Cryogenic hardware based phase control with classical monitoring of phase noise errors in quantum circuits

A method, comprising:

• controlling, by a system comprising at least one processor, a photon source to output a first microwave signal to interact with a quantum bit (qubit);
• controlling, by the system, a phase shifter between the photon source and the qubit to apply a first phase shift to the first microwave signal prior to interaction with the qubit;
• monitoring, by the system, state information of the qubit following interaction with the first microwave signal;
• controlling, by the system, the photon source to output a second microwave signal to interact with the qubit;
• determining, by the system, a second phase shift based on the state information;
• and
• controlling, by the system, the phase shifter to apply the second phase shift to the second microwave signal prior to interaction with the qubit.

A system, comprising:

• a computing device;
• a microwave photon source coupled to the computing device;
• a cryogenic phase shifter coupled to the computing device, coupled to the microwave photon source, and coupled to a quantum bit (qubit);
• and
• a detection device coupled to the qubit, and coupled to the computing device,
• wherein the computing device is configured to:
• control the microwave photon source to generate a microwave signal that is obtained by the cryogenic phase shifter,
• determine a controlled phase shift to be applied to the microwave signal,
• control the cryogenic phase shifter to apply the controlled phase shift to the microwave signal, resulting in output of a phase-shifted instance of the microwave signal for interaction with the qubit, and
• obtain information from the detection device, the information associated with a state of the qubit following interaction with the phase-shifted instance of the microwave signal.