Effects of weak measurements on sudden change of quantum discord

TL;DR

This paper investigates how weak measurements influence the sudden change behavior of quantum discord in two-qubit systems, revealing that weak measurements lead to monotonic decay and that environment is not the primary cause of sudden changes.

Contribution

It demonstrates that weak measurements prevent the sudden change in quantum discord, highlighting the intrinsic role of quantum correlation rather than environment in this phenomenon.

Findings

Quantum discord decays monotonically under weak measurements.

Sudden change occurs only with strong (projective) measurements.

Environment is not the main factor causing sudden change.

Abstract

We study the peculiar dynamics of two qubits quantum discord with a sudden change in behavior. It is widely agreed in the literature nowadays that environment induce sudden change behavior of quantum discord. We explore the sudden change phenomenon under the action of local-independent environments, considering the discord of two-qubit which is obtained by means of the weak measurements on one of the two-qubit. It is shown that the sudden change phenomenon does not appear under weak measurements. We find that the quantum discord with weak measurements decays in a monotonic fashion, and show that quantum discord might exhibit a sudden change only for the strong (projective) measurement. We believe that environment is not the main role of the sudden change, but the quantum correlation itself is.