The technology described herein is directed towards a cryogenic-stripline microwave attenuator. A first high thermal conductivity substrate such as sapphire and a second high thermal conductivity substrate such as sapphire, along with a signal conductor comprising one or more attenuator lines between the substrates form a stripline. A compression component such as one or more screws, vias (plus clamps) and/or clamps presses the first high thermal conductivity substrate against one side of the signal conductor and presses the second high thermal conductivity substrate against another side of the signal conductor. The high thermal conductivity of the substrates facilitates improved thermalization, while the pressing of the substrates against the conductor reduces the thermal boundary (Kapitza) resistance and thereby, for example, improves thermalization and reduces thermal noise.

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.

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.

A variable attenuator is an attenuator which is formed by coupling two transmission lines having an electrical length of /4 corresponding to a wavelength of an input signal, has one end of one transmission line as an input terminal, has the other end of the one transmission line as a through terminal, has one end of the other transmission line as a coupling terminal and has the other end of the other transmission line as an output terminal, wherein the variable attenuator has a resistor pair having the same impedance at both the through terminal and the coupling terminal, and has a resistor pair having the same impedance at both the input terminal and the output terminal.

One or more systems, devices, and/or methods of use provided herein relate to signal filters for scalable quantum computing architectures. According to one embodiment, a device can comprise a circuit board comprising a plurality of layers, wherein various ones of the plurality of layers comprises a different absorptive material, and a plurality of signal lines that pass through the circuit board, wherein a first layer of the circuit board is comprised of a first material that filters a first signal line that traverses through at least the first layer of the plurality of layers.

Techniques related to microwave attenuator son 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 thin film lines, on a top surface of the substrate, comprising an evaporated alloy. Further, the device can comprise one or more vias within the substrate. Respective first ends of the one or more vias are can be connected to respective thin film connectors. Further, respective second ends of the one or more vias can be connected to an electrical ground.

Designs and methodologies related to attenuators having a thin-film resistor assembly are disclosed. In some embodiments, the thin-film assembly can include a first and second thin-film resistor, each having a main portion with an input end and an output end. The input end of the first thin-film resistor is interconnected to the input end of the second thin-film resistors, and the output end of the first thin-film resistor is interconnected to the output end of the second thin-film resistor. The first and second thin-film resistors are disposed relative to one another so as to define a separation. The separation region reduces the likelihood of hot spot regions forming at or near the center of the thin-film structure and improves power handling capability for a given resistor width. Also disclosed are examples of how the foregoing features can be implemented in different products and methods of fabrication.

There is provided a cable tap device comprising a microstrip directional coupler having a first input port, a first output port, an isolation port and a first coupling port and a ferrite directional coupler having a second input port, a second output port and a second coupling port, wherein the microstrip directional coupler and the ferrite directional coupler are connected together to form a tap unit such that the first output port is connected to the second input port, the isolation port is connected to the second coupling port and the first coupling port connects to one or more tap ports. Capacitive elements can be associated with both types of directional coupler to prevent passage of low frequency signals through the directional couplers. Inductive elements to prevent passage of high frequency signals through the directional couplers.

The technology described herein is directed towards a cryogenic-stripline microwave attenuator. A first high thermal conductivity substrate such as sapphire and a second high thermal conductivity substrate such as sapphire, along with a signal conductor comprising one or more attenuator lines between the substrates form a stripline. A compression component such as one or more screws, vias (plus clamps) and/or clamps presses the first high thermal conductivity substrate against one side of the signal conductor and presses the second high thermal conductivity substrate against another side of the signal conductor. The high thermal conductivity of the substrates facilitates improved thermalization, while the pressing of the substrates against the conductor reduces the thermal boundary (Kapitza) resistance and thereby, for example, improves thermalization and reduces thermal noise.

Systems and techniques that facilitate high-density embedded broadside-coupled attenuators are provided. In various embodiments, an attenuator can comprise an output line. In various aspects, the attenuator can further comprise a reflectively-terminated input line that is broadside coupled to the output line. In various instances, a downstream end of the reflectively-terminated input line can be shorted to ground. In other instances, a downstream end of the reflectively-terminated input line can be open from ground. In various cases, the output line can exhibit a non-looped-back-layout.