Protecting an unknown qubit state by weak measurement

Abstract

The problem of combating de-coherence by weak measurements has already been studied for the amplitude damping channel and for specific input states. We generalize this to a large four-parameter family of qubit channels and for the average fidelity over all pure states. As a by-product we classify all the qubit channels which have one invariant pure state and show that the parameter manifold of these channels is isomorphic to $S^2\times S^1\times S^1$ and contains many interesting subclasses of channels. The figure of merit that we use is the average input-output fidelity which we show can be increased up to $30$ percents in some cases, by tuning of the weak measurement parameter.

14 pages, Substantial revision, one author added

References in corpus (7)

• Quantum Control of a Single Qubit
• Feed-forward control for quantum state protection against decoherence
• Quantum phase communication channels assisted by non-deterministic noiseless amplifiers
• Improving the capacity of quantum dense coding by weak measurement and reversal measurement
• Quasi inversion of qubit channels
• Protecting quantum correlations in presence of generalised amplitude damping channel: the two-qubit case
• Quasi-inversion of quantum and classical channels in finite dimensions

Cited by in corpus (1)

• Effect of Weak Measurement Reversal on Quantum Correlations in a Correlated Amplitude Damping Channel, with a Neural Network Perspective