Quantum repeater protocol in mixed single- and two-mode Tavis-Cummings models

Abstract

In this paper we study the production of entanglement between two atoms which are far from each other. We consider a system including eight two-level atoms (1, 2, • • • , 8) such that any atom with its adjacent atom is in atomic Bell state, so that we have four separate pairs of maximally entangled states (i, i + 1) where i = 1, 3, 5, 7. Our purpose is to produce entanglement between the atomic pair (1, 8), while these two distant atoms have no interaction. By performing the interaction between adjacent nonentangled atomic pairs (2, 3) as well as (6, 7), each pair with a two-mode quantized field, the entanglement is produced between atoms (1, 4) and (5, 8), respectively. Finally, by applying an appropriate Bell state measurement (BSM) on atoms (4, 5) or performing an interaction between them with a single-mode field (quantum electrodynamic: QED method), the qubit pair (1, 8) becomes entangled and so the quantum repeater is successfully achieved. This swapped entanglement is then quantified via concurrence measure and the effects of coupling coefficients and detuning on the concurrence and success probability are numerically investigated. The maxima of concurrence and success probability and the corresponding time periods have been decreased by increasing the detuning in asymmetric condition in BSM method. Also, the effects of detuning, initial interaction time and coupling coefficient on the produced entanglement by QED method are considered. Increasing (decreasing) of the detuning (interaction time) has destructive effect on the swapped entanglement in asymmetric condition.

Quantum repeater protocol using an arrangement of QED–optomechanical hybrid systems

“…Using the effective Hamiltonian (24), the time-dependent Schrödinger equation 17), ( 22), these states are set aside), the entangled state of atoms (1,4,5,8) is achieved as…”

“…Heralded quantum repeater based on quantum dots has been investigated in [7]. Recently, we have considered the quantum repeater based on atoms where the entanglement has been swapped between atoms via performing interaction in the optical cavities [?, [8][9][10]. Quantum repeater is very useful in quantum internet issue [11].…”

“…As a result, the optomechanical systems can provide macroscopic systems by which one can find some quantum mechanical phenomena inherent in their structural mechanisms. Quantum repeater protocols have been considered in the presence of optical cavities in the previous literature [2,[8][9][10][58][59][60], moreover, the main feature of our present work is to extend, even partially, a particular quantum information protocol, in this case, the quantum repeaters, to the macroscopic quantum systems instead of microscopic quantum systems. In the present paper we want to consider the quantum repeater based on threelevel V-type atomic states, in which entanglement can be transferred to two distant atoms.…”

“…and modes (a 1 , a 2 ; b 1 , b 2 ). Finally, by applying the projection operators which are performed with the states |0; 0 ⊗ | 3; 1 , |0; 0 ⊗ | 1; 3 and |1; 1 ⊗ | 3; 3 related to the state of field modes (a 1 ; b 1 ) and the state of atomic pair (6; 7) on entangled state (5) related to atoms(5,6,7,8), the following entangled states are respectively achieved for atoms(5,8) …”

Teleportation of squeezed states in the absence and presence of dissipation

“…In this respect, the quantum channel which is used for teleportation purpose should be entangled. These channels can be produced by using the beam splitter [3], entanglement swapping process [4][5][6] and performing appropriate interaction performance [7][8][9][10][11]. After preparation of proper quantum channel, quantum teleportation can be implemented.…”