Ultra-high impedance superconducting circuits

dc.contributor.advisorManucharyan, Vladimir Een_US
dc.contributor.authorMencia, Raymonden_US
dc.contributor.departmentPhysicsen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2023-06-25T05:32:17Z
dc.date.available2023-06-25T05:32:17Z
dc.date.issued2023en_US
dc.description.abstractChains of Josephson junctions are known to produce some of the largest kinetic per unit-length inductance, which can exceed the conventional geometric one by about 104. However, the maximum total inductance is still limited by the stray capacitance of the chain, which results in parasitic self-resonances. This stray capacitance is unnecessarily large in most circuits due to the high dielectric constant of silicon or sapphire substrates used. Here, we explore a regime of ultra-high impedance superconducting circuits by introducing the technique of releasing the Josephson chain off the substrate. The ultra-high impedance regime (Z > 4xRQ ~ 25.8 kOhms) is realized by combining a maximal per-unit-length inductance with a minimal stray capacitance and demonstrating the highest impedance electromagnetic structures available today. We begin with suspended “telegraph” transmission lines, composed of 30,000+ junctions, and show that the wave impedance can exceed 5 x RQ (33 kOhms) while the line still maintains a negligible DC resistance. To quantify the effects of parasitic chain modes in ultra-high impedance circuits, we use high-inductance fluxonium qubits. We show that chain modes are ultra-strongly coupled to the qubit but can be moved to a higher frequency with the Josephson chain releasing technique. Finally, we create a superconducting quasicharge qubit (blochnium), dual of transmon, whose impedance reaches over 30 x RQ (200 kOhms) with no evidence of parasitic modes below 10 GHz. This qubit completes the periodic table of superconducting atoms and demonstrates the dual nature of a small Josephson junction in ultra-high impedance circuits, which we probe in a DC experiment in the final chapter.en_US
dc.identifierhttps://doi.org/10.13016/dspace/rk3w-adp0
dc.identifier.urihttp://hdl.handle.net/1903/30108
dc.language.isoenen_US
dc.subject.pqcontrolledQuantum physicsen_US
dc.subject.pqcontrolledNanotechnologyen_US
dc.subject.pqcontrolledLow temperature physicsen_US
dc.subject.pquncontrolledBlochniumen_US
dc.subject.pquncontrolledFluxoniumen_US
dc.subject.pquncontrolledJosephson junctionen_US
dc.subject.pquncontrolledSuperconducting circuitsen_US
dc.subject.pquncontrolledSuperconducting qubitsen_US
dc.subject.pquncontrolledTransmonen_US
dc.titleUltra-high impedance superconducting circuitsen_US
dc.typeDissertationen_US

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