Microwave-coupled superconducting devices for sensing and quantum information processing: Dissertation

    Research output: ThesisDissertationCollection of Articles

    Abstract

    Superconducting circuits and devices have unique properties that make them interesting from both theoretical and practical perspective. In a superconductor cooled below its critical temperature, electrons bound in Cooper pairs have the ability to carry current without dissipation. A structure where the Cooper pairs are coherently tunneling across a weak link is called a Josephson junction (JJ). The dissipationless and non-linear character of the JJ has found applications, e.g., in microwave amplifiers and quantum circuits. These two subjects are closely related since superconducting quantum bits (qubits) are artificial atoms with a transition spectrum in the microwave range. Mediated by microwave photons, qubit readout in circuit quantum electrodynamics (cQED) architecture requires signal boosting with a lownoise preamplifier. In this thesis, a new type of ultrasensitive JJ microwave amplifier was characterized and its noise performance was found to be close to a bound set by quantum mechanics. The amplifier uses the intrinsic negative differential resistance of a current-biased JJ. This work also addressed a challenge related to the scalability of the cQED architecture when the qubits are weakly anharmonic. In a frequency-crowded multiqubit system, driving individual qubits may cause leakage into non-computational levels of the others. Leakage-avoiding single-qubit Wah-Wah control was implemented. At maximum gate speed corresponding to the frequency crowding, microwave control of two transmon qubits on a 2D cQED quantum processor was decoherence limited. The results disclose the usefulness of Wah-Wah in a future quantum computing platform. Quasiparticles are excitations from the paired superconducting ground state of conduction electrons. As the third topic, the generation-recombination dynamics of quasiparticles was employed in sensing. In electrodynamical terms, superconducting thin films have kinetic inductance from the inertia of the Cooper pairs and resistive dissipation from the quasiparticles. If the film is a part of an electrical resonator, quasiparticle density steers its microwave eigenfrequency and quality factor. In this work, submillimetre-wave radiation and external magnetic field were first converted into quasiparticle-generating temperature variations and screening currents in a superconductor, respectively. In the two devices called kinetic inductance bolometer and magnetometer, the corresponding changes in resonator parameters were read out to extract the encoded signal. Sensor characterization indicated potential for high sensitivity and low noise. Future applications of the bolometer and the magnetometer include security screening and biomagnetism, respectively. Here, multiplexability in frequency domain facilitates the scale-up to large sensor arrays.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Aalto University
    Supervisors/Advisors
    • Seppä, Heikki, Supervisor
    • Hassel, Juha, Supervisor
    Award date18 Jun 2015
    Place of PublicationEspoo
    Publisher
    Print ISBNs978-951-38-8311-9
    Electronic ISBNs978-951-38-8312-6
    Publication statusPublished - 2015
    MoE publication typeG5 Doctoral dissertation (article)

    Fingerprint

    superconducting devices
    microwaves
    Josephson junctions
    quantum electrodynamics
    microwave amplifiers
    bolometers
    inductance
    magnetometers
    biomagnetism
    leakage
    screening
    dissipation
    resonators
    crowding
    submillimeter waves
    theses
    preamplifiers
    sensors
    kinetics
    quantum computation

    Keywords

    • superconductivity
    • Josephson junction
    • superconducting qubit
    • singlequbit control
    • quantum-limited amplifier
    • kinetic inductance
    • submillimetre-wave detector
    • magnetometer

