Cryogenic thermometer based on a two-level systems (TLS)

An apparatus configured to measure a temperature of a target device that resides in a cryogenic environment and that comprises resonators that indicate qubit states, the apparatus comprising:

• transceiver circuitry configured to
• send a probe signal through the target device;
• a lumped-element resonator device configured to:
• interact with the probe signal;
• and
• modulate a phase and an amplitude of the probe signal, wherein the lumped-element resonator device is proximate to a surface of the target device;
• and
• processing circuitry configured to:
• read the probe signal transmitted through the target device;
• responsively measure a resonance frequency of the lumped-element resonator device;
• and
• determine the temperature of the target device by correlating the resonance frequency of the lumped-element resonator device with the temperature of the target device.

An apparatus configured to measure a temperature of a qubit resonator device that resides in a cryogenic environment, the apparatus comprising:

• transceiver circuitry configured to
• send a probe signal through the qubit resonator device;
• the qubit resonator device being configured to:
• interact with the probe signal;
• and
• modulate a phase and an amplitude of the transmitted probe signal,
• wherein the qubit resonator device comprises one or more qubit resonators and a temperature resonator that resonates at a different frequency than the one or more qubit resonators;
• and
• processing circuitry configured to:
• read the probe signal through the qubit resonator device;
• measure a resonance frequency of the temperature resonator;
• and
• responsively determine the temperature of the qubit resonator device by correlating the resonance frequency of the temperature resonator with the temperature of the qubit resonator device.