Abstract: Embodiments of the present disclosure describe a method of fabricating spin qubit device assemblies that utilize dopant-based spin qubits, i.e. spin qubit devices which operate by including a donor or an acceptor dopant atom in a semiconductor host layer. The method includes, first, providing a pair of gate electrodes over a semiconductor host layer, and then providing a window structure between the first and second gate electrodes, the window structure being a continuous solid material extending between the first and second electrodes and covering the semiconductor host layer except for an opening through which a dopant atom is to be implanted in the semiconductor host layer. By using a defined gate-first process, the method may address the scalability challenges and create a deterministic path for fabricating dopant-based spin qubits in desired locations, promoting wafer-scale integration of dopant-based spin qubit devices for use in quantum computing devices.

Abstract: 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 substrate and a quantum well stack disposed on the substrate. The quantum well stack may include a quantum well layer and a back gate, and the back gate may be disposed between the quantum well layer and the substrate.

Abstract: 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 above the quantum well stack, wherein the first gate includes a first gate metal and a first gate dielectric; and a second gate above the quantum well stack, wherein the second gate includes a second gate metal and a second gate dielectric, and the first gate is at least partially between a portion of the second gate and the quantum well stack.

Abstract: 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.

Abstract: Disclosed herein are quantum dot devices with trenched substrates, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a substrate having a trench disposed therein, wherein a bottom of the trench is provided by a first material, and a quantum well stack at least partially disposed in the trench. A material of the quantum well stack may be in contact with the bottom of the trench, and the material of the quantum well stack may be different from the first material.

Abstract: 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 including a quantum well layer and a barrier layer; a first gate metal above the quantum well stack, wherein the barrier layer is between the first gate metal and the quantum well layer; and a second gate metal above the quantum well stack, wherein the barrier layer is between the second gate metal and the quantum well layer, and a material structure of the second gate metal is different from a material structure of the first gate metal.

Abstract: 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.

Abstract: Disclosed herein are quantum dot devices with trenched substrates, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a substrate having a trench disposed therein, wherein a bottom of the trench is provided by a first material, and a quantum well stack at least partially disposed in the trench. A material of the quantum well stack may be in contact with the bottom of the trench, and the material of the quantum well stack may be different from the first material.

Abstract: 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 including a quantum well layer, wherein the quantum well layer includes an isotopically purified material; a gate dielectric above the quantum well stack; and a gate metal above the gate dielectric, wherein the gate dielectric is between the quantum well layer and the gate metal.

Abstract: 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 including a quantum well layer, wherein the quantum well layer includes an isotopically purified material; a gate dielectric above the quantum well stack; and a gate metal above the gate dielectric, wherein the gate dielectric is between the quantum well layer and the gate metal.

Abstract: Embodiments of the present disclosure describe integrated quantum circuit assemblies that include quantum circuit components pre-packaged, or integrated, with some other electronic components and mechanical attachment means for easy inclusion within a cooling apparatus. An example integrated quantum circuit assembly includes a package and mechanical attachment means for securing the package within a cryogenic chamber of a cooling apparatus. The package includes a plurality of components, such as a quantum circuit component, an attenuator, and a directional coupler, which are integral to the package. Such an integrated assembly may significantly speed up installation and may help develop systems for rapidly bringing up quantum computers.

Abstract: Disclosed herein are quantum dot devices with gate interface materials, as well as related computing devices and methods. For example, a quantum dot device may include a quantum well stack, a gate interface material, and a high-k gate dielectric. The gate interface material may be disposed between the high-k gate dielectric and the quantum well stack.

Abstract: Disclosed herein are quantum dot devices with patterned gates, as well as related computing devices and methods. For example, a quantum dot device may include gates disposed on a quantum well stack. In some embodiments, the gates may include a first gate with a first length; two second gates with second lengths arranged such that the first gate is disposed between the second gates; and two third gates with third lengths arranged such that the second gates are disposed between the third gates; and the first, second, and third lengths may all be different. In some embodiments, the gates may include a first set of gates alternatingly arranged with a second set of gates, spacers may be disposed between gates of the first set and gates of the second set, and gates in the first or second set may include a gate dielectric having a U-shaped cross-section.

Abstract: 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 including a quantum well layer, wherein the quantum well layer includes an isotopically purified material; a gate dielectric above the quantum well stack; and a gate metal above the gate dielectric, wherein the gate dielectric is between the quantum well layer and the gate metal.

Abstract: 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 base; a fin extending away from the base, wherein the fin has a first side face and a second side face, and the fin includes a quantum well layer; and a gate above the fin, wherein the gate extends down along the first side face.

Abstract: Embodiments of the present disclosure relate to quantum circuit assemblies implementing superconducting qubits, e.g., transmons, in which SQUID loops and portions of FBLs configured to magnetically couple to the SQUID loops extend substantially vertically. In contrast to conventional implementations, for a vertical SQUID according to various embodiments of the present disclosure, a line that is perpendicular to the SQUID loop is parallel to the qubit substrate. A corresponding FBL is also provided in a vertical arrangement, in order to achieve efficient magnetic coupling to the vertical SQUID loop, by ensuring that at least a portion of the FBL designed to conduct current responsible for generating magnetic field for tuning qubit frequency is substantially perpendicular to the substrate.

Abstract: Embodiments of the present disclosure describe integrated quantum circuit assemblies that include quantum circuit components pre-packaged, or integrated, with some other electronic components and mechanical attachment means for easy inclusion within a cooling apparatus. An example integrated quantum circuit assembly includes a package and mechanical attachment means for securing the package within a cryogenic chamber of a cooling apparatus. The package includes a plurality of components, such as a quantum circuit component, an attenuator, and a directional coupler, which are integral to the package. Such an integrated assembly may significantly speed up installation and may help develop systems for rapidly bringing up quantum computers.

Abstract: Embodiments of the present disclosure propose qubit substrates, as well as methods of fabricating thereof and related device assemblies. In one aspect of the present disclosure, a qubit substrate includes a base substrate of a doped semiconductor material, and a layer of a substantially intrinsic semiconductor material over the base substrate. Engineering a qubit substrate in this manner allows improving coherence times of qubits provided thereon, while, at the same time, being sufficiently mechanically robust so that it can be efficiently used in large-scale manufacturing.

Abstract: Embodiments of the present disclosure describe two approaches to providing flux bias line structures for superconducting qubit devices. The first approach, applicable to flux bias line structures that include at least one portion that terminates with a ground connection, resides in terminating such a portion with a ground connection that is electrically isolated from the common ground plane of a quantum circuit assembly. The second approach resides in providing a SQUID loop of a superconducting qubit device and a portion of the flux bias line structure over a portion of a substrate that is elevated with respect to other portions of the substrate. These approaches may be used or alone or in combination, and may improve grounding of and reduce crosstalk caused by flux bias lines in quantum circuit assemblies.

Abstract: Disclosed herein are superconducting qubit devices with Josephson Junctions utilizing resistive switching materials, i.e., resistive Josephson Junctions (RJJs), as well as related methods and quantum circuit assemblies. In some embodiments, an RJJ may include a bottom electrode, a top electrode, and a resistive switching layer (RSL) disposed between the bottom electrode and the top electrode. Using the RSLs in Josephson Junctions of superconducting qubits may allow fine tuning of junction resistance, which is particularly advantageous for optimizing performance of superconducting qubit devices. In addition, RJJs may be fabricated using methods that could be efficiently used in large-scale manufacturing, providing a substantial improvement with respect to approaches for forming conventional Josephson Junctions, such as e.g. double-angle shadow evaporation approach.