    Cite this

    @phdthesis{14d8b9383984458f9e03869c025f9608,
    title = "Microwave-coupled superconducting devices for sensing and quantum information processing: Dissertation",
    abstract = "Superconducting circuits and devices have unique properties that make them interesting from both theoretical and practical perspective. In a superconductor cooled below its critical temperature, electrons bound in Cooper pairs have the ability to carry current without dissipation. A structure where the Cooper pairs are coherently tunneling across a weak link is called a Josephson junction (JJ). The dissipationless and non-linear character of the JJ has found applications, e.g., in microwave amplifiers and quantum circuits. These two subjects are closely related since superconducting quantum bits (qubits) are artificial atoms with a transition spectrum in the microwave range. Mediated by microwave photons, qubit readout in circuit quantum electrodynamics (cQED) architecture requires signal boosting with a lownoise preamplifier. In this thesis, a new type of ultrasensitive JJ microwave amplifier was characterized and its noise performance was found to be close to a bound set by quantum mechanics. The amplifier uses the intrinsic negative differential resistance of a current-biased JJ. This work also addressed a challenge related to the scalability of the cQED architecture when the qubits are weakly anharmonic. In a frequency-crowded multiqubit system, driving individual qubits may cause leakage into non-computational levels of the others. Leakage-avoiding single-qubit Wah-Wah control was implemented. At maximum gate speed corresponding to the frequency crowding, microwave control of two transmon qubits on a 2D cQED quantum processor was decoherence limited. The results disclose the usefulness of Wah-Wah in a future quantum computing platform. Quasiparticles are excitations from the paired superconducting ground state of conduction electrons. As the third topic, the generation-recombination dynamics of quasiparticles was employed in sensing. In electrodynamical terms, superconducting thin films have kinetic inductance from the inertia of the Cooper pairs and resistive dissipation from the quasiparticles. If the film is a part of an electrical resonator, quasiparticle density steers its microwave eigenfrequency and quality factor. In this work, submillimetre-wave radiation and external magnetic field were first converted into quasiparticle-generating temperature variations and screening currents in a superconductor, respectively. In the two devices called kinetic inductance bolometer and magnetometer, the corresponding changes in resonator parameters were read out to extract the encoded signal. Sensor characterization indicated potential for high sensitivity and low noise. Future applications of the bolometer and the magnetometer include security screening and biomagnetism, respectively. Here, multiplexability in frequency domain facilitates the scale-up to large sensor arrays.",
    keywords = "superconductivity, Josephson junction, superconducting qubit, singlequbit control, quantum-limited amplifier, kinetic inductance, submillimetre-wave detector, magnetometer",
    author = "Visa Vesterinen",
    year = "2015",
    language = "English",
    isbn = "978-951-38-8311-9",
    series = "VTT Science",
    publisher = "VTT Technical Research Centre of Finland",
    number = "96",
    address = "Finland",
    school = "Aalto University",

    }

    Microwave-coupled superconducting devices for sensing and quantum information processing : Dissertation. / Vesterinen, Visa.

    Espoo : VTT Technical Research Centre of Finland, 2015. 148 p.

    Research output: ThesisDissertationCollection of Articles

    TY - THES

    T1 - Microwave-coupled superconducting devices for sensing and quantum information processing

