Relaxation of a two-level system strongly coupled to a resevoir: anomalously slow decoherence

Abraham G. Kofman

doi:10.1117/12.514252

16 May 2003 Relaxation of a two-level system strongly coupled to a resevoir: anomalously slow decoherence

Abraham G. Kofman

Proceedings Volume 5111, Fluctuations and Noise in Photonics and Quantum Optics; (2003) https://doi.org/10.1117/12.514252
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States

Abstract

Relaxation of a two-level system (TLS) into a resonant infinite-temperature reservoir with a Lorentzian spectrum is studied. The reservoir is described by a complex Gaussian-Markovian field coupled to the nondiagonal elements of the TLS Hamiltonian. The theory can be relevant for electromagnetic interactions in microwave high-Q cavities and muon spin depolarization. Analytical results are obtained for the strong-coupling regime, ₀>ν, where Ω₀ is the rms coupling amplitude (Rabi frequency) and ν is the width of the reservoir spectrum. In this regime, the population difference and half of the initial coherence decay with two characteristic rates: the most part of the decay occurs at t < (Ω₀ν)^-1/3 the relaxation becomes reversible for t ~ Ω₀^-1/3, whereas for t > (Ω₀²ν)^-1/3 the relaxation becomes irreversible and is practically over. The other half of the coherence decays with the rate on the order of ν, which may be slower by orders of magnitude than the time scale of the population relaxation. The above features are explained by the fact that at t < ν^-1 the reservoir temporal fluctuations are effectively one-dimensional (adiabatic). Moreover, we identify the pointer basis, in which the reduction of the state vector occurs. The pointer states are correlated with the reservoir, being dependent on the reservoir phase.

Citation Download Citation

Abraham G. Kofman "Relaxation of a two-level system strongly coupled to a resevoir: anomalously slow decoherence", Proc. SPIE 5111, Fluctuations and Noise in Photonics and Quantum Optics, (16 May 2003); https://doi.org/10.1117/12.514252

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