# US 2018/0322408 A1 · Co-planar waveguide flux qubits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0322408 A1 - Document ID: US20180322408A1 - Status: Published application - Kind: A1 - Application number: 15/764,021 - Filed: 2015-09-30 - Published: 2018-11-08 - Earliest claimed: 2015-09-30 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: Yu CHEN; John MARTINIS; Daniel Thomas SANK; Alireza Shabani BARZEGAR - Web page: https://patentgrep.com/patent/US20180322408A1 ## CPC - G06N 10/40: Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control - G06F 13/4068: {Electrical coupling} - H01P 3/003: {Coplanar lines} - H10N 60/805: {for Josephson-effect devices} - H10N 69/00: Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00 - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A qubit device includes an elongated thin film uninterrupted by Josephson junctions, a quantum device in electrical contact with a proximal end of the elongated thin film, and a ground plane that is co-planar with the elongated thin film and is in electrical contact with a distal end of the elongated thin film, in which the thin film, the quantum device, and the ground plane comprise a material that is superconducting at a designed operating temperature. ## Claims ### Claim 1 A qubit device comprising: an elongated thin film uninterrupted by Josephson junctions; a superconducting quantum interference device (SQUID) in electrical contact with a proximal end of the elongated thin film, wherein the SQUID comprises less than three Josephson junctions; and a ground plane that is co-planar with the elongated thin film and is in electrical contact with a distal end of the elongated thin film, wherein the thin film, the SQUID, and the ground plane comprise a material that is superconducting at a designed operating temperature. ### Claim 2 (depends on 1) The qubit device of claim 1, wherein the elongated thin film comprises a first side and a second opposite side and wherein each of the first side and the second side is separated from the superconducting ground plane by a respective gap. ### Claim 3 (depends on 2) The qubit device of claim 2, wherein a width of each respective gap is constant along the length of the elongated thin film. ### Claim 4 (depends on 1) The qubit device of claim 1, wherein each of the elongated thin film, the superconducting loop, and the ground plane comprises aluminum or niobium. ### Claim 5 (depends on 1) The qubit device of claim 1, wherein the SQUID comprises a superconducting loop interrupted by at least one Josephson junction. ### Claim 6 (depends on 5) The qubit device of claim 5, wherein the SQUID comprises two Josephson junctions interrupting the superconducting loop. ### Claim 7 (depends on 1) The qubit device of claim 1, further comprising a substrate, wherein the elongated thin film, the ground plane and the SQUID are on a surface of the substrate. ### Claim 8 (depends on 7) The qubit device of claim 7, wherein the substrate is sapphire. ### Claim 9 (depends on 1) The qubit device of claim 1, wherein the elongated thin film comprises a first section extending along a first direction and a second section extending along a second different direction. ### Claim 10 (canceled) ### Claim 11 A qubit device comprising: an elongated thin film uninterrupted by Josephson junctions and comprising a first section extending along a first direction and a second section extending along a second direction; a quantum device in electrical contact with the elongated thin film at a position between the first and second section, wherein the quantum device comprises less than three Josephson junctions; and a ground plane that is co-planar with the elongated thin film and is in electrical contact with the elongated thin film; wherein the thin film, the quantum device, and the ground plane comprise a material that is superconducting at a designed operating temperature. ### Claim 12 (depends on 11) The qubit device of claim 11, wherein the quantum device is a superconducting quantum interference device. ### Claim 13 A qubit control system comprising: a qubit device comprising (a) an elongated thin film uninterrupted by Josephson junctions, (b) a superconducting quantum interference device (SQUID) in electrical contact with a proximal end of the elongated thin film, wherein the SQUID comprises less than three Josephson junctions, and (c) a ground plane that is co-planar with the elongated thin film and is in electrical contact with a distal end of the elongated thin film, wherein the thin film, the SQUID, and the ground plane comprise a material that is superconducting at a designed operating temperature; a qubit bias control device adjacent to the elongated thin film such that the qubit bias control device is electrically coupled to the elongated thin film during operation; and a SQUID bias control device adjacent to the SQUID of the qubit device such that the SQUID bias control device is inductively coupled to the SQUID during operation. ### Claim 14 (depends on 13) The qubit control system of claim 13, wherein the qubit bias control device is in electrical contact with the distal end of the elongated superconducting thin film. ### Claim 15 (depends on 13) The qubit control system of claim 13, wherein the qubit bias control device comprises a current divider. ### Claim 16 (depends on 15) The qubit control system of claim 15, wherein the current divider comprises a plurality of inductors. ### Claim 17 (depends on 15) The qubit control system of claim 15, wherein the current divider comprises: a center thin film trace; and an outer thin film trace forming an open loop that circumscribes the center thin film trace and that is in electrical contact with the elongated thin film, wherein an end of the center thin film trace is in electrical contact with the outer thin film trace at a plurality of different locations along the open loop. ### Claim 18 (depends on 13) The qubit control system of claim 13, wherein the SQUID bias control device comprises: an inner thin film loop; and an outer thin film loop that at least partially circumscribes the inner thin film loop and that is in electrical contact with the SQUID. ### Claim 19 (depends on 13) The qubit control system of claim 13, wherein the qubit bias control device has a mutual inductance with the elongated thin film of between about 0.1 pH and 0.2 pH. ### Claim 20 (depends on 13) The qubit control system of claim 13, wherein the quantum device bias control device has a mutual inductance with the quantum device of about 0 pH. ### Claim 21 (canceled) ### Claim 22 A quantum processor comprising: a plurality of co-planar waveguide flux qubit devices, each co-planar waveguide flux qubit device comprising (a) an elongated thin film waveguide uninterrupted by Josephson junctions, (b) a quantum device in electrical contact with a first end of the elongated thin film waveguide, wherein the quantum device comprises less than three Josephson junctions and (c) a ground plane that is co-planar with the elongated thin film waveguide and is in electrical contact with the elongated thin film, wherein each co-planar waveguide flux qubit device is operatively coupled to each other co-planar waveguide flux qubit device in the quantum processor. ### Claim 23 (depends on 22) The quantum processor of claim 22 wherein the elongated thin film waveguide of each co-planar waveguide flux qubit crosses a plurality of elongated thin film waveguides associated with other co-planar waveguide flux qubits in the processor. ### Claim 24 (depends on 23) The quantum processor of claim 23, further comprising a plurality of inductive couplers, wherein each inductive coupler is arranged adjacent to a crossing between two elongated thin film waveguides associated with different co-planar waveguide flux qubits. ### Claim 25 (depends on 22) The quantum processor of claim 22, wherein the quantum device is a superconducting quantum interference device.