Polaron dynamics and decoherence in an interacting two-spin system coupled to an optical-phonon environment

Abstract

We study two anisotropically interacting spins coupled to optical phonons; we restrict our analysis to the regime of strong coupling to the environment, to the antiadiabatic region, and to the subspace with zero value for S z T (the z-component of the total spin). In the case where each spin is coupled to a different phonon bath, we assume that the system and the environment are initially uncorrelated (and form a simply separable state) in the polaronic frame of reference. By analyzing the polaron dynamics through non-Markovian quantum master equation, we find that the system manifests a small amount of decoherence that decreases both with increasing non-adiabaticity and with enhancing strength of coupling; whereas, under the Markovian approximation, the polaronic system exhibits a decoherence free behavior. For the situation where both spins are coupled to the same phonon bath, we also show that the system is decoherence free in the subspace where S z T is fixed. To suppress decoherence through quantum control, we employ a train of pi pulses and demonstrate that unitary evolution of the system can be retained.We propose realization of a weakly decohering charge qubit from an electron in an oxide-based (tunnel-coupled) double quantum dot system.

Interference Effect betweenϕandΛ(1520)Production Channels in theγpRyu1, Ahn2, Nakano3 et al. 2016Phys. Rev. Lett.20020View full textAdd to dashboardCite

“…However, it is worth noting that the φ-Λ(1520) interference effect does not account for the 2.1-GeV bump structure in forward differential cross sections for φ photoproduction. This result is consistent with a recent report from CLAS regarding the Λ(1520) effect [10]. The energy dependence of the phase may indicate nontrivial rescattering contributions from other hyperon resonances.…”

“…However, a bump structure at √ s = 2.1 GeV in forward differential cross sections was first reported by the LEPS collaboration [8]. Despite extensive experimental efforts devoted for the photoproduction of φ mesons near threshold, the nature of the bump structure has not yet been explained in detail [9,10]. Kiswandhi et al [11] suggested that the bump structure is the result of an excitation of missing nucleon resonances.…”

“…Kiswandhi et al [11] suggested that the bump structure is the result of an excitation of missing nucleon resonances. However, the bump structure observed from CLAS appears only at forward angles; thus, a conventional resonance interpretation seems less likely [10]. Very recently, the LHCb collaboration [12] claimed to have observed two J/ψ p resonances referred to as hidden-charm pentaquark states (ccuud) from Λ 0 b decays.…”

Recent results from LEPS and status of LEPS2

“…1. This behavior was also observed by CLAS [6,7]. The spin density matrix element obtained by the K + K − decay angular distribution shows about 30% contribution of unnatural-parity exchanges such as π 0 and η in the measured energy region.…”

Matrix-product-state method with a dynamical local basis optimization for bosonic systems out of equilibrium

“…Here we restrict ourselves to the nonequilibrium dynamics of an electron coupled to phonons (i.e., the polaron dynamics), which has recently become a widely studied topic [20,[34][35][36][37][38][39][40][41][42][43][44][45]. One-electron problems have MPS with low bond dimensions D, which can easily be simulated on a workstation when the effective local dimension is small (d or d O 10).…”