Periodically Pulsed Quantum Light from a Superconducting Qubit Ensemble

Nonclassical light sources are extremely important in the fields of quantum information, quantum communication, and photonic quantum technologies. We study a driven inhomogeneous ensemble of superconducting qubits coupled to a microwave resonator. The constructive rephasing of spins in the frequency comb is predicted to result in a periodic pulse train of quantum light (g₂(t,0)<1) which corresponds to the collective transfer of excitations from the qubit ensemble to the resonator [1]. Such periodic nonclassical pulses are interesting for a temporal synchronization in quantum memory protocols. We will present results of our ongoing experiments on periodic quantum light generation in the system of five transmon qubits capacitively coupled to a coplanar waveguide resonator.

[1] Himadri Shekhar Dhar, Matthias Zens, Dmitry O. Krimer, and Stefan Rotter. Variational renormalization group for dissipative spin-cavity systems: Periodic pulses of nonclassical photons from mesoscopic spin ensembles. Phys. Rev. Lett., 121:133601, Sep 2018.