2003/04/08 by Silvia Kleff, S. Kleff, Stefan Kehrein +3
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum and electron transport phenomena #Spectroscopy and Quantum Chemical Studies #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.70.014516
5 psges, 5 figures
arxiv created 2003/04/08 · openalex publication_date 2004/07/29 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We discuss dephasing times for a two-level system (including bias) coupled to a damped harmonic oscillator. This system is realized in measurements on solid-state Josephson qubits. It can be mapped to a spin-boson model with a spectral function with an approximately Lorentzian resonance. We diagonalize the model by means of infinitesimal unitary transformations (flow equations) and calculate correlation functions, dephasing rates, and qubit quality factors. We find that these depend strongly on the environmental resonance frequency \ensuremathΩ; in particular, quality factors can be enhanced significantly by tuning \ensuremathΩ to lie below the qubit frequency \ensuremathΔ.