Provided is a filter capable of suppressing variation in characteristics. A filter has: a plurality of resonators each having a via electrode and a first strip line that is opposed to a first shielding conductor and connected to one end of the via electrode; a first coupling capacitive electrode that has a first comb-shaped electrode including a plurality of first electrodes and that is provided to the first resonator; and a second coupling capacitive electrode that is provided to the second resonator, that has a second comb-shaped electrode including a plurality of second electrodes, and that is formed on the same layer as that of the first coupling capacitive electrode, wherein the first and second electrodes are arranged so as to be adjacent to each other.

An exemplary semiconductor technology implemented microwave filter includes a dielectric substrate with metal traces on one surface that function as frequency selective circuits and reference ground. Other metal traces on the other surface of the substrate also provide reference ground. Bottom and top enclosures that enclose the substrate have respective interior recesses with deposited continuous metal coatings. A plurality of metal bonding bumps or bonding wall extends outwardly from the projecting walls of the bottom and top enclosures. The bonding bumps on the bottom and top enclosures engage reference ground metal traces on respective surfaces of the substrate. As a result of applied pressure, the bonding bumps and respective reference ground metal traces together with the through-substrate vias form a metal-to-metal singly-connected ground reference structure for the entire circuitry.

Embodiments of the present invention provide an electrical filter structure having a direct-coupled-stub filter (DCSF). The lengths of the transmission line portions can be arranged such that electrical lengths of the transmission line portions are shorter, by at least 10 percent, than a fourth of a wavelength of a signal having a frequency of a passband center frequency of the electrical filter structure. Moreover, lengths of the stubs can be selected so that the electrical lengths of the stubs are longer, by at least 2%, than a fourth of a wavelength of a signal having a frequency of a passband center frequency of the electrical filter structure. The filter structures of embodiments of the present invention can advantageously improve filter characteristics without changing the topological structure of the filter.

Protecting qubits of a quantum processor from spontaneous emission and thermal photon noise includes connecting a first port of a filter to a signal line of a readout resonator of a qubit circuit of a quantum processor. The filter has a passband including a readout resonator frequency associated with the readout resonator and a first stopband including a qubit transition frequency associated with the qubit circuit. A second port of the filter is connected to a measurement device. a signal line of the filter is galvanically connected to a reference ground in thermal contact to a stage of a cryostat. The galvanic connection further makes a thermal connection to an input signal line of the qubit circuit.

Disclosed herein are dual-spiral common-mode filters, printed circuit boards (PCBs) comprising such dual-spiral common-mode filters, and devices comprising such dual-spiral common-mode filters and PCBs. A dual-spiral common-mode filter is patterned into the reference plane of a PCB. The dual-spiral common-mode filter comprises a first spiral portion connected to a second spiral portion. The spiral portions may be substantially identical, or mirror images of each other, or different from each other. One or more signal traces in a signal trace layer of the PCB pass over the dual-spiral common-mode filter. The disclosed dual-spiral common-mode filters can replace both conventional patterned ground structure (PGS) filters used for radio-frequency interference mitigation and the cutouts often used in the reference plane of a PCB to mitigate impedance mismatches due to DC blocking capacitors. Also disclosed herein are methods of making PCBs that include dual-spiral common-mode filters.

A filter includes first and second resonators and first and second stub resonators. Each of the first and second resonators includes a first conductor part and a second conductor part electrically connected to the first conductor part and having an impedance smaller than an impedance of the first conductor part. The first stub resonator is electrically connected to the first conductor part of the first resonator. The second stub resonator is electrically connected to the first conductor part of the second resonator. The shape of the first stub resonator and the shape of the second stub resonator are different from each other.

A superconducting device is described wherein the device comprises a substrate; a capacitor structure (604) and a superconducting inductor structure (602) disposed on the substrate, the capacitor structure an the superconducting inductor structure forming a superconducting microwave filter structure, in particular a low-pass filter, the superconducting inductor structure including a plurality of nanowires of a superconducting material, each of the plurality of nanowires being galvanically connected to one of a plurality of capacitor electrodes (608) forming the capacitor structure, wherein the cross-sectional dimensions of the plurality of nanowires are selected such that the kinetic inductance of each of the one or more nanowires is larger, preferably substantially larger, than the geometrical inductance of the nanowire.

A method includes after application of a bonding material, such as a metal paste, on a second dielectric substrate, a first dielectric substrate with a recess formed therein is laminated on the second dielectric substrate. Thereafter, the bonding material is sintered to form a cavity inside the dielectric substrate.

A method includes after application of a bonding material, such as a metal paste, on a second dielectric substrate, a first dielectric substrate with a recess formed therein is laminated on the second dielectric substrate. Thereafter, the bonding material is sintered to form a cavity inside the dielectric substrate.

The present disclosure relates to coupled slow-wave transmission lines. In this regard, a transmission line structure is provided. The transmission line structure includes a first undulating signal path formed from first loop structures. The transmission line structure also includes a second undulating signal path formed from second loop structures. The second undulating signal path is disposed alongside of the first undulating signal path. Further, a first ground structure is disposed above or below either one or both of the first undulating signal path and the second undulating signal path.