Two-photon blockade in quantum electrodynamics
Karl Nicolas Tolazzi, Christoph Hamsen, Tatjana Wilk, Gerhard Rempe · 2017
Summary form only given. Open driven quantum systems exhibit fluctuations during their walk through Hilbert space. These can be reduced by blocking parts of the Hilbert space. For discrete variables such as particle number a blockade can result from a sufficiently strong interaction between the involved quanta, for example, the effective interaction of photons in an optically nonlinear medium.We implemented the blockade in a strongly coupled cavity quantum electrodynamics system consisting of a single two-level atom strongly coupled to a high finesse optical resonator (see Fig. 1a). This combined system exhibits a new energy structure with an anharmonic ladder of dressed states that scales with ,/n (see Fig. 1b), where n is the number of excitations. Only this special structure provides a photon-number dependent nonlinearity which is necessary to address specific manifolds with the drive.