Efficacy of measurement reversal for stochastic disturbances

We analyze the statistical properties of entanglement for pairs and triples of entangled qubits subject to a random disturbance followed by restoration. After the random disturbance, which is modeled as a null-result weak measurement, the state is restored by applying a static measurement reversal. We then show that the fidelity of the resulting state, and therefore its entanglement, can be restored with a high success, despite the statistical fluctuations of the disturbance. In particular, we show that the variance of the entanglement of an ensemble of restored states is substantially reduced, despite large disturbances. We conclude with a proposed experimental implementation.