An attenuator module having a substrate; a attenuator disposed on one surface of the substrate, the attenuator having an input terminal at one end of the attenuator and an output terminal at an opposite end of the attenuator; an electrical conductor disposed on an opposite surface of the substrate; and an electrically conductive via passing from the output terminal through the substrate to the electrical conductor disposed on the opposite surface of the substrate.

An attenuator arranged to thermalize radio frequency components, or a dissipating element arranged to thermalize lower frequency components than the radio frequency components, comprising: at least a first heat sink and a second heat sink; and at least one tunnel junction coupled to the first heat sink and the second heat sink, wherein the first heat sink and the second heat sink are capacitively grounded and arranged to provide heat dissipation via electron-phonon coupling; and wherein a combined resistance of the at least one tunnel junction and a heat sink coupled to it is below

[00001]$\frac{h}{e^2},$ and/or a total capacitance of the first heat sink is above

[00002]$\frac{e^2}{2k_{b}T}$ and a total capacitance of the second heat sink is above

[00003]$\frac{e^2}{2k_{b}T},$ wherein h is the Planck constant, e is the elementary charge, k.sub.b is the Boltzmann constant and T is the minimum temperature, where the attenuator or the dissipating element is arranged to be used.

A device includes a thermally conductive and electrically insulative substrate having a first major surface and a second major surface. A coupling structure is configured to reduce the RF input signal by substantially a predetermined amount of attenuation power. A tuning circuit is characterized by a tuning reactance substantially matched to a predetermined system impedance. A resistor is disposed on a majority of the first major surface and is characterized by a parasitic capacitance that is substantially negated by the tuning reactance. The resistor includes a first resistive portion and a second resistive portion; each of the first resistive portion and the second resistive portion being configured to direct approximately one-half of the attenuation power to the ground portion.

A laminated circuit assembly for filtering signals in one or more signal lines in, for instance, a quantum computing system is provided. In one example, the laminated circuit assembly includes one or more signal lines disposed within a substrate in a first direction. The laminated circuit assembly includes a dielectric portion of the substrate. The laminated circuit assembly includes a filter portion of the substrate extending in a first direction and containing a frequency absorbent material providing less attenuation to a first signal of a first frequency than to a second signal of a second, higher frequency. The filter portion is configured to attenuate infrared signals passing through the one or more signal lines.

A computing cable that connects computing elements, including: a trace including a first trace segment and a second trace segment, the trace having a first impedance; and an attenuator connecting the first trace segment to the second trace segment, the attenuator including: a resistor having a resistance, and a conductor having a second impedance, wherein the combination of the resistance and the second impedance is based on the first impedance.

An interface between cryogenic computational hardware and room temperature computational hardware includes a plurality of discrete stages, including a first stage at room temperature and a last stage at a cryogenic temperature. Each successive stage is configured for operation at a corresponding refrigeration temperature that is lower than the refrigeration temperature of each preceding stage and includes a set of planar transmission lines. The transmission lines of any given stage other than the first stage are proximally coupled to and contiguous with the transmission lines of an immediately preceding stage. The transmission lines of the first stage are proximally coupled to the room temperature computational hardware, and the transmission lines of the last stage are proximally coupled to the cryogenic computational hardware. Each stage has shielding configured to block electromagnetic radiation external to such stage.