Abstract: A system includes a first superconducting wire and a second superconducting wire connected in parallel. The system includes a first current source coupled to the first superconducting wire and configured to supply a first current in response to a trigger event. The system includes a second current source coupled in series with the parallel combination of the first superconducting wire and the second superconducting wire and configured to supply a second current. The superconducting wires are configured to, while receiving the second current, operate in a superconducting state in the absence of the first current. The first superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first current. The second superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first superconducting wire transitioning to the non-superconducting state.

Abstract: The various embodiments described herein include methods, devices, and systems for operating superconducting circuitry. In one aspect, a programmable circuit includes: (1) a superconducting component arranged in a multi-dimensional array of alternating narrow and wide portions; (2) a plurality of heat sources, each heat source thermally-coupled to, and electrically-isolated from, a respective narrow portion of the multi-dimensional array; and (3) a plurality of electrical terminals, each electrical terminal coupled to a respective wide portion of the multi-dimensional array.

Abstract: An electronic device (e.g., a diode) is provided that includes a substrate and a patterned layer of superconducting material disposed over the substrate. The patterned layer forms a first electrode, a second electrode, and a loop coupling the first electrode with the second electrode by a first channel and a second channel. The first channel and the second channel have different minimum widths. For a range of current magnitudes, when a magnetic field is applied to the patterned layer of superconducting material, the conductance from the first electrode to the second electrode is greater than the conductance from the second electrode to the first electrode.

Abstract: A Mach-Zehnder interferometer (MZI) filter comprising one or more passive compensation structures are described. The passive compensation structures yield MZI filters that are intrinsically tolerant to perturbations in waveguide dimensions and/or other ambient conditions. The use of n+1 waveguide widths can mitigate n different sources of perturbation to the filter. The use of at least three different waveguide widths for each Mach-Zehnder waveguide can alleviate sensitivity of filter performance to random width or temperature variations. A tolerance compensation portion is positioned between a first coupler section and a second coupler section, wherein the tolerance compensation portion includes a first compensation section having a second width, a second compensation section having a third width and a third compensation section having a fourth width, wherein the fourth width is greater than the third width and the third width is greater than the second width.

Abstract: A device (e.g., a photonic multiplexer) is provided that includes a plurality of first switches. Each first switch in the plurality of first switches includes a plurality of first channels. Each first switch is configured to shift photons in the plurality of first channels by zero or more channels, based on first configuration information provided to the first switch. The device further includes a plurality of second switches. Each second switch includes a plurality of second channels. Each second channel is coupled with a respective first channel from a distinct first switch of the plurality of first switches. Each second switch is configured to shift photons in the plurality of second channels by zero or more channels, based on second configuration information provided to the second switch.

Abstract: A system for generating clock signals for a photonic quantum computing system includes a pump photon source configured to generate a plurality of pump photon pulses at a first repetition rate, a waveguide optically coupled to the pump photon source, and a photon-pair source optically coupled to the first waveguide. The system also includes a photodetector optically coupled to the photon-pair source and configured to generate a plurality of electrical pulses in response to detection of at least a portion of the plurality of pump photon pulses at the first repetition rate and a clock generator coupled to the photodetector and configured to convert the plurality of electrical pulses into a plurality of clock signals at the first repetition rate.

Abstract: An optical switch structure includes a substrate, a first electrical contact, and a first material having a first conductivity type electrically connected to the first electrical contact. The optical switch structure also includes a second material having a second conductivity type coupled to the first material, a second electrical contact electrically connected to the second material, and a waveguide structure disposed between the first electrical contact and the second electrical contact. The waveguide structure includes a waveguide core coupled to the substrate and including a first material characterized by a first index of refraction and a first electro-optic coefficient and a waveguide cladding at least partially surrounding the waveguide core and including a second material characterized by a second index of refraction less than the first index of refraction and a second electro-optic coefficient greater than the first electro-optic coefficient.

Abstract: An optical switch device includes a first semiconductor structure configured to operate as a first waveguide and a second semiconductor structure configured to operate as a second waveguide. The second semiconductor structure is located above or below the first semiconductor structure and separated from the first semiconductor structure. The second semiconductor structure includes a first portion having a first width and a second portion having a width different from the first width and located on the first portion. The first portion is located between a first doped region and a second doped region.

Abstract: A photon detector is provided. The photon detector includes a superconducting wire having a plurality of alternating narrow and wide portions; a current source electrically-coupled to the superconducting wire and configured to supply the superconducting wire with electrical current; and an optical waveguide optically coupled to the plurality of narrow portions of the superconducting wire.

Abstract: A device (e.g., a photonic multiplexer) is provided that includes a plurality of first switches. Each first switch in the plurality of first switches includes a plurality of first channels. Each first switch is configured to shift photons in the plurality of first channels by zero or more channels, based on first configuration information provided to the first switch. The device further includes a plurality of second switches. Each second switch includes a plurality of second channels. Each second channel is coupled with a respective first channel from a distinct first switch of the plurality of first switches. Each second switch is configured to shift photons in the plurality of second channels by zero or more channels, based on second configuration information provided to the second switch.

