Experimentally freezing quantum discord in a dissipative environment using dynamical decoupling

TL;DR

This paper demonstrates experimentally that dynamical decoupling can effectively freeze quantum discord in a two-qubit NMR system, preserving quantum correlations in a noisy environment over extended periods.

Contribution

It introduces the use of robust dynamical decoupling sequences to experimentally preserve quantum discord in a dissipative environment, extending its lifetime significantly.

Findings

Dynamical decoupling prolongs quantum discord in NMR qubits.

Quantum and classical correlations are preserved using decoupling.

Quantum discord can be frozen over long times with appropriate schemes.

Abstract

The discovery of the intriguing phenomenon that certain kinds of quantum correlations remain impervious to noise up to a specific point in time and then suddenly decay, has generated immense recent interest. We exploit dynamical decoupling sequences to prolong the persistence of time-invariant quantum discord in a system of two NMR qubits decohering in independent dephasing environments. We experimentally prepare two-qubit Bell-diagonal quantum states that interact with individual dephasing channels and demonstrate the effect of dynamical decoupling on the preservation of both quantum and classical correlations. We are able to freeze quantum discord over long time scales in the presence of noise, using dynamical decoupling. We use robust state-independent dynamical decoupling schemes for state preservation and demonstrate that these schemes are able to successfully preserve quantum discord.