Techniques for implementing multiple microwave attenuators on a high thermal conductivity substrate for cryogenic applications to reduce heat and thermal noise during quantum computing are provided. In one embodiment, a device for using in cryogenic environment is provided that comprises a substrate having a thermal conductivity above a defined threshold, a plurality of transmission lines fabricated on the substrate and arranged with a separation gap between the plurality of transmission lines to maintain crosstalk below 50 decibels, and one or more microwave attenuators embedded on the plurality of transmission lines.

In an embodiment, a microwave circuit (circuit) includes an attenuator configured to attenuate a plurality of frequencies in a microwave signal. In an embodiment, the attenuator comprises a component of a first material, the first material exhibiting superconductivity in a cryogenic temperature range. In an embodiment, the circuit includes a magnet configured to generate a magnetic field at the attenuator, wherein the magnetic field is at least equal to a critical magnetic field strength of the first material. In an embodiment, the critical magnetic field strength causes the first material to become non-superconductive in the cryogenic temperature range.

A circuit includes: a first line (11) in which one end thereof (11a) is coupled to a first signal input terminal (la); a second line (12) in which one end thereof (12a) is grounded and the other end thereof (12b) is coupled to a first signal output terminal (4a), the second line (12) being electromagnetically coupled to the first line (11); a third line (13) in which one end thereof (13a) is open, the third line (13) being electromagnetically coupled to the second line (12); a fourth line (21) in which one end thereof (21a) is coupled to the other end (11b) of the first line (11) and the other end thereof (21b) is open; a fifth line (22) in which one end thereof (22a) is coupled to a second signal output terminal (4b) and the other end thereof (22b) is grounded, the fifth line (22) being electromagnetically coupled to the fourth line (21); and a sixth line (23) in which one end thereof (23a) is coupled to the other end (13b) of the third line (13) and the other end thereof (23b) is coupled to a second signal input terminal (1b), the sixth line (23) being electromagnetically coupled to the fifth line (22).

A frequency selective limiter (FSL) is provided having a transmission line structure with a tapered width. The FSL includes a magnetic material having first and second opposing surfaces. A first conductor is disposed on the first surface of the magnetic material, where a width of the first conductor decreases from a first end of the FSL to a second end of the FSL along a length of the FSL. Two second conductors are disposed on the second surface of the magnetic material, where a width of a gap between the two second conductors decreases from the first end of the FSL to the second end of the FSL along a length of the FSL. The first conductor and two second conductors form a biplanar waveguide transmission line.

An apparatus includes first and second electronically tunable transmission lines configured to transmit or receive a signal pair and provide a selected phase delay difference to the signal pair corresponding to a selected polarization, a first attenuation element connected to the first electronically tunable transmission line and a second attenuation element connected to the second electronically tunable transmission line. The first and second attenuation elements may each be configured to selectively attenuate signals carried on the electronically tunable transmission line to which they are connected according to a selected attenuation setting of a plurality of selectable attenuation settings provided by one or more attenuation control signals and thereby provide a selected attenuation to the signal pair that corresponds to the selected polarization. A corresponding method is also disclosed herein.

Techniques for facilitating reduced thermal resistance attenuator on high-thermal conductivity substrates for quantum applications are provided. A device can comprise a substrate that provides a thermal conductivity level that is more than a defined thermal conductivity level. The device can also comprise one or more grooved transmission lines formed in the substrate. The one or more grooved transmission lines can comprise a powder substance. Further, the device can comprise one or more copper heat sinks formed in the substrate. The one or more copper heat sinks can provide a ground connection. Further, the one or more copper heat sinks can be formed adjacent to the one or more grooved transmission lines.

A resistive component in a hybrid microwave attenuator circuit is configured to attenuate a plurality of frequencies in an input signal. The hybrid microwave attenuator circuit is further configured with a dispersive component to attenuate a second plurality of frequencies within a frequency range by reflecting off portions of the input signal at those frequencies that are within the frequency range. The resistive component and the dispersive component are arranged in a series configuration relative to one another in the hybrid microwave attenuator circuit.

In an embodiment, a microwave circuit (circuit) includes an attenuator configured to attenuate a plurality of frequencies in a microwave signal. In an embodiment, the attenuator comprises a component of a first material, the first material exhibiting superconductivity in a cryogenic temperature range. In an embodiment, the circuit includes a magnet configured to generate a magnetic field at the attenuator, wherein the magnetic field is at least equal to a critical magnetic field strength of the first material. In an embodiment, the critical magnetic field strength causes the first material to become non-superconductive in the cryogenic temperature range.

Techniques for facilitating reduced thermal resistance attenuator on high-thermal conductivity substrates for quantum applications are provided. A device can comprise a substrate that provides a thermal conductivity level that is more than a defined thermal conductivity level. The device can also comprise one or more grooved transmission lines formed in the substrate. The one or more grooved transmission lines can comprise a powder substance. Further, the device can comprise one or more copper heat sinks formed in the substrate. The one or more copper heat sinks can provide a ground connection. Further, the one or more copper heat sinks can be formed adjacent to the one or more grooved transmission lines.

A resistive component in a hybrid microwave attenuator circuit is configured to attenuate a plurality of frequencies in an input signal. The hybrid microwave attenuator circuit is further configured with a dispersive component to attenuate a second plurality of frequencies within a frequency range by reflecting off portions of the input signal at those frequencies that are within the frequency range. The resistive component and the dispersive component are arranged in a series configuration relative to one another in the hybrid microwave attenuator circuit.