An embodiment of the invention provides a fabrication method of a field-effect transistor. The method includes: forming a support structure with a superlattice feature on a semiconductor substrate, where the support structure includes a first semiconductor material layer and a second semiconductor material layer that are alternately disposed, and an isolation layer is disposed on two sides of the support structure; forming, along a boundary between the isolation layer and the support structure, a dummy gate structure that covers the support structure, where a length of the dummy gate structure in a gate length direction is less than the first semiconductor material layer; removing, along the gate length direction, an area other than a sacrificial layer in the first semiconductor material layer to form an insulation groove; and forming a source and a drain in a preset source drain area along the gate length direction.

Disclosed herein are quantum dot devices, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a quantum well stack; an insulating material disposed above the quantum well stack, wherein the insulating material includes a trench; and a gate metal disposed on the insulating material and extending into the trench.

Disclosed herein are single electron transistor (SET) devices, and related methods and devices. In some embodiments, a SET device may include: first and second source/drain (S/D) electrodes; a plurality of islands, disposed between the first and second S/D electrodes; and dielectric material disposed between adjacent ones of the islands, between the first S/D electrode and an adjacent one of the islands, and between the second S/D electrode and an adjacent one of the islands.

Processor elements are disclosed herein. A processor element comprises a silicon layer. The processor element further comprises a dielectric layer disposed upon and forming an interface with the silicon layer. The processor element further comprises a conductive via in contact with the dielectric layer, the conductive via comprising a metallic portion having an interface end closest to the dielectric layer and a distal end. A cross-sectional area of the interface end of the metallic portion of the conductive via is less than or equal to 100 nm by 100 nm. In use, the application of a bias potential to the distal end of the conductive via induces a quantum dot at the interface between the dielectric layer and the silicon layer, the quantum dot for confining one or more electrons or holes in the silicon layer. Methods are also described herein.

Semiconductor element, method of reading out a quantum dot device and system. The present document relates to a semiconductor element for providing a source reservoir for a charge sensor of a quantum dot device. The element comprises a semiconductor heterostructure (2, 3, 5) including a quantum well layer (5) contiguous to a semiconductor functional layer (3), one or more ohmic contacts (9) for providing charge carriers, and a first accumulation gate electrode (13) located opposite the quantum well layer and spaced apart therefrom at least by the semiconductor functional layer for enabling to form a two dimensional charge carrier gas (14) in a first area of the quantum well layer upon applying a first biasing voltage to the first accumulation gate electrode. The device further comprises a second accumulation gate electrode (17) opposite the quantum well layer and electrically isolated from the first accumulation gate electrode (13), the second accumulation gate electrode enabling to be biased with a second biasing voltage, for enabling to extend the two dimensional charge carrier gas in a second area (18) contiguous to the first area. This document further relates to a method of determining a spin state in a quantum dot device, as well as a system comprising a quantum dot device and a semiconductor element.

A method of fabricating semiconductor-superconductor nanowires, comprising: forming a first mask amorphous mask having first openings over trenches in a substrate; forming a monocrystalline conducting material in the first openings by selective area growth, thus forming gates for the nanowires in the trenches pf the substrate; forming a second mask over the substrate and gates, the second mask also being amorphous and having a pattern of second openings; forming an insulating crystalline buffer in the second openings; forming a crystalline semiconductor material on the buffer in the second openings by selective area growth in order to form the cores of the nanowires, wherein the gates intersect with the cores in the plane of the substrate; and forming the coating of superconductor material over at least part of each of the cores.

A silicon-based quantum device for confining charge carriers is provided. The device comprises: a substrate having a first planar region 137; a silicon layer 32 which forms part of the substrate and includes a step 33 with an edge 34 and a second planar region 135, wherein the second planar region 135 is substantially parallel to and offset from the first planar region 137; a first electrically insulating layer 42 provided on the silicon layer 32, overlying the step 33; a first metallic layer 51, provided on the first electrically insulating layer 42, overlying the step 33, arranged to be electrically connected such that a first confinement region 10 can be induced in which a charge carrier or charge carriers can be confined at the edge 34; and a second metallic layer 52, provided overlying the second planar region 135 of the silicon layer, wherein the second metallic layer is: electrically separated from the first metallic layer 51; and arranged to be electrically connected such that a second confinement region 11 can be induced in which a charge carrier or charge carriers can be confined only in the second planar region 135 of the silicon layer 32 under the second metallic layer 52, and the first confinement region 10 is couplable to the second confinement region 11; wherein the first confinement region 10 is displaced from the second confinement region 11 in a direction that is perpendicular to the edge 34. A method of assembling a silicon-based quantum device and a method of using a silicon-based quantum device are also provided.

Disclosed herein are assemblies for optical communication in quantum computing. For example, in some embodiments, a quantum computing assembly may include control circuitry having an optical interface to external electronic circuitry.

A method for monitoring the state of a qubit device comprising a chiral nanocrystal includes measuring a voltage, a current, or a magnetic field of the nanocrystal; assigning the nanocrystal a superposition state if the measured voltage, current, or magnetic field is less than a superposition threshold; and assigning a base state value of the nanocrystal if the measured voltage is greater than a base state threshold. The measured voltage, current, or magnetic field corresponds to a clockwise or counter clockwise flow of electrons around the nanocrystal.

We disclose a magnetic device having a pair of coplanar thin-film magnetic electrodes arranged on a substrate with a relatively small edge-to-edge separation. In an example embodiment, the magnetic electrodes have a substantially identical footprint that can be approximated by an ellipse, with the short axes of the ellipses being collinear and the edge-to-edge separation between the ellipses being smaller than the size of the short axis. In some embodiments, the magnetic electrodes may have relatively small tapers that extend toward each other from the ellipse edges in the constriction area between the electrodes. Some embodiments may also include an active element inserted into the gap between the tapers and electrical leads connected to the magnetic electrodes for passing electrical current through the active element. When subjected to an appropriate external magnetic field, the magnetic electrodes can advantageously be magnetized to controllably enter parallel and antiparallel magnetization states.