Temperature quantum sensor on superradiant phase-transition

Bazhenov, A. Yu.; Tsarev, D. V.; Alodjants, A. P.

doi:10.1016/j.physb.2019.411879

Cited by 8 publications

(1 citation statement)

References 29 publications

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“…In particular, in [42,43] it is demonstrated that such systems permit a first order phase transition depending on the character of spin-spin interaction. Some important applications in quantum metrology are also found [44].…”

Section: Introductionmentioning

confidence: 99%

Superradiant phase transition in complex networks

Bazhenov,

Tsarev,

Alodjants

2020

Preprint

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In this work we consider a superradiant phase transition problem for the Dicke-Ising model, which generalizes the Dicke and Ising models for annealed complex networks presuming spin-spin interaction. The model accounts the interaction between a spin (two-level) system and external classical (magnetic) and quantized (transverse) fields. We examine regular, random, and scale-free network structures characterized by the delta-function, random (Poisson), and power-law exponent (p(k) ∝ k −γ ) degree distributions, respectively. To describe paramagnetic (PM) -ferromagrenic (FM) and superradiant (SR) phase transitions we introduce two order parameters: the total weighted spin z-component and the normalized transverse field amplitude, which correspond to the spontaneous magnetization in z and x directions, respectively. Due to the interplay between the spin interaction and the finite size effects in the networks we first elucidate novel features of the SR state in the presence of the PM-FM phase transition. In particular, we show that the critical temperature essentially depends on parameter ζ = k 2 / k , which characterizes statistical properties of the network structure. Moreover, we reveal that the critical temperature of the SR phase transition grows monotonically from some certain value that corresponds to the critical number of nodes. For the scale-free networks we find that this critical temperature rises with the degree exponent increase accompanied both by establishing spontaneous magnetization in a quantum transverse field and vanishing of the collective spin component in z direction. In addition, we establish the conditions for the network parameters to obtain a quantum phase transition in the spin system when the critical temperature approaches zero. The fundamental features, which involve critical values of the classical and quantum field parameters, are discussed for the occurrence of the superradiance phase in this limit.

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Section: Introductionmentioning

confidence: 99%