Fighting Decoherence by Feedback-controlled Dissipation
arXiv:1203.4977 · doi:10.1103/PhysRevA.85.062118
Abstract
Repeated closed-loop control operations acting as piecewise-constant Liouville superoperators conditioned on the outcomes of regularly performed measurements may effectively be described by a fixed-point iteration for the density matrix. Even when all Liouville superoperators point to the completely mixed state, feedback of the measurement result may lead to a pure state, which can be interpreted as selective dampening of undesired states. Using a microscopic model, we exemplify this for a single qubit, which can be purified in an arbitrary single-qubit state by tuning the measurement direction and two qubits that may be purified towards a Bell state by applying a special continuous two-local measurement. The method does not require precise knowledge of decoherence channels and works for large reservoir temperatures provided measurement, processing, and control can be implemented in a continuous fashion.
to appear in PRA
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Cited by in corpus (8)
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- Maxwell's demon in the quantum-Zeno regime and beyond
- Delayed feedback control in quantum transport
- Revisiting Quantum Feedback Control: Disentangling the Feedback-induced Phase from the Corresponding Amplitude
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