A magnetic field concentrating or guiding device can include one or more coils, and one or more foil, tape and/or bulk superconductor structures disposed in one or more predetermined positions with relation to the coils. The one or more superconductor structures can form one or more magnetic field carrying regions. During operation, current passing through the one or more coils can generate one or more magnetic fields that are compressed or guided in the magnetic field carrying regions.

Techniques for creating a low pass filter associated with a flux line are presented. A qubit device can comprise a first substrate and second substrate. A low pass filter, comprising at least one inductor and at least one capacitor can be formed, wherein respective components of or associated with the low pass filter can be formed on the first or second substrates, and wherein one or more bump bonds can extend between the substrates to connect respective components that are on respective substrates. The filter can receive an input signal via an input line and filter the signal to produce a filtered signal as output to a flux line that is in proximity to a coupler with SQUID loop and one or more flux-tunable qubits that are formed on one of the substrates. The filter can reduce electrical noise and Purcell decay associated with the flux line.

Described herein are structures that include flux bias lines for controlling frequencies of qubits in quantum circuits. An exemplary structure includes a substrate, a qubit provided over a surface of the substrate, and a flux bias line provided below the surface of the substrate and configured to control the frequency of the qubit via a magnetic field generated as a result of a current flowing through the flux bias line. Methods for fabricating such structures are disclosed as well.

Described herein are structures that include flux bias lines for controlling frequencies of qubits in quantum circuits. An exemplary structure includes a substrate, a qubit provided over a surface of the substrate, and a flux bias line provided below the surface of the substrate and configured to control the frequency of the qubit via a magnetic field generated as a result of a current flowing through the flux bias line. Methods for fabricating such structures are disclosed as well.

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 quantum interference device according to the present invention includes a light generating unit configured to generate an excitation light having at least two frequency components, an alkali metal atom cell to which the excitation lights are emitted, a light detecting unit configured to detect a transmitted light from the alkali metal atom cell, and a control unit configured to execute a frequency determination process to determine a resonance frequency in a quantum interference state to be a reference based on the transmitted light. Then, the control unit is configured to detect resonance frequencies in at least two quantum interference states from the transmitted light, and control the frequency determination process based on the detected resonance frequencies in the at least two quantum interference states and magnetic field information representing preset variation amounts of the resonance frequencies in the at least two quantum interference states with respect to a magnetic field.

A quantum Hall resistance apparatus is to improve resistance standards and includes a substrate, a graphene epitaxially grown on the substrate and having a plurality of first contact patterns at edges of the graphene, a plurality of contacts, each including a second contact pattern and configured to connect to a corresponding first contact pattern, and a protective layer configured to protect the graphene and to increase adherence between the first contact patterns and the second contact patterns. The contacts become a superconductor at a temperature lower than or equal to a predetermined temperature and under up to a predetermined magnetic flux density.

A quantum Hall resistance apparatus is to improve resistance standards and includes a substrate, a graphene epitaxially grown on the substrate and having a plurality of first contact patterns at edges of the graphene, a plurality of contacts, each including a second contact pattern and configured to connect to a corresponding first contact pattern, and a protective layer configured to protect the graphene and to increase adherence between the first contact patterns and the second contact patterns. The contacts become a superconductor at a temperature lower than or equal to a predetermined temperature and under up to a predetermined magnetic flux density.

A magnetic field detector for detecting magnetic fields over a broad operational temperature range comprising: a plurality of Josephson junctions connected to each other by superconducting interconnecting paths, wherein the plurality of Josephson junctions are arranged in an array; and wherein the superconducting interconnecting paths connecting the plurality of Josephson junctions in the array are designed to not all have a uniform cross-sectional geometry with respect to each other.

A superconducting quantum processor unit for quantum computing is provided. The processor unit is formed from the union of a qubit chip and a wiring chip with superconducting bonding bumps and spacers. The bumps may be densely distributed around active elements between the two chips and effectively form a Faraday-Cage around the qubits, control signal waveguides etc. The qubit chip has strategically spaced qubits and an inductively coupled probe line and the wiring chip has a bus coupling resonator with a number of voltage nodes and anti-nodes, a resonator pump and at least one SQUID. Magnetic flux applied through the SQUIDs changes their impedances and modifies the microwave boundary conditions of the bus. This allows in-situ shifting of electric field distributions of the resonance modes of the bus along the length of the bus. This tunes the coupling rates of the bus to all qubits simultaneously.