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arXiv:quant-ph/0408073 · Physical Review Letters

Spontaneous Relaxation of a Charge Qubit under Electrical Measurement

Xin-Qi Li, Ping Cui, YiJing Yan

Published Feb 17, 2005• 84 citations
arXivHTMLPDF

Abstract

In this work we first derive a generalized conditional master equation for quantum measurement by a mesoscopic detector, then study the readout characteristics of qubit measurement where a number of remarkable new features are found. The work would, in particular, highlight the qubit spontaneous relaxation effect induced by the measurement itself rather than an external thermal bath.

DOI
10.1103/physrevlett.94.066803

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Quantum measurement always disturbs the quantum system being measured, which is known as measurement-induced backaction. We consider a specific model, a double quantum dot charge qubit measured by a nearby quantum point contact. We explore the evolution by deriving a master equation. The advantages of this master equation are (i) it has the Lindblad form and the non-Markovian effects are embodied in the time-dependent coefficients, (ii) the tunnelling and decay effect can be clearly understood in the master equation, and (iii) it can be further easily controlled by manipulate the Hamiltonian.