Simultaneous control of two four-wave-mixing fields via atomic spin coherence

Abstract

We report the experimental observation of simultaneous control of two four-wave-mixing fields via an induced atomic spin coherence formed by a Raman process with one coupling field and one probe field in a triple--type 85 Rb atomic system. It is shown that by changing the atomic density, intensity, or detuning of the coupling field, the relative intensities of the two four-wave-mixing fields can be manipulated. This behavior can be explained as the change in the spin coherence for varying the coupling field intensity and the large difference in the attenuation coefficients of the two produced four-wave-mixing fields for varying the atomic density. This controlling process may find applications in coherent control of nonlinear optical processes and quantum information processing.

Generation of correlated and anticorrelated multiple fields via atomic spin coherence

“…The experimental setup is similar to our previous one used to generate two controllable FWM fields [15]. The three input laser beams are carefully aligned spatially on the three corners of a square-box pattern as indicated in Fig.…”

Generation of multipartite continuous-variable entanglement via atomic spin wave

“…As previously shown [13,14] also one probe (coupling) photon and one mixing photon are absorbed and one coupling (probe) photon and one anti-Stokes E 4 (Stokes E 3 ) photon are emitted. In fact, the above simultaneously generated four FWM fields can be equivalently viewed as scattering the coupling, probe, and mixing fields off the atomic spin wave (S) pre-established by the strong (on-resonant) coupling and probe fields in the -type EIT configuration formed by levels 1 , 2 , and 3 , where the induced spin wave acts as a frequency converter with frequency equal to the separation between the two lower states [15].…”

“…[13], in this EIT-based configuration, the atomic spin wave, which mixes with the scattering fields to generate multipartite entanglements, plays a role similar to the polarizing beam splitter used in the traditional way; however, there is a critical difference, that is, the polarizing beam splitter is a linear element, and the atomic medium acts as a nonlinear element for the FWM. Third, by using the experimental setup with a square-box pattern for the laser beams and with different beam polarizations [13], the produced FWM signals can be spatially separated conveniently. Moreover, this configuration with laser beams propagating through the atomic medium in the same direction with small angles among them can benefit from the cancellation of first-order Doppler broadening in the multi--type system.…”

“…In this Letter, we propose a convenient and flexible way to create multicolor multipartite CV entanglements via an atomic spin wave established by the strong on-resonant coupling and probe fields in the -type EIT configuration, motivated by our experimental observation of generating classical multi-field correlations and anti-correlations via atomic spin coherence in 85 Rb atomic system [13]. Multiple entangled Stokes and anti-Stokes fields, simultaneously produced through scattering the applied laser fields off the atomic spin wave, can be obtained by using an atomic ensemble.…”

“…1a, is based on our experimental configuration used in Ref. [13], where the relevant energy levels and the applied/generated laser fields form a quintuple--type system. are relatively strong and tuned to resonance with the transitions 1 -3 and 2 -3 , respectively.…”