Abstract: A device includes a first semiconductor layer; a portion of a second semiconductor layer disposed on the first semiconductor layer; and a third semiconductor layer including a first region disposed on the portion of the second semiconductor layer and a second region disposed on the first semiconductor layer. A thickness of the first region is less than a predefined thickness. The device also includes an etch stop layer disposed on the third semiconductor layer; a plurality of distinct portions of a fourth semiconductor layer disposed on the etch stop layer and exposing one or more distinct portions of the etch stop layer over the portion of the second semiconductor layer; and a plurality of distinct portions of a superconducting layer disposed on the plurality of distinct portions of the fourth semiconductor layer and the exposed one or more distinct portions of the etch stop layer.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting photon detectors. In one aspect, a photon detector includes: (1) a first waveguide configured to guide photons from a photon source; (2) a second waveguide that is distinct and separate from the first waveguide and optically-coupled to the first waveguide; and (3) a superconducting component positioned adjacent to the second waveguide and configured to detect photons within the second waveguide.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating transistors. In one aspect, a transistor includes: (1) a semiconducting component configured to operate in an on state at temperatures above a semiconducting threshold temperature; and (2) a superconducting component configured to operate in a superconducting state while: (a) a temperature of the superconducting component is below a superconducting threshold temperature; and (b) a first current supplied to the superconducting component is below a current threshold; where: (i) the semiconducting component is located adjacent to the superconducting component; and (ii) in response to a first input voltage, the semiconducting component is configured to generate an electromagnetic field sufficient to lower the current threshold such that the first current exceeds the lowered current threshold, thereby transitioning the superconducting component to a non-superconducting state.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting switch devices. In one aspect, an electrical circuit includes: (1) a switch device configured to switch between an on state and an off state in response to a first voltage, the switch device comprising: (a) a superconductor layer adapted to transition from a superconducting state to an insulating state in response to a first strain; and (b) a piezoelectric layer positioned adjacent to the superconductor layer, the piezoelectric layer configured to apply the first strain to the superconductor layer in response to the first voltage; (2) a voltage source electrically coupled to the piezoelectric layer of the switch device and configured to supply the first voltage; and (3) an output component coupled to the superconductor layer of the switch device.

Abstract: A voltage driver is provided that includes a driver circuit, comprising (i) first positive channel transistor devices (PCTDs) coupled in series between a reference node and an output node; and (ii) first negative channel transistor devices (NCTDs) coupled in series between the output node and an electrical ground node. The voltage driver further includes a speed-up circuit comprising: (i) second NCTDs coupled to the first PCTDs, configured to discharge gate-source capacitances of the first PCTDs; and (ii) second PCTDs coupled to the first NCTDs, configured to discharge gate-source capacitances of the first NCTDs. The voltage driver further includes a gate voltage circuit coupled to the driver circuit that includes third NCTDs and third PCTDs to provide respective first and second gate voltages to each of a subset of the first PCTDs and a subset of the first NCTDs.

Abstract: The various implementations described herein include methods, devices, and systems for detecting light. In one aspect, a photodetector device includes: a superconducting wire, and a transistor that includes a semiconducting component and a superconducting component. The superconducting wire is electrically coupled to the superconducting component. The semiconducting component is located adjacent to the superconducting component. The superconducting component is configured to, in response to receiving an input current exceeding a current threshold, transition from a superconducting state to a non-superconducting state and generate heat sufficient to increase a temperature of the semiconducting component from a temperature below a semiconducting threshold temperature to a temperature above the semiconducting threshold temperature.

Abstract: A Mach-Zehnder interferometer (MZI) filter comprising one or more passive compensation structures are described. The passive compensation structures yield MZI filters that are intrinsically tolerant to perturbations in waveguide dimensions and/or other ambient conditions. The use of n+1 waveguide widths can mitigate n different sources of perturbation to the filter. The use of at least three different waveguide widths for each Mach-Zehnder waveguide can alleviate sensitivity of filter performance to random width or temperature variations. A tolerance compensation portion is positioned between a first coupler section and a second coupler section, wherein the tolerance compensation portion includes a first compensation section having a second width, a second compensation section having a third width and a third compensation section having a fourth width, wherein the fourth width is greater than the third width and the third width is greater than the second width.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting circuits. In one aspect, an electric circuit includes: (1) a first superconducting component having a first terminal, a second terminal, and a constriction region between the first terminal and the second terminal; (2) a second superconducting component having a third terminal and a fourth terminal; and (3) a first electrically-insulating component that thermally couples the first superconducting component and the second superconducting component such that heat produced at the constriction region is transferred through the first component to the second superconducting component.

Abstract: An electronic device (e.g., a diode) is provided that includes a substrate and a patterned layer of superconducting material disposed over the substrate. The patterned layer forms a first electrode, a second electrode, and a loop coupling the first electrode with the second electrode by a first channel and a second channel. The first channel and the second channel have different minimum widths. The device further includes a magnet that applies a magnetic field to the loop, which produces an expulsion current in the loop that travels toward the second electrode in the first channel and toward the first electrode in the second channel. For a range of current magnitudes, when the magnetic field is applied to the patterned layer of superconducting material, the conductance from the first electrode to the second electrode is greater than the conductance from the second electrode to the first electrode.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting circuitry. In one aspect, an electronic system includes: (1) a first circuit that includes a plurality of superconducting wires connected in parallel with one another, the plurality of superconducting wires including: (a) a first superconducting wire with a corresponding first threshold superconducting current; and (b) a second superconducting wire; (2) a second circuit connected in parallel to the first circuit; (3) a first current source coupled to the first superconducting wire and configured to selectively supply a first current; and (4) a second current source coupled to a combination of the first circuit and the second circuit and configured to supply a second current such that the plurality of superconducting wires operate in a superconducting state; where a combination of the first current and the second current exceeds the first threshold superconducting current.