Quantum Entanglement in a two-atom two photon system

Jin Li-Juan, Mao-Fa Fang

We investigate the entanglement in a system of two coupling atoms interacting with a single-mode field by means of quantum information entropy theory. The quantum entanglement between the two atoms and the coherent field is discussed by using the quantum reduced entropy, and the entanglement between the two coupling atoms is also investigated by using the quantum relative entropy. In addition, the influences of the atomic dipole–dipole interaction intensity and the average photon number of the coherent field on the degree of the entanglement is examined. The results show that the evolution of the degree of entanglement between the two atoms and the field is just opposite to that of the degree of entanglement between the two atoms. And the properties of the quantum entanglement in the system rely on the atomic dipole–dipole interaction and the average photon number of the coherent field.

Yoon-Ho Kim

Joerg Bochmann, B. Weber, Holger Specht +6 more

Xiaojuan Liu, Bingju Zhou, Liu Ming-Wei +1 more

We investigate the preparation and the control of entangled states in a system with the two-mode coherent fields interacting with a moving two-level atom via the two-photon transition. We discuss entanglement properties between the two-mode coherent fields and a moving two-level atom by using the quantum reduced entropy, and those between the two-mode coherent fields by using the quantum relative entropy. In addition, we examine the influences of the atomic motion and field-mode structure parameter p on the quantum entanglement of the system. Our results show that the period and the duration of the prepared maximal atom-field entangled states and the frequency of maximal two-mode field entangled states can be controlled, and that a sustained entangled state of the two-mode field, which is independent of atomic motion and the evolution time, can be obtained, by choosing appropriately the parameters of atomic motion, field-mode structure, initial state and interaction time of the system.

Zeinab Kordi, Saeed Ghanbari, Mohammad Mahmoudi

Jin-Song 劲松 Huang 黄, Hong-Wu 红武 Huang 黄, Yan-Ling 艳玲 Li 李 +1 more

We theoretically investigate coherent scattering of single photons and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system. Using the real-space Hamiltonian, analytical expressions are derived for the transport spectra scattered by these two giant atoms with four azimuthal angles. Fano-like resonance can be exhibited in the scattering spectra by adjusting the azimuthal angle difference. High concurrence of the entangled state for two atoms can be implemented in a wide angle-difference range, and the entanglement of the atomic states can be switched on/off by modulating the additional azimuthal angle differences from the giant atoms. This suggests a novel handle to effectively control the single-photon scattering and quantum entanglement.