Decoherence dynamics of a qubit coupled to a quantum two-level system

S. Ashhab, J. R. Johansson, Franco Nori

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10 Citations (Scopus)


We study the decoherence dynamics of a qubit coupled to a quantum two-level system (TLS) in addition to its weak coupling to a background environment. We analyze the different regimes of behaviour that arise as the values of the different parameters are varied. We classify those regimes as two weak-coupling regimes, which differ by the relation between the qubit and TLS decoherence times, and a strong-coupling one. We also find analytic expressions describing the decoherence rates in the weak-coupling regimes, and we verify numerically that those expressions have a rather wide range of validity. Along with obtaining the above-mentioned results, we address the questions of qubit-TLS entanglement and the additivity of multiple TLS contributions. We also discuss the transition from weak to strong-coupling as the parameters are varied, and we numerically determine the location of the boundary between the two regimes.

Original languageEnglish
Pages (from-to)45-52
Number of pages8
JournalPhysica C: Superconductivity and its applications
Issue number1-2
Publication statusPublished - 15 Sep 2006



  • Decoherence
  • Quantum computing
  • Two-level systems

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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