(3) Landau-Zener interferometry with a transverse periodic drive

2017

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Quantum triangles can work as interferometers. Depending on their geometric size and interactions between paths, "beats" and/or "steps" patterns are observed. We show that when inter-level distances between level positions in quantum triangles periodically change with time, formation of beats and/or steps no longer depends only on the geometric size of the triangles but also on the characteristic frequency of the transverse signal. For large-size triangles, we observe the coexistence of beats and steps when the frequency of the signal matches that of non-adiabatic oscillations and for large frequencies, a maximum of four steps instead of two as in the case with constant interactions is observed. Small-size triangles also revealed counter-intuitive interesting dynamics for large frequencies of the field: unexpected two-step patterns are observed. When the frequency is large and tuned such that it matches the uniaxial anisotropy, three-step patterns are observed. We have equally observed that when the transverse signal possesses a static part, steps maximize to six. These effects are semi-classically explained in terms of Fresnel integrals and quantum mechanically in terms of quantized fields with a photon-induced tunneling process. Our expressions for populations are in excellent agreement with the gross temporal profiles of exact numerical solutions. We compare the semi-classical and quantum dynamics in the triangle and establish the conditions for their equivalence.

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Quantum sweeps, synchronization, and Kibble-Zurek physics in dissipative quantum spin systems

Cited by 17 publications

References 110 publications

Noise switching at a dynamical critical point in a cavity-conductor hybrid

Noise switching at a dynamical critical point in a cavity-conductor hybrid

Topology of a dissipative spin: Dynamical Chern number, bath-induced nonadiabaticity, and a quantum dynamo effect

SU(3) Landau-Zener interferometry with a transverse periodic drive

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