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; a plurality of gates disposed on the quantum well stack; and a top gate at least partially disposed on the plurality of gates such that the plurality of gates are at least partially disposed between the top gate and the quantum well stack.

Provided are P-type semiconductor layer, P-type multilevel element, and manufacturing method for the element. The P-type multilevel element comprises a gate electrode, an active structure overlapping the gate electrode, a gate insulating layer disposed between the gate electrode and the active structure, and source and drain electrodes electrically connected to both ends of the active structure, respectively. The active structure has a first P-type active layer, a second P-type active layer, and a barrier layer disposed between the first P-type active layer and the second P-type active layer. A threshold voltage for forming a channel in the first P-type active layer and a threshold voltage for forming a channel in the second P-type active layer have different values.

A layered heterostructure, comprising alternating layers of different semiconductors, wherein one of the atom species of one of the semiconductors has a faster diffusion rate along an oxidizing interface than an atom species of the other semiconductor at an oxidizing temperature, can be used to fabricate embedded nanostructures with arbitrary shape. The result of the oxidation will be an embedded nanostructure comprising the semiconductor having slower diffusing atom species surrounded by the semiconductor having the higher diffusing atom species. The method enables the fabrication of low- and multi-dimensional quantum-scale embedded nanostructures, such as quantum dots (QDs), toroids, and ellipsoids.

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; a plurality of gates disposed on the quantum well stack; and a top gate at least partially disposed on the plurality of gates such that the plurality of gates are at least partially disposed between the top gate and the quantum well stack.

Described is a monolithic integrated circuit for use in quantum computing based on single and multiple coupled quantum dot electron- and hole-spin qubits monolithically integrated with the mm-wave spin manipulation and readout circuitry in commercial complementary metal-oxide-semiconductor (CMOS) technology. The integrated circuit includes a plurality of n-channel or p-channel metal-oxide-semiconductor field-effect transistor (MOSFET) cascodes each including a single-spin qubit or two coupled quantum dot qubits formed in an undoped semiconductor film adjacent at least one top gate. There is also a back gate formed in a silicon substrate adjacent a buried oxide layer or the at least one top gate, where the back gate controls the electron or hole entanglement and exchange interaction between the two coupled quantum dot qubits. The monolithic integrated circuits described may be used for monolithically integrated semiconductor quantum processors for quantum information processing.

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 structure of a quantum dot device, wherein the quantum well stack structure includes an insulating material to define multiple rows of quantum dot formation regions; and a gate that extends over multiple ones of the rows.

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.

A silicon-based quantum device is provided. The device comprises: a first metallic structure (501); a second metallic structure (502) laterally separated from the first metallic structure; and an L-shaped elongate channel (520) defined by the separation between the first and second metallic structures; wherein the elongate channel has a vertex (505) connecting two elongate parts of the elongate channel. The device further comprises: a third metallic structure (518), mediator gate, positioned in the elongate channel; a fourth metallic structure (531) forming a first barrier gate, arranged at a first end of the third metallic structure; and a fifth metallic structure (532) forming a second barrier gate arranged at a second end of the third metallic structure. The first, second, third, fourth and fifth metallic structures are configured for connection to first, second, third, fourth and fifth electric potentials respectively. The first, second, fourth and fifth electric potentials are controllable to define an electrical potential well to confine quantum charge carriers in an elongate quantum dot beneath the elongate channel. The fourth and fifth electric potentials and the position of the fourth and fifth metallic structures define first and second ends of the elongate channel respectively. The width of the electrical potential well is defined by the position of the first and second metallic structures and their corresponding electric potentials; and the length of the electrical potential well is defined by the position of the fourth and fifth metallic structures and their corresponding electric potentials. The third electric potential is controllable to adjust quantum charge carrier energy levels in the electrical potential well.

A quantum processing element is disclosed. The element includes a semiconductor substrate, a dielectric material forming an interface with the semiconductor substrate, and a donor molecule embedded in the semiconductor. The donor molecule includes a plurality of dopant dots embedded in the semiconductor, each dopant dot includes one or more dopant atoms, and one or more electrons/holes confined to the dopant dots. A distance between the dopant dots is between 3 and 9 nanometres.

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; a first gate and an adjacent second gate above the quantum well stack; and a gate wall between the first gate and the second gate, wherein the gate wall includes a spacer and a capping material, the spacer has a top and a bottom, the bottom of the spacer is between the top of the spacer and the quantum well stack, and the capping material is proximate to the top of the spacer.