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Aspects of quantum coherence in the optical Bloch equations

A. S. Sanz·H. Han·P. Brumer
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Abstract

Aspects of coherence and decoherence are analyzed within the optical Bloch equations. By rewriting the analytic solution in an alternate form, we are able to emphasize a number of unusual features: (a) despite the Markovian nature of the bath, coherence at long times can be retained; (b) the long-time asymptotic degree of coherence in the system is intertwined with the asymptotic difference in level populations; (c) the traditional population-relaxation and decoherence times, $T_1$ and $T_2$, lose their meaning when the system is in the presence of an external field, and are replaced by more general overall timescales; (d) increasing the field strength, quantified by the Rabi frequency, $Ω$, increases the rate of decoherence rather than reducing it, as one might expect; and (e) maximum asymptotic coherence is reached when the system parameters satisfy $Ω^2 = 1/(T_1 T_2)$.

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A. S. Sanz, H. Han, P. Brumer. 2006-04-12. Aspects of quantum coherence in the optical Bloch equations. https://doi.org/10.1063/1.2200703

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