Decoherence is believed to deteriorate the ability of a purification scheme that is based on the idea of driving a system to a pure state by repeatedly measuring another system in interaction with the former and hinder for a pure state to be extracted asymptotically. Nevertheless, we find a way out of this difficulty by deriving an analytic expression of the reduced density matrix for a two-qubit system immersed in a bath. It is shown that we can still extract a pure state if the environment brings about only dephasing effects. In addition, for a dissipative environment, there is a possibility of obtaining a dominant pure state when we perform a finite number of measurements.
NAKAZATO H, YUASA K, MILITELLO B, MESSINA A (2008). Estimation of the repeatedly projected reduced density matrix under decoherence. PHYSICAL REVIEW A, 77, 042114-1-042114-12 [10.1103/PhysRevA.77.042114].
Estimation of the repeatedly projected reduced density matrix under decoherence
MILITELLO, Benedetto;MESSINA, Antonino
2008-01-01
Abstract
Decoherence is believed to deteriorate the ability of a purification scheme that is based on the idea of driving a system to a pure state by repeatedly measuring another system in interaction with the former and hinder for a pure state to be extracted asymptotically. Nevertheless, we find a way out of this difficulty by deriving an analytic expression of the reduced density matrix for a two-qubit system immersed in a bath. It is shown that we can still extract a pure state if the environment brings about only dephasing effects. In addition, for a dissipative environment, there is a possibility of obtaining a dominant pure state when we perform a finite number of measurements.File | Dimensione | Formato | |
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2008 PRA 77_042114 [Nakazato].pdf
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