Fast and Efficient All-Microwave Reset of a Transmon-Qutrit Coupled to a Large Bandwidth Resonator

Fast and efficient reset of qubits is a key operation in many quantum algorithms, and particularly in error correction codes. We experimentally demonstrate a reset scheme of a qutrit coupled to a low Q resonator. The reset protocol uses the microwave induced interaction between the |f,0〉 and |g,1〉 states of the system, with |g〉 and |f〉 denoting the ground and second excited state of the qutrit, and |0〉 and |1〉 the photon Fock states of the resonator. We characterize the reset process and demonstrate reinitialization of the transmon-resonator system to its ground state with 99.8% fidelity in less than 500 ns. Our protocol is of practical interest as it has no requirements on the chip design, in addition to those for fast and efficient single-shot readout of the transmon [1], and does not require any feedback for initialization.
[1] T. Walter et al., Phys. Rev. Applied 7, 054020