Deterministic reset of superconducting qubit and cavity modes with a microwave photon counter
AssigneeWisconsin Alumni Research Foundation
InventorsRobert Francis McDermott, III, Alexander M. Opremcak
Life of this patent
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Abstract
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.
Claims20
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) a qubit circuit,
- (b) a microwave photon counter circuit, and
- (c) 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.
A method for microwave photon counter-assisted resonator reset or microwave photon counter-assisted qubit reset, the method comprising frequency tuning a qubit-microwave photon counter pair, the qubit-microwave photon counter pair comprising:
- (a) a qubit circuit,
- (b) a microwave photon counter circuit, and
- (c) a resonant cavity coupling the qubit circuit and the microwave photon counter circuit,
- wherein the qubit-microwave photon counter pair is coupled to at least one other qubit-microwave photon counter pair by a qubit-qubit coupling and
- wherein the microwave photon counter circuit is frequency tuned into resonance with the qubit circuit or the resonant cavity.
A method for quantum information processing or for a quantum computation, the method comprising:
- (a) preparing a qubit cavity pointer state by applying a microwave drive frequency for a resonator drive time with a controller configured to provide the microwave drive frequency, wherein coupling of a qubit circuit and a 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;
- (b) frequency tuning a microwave photon counter circuit, the microwave photon counter circuit configured to yield a double-well potential energy landscape, coupled to the resonant cavity into resonance with the resonant cavity for a photodetection time, thereby inducing an intrawell excitation of a phase particle conditioned on the qubit cavity pointer state;
- (c) frequency tuning the microwave photon counter circuit at a tunneling flux for a tunneling time, thereby allowing interwell tunneling of the phase particle;
- (d) frequency tuning the microwave photon counter at a relaxation flux for a relaxation time, thereby allowing for relaxation of a tunneled phase particle;
- (e) determining the flux state of the microwave photon counter circuit;
- and
- (f) resetting the resonant cavity or the qubit circuit.
Dependencies are inferred from the claim text.