A quantum processing unit is disclosed. The quantum processing unit includes at least one superconducting qubit that is based on phase-biased linear and non-linear inductive-energy elements. A superconducting phase difference across the linear and non-linear inductive-energy elements is biased, for example, by an external magnetic field, such that quadratic potential energy terms of the linear and non-linear inductive-energy elements are cancelled at least partly. In a preferred embodiment, such cancellation is at least 30%. The partial cancellation of the quadratic potential energy terms makes it possible to implement a high-coherence high-anharmonicity superconducting qubit design.

The present invention relates to the manufacture of Josephson junctions. Such Josephson junctions may be suitable for use in qubits. High-quality, potentially monocrystalline, electrode and dielectric layers are formed using blanket deposition. Subsequently, the structure of one of more Josephson junctions is formed using multi-photon lithography to create openings in a resist followed by etching the electrode and dielectric layers.

Superconducting metamaterials composed of lumped-element inductors and capacitors are used to implement microwave photonics with novel dispersion relations and dense mode spectra that can be coupled to qubits. Metamaterial lattices may have qubits coupled to different unit cells in the metamaterial such that each qubit will couple strongly to modes with an antinode at the qubit location. Through simultaneous driving of combinations of modes, large amplitudes are produced at only one or a few unit cells, resulting in large ac Stark shifts of qubits located there, and providing a frequency-addressable qubit array without requiring flux-tunability and with reduced control wiring.

A qubit device for use in a quantum computing environment includes a semiconductor substrate, an insulating layer disposed on at least a portion of an upper surface of the substrate, and a transition metal silicide (TMSi) heterojunction disposed on at least a portion of an upper surface of the insulating layer. The TMSi heterojunction includes a link layer and at least first and second TMSi regions coupled with the link layer. The link layer may include a normal conductor, thereby forming a superconductor-normal conductor-superconductor (SNS) junction, or a geometric constriction, thereby forming a superconductor-geometric constriction-superconductor (ScS) junction. The link layer may form at least a portion of a channel including intrinsic or doped silicon.

A device includes: a substrate; a superconducting quantum interference device (SQUID) including a superconductor trace arranged on an upper surface of the substrate and having at least one Josephson junction interrupting a path of the superconductor trace, in which the superconductor trace includes a first superconductor material that exhibits superconducting properties at or below a corresponding superconducting critical temperature; and a dielectric capping layer on an upper surface of the SQUID, in which the dielectric capping layer covers a majority of the superconductor trace of the SQUID, and the capping layer includes an opening through which a first region of the SQUID is exposed, the first region of the SQUID including a first Josephson junction.

A device includes a first substrate formed of a first material that exhibits a threshold level of thermal conductivity. The threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum circuit operates. In an embodiment, the device also includes a second substrate disposed in a recess of the first substrate, the second substrate formed of a second material that exhibits a second threshold level of thermal conductivity. The second threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum circuit operates. In an embodiment, at least one qubit is disposed on the second substrate. In an embodiment, the device also includes a transmission line configured to carry a microwave signal between the first substrate and the second substrate.

A Josephson junction device includes a planar arrangement including a first two-dimensional (2D) material layer, a graphene layer, and a second 2D material layer planarly arranged on a device substrate, the first 2D material layer including at least one layer of a 2D material, the graphene layer forming a first junction with the first 2D material layer, and the second 2D material layer forming a second junction with the graphene layer and including at least one layer of a 2D material. A distance between the first junction and the second junction is within a range configured to cause a Josephson effect.

A three-dimensional superconducting qubit and a method for manufacturing the same are disclosed. In an example, a three-dimensional superconducting qubit comprises a structural base comprising one or more insulating materials, and superconductive patterns on surfaces of the structural base. The superconductive patterns form at least a capacitive part and an inductive part of the three-dimensional superconducting qubit. A first surface of the surfaces of the structural base defines a first plane and a second surface of the surfaces of the structural base defines a second plane, the second plane being oriented differently than the first plane. At least one superconductive pattern of the superconductive patterns extends from the first surface to the second surface.

A superconducting qubit is manufactured by stacking up atomically-thin, crystalline monolayers to form a heterostructure held together by van der Waals forces. Two sheets of superconducting material are separated by a third, thin sheet of dielectric to provide both a parallel plate shunting capacitor and a Josephson tunneling barrier. The superconducting material may be a transition metal dichalcogenide (TMD), such as niobium disilicate, and the dielectric may be hexagonal boron nitride. The qubit is etched, or material otherwise removed, to form a magnetic flux loop for tuning. The heterostructure may be protected by adhering additional layers of the dielectric or other insulator on its top and bottom. For readout, the qubit may be coupled to an external resonator, or the resonator may be integral with one of the sheets of superconducting material.

One example includes a magnetic Josephson junction (MJJ) system. The system includes a first superconducting material layer and a second superconducting material layer each configured respectively as a galvanic contacts. The system also includes a ferrimagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a fixed net magnetic moment at a predetermined operating temperature of the MJJ system. The system also includes a ferromagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a variable magnetic orientation in response to an applied magnetic field. The MJJ system can be configured to store a binary logical value based on a direction of the variable magnetic orientation of the ferromagnetic material layer. The system further includes a spacer layer arranged between the ferromagnetic and the ferrimagnetic material layers.