Effects of Entanglement in Controlled Dephasing

Abstract

In controlled dephasing as a result of the interaction of a controlled environment (dephasor) and the system under observation (dephasee) the states of the two subsystems are entangled. Using as an example the ``Which Path Detector'', we discuss how the entanglement influences the controlled dephasing. In particular, we calculate the suppression $ν$ of A-B oscillations as a function of the bias $eV$ applied to the QPC and the coupling $Γ$ of the QD to the leads. At low temperatures the entanglement produces a smooth crossover from $ν\propto (eV/Γ)^2$, when $eV \ll Γ$ to $ν\propto eV/Γ$, for $eV \gg Γ$.

4 pages, 1 figure