Entanglement is known to be an essential resource for many quantum information processes. However, it is now known that some quantum features may be acheived with quantum discord, a generalized measure of quantum correlation. In this paper, we study how quantum discord, or more specifically, the measures of entropic discord and geometric discord are affected by the influence of amplitude damping decoherence. We also show that a protocol deploying weak measurement and quantum measurement reversal can effectively protect quantum discord from amplitude damping decoherence, enabling to distribute quantum correlation between two remote parties in a noisy environment.
A quantum memory interacts with its environment and loses information via decoherence as well as incoherence. A robust quantum control that prepares, preserves, and manipulates nonclassical correlations even in the presence of environmental influence is of paramount importance in quantum information processing. A well-known technique to suppress decoherence, namely Dynamical Decoupling (DD), consists of a sequence of rapid flips applied to the system in order to refocus the system-environment interactions. In this work, we integrate DD with quantum gates using optimal control techniques to realize robust quantum gates which offer protection against decoherence. To investigate the protection of non-classical correlation, we study the evolution of quantum discord in Grover's search algorithm implemented with dynamically protected gates. Using a two-qubit NMR system, we experimentally demonstrate a significant protection against decoherence and incoherence. We find better performances by phase alternating DD sequences with suitable spacings between the DD pulses. Interestingly, we also find that DD sequences based on
π/2 pulses perform as well as or even better than those with
π pulses in protecting the non-classical correlation. We also support the experimental results by analyzing the robustness of various DD schemes.