Cryogenic on-chip microwave filter for quantum devices

A method comprising:

• forming a substrate, the substrate being formed of a first material that exhibits at least a threshold level of thermal conductivity, wherein the threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum computing circuit operates;
• and
• forming an on-chip microwave filter on the substrate by assembling a circuit having two ports, the circuit comprising:
• a dispersive component to filter a plurality of frequencies in an input signal, the dispersive component comprising:
• a first transmission line deposited on the substrate and configured to receive a signal from a first fridge stage in a series of fridge stages, the first transmission line being formed of a second material that exhibits at least a second threshold level of thermal conductivity, wherein the second threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum computing circuit operates, and wherein a filtered frequency in the plurality of frequencies is a function of a width of the first transmission line, and
• a second transmission line disposed on the substrate and configured to receive a reflected signal from a second fridge stage in the series of fridge stages, the second transmission line being formed of the second material.

A fabrication system performing operations comprising:

• forming a substrate, the substrate being formed of a first material that exhibits at least a threshold level of thermal conductivity, wherein the threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum computing circuit operates;
• and
• forming an on-chip microwave filter on the substrate by assembling a circuit having two ports, the circuit comprising:
• a dispersive component to filter a plurality of frequencies in an input signal, the dispersive component comprising:
• a first transmission line deposited on the substrate and configured to receive a signal from a first fridge stage in a series of fridge stages, the first transmission line being formed of a second material that exhibits at least a second threshold level of thermal conductivity, wherein the second threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum computing circuit operates, and wherein a filtered frequency in the plurality of frequencies is a function of a width of the first transmission line, and
• a second transmission line disposed on the substrate and configured to receive a reflected signal from a second fridge stage in the series of fridge stages, the second transmission line being formed of the second material.