Abstract: A fault-tolerant quantum computer using topological codes such as surface codes can have an architecture that reduces the amount of idle volume generated. The architecture can include qubit modules that generate surface code patches for different qubits and a network of interconnections between different qubit modules. The interconnections can include “port” connections that selectably enable coupling of boundaries of surface code patches generated in different qubit modules and/or “quickswap” connections that selectably enable transferring the state of a surface code patch from one qubit module to another. Port and/or quickswap connections can be made between a subset of qubit modules. For instance port connections can connect a given qubit module to other qubit modules within a fixed range. Quickswap connections can provide a log-tree network of direct connections between qubit modules.

Abstract: A superconductor device includes a barrier layer over a substrate including silicon, the barrier layer including silicon and nitrogen, and a seed layer for a superconductor layer over the barrier layer, the seed layer including aluminum and nitrogen, and superconductor layer over the seed layer, the superconductor layer including a layer of a superconductor material, the barrier layer serving as an oxidation barrier between the layer superconductor material and the substrate. In some embodiments, the superconductor device includes a waveguide and a metal contact at a sufficient distance from the waveguide to prevent optical coupling between the metal contact and the waveguide.

Abstract: The various embodiments described herein include methods, devices, and systems for operating superconducting circuitry. In one aspect, a programmable circuit includes a configurable superconducting component and control circuitry coupled to the configurable superconducting component. The superconducting component includes an input terminal, an output terminal, and a plurality of gate terminals. The control circuitry is coupled to the superconducting component via the plurality of gate terminals. The control circuitry is adapted to selectively transition portions of the superconducting component from a superconducting state to a non-superconducting state. The control circuitry is configured to operate the superconducting component in a first configuration in which the programmable circuit is configured to perform a first function.

Abstract: An example memory cell includes a superconducting loop configured to receive a write current and form a persistent current that stores a data bit in the superconducting loop. The example memory cell further includes a superconducting wire coupled to the superconducting loop and configured to selectively read-out the data bit in the superconducting loop in response to a control signal. An example method of reading data from the memory cell includes receiving, at the superconducting loop, a write current to store a data bit in a superconducting loop, and forming a persistent current that circulates in the superconducting loop as a stored data bit. The example method further includes, in accordance with a control signal, transferring, via a superconducting wire of the memory cell that is coupled to the superconducting loop, at least a portion of the persistent current to an output of the memory cell.

Abstract: A device includes a spot size converter on a substrate. The substrate includes an optical fiber alignment structure formed thereon. The spot size converter is aligned with the optical fiber alignment structure. The spot size converter includes an oxide layer that has a first refractive index and includes a tapered section such that a first end of the spot size converter is smaller than a second end of the spot size converter. The spot size converter also includes a waveguide core in the oxide layer. The waveguide core is tapered and is smaller at the first end than at the second end of the spot size converter. The spot size converter further includes a cladding layer surrounding the oxide layer, the cladding layer having a second refractive index lower than the first refractive index of the oxide layer.

Abstract: An example circuit includes a superconducting component having a plurality of narrow portions and a plurality of wide portions. The example circuit further includes a plurality of photon detector components, each photon detector component coupled to a corresponding narrow portion of the plurality of narrow portions and configured to provide an output that causes the corresponding narrow portion to transition from a superconducting state to a non-superconducting state. The example circuit also includes an output component coupled to the superconducting component, the output component configured to determine a number of the plurality of narrow portions of the superconducting component that are in the non-superconducting state.

Abstract: A tool for an assembly machine comprising a gantry mechanism is disclosed. The tool includes a connector for connecting the tool to the gantry mechanism; a first surface for temporarily interfacing the tool to an optical die; a retention apparatus configured to temporarily couple the optical die to the first surface; and a first tool optical coupler positioned at the first surface and configured to form a first optical connection to the optical die when the optical die is positioned at the first surface.

Abstract: The various embodiments described herein include methods for manufacturing superconductor devices. A method for manufacturing superconductors may include: (i) generating spectra data from a first superconductor device; (iii) identifying a first peak ratio between a first phase peak and a second phase peak in the spectra data; (iv) generating additional spectra data from a second superconductor device; (v) identifying a second peak ratio of the additional spectra data from the second superconductor device; (vi) adjusting a manufacturing parameter based on the first peak ratio and the second peak ratio; and (vii) manufacturing a third superconductor device based on the adjusted manufacturing parameter.

