Quantum computing and condensed matter physics with microwave photons

Broadband Filters for Abatement of Spontaneous Emission in Circuit Quantum Electrodynamics

Nicholas T. Bronn, Yanbing Liu, Jared B. Hertzberg, Antonio D. C ́orcoles, Andrew A. Houck, Jay M. Gambetta, and Jerry M. Chow

 

The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous emission. Here we use impedance engineering to design a filter by which photons may easily leave the resonator at the cavity frequency but not at the qubit frequency. We implement this broadband filter in both an on-chip and off-chip configuration.