Single microwave photon switch controlled by an external electrostatic field

We design a single microwave photon switch through a one-dimensional waveguide coupled with a side Jaynes-Cummings system, namely, a single-mode cavity with an embedded Rydberg atom Rb87. Since the energy spectra of the Rb87 atom depend on the electrostatic field, the Rb87 atom can couple with the cavity in tune and out of tune, corresponding to the switch on and off states, respectively. The influences of the single photon pulse width, cavity dissipation, and Rabi coupling on the on/off ratio are studied in detail by a non-Hermitian Hamiltonian. We find that the on/off ratio can be larger than 100 in a wide parameter space and the decay time and rise time are both about 0.75 ns. Within the master equation of the density matrix we also demonstrate that the on/off ratio can be reduced by the quantum noise but is still large enough for application. The transition energy of the two-level Rydberg atom Rb87 gives the switch operating frequency which is in the range of microwave regime. Accordingly, the switch is viable in practice and has potential in quantum informatics.