Abstract
Weak measurement is a kind of state partial collapse measurement developed on the basis of von Neumann measurement and positive operator value measurement, which allows us to explore the quantum world which has the least influence on the research system. Based on the weak measurement theory, the dynamics of quantum discord for two isolated atoms in their own thermal reservoirs is presented. We examine the time evolution of both standard quantum discord and quantum discord with weak measurement for the two-atom system, and analyzes the differences between the standard quantum discord and quantum discord with weak measurement in the evolution process with time, as well as the general role of the strength parameter in determing the discord and affecting its dynamic evolution. We show that quantum discords depend on how weak or strong one perturbs the quantum system. We also show that the difference of the standard quantum discord and the quantum discord with weak measurements increases as the strength parameter decreases. This means that the weak measurements can capture more quantum discord of a bipartite system. Our results show that the weak measurement performed on one of the subsystems can lead to the quantum discord that is a more natural measure of quantum correlations than the standard quantum discord captured by the projective measurements.
Highlights
The development of quantum information and quantum computing over the last two decades has led to increasing attention to quantum correlations [1,2,3,4,5,6,7,8]
We note that both of the quantum correlations disappear in the asymptotic limit in thermal reservoirs of nonzero mean photon number
We have studied the time evolution of the standard quantum discord and quantum discord with weak measurements for two isolated atoms, each in its own thermal reservoir
Summary
The development of quantum information and quantum computing over the last two decades has led to increasing attention to quantum correlations [1,2,3,4,5,6,7,8]. It has been shown that quantum discord is more general and important than entanglement for the fundamentals of physics and for quantum information processing tasks. Quantum correlations with weak measurement is an emerging research subject Their properties are different from those by the means of projective measurement [27]. Another interesting subject is to investigate the dynamics of different kinds of correlations in noisy environments. Despite the fact that the correlation dynamics has been broadly studied for the quantum systems in dissipation environments, the problem is still open for effect of the environment on quantum discord with weak measurement. Our results show that the weak measurements can reveal more quantum correlations of bipartite quantum states under dissipation environments
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