266,973 research outputs found
Dynamics of a two-level system under the simultaneous influence of a spin bath and a boson bath
We study dynamics of a two-level system coupled simultaneously to a pair of
dissimilar reservoirs, namely, a spin bath and a boson bath, which are
connected via finite interbath coupling. It is found that the steady-state
energy transfer in the two-level system increases with its coupling to the spin
bath while optimal transfer occurs at intermediate coupling in the transient
process. If the two-level system is strongly coupled to the spin bath, the
population transfer is unidirectional barring minor population oscillations of
minute amplitudes. If the spin bath is viewed as an atomic ensemble, robust
generation of macroscopic superposition states exists against parameter
variations of the two-level system and the boson bath.Comment: 12 pages, 4 figure
Weak Measurements Beyond the Aharonov-Albert-Vaidman Formalism
We extend the idea of weak measurements to the general case, provide a
complete treatment and obtain results for both the regime when the pre-selected
and post-selected states (PPS) are almost orthogonal and the regime when they
are exactly orthogonal. We surprisingly find that for a fixed interaction
strength, there may exist a maximum signal amplification and a corresponding
optimum overlap of PPS to achieve it. For weak measurements in the orthogonal
regime, we find interesting quantities that play the same role that weak values
play in the non-orthogonal regime.Comment: 5 pages, 2 figure
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