Quantum-discord-triggered superradiance and subradiance in a system of two separated atoms

• Published in: Quantum information processing Vol. 14; no. 8; pp. 2883 - 2894
• Main Authors: Tang, Shi-Qing, Yuan, Ji-Bing, Kuang, Le-Man, Wang, Xin-Wen
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2015
• Subjects: Data Structures and Information Theory; Mathematical Physics; Physics; Physics and Astronomy; Quantum Computing; Quantum Information Technology; Quantum Physics; Spintronics; Quantum statistical properties; Quantum discord; Subradiance; Superradiance
• ISSN: 1570-0755; 1573-1332
• DOI: 10.1007/s11128-015-1026-9

We investigate collective radiant properties of two separated atoms in X-type quantum states. We show that quantum correlations measured by quantum discord (QD) can trigger and enhance superradiance and subradiance in the two-atom system even though in the absence of interatomic quantum entanglement. We also explore quantum statistical properties of photons in the superradiance and subradiance by addressing the second-order correlation function. In particular, when the initial state of the two separated atoms is the Werner state with nonzero QD, we find that radiation photons in the superradiant region exhibit the nonclassical sub-Poissonian statistics and the degree of the sub-Poissonian statistics increases with increasing of the QD amount, while radiation photons in the subradiant region have either the sub-Poissonian or super-Poissonian statistics depending on the amount of QD and the directional angle. In the subradiant regime, we predict the QD-triggered photon statistics transition from the super-Poissonian to sub-Poissonian statistics. These results shed a new light on applications of QD as a quantum resource.