    T2 - Dissertation

    AU - Vesterinen, Visa

    PY - 2015

    Y1 - 2015

    N2 - Superconducting circuits and devices have unique properties that make them interesting from both theoretical and practical perspective. In a superconductor cooled below its critical temperature, electrons bound in Cooper pairs have the ability to carry current without dissipation. A structure where the Cooper pairs are coherently tunneling across a weak link is called a Josephson junction (JJ). The dissipationless and non-linear character of the JJ has found applications, e.g., in microwave amplifiers and quantum circuits. These two subjects are closely related since superconducting quantum bits (qubits) are artificial atoms with a transition spectrum in the microwave range. Mediated by microwave photons, qubit readout in circuit quantum electrodynamics (cQED) architecture requires signal boosting with a lownoise preamplifier. In this thesis, a new type of ultrasensitive JJ microwave amplifier was characterized and its noise performance was found to be close to a bound set by quantum mechanics. The amplifier uses the intrinsic negative differential resistance of a current-biased JJ. This work also addressed a challenge related to the scalability of the cQED architecture when the qubits are weakly anharmonic. In a frequency-crowded multiqubit system, driving individual qubits may cause leakage into non-computational levels of the others. Leakage-avoiding single-qubit Wah-Wah control was implemented. At maximum gate speed corresponding to the frequency crowding, microwave control of two transmon qubits on a 2D cQED quantum processor was decoherence limited. The results disclose the usefulness of Wah-Wah in a future quantum computing platform. Quasiparticles are excitations from the paired superconducting ground state of conduction electrons. As the third topic, the generation-recombination dynamics of quasiparticles was employed in sensing. In electrodynamical terms, superconducting thin films have kinetic inductance from the inertia of the Cooper pairs and resistive dissipation from the quasiparticles. If the film is a part of an electrical resonator, quasiparticle density steers its microwave eigenfrequency and quality factor. In this work, submillimetre-wave radiation and external magnetic field were first converted into quasiparticle-generating temperature variations and screening currents in a superconductor, respectively. In the two devices called kinetic inductance bolometer and magnetometer, the corresponding changes in resonator parameters were read out to extract the encoded signal. Sensor characterization indicated potential for high sensitivity and low noise. Future applications of the bolometer and the magnetometer include security screening and biomagnetism, respectively. Here, multiplexability in frequency domain facilitates the scale-up to large sensor arrays.

    AB - Superconducting circuits and devices have unique properties that make them interesting from both theoretical and practical perspective. In a superconductor cooled below its critical temperature, electrons bound in Cooper pairs have the ability to carry current without dissipation. A structure where the Cooper pairs are coherently tunneling across a weak link is called a Josephson junction (JJ). The dissipationless and non-linear character of the JJ has found applications, e.g., in microwave amplifiers and quantum circuits. These two subjects are closely related since superconducting quantum bits (qubits) are artificial atoms with a transition spectrum in the microwave range. Mediated by microwave photons, qubit readout in circuit quantum electrodynamics (cQED) architecture requires signal boosting with a lownoise preamplifier. In this thesis, a new type of ultrasensitive JJ microwave amplifier was characterized and its noise performance was found to be close to a bound set by quantum mechanics. The amplifier uses the intrinsic negative differential resistance of a current-biased JJ. This work also addressed a challenge related to the scalability of the cQED architecture when the qubits are weakly anharmonic. In a frequency-crowded multiqubit system, driving individual qubits may cause leakage into non-computational levels of the others. Leakage-avoiding single-qubit Wah-Wah control was implemented. At maximum gate speed corresponding to the frequency crowding, microwave control of two transmon qubits on a 2D cQED quantum processor was decoherence limited. The results disclose the usefulness of Wah-Wah in a future quantum computing platform. Quasiparticles are excitations from the paired superconducting ground state of conduction electrons. As the third topic, the generation-recombination dynamics of quasiparticles was employed in sensing. In electrodynamical terms, superconducting thin films have kinetic inductance from the inertia of the Cooper pairs and resistive dissipation from the quasiparticles. If the film is a part of an electrical resonator, quasiparticle density steers its microwave eigenfrequency and quality factor. In this work, submillimetre-wave radiation and external magnetic field were first converted into quasiparticle-generating temperature variations and screening currents in a superconductor, respectively. In the two devices called kinetic inductance bolometer and magnetometer, the corresponding changes in resonator parameters were read out to extract the encoded signal. Sensor characterization indicated potential for high sensitivity and low noise. Future applications of the bolometer and the magnetometer include security screening and biomagnetism, respectively. Here, multiplexability in frequency domain facilitates the scale-up to large sensor arrays.

    KW - superconductivity

    KW - Josephson junction

    KW - superconducting qubit

    KW - singlequbit control

    KW - quantum-limited amplifier

    KW - kinetic inductance

    KW - submillimetre-wave detector

    KW - magnetometer

    M3 - Dissertation

    SN - 978-951-38-8311-9

    T3 - VTT Science

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -