Measurement-induced quantum entanglement recovery

TL;DR

This paper demonstrates experimentally that measurement can recover quantum entanglement in a two-qubit system affected by dephasing, with recovered states still violating Bell's inequality, highlighting the dynamics of entanglement and nonlocality.

Contribution

It provides experimental evidence that measurement can restore entanglement and nonlocality in a dephasing environment, revealing new insights into entanglement dynamics.

Findings

Measurement recovers entanglement in dephasing environments.

Recovered states violate Bell's inequality, showing nonlocality.

Entanglement exhibits sudden death and rebirth phenomena.

Abstract

By using photon pairs created in parametric down conversion, we report on an experiment, which demonstrates that measurement can recover the quantum entanglement of two qubit system in a pure dephasing environment. The concurrence of the final state with and without measurement are compared and analyzed. Furthermore, we verify that recovered states can still violate Bell's inequality, that is, to say, such recovered states exhibit nonlocality. In the context of quantum entanglement, sudden death and rebirth provide clear evidence, which verifies that entanglement dynamics of the system is sensitive not only to its environment, but also on its initial state.