Dephasing and Renormalization in Quantum Two-Level Systems

TL;DR

This paper investigates how environmental interactions cause relaxation, dephasing, and renormalization in quantum two-level systems, highlighting the influence of initial conditions and analyzing exact solutions and response functions.

Contribution

It provides an exact analysis of the interplay between dephasing and renormalization effects in quantum two-level systems coupled to environments, emphasizing initial state dependence.

Findings

Initial state preparation affects dephasing and renormalization outcomes.

Exact solutions demonstrate the relationship between dephasing and renormalization.

Response functions are significantly influenced by environmental effects.

Abstract

Motivated by fundamental questions about the loss of phase coherence at low temperature we consider relaxation, dephasing and renormalization effects in quantum two-level systems which are coupled to a dissipative environment. We observe that experimental conditions, e.g., details of the initial state preparation, determine to which extent the environment leads to dephasing or to renormalization effects. We analyze an exactly solvable limit where the relation between both can be demonstrated explicitly. We also study the effects of dephasing and renormalization on response functions.