Generation of entangled states of two atoms inside a leaky cavity

Abstract

An in-depth theoretical study is carried out to examine the quasi-deterministic entanglement of two atoms inside a leaky cavity. Two Λ-type three-level atoms, initially in their ground states, may become maximally entangled through the interaction with a single photon. By working out an exact analytic solution, we show that the probability of success depends crucially on the spectral function of the injected photon. With a cavity photon, one can generate a maximally entangled state with a certain probability that is always less than 50%. However, for an injected photon with a narrower spectral width, this probability can be significantly increased. In particular, we discover situations in which entanglement can be achieved in a single trial with an almost unit probability.

Efficiency of a feedback process in cavity quantum electrodynamics

“…The atoms become maximally entangled if the emitted photon is right-circularly polarized, or otherwise remain intact. The probability of success of the entangling process is shown to approach unity if the input photon is quasi-monochromatic [21]. It is worthwhile to remark that other fundamental processes in quantum computing like quantum state-swapping and controlled phase-flip gates can also be achieved with high success rates via CQED interaction between atoms and such quasi-monochromatic single photons [26,27].…”

“…Being a well-studied topic in quantum optics, cavity quantum electrodynamics (CQED) provides a full arsenal of techniques to generate entangled atom pairs [18][19][20][21][22] and also entangled photon pairs [23,24]. In particular, previous studies have shown that cavity loss as well as environmental noise can help to generate entanglement and increase the success rate [19,21,22,25]. However, most of these schemes referred above are probabilistic.…”

“…Therefore, it presents a challenging task for researchers in this field to work out a deterministic entangling scheme. With this end in view, an appealing scheme to generate a maximally entangled state of two atoms inside a leaky cavity in a 'quasi-deterministic' manner has been proposed [21]. Two -type three-level atoms, situated inside a leaky optical cavity and initially prepared in the ground state |L , interact with a single left-circularly polarized input photon.…”

“…Needless to say, the feasibility of the scheme proposed in [21] hinges on the availability of quasi-monochromatic single photon sources, which is an issue of current interest in its own right. On the other hand, it is also possible to repeatedly redirect the emitted photon into the cavity till it becomes right-circularly polarized.…”

“…However, the quantum states of the incident and emitted photons are not properly considered. To provide a correct description for the incident and emitted photons, in the present paper we study the same problem using continuous frequency modes [29][30][31][32] and describe the quantum states of photons in terms of their spectral functions [21]. In the continuous frequency mode approach [29][30][31][32], the incident (emitted) photon is described by a spectral function f in (k) (f out (k)), with k being the wave number.…”