Technologies for scalable spin qubit readout are disclosed. In the illustrative embodiment, superconducting and semiconducting components are integrated onto a single chip, allowing for frequency and temporal multiplexing components to be integrated onto the same die. The semiconducting components on the die can include transistors, varactors, and amplifiers, and the superconducting components can include an inductor and a capacitor that form part of an impedance matching network.

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.

A method for readout of a singlet-triplet qubit in a donor based quantum processing element is disclosed. The method includes: initialising the singlet-triplet qubit in a ground state |G; performing a shelving readout; using a final measured charge configuration of the singlet-triplet qubit to determine information about a current Zeeman energy difference; and using the information about the current Zeeman energy difference to adjust mapping of the shelving readout.

Apparatus, methods, and systems are disclosed for robust scalable topological quantum computing. Quantum dots are fabricated as van der Waals heterostructures, supporting localized topological phases and non-Abelian anyons (quasiparticles). Large bandgaps provide noise immunity. Three-dot structures include an intermediate quantum dot between two computational quantum dots. With the intermediate quantum dot in an OFF state, quasiparticles at the computational quantum dots can be isolated, with long lifetimes. Alternatively, the intermediate quantum dot can be controlled to decrease the quasiparticle tunneling barrier, enabling fast computing operations. A computationally universal suite of operations includes quasiparticle initialization, braiding, fusion, and readout of fused quasiparticle states, with, optionally, transport or tunable interactions—all topologically protected. Robust qubits can be operated without error correction. Quasilinear arrays of quantum dots or qubits can be scaled arbitrarily, up to resource limits, and large-scale topological quantum computers can be realized. Extensive two-dimensional arrays can also be used.

A device includes a source region, a drain region, a channel region, a pair of depletion gates, an accumulation gate, and a superconductive resonator. The channel region is between the source region and the drain region. The pair of depletion gates are spaced apart from each other. The pair of depletion gates both overlap the channel region and define a quantum dot qubit region in the channel region and between the pair of depletion gates. The accumulation gate is above and crossing the pair of depletion gates. The superconductive resonator is laterally adjacent the quantum dot qubit region.

A reinforced thin-film device is disclosed. The reinforced thin-film device comprising: a substrate having a top surface for supporting an epilayer; a mask layer patterned with a plurality of nanosize cavities disposed on said substrate to form a needle pad; a thin-film of, relative to the substrate, lattice-mismatched semiconductor disposed on said mask layer, wherein said thin-film comprises a plurality of in parallel spaced semiconductor needles of said lattice-mismatched semiconductor embedded in said thin-film, wherein said plurality of semiconductor needles are vertically disposed in the axial direction towards said substrate in said plurality of nanosize cavities of said mask layer; a, relative to the substrate, lattice-mismatched semiconductor epilayer provided on said thin-film and supported thereby; and a FinFET transistor arranged on the lattice-mismatched semiconductor epilayer. The FinFET transistor comprising: a fin semiconductor structure comprising an elongate protruding core portion, the fin semiconductor structure being arranged on the lattice-mismatched semiconductor epilayer, a first and a second nanostructured electrode radially enclosing respectively a source end and a drain end of the protruding core portion, and a nanostructured gate electrode radially enclosing a central portion of the protruding core portion, the central portion being a portion of the protruding core portion between the source end and the drain end.

An electronic component is formed by a semiconductor component or a semiconductor-like structure having gate electrode assemblies for manipulating the quantum state of qubits in quantum dots. It comprises a substrate comprising a two-dimensional electron gas or electron hole gas. Electrical contacts connect the gate electrode assemblies to voltage sources. A first gate electrode assembly having gate electrodes is arranged on a surface of the electronic component to generate movable potential wells in the substrate. A second gate electrode assembly serves to generate a potential barrier, which is adjacent to the first gate electrode assembly. The gate electrode assemblies have parallel electrode fingers, whereby the electrode fingers of the first gate electrode assembly are periodically and alternately interconnected in order to effect an almost continuous movement of the potential wells through the substrate.

Among other things, an apparatus comprises quantum units; and couplers among the quantum units. Each coupler is configured to couple a pair of quantum units according to a quantum Hamiltonian characterizing the quantum units and the couplers. The quantum Hamiltonian includes quantum annealer Hamiltonian and a quantum governor Hamiltonian. The quantum annealer Hamiltonian includes information bearing degrees of freedom. The quantum governor Hamiltonian includes non-information bearing degrees of freedom that are engineered to steer the dissipative dynamics of information bearing degrees of freedom.

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.