Quantum and optical technology

Abstract:

We experimentally demonstrate a communication protocol that enables frequency conversion and routing of quantum information in an adiabatic and thus robust way. The protocol is based on electromagnetically induced transparency (EIT) in systems with multiple excited levels: transfer and/or distribution of optical states between different signal modes is implemented by adiabatically changing the control fields. The proof-of-principle experiment is performed using the hyperfine levels of the rubidium D1 line.

Abstract:

We demonstrate the preparation and probing of the coherence between the hyperfine ground states |S(1/2),F=1> and |5S(1/2),F=2> of the Rb87 isotope. The effects of various coherence control techniques, i.e., fractional stimulated Raman adiabatic passage and coherent population return, on the coherence are investigated. These techniques are implemented using nearly degenerate pump and Stokes lasers at 795 nm (Rb D1 transition), which couple the two hyperfine ground states via the excited state |5P(1/2),F=1> through a resonant two-photon process in which a coherent superposition of the two hyperfine ground states is established. The medium is probed by an additional weak laser, which generates a four-wave mixing signal proportional to the ground state coherence and allows us to monitor its evolution in time. The experimental data are compared with numerical simulations.