Continuous variable quantum discord in a correlated emission laser

Hua-tang, Tan, Shi-yao +3 more

Sitotaw Eshete

Girma Bekele Chaka, Tesfay Gebremariam Tesfahannes, Tewodros Yirgashewa Darge +5 more

In this paper, we explore the generation of continuous-variable quantum correlations in an optomechanical nanobeam crystal, which consists of two dielectric mirrors designed as Bragg reflectors. These mirrors are constructed from alternating layers, with varying refractive indices, and their transmissive and reflective properties are analyzed using the transfer matrix method. The system is driven by a laser field tuned to the blue-detuned sideband, enabling coupling between the cavity and mechanical modes through radiation pressure. We explore various forms of quantum correlations, including entanglement, quantum steering, and quantum discord. Logarithmic negativity is employed to quantify entanglement, while quantum steering is assessed to evaluate the steerability between subsystems. Quantum discord is employed to measure non-classical correlations that extend beyond entanglement. Our findings emphasize that the strength of quantum correlation is affected by several factors, including laser power, single-photon coupling strength, and the refractive index of the mirror layers. Notably, all forms of correlations diminished with increasing temperature. These results underline the potential of the proposed system for advancing continuous-variable quantum information processing, offering versatile platforms for studying and harnessing quantum correlations in practical applications.

Jin‐Shi Xu, Chuan‐Feng Li, Guang‐Can Guo

Tao Shang, Ran Liu, Jianwei Liu +1 more

Establishing entanglement is an essential task of quantum communication technology. Beyond entanglement, quantum discord, as a measure of quantum correlation, is a necessary prerequisite to the success of entanglement distribution. To realize efficient quantum communication based on quantum discord, in this paper, we consider the practical advantages of continuous variables and propose a feasible continuous-variable quantum network coding scheme based on quantum discord. By means of entanglement distribution by separable states, it can achieve quantum entanglement distribution from sources to targets in a butterfly network. Compared with the representative discrete-variable quantum network coding schemes, the proposed continuous-variable quantum network coding scheme has a higher probability of entanglement distribution and defends against eavesdropping and forgery attacks. Particularly, the deduced relationship indicates that the increase in entanglement is less than or equal to quantum discord.

Abderrahim El Allati, Salvador Robles-Pérez, M. El Baz