Effects of symmetry breaking of the structurally-disordered Hamiltonian ensembles on the anisotropic decoherence of qubits

TL;DR

This paper explores how symmetry breaking in disordered Hamiltonian ensembles influences anisotropic decoherence in qubits, revealing new effects on incoherent quantum dynamics through a geometrical and analytical approach.

Contribution

It extends the Hamiltonian ensemble approach to structural disorder, analyzing how symmetry breaking affects qubit decoherence beyond traditional dephasing models.

Findings

Symmetry breaking introduces additional terms in master equations.

Different types of symmetry breaking lead to varied incoherent dynamics.

The approach visualizes geometrical structures related to disorder and symmetry.

Abstract

It is commonly known that the dephasing in open quantum systems is due to the establishment of bipartite correlations with ambient environments, which are typically difficult to be fully characterized. Recently, a new approach of average over disordered Hamiltonian ensemble is developed and shown to be capable of describing the nonclassicality of incoherent dynamics based on inferring the nonclassical nature of the correlations. Here we further extend the approach of Hamiltonian ensemble in the canonical form to the realm of structural disorder. Under the variable separation of the probability distribution within the Hamiltonian ensemble, the geometrical structure is easily visualized and can be characterized according to the degree of symmetry. We demonstrate four degrees and investigate the effects of different types of symmetry breaking on the incoherent dynamics. We show that these effects are easily understood from the emergences of additional terms in the master equations, leading to rather general master equations and, consequently, going beyond the previous frameworks of pure dephasing or isotropic depolarization.