Raman adiabatic transfer of optical states

Electromagnetically induced transparency (EIT) is a quantum interference effect occurring when a weak signal light field and a stronger control field interact in atomic ensembles with a lambda-shaped energy level configuration. This effect attracts great interest due to its possible applications in non-linear optics and quantum information processing. The range of possible applications of EIT extends further in lambda-systems with multiple excited levels. In this work, we show experimentally that by an adiabatic change of the control fields, a transfer of optical states between different signal modes can be implemented [1]. This procedure resembles stimulated Raman adiabatic passage (STIRAP) but applies to optical rather than atomic states. It can be useful for routing and distribution of optically encoded information in classical and quantum communication. The experiments were performed using the hyperfine levels of Rb 87 atoms at the D1 line. First, we placed a signal pulse (resonant to the F=1, F=1 transition) into the cell under EIT conditions created by a control laser (resonant to F=2, F=1). This laser is adiabatically switched off while another control laser (resonant to F=2, F=2) is switched on. The information carried by the state of the original signal pulse is transferred to the optical mode resonant with the F=1, F=2 transition. Transfer efficiencies above 50 % have been achieved. While the experiment was conducted with classical light pulses, the implemented procedure can be extended to nonclassical light [1] and thus can be used for a variety of applications in quantum information processing. 1. J. Appel, K. P. Marzlin and A. I. Lvovsky. PRA 73, 013804 (2006) * This work is being supported by NSERC, CFI, AIF, CIAR