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: An optical phase shift circuit can include: a first Mach Zehnder lattice and a second Mach Zehnder lattice. Each Mach Zehnder lattice can have a first waveguide and a second waveguide, with a set of active phase shifters disposed along one of the waveguides and a plurality of directional coupler regions disposed along both waveguides between the active phase shifters. A first passive phase shifter can be coupled between one output path of the first Mach Zehnder lattice and one input path of the second Mach Zehnder lattice, and a second passive phase shifter can be coupled between the other output path of the first Mach Zehnder lattice and the other input path of the second Mach Zehnder lattice. Optical phase shift circuits of this kind can be used to implement phase shifters in a Generalized Mach Zehnder interferometer.

Abstract: A device includes a substrate and a dielectric layer on the substrate. The device also includes a light sensitive component in the dielectric layer and a trench having a first portion disposed in the substrate and a second portion disposed in the dielectric layer. The trench is adjacent the light sensitive component and includes an adhesion layer in the first portion and the second portion, an optical isolation layer on the adhesion layer, and a first fill material in the first portion and a second fill material in the second portion. The first fill material is characterized by a first coefficient of thermal expansion (CTE) that matches a CTE of the substrate and the second fill material is characterized by a second CTE that matches a CTE of the dielectric layer.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating diodes. In one aspect, an electrical circuit includes: (1) a diode component having a particular energy band gap; (2) an electrical source electrically coupled to the diode component and configured to bias the diode component in a particular state; and (3) a heating component thermally coupled to a junction of the diode component and configured to selectively supply heat corresponding to the particular energy band gap.

Abstract: A device includes a die stack including a first die including a quantum circuit and a second die including an electronic circuit. The second die and the first die face each other. A coupler is bonded to a first surface of the first die, an optical fiber is coupled to the coupler for coupling light from the optical fiber to the quantum circuit.

Abstract: A waveguide structure includes a substrate and 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. The waveguide structure also includes a first cladding layer 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. The second cladding layer is coupled to the first cladding layer.

Abstract: A system for generating clock signals for a photonic quantum computing system includes a first pump photon source, a first photon-pair source optically coupled to the first pump photon source, and a first photodetector optically coupled to the first photon-pair source. The system also includes a first clock generator electrically coupled to the first photodetector, a second pump photon source, a second photon-pair source optically coupled to the second pump photon source, and a second photodetector optically coupled to the second photon-pair source. The system further includes a second clock generator electrically coupled to the second photodetector and a clock mediator coupled to the first clock generator and the second clock generator.

Abstract: An example electric circuit includes a superconductor component having a first terminal at a first end and a second terminal at a second end. The superconductor component includes a first portion coupled to the first terminal, a second portion coupled to the second terminal, and a third portion coupling the first portion and the second portion. The third portion has a curved shape such that the first portion of the superconductor component is proximate to, and thermally coupled to, the second portion of the superconductor component. The example electric circuit further includes a coupling component coupled to the third portion of the superconductor component, and a gate component configured to generate a resistive heat that exceeds a superconducting threshold temperature of the superconductor component, where the gate component is separated from the superconductor component by the coupling component.

Abstract: A device includes a superconductor layer and a piezoelectric layer positioned adjacent to the superconductor layer. The piezoelectric layer is configured to apply a first strain to the superconductor layer in response to receiving a first voltage that is below a predefined voltage threshold and to apply a second strain to the superconductor layer in response to receiving a second voltage that is above the predefined voltage threshold. While the device is maintained below a superconducting threshold temperature for the superconductor layer and is supplied with current below a superconducting threshold current for the superconductor layer, the superconductor layer is configured to 1) operate in a superconducting state when the piezoelectric layer applies the first strain to the superconductor layer and 2) operate in an insulating state when the piezoelectric layer applies the second strain to the superconductor layer.

Abstract: A quantum repeater circuit can include a resource state interconnect circuit that outputs one resource state per clock cycle, with each resource state having a number of entangled qubits. The circuit can also include circuits and delay lines to perform entangling measurement operations on qubits of resource states generated by the same resource state generator in different clock cycles. The circuit can be operated as a quantum repeater that receives an encoded logical qubit and produces a reduced-noise version of the encoded logical qubit.

Abstract: The various embodiments described herein include methods, devices, and systems for fabricating and operating superconducting circuitry. In one aspect, an amplification circuit includes: (1) a superconducting component; (2) an amplifier coupled in parallel with the superconducting component such that the superconducting component is in a feedback loop of the amplifier; (3) a voltage source coupled to a first input of the amplifier; (4) one or more resistors coupled to a second input of the amplifier; and (5) an output terminal coupled to an output of the amplifier.