A multifunctional quantum node device involving a semiconductor vacancy qubit structure, a superconductor quantum memory nanowire coupled with a spin state of the semiconductor vacancy qubit structure, and a superconductor qubit logic circuit coupled with the superconductor quantum memory nanowire and the semiconductor vacancy qubit structure, whereby the device is a hybrid device operable as an interface for at least one of computing and quantum-entangled networking.

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.

A superconducting medium includes a first layer made of a first superconductor and a second layer made of a second superconductor. The first layer has a first thickness less than a first coherence length of the first superconductor. The second layer has a second thickness less than a second coherence length of the second superconductor so as to induce a proximity effect between the first layer and the second layer. The proximity effect can induce desirable properties in the resulting superconducting medium. Controlling the thickness ratio of the first layer to the second layer can also tune the property of the superconducting medium.

A photon source includes a photo-pair generator and a detection device. The photo-pair generator is configured to generate a photon-pair in receiving an input signal. A first photon of the photon-pair is output from the photon source via a first optical path. The detection device is configured to receive a second photon of the photon-pair. The detection device includes a transistor that has a semiconducting component that is a source and a drain of the transistor, and a superconducting component that is adjacent to the semiconducting component and is a gate of the transistor. The transistor is configured to transition from an off state to an on state in response a photon being incident upon the detection device.

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.

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.

The disclosure concerns fabricating a quantum device. In an embodiment, a method is disclosed comprising: providing a substrate and an insulator formed on the substrate; from combinations of selective-area-grown semiconductor material along with regions of a superconducting material, forming a network of nanowires oriented in a plane of the substrate which can be used to produce a Majorana-based topological qubit; and fabricating a side gate for controlling a topological segment of the qubit; wherein the selective-area-grown semiconductor material is grown on the substrate, by etching trenches in the insulator formed on the substrate to define the nanowires and depositing the semiconductor material in the trenches defining the nanowires; and wherein the fabricating of the side gate comprises etching the dielectric to create a trench for the side gate and depositing the side gate in the trench for the side gate.

The various embodiments described herein include methods, devices, and systems for operating superconducting circuitry. In one aspect, a superconducting component includes: (1) a superconductor having a plurality of alternating narrow and wide portions, each wide portion having a corresponding terminal; and (2) a plurality of heat sources, each heat source thermally coupled to a corresponding narrow portion such that heat from the heat source is transmitted to the corresponding narrow portion; where the plurality of heat sources is electrically isolated from the superconductor.

The present subject matter provides technical solutions for the technical problems facing quantum computing by improving the accuracy and precision of qubit readout. Technical solutions described herein improves the readout fidelity by reducing the ambiguity between the bright and dark states. In an embodiment, this includes transferring the qubit population that is in the dark quantum state to an auxiliary third state. The auxiliary third state remains dark and reduces the mixing between the logical bright and dark states. This process uses multiple laser pulses to ensure high fidelity population transfer, thus preserving the dark nature of the dark state. Improving readout fidelity of 171Yb+ qubits may improve fidelity by an order of magnitude, such as by improving readout fidelity from 99.9% to 99.99%. This improvement in detection fidelity may substantially increase the computational power of a quantum computer.

According to one aspect of the present invention, a switching device using an electron shuttle includes a substrate, a center portion fixed onto the substrate, a first wing portion extending from the center portion in a first direction and spaced apart from the substrate, a second wing portion extending from the center portion in a second direction and spaced apart from the substrate, a conductive first electron shuttle connected to the first wing portion and disposed to be spaced apart from the substrate, and a conductive second electron shuttle connected to the second wing portion and disposed to be spaced apart from the substrate.