Producing slow light in warm alkali vapor using electromagnetically induced transparency

Abstract

We present undergraduate-friendly instructions on how to produce light pulses propagating through warm Rubidium vapor with speeds less than 400 m/s, i.e., nearly a million times slower than c. We elucidate the role played by electromagnetically induced transparency (EIT) in producing slow light pulses and discuss how to achieve the required experimental conditions. The optical setup is presented, and details provided for preparation of pump, probe, and reference pulses of the required size, frequency, intensity, temporal width, and polarization purity. EIT-based slow light pulses provide the most widely studied architecture for creating quantum memories. Therefore, the basic concepts presented here are useful for physics and engineering majors who wish to get involved in the development of cutting-edge quantum technologies.

A practical guide to electromagnetically induced transparency in atomic vapor

“…Since then, this effect has been demonstrated in a wide variety of systems and has been considered for many applications. More detailed descriptions and experimental realizations of EIT-based slow light experiments in Rb vapor are discussed in [44][45][46]. Similarly, tuning to the bottom of the Raman absorption resonance can provide equally large but negative dispersion dn/dν p , making the group velocity exceed the speed of light or even reach negative values (the 'fast' or 'superluminal' regime) [47].…”

“…An optical layout showing some general features of an EIT setup, in the specific context of Zeeman EIT in 87 Rb, is depicted in figure 10(a) and briefly discussed below. For further experimental details, please refer to [46].…”

“…The vapor cell and solenoid are enclosed by a triple-layer of high-magnetic permeability alloy which shields the cell from unwanted external magnetic fields. Before taking any data, the shield must be demagnetized by a degaussing technique using coils wound around one or more of the shielding layers [46].…”

“…Another important decoherence mechanism that contributes to the ground-state decoherence rate is residual magnetic field inhomogeneity [31,46]. In the case of Zeeman EIT, for example, this causes spatial variation of the dark state leading to dephasing.…”

Magnetic splitting of electromagnetically induced transparency and absorption spectra in a standing-wave coupled lambda-type system

“…These effects include the EIT [1,2], EIA [3,4], EIG [5][6][7], Hanle effect [8], and many others. In the domain of research, EIT has been used to slow light [9] and stop light [10], to achieve lasing without inversion [11], to perform high resolution atomic spectroscopy [12], to perform all optical switching of laser beams [6] and to store pulses of laser light in thermal vapor of atoms [13], etc. On the applications side, EIT has grown to be used in the fields of vector magnetometry [14,15], quantum RF-sensing [16], laser frequency stabilization [17,18], as time standard [19,20] and in many more applications.…”