Microwave irradiation and quasiparticles in a superconducting double dot
Physical Review B
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Lambert, N., Esmail, A., Pollock, F., Edwards, M., