Terahertz sensing and imaging using Rydberg atoms

We demonstrate sensing and imaging of terahertz (THz) fields using Rydberg atoms in a thermal vapour. Rydberg atoms have a large manifold of strong electric dipole transitions spanning the microwave and THz frequency range; a fact that has been exploited to enable highly-sensitive electric field measurements [1]. We show that by using off-resonant excitation in a Raman configuration we can achieve real-time imaging of THz fields [2]. Figure 1 shows a sequence of frames from a video of a THz standing wave. In addition, we exploit a Rydberg phase transition [3] to configure the atomic vapour as a sensitive transition-edge sensor for THz radiation [4].