Deterministic reset of superconducting qubit and cavity modes with a microwave photon counter
The disclosed technology is directed to systems and methods for deterministic reset of superconducting qubit and cavity modes with a microwave photon counter. The system comprises a multiplicity of qubit-microwave photon counter pairs coupled by a qubit-qubit coupling. Each of the qubit-microwave photon counter pairs comprise a qubit circuit, a microwave photon counter circuit, and a resonant cavity coupling the qubit circuit and the microwave photon counter circuit.
1. A system for quantum information processing, the system comprising a multiplicity of qubit-microwave photon counter pairs coupled by a qubit-qubit coupling, each of the qubit-microwave photon counter pairs comprising:
a qubit circuit,
a microwave photon counter circuit, and
a resonant cavity coupling the qubit circuit and the microwave photon counter circuit,
wherein the coupling of the qubit circuit and resonant cavity is configured to yield distinct frequencies corresponding to a bright cavity pointer state and a dark cavity pointer state characterized by differential photon occupation,
wherein the system is configured to displace a photon field inside the resonant cavity in a qubit state-dependent manner when a microwave drive frequency is applied, and
wherein the microwave photon counter circuit is a threshold detector of microwave photon occupation of the resonator cavity.
2. The system of claim 1 further comprising a controller configured to frequency tune the microwave photon counter circuit into or out of resonance with the qubit circuit or the resonant cavity.
3. The system of claim 2 , wherein the controller is configured to frequency tune the microwave photon counter circuit and qubit circuit into simultaneous resonance with the resonant cavity.
4. The system of claim 1 , wherein the microwave photon counter circuit is configured to yield a double-well potential energy landscape.
5. The system of claim 1 further comprising a controller configured to provide the microwave drive frequency to prepare cavity pointer states.
6. The system of claim 1 , wherein the multiplicity of qubits of each qubit-microwave photon counter pair are coupled on a single chip.
7. The system of claim 1 , wherein the microwave photon counter circuit is a Josephson photomultiplier (JPM) circuit.
8. The system of claim 1 , wherein the qubit circuit is a frequency-tunable transmon qubit circuit.
9. The system of claim 1 , wherein the resonant cavity is a half-wave coplanar waveguide (CPW).