Measurement scheme for the Lamb shift in a superconducting circuit with broadband environment

TL;DR

This paper proposes a measurement scheme to observe Lamb shifts in superconducting circuits influenced by broadband environmental fluctuations, including thermal phase reservoirs, supported by theoretical and numerical analysis.

Contribution

It introduces a novel experimental protocol for measuring Lamb shifts in superconducting circuits affected by broadband environments, extending beyond cavity-based systems.

Findings

The scheme effectively detects Lamb shifts in superconducting circuits.

The analysis includes both weak-coupling master equations and non-perturbative models.

Numerical simulations support the feasibility of the proposed measurement protocol.

Abstract

Motivated by recent experiments on quantum mechanical charge pumping in a Cooper pair sluice, we present a measurement scheme for observing shifts of transition frequencies in two-level quantum systems induced by broadband environmental fluctuations. In contrast to quantum optical and related set-ups based on cavities, the impact of a thermal phase reservoir is considered. A thorough analysis of Lamb and Stark shifts within weak-coupling master equations is complemented by non-perturbative results for the model of an exactly solvable harmonic system. The experimental protocol to measure the Lamb shift in experimentally feasible superconducting circuits is analysed in detail and supported by numerical simulations.