Surface Acoustic Wave Filters for Superconducting Qubits
In an open system, the dynamical evolution of a qubit state is non-deterministic due to stochastic noise, leading to qubit state decoherence. In the case of the dispersive circuit-QED qubit readout circuit, even when the readout resonator is far off-resonance, the qubit is still damped to some degree, causing decoherence. By using a Purcell filter, qubit loss may be reduced by several orders of magnitude.
In this work, we propose to use acoustic wave filters, well-established in the Telecommunications industry, as a Purcell filter. Using acoustic wave filters, like bulk acoustic wave (BAW) or surface acoustic wave (SAW), versus the current state-of-the-art Purcell filters would provide several advantages: higher isolation of the qubit to the readout frequencies as well as being quite miniaturized compared to usual filter alternatives.
In this work, we characterize a 1.5GHz LiNbO SAW resonator. The characterization is done maintaining qubit environmental conditions of single photon-level powers and millikelvin temperatures. We characterize its frequency and internal quality factor dependence on temperature and drive power.