Single-phonon sensing with "click" detection using superconducting qubits

The single photon “click” detector (SPD) is an essential component in experimental quantum optics. Familiar SPD technologies rely on material properties that make them best suited for photonic platforms with energy scales at or above infrared frequencies. Microwave quantum platforms, including certain spin systems, superconducting qubits, and quantum acoustics, operate at lower energies and thus cannot benefit from direct integration with these detectors. We are implementing a single microwave photon detector (SMPD) based on dissipation engineering [1] that is coupled to a surface acoustic wave channel using flip-chip integration, thus aiming for a single microwave phonon detector. The detector will use a parametric microwave-frequency pump tone to irreversibly convert an incoming phonon into an excitation of a superconducting qubit, which can be measured using dispersive readout. We have characterized our device first as a photon detector and find a detection efficiency of 68.7% and a dark count rate of 5.10 ms^-1. Development of a detector coupled to an acoustic channel is in progress. We aim to utilize this device as a building block for experiments in linear mechanical quantum computing [2], for solid-state based quantum sensing of massive particles, and for other condensed matter applications.

[1] L. Balembois et al., Phys. Rev. Applied (2024)

[2] H. Qiao et al., Science (2023)