Quantum Entanglement in Two Mode Bose-Einstein Condensate

Citlali Pérez Campos, José Raúl González Alonso, Octavio Castaños +1 more

S. K. Giri

Ultracold atoms in the atomic Bose-Einstein condensate (ABEC) state can form molecular Bose-Einstein condensate (MBEC) through photoassociation.In the atom-molecule Bose-Einstein condensates (BECs), two or more atoms in the ABEC can combine to form a molecule in the MBEC and again a molecule from a MBEC can decompose to atoms in the ABEC.The Bose-stimulated Raman adiabatic passage is an efficient mechanism for conversion of an atomic BEC to a molecular BEC.A three-mode atom-molecule Bose-Einstein condensates system can be prepared through the photoassociative Bose-stimulated Raman adiabatic passage.In our system, three modes are one ABEC, one excited MBEC, and one stable MBEC.The intramodal interactions due to the  (3) nonlinearity is present in all three BEC modes along with ABEC-excited MBEC and excited MBEC-stable MBEC intermodal couplings.The quantum mechanical Hamiltonian of the system is constructed considering all three intraspecies interactions and intermodal couplings among the modes.The Hamiltonian of the system is solved analytically using a special intuitive approach which is more general and gives more accurate result than the well-known short time approximation method.The correctness of the solution is verified through the equal time commutation relation.Staring from a three-mode composite coherent state we compute the time evolution of the field annihilation operators of all three modes in presence of all possible interactions and couplings.Using these solutions, we investigate the quantum entanglement properties of the system for all three two-mode combinations.Entanglement is found for two combinations of modes, where as one combination is always separable.Also, we study the dependence of the entanglement properties of the system with the interaction and coupling constants.

Diyou Jiang

Cheng Rong, Liang Jiu-Qing

This paper obtains the energy-spectrum and eigenstate corrections of two-mode Bose–Einstein condensates (BECs) coupled by quantum tunnelling by perturbation method in both strong and weak tunnelling regions. The population imbalance between two BECs are then studied in terms of the low-lying eigenstates which also characterize the intrinsic entanglement between the two-mode BECs. The strong parity effect in the weak tunnelling region is also investigated.

Sun Chang-yong

The entanglement in the system which consists of two-mode squeezed vacuum state and Bose- Einstein condensate in two-photon process is investigated.The entanglement of field-atom and the entangle- ment between the two-mode field are investigated using the quantum reduced entropy and quantum relative entropy,respectively.The influences of the initial squeezed parameter of field and the interaction between atoms on the evolution of the entanglement of field-atom and one of two modes of field are discussed.

Jérôme Estève, C. Gross, A. Weller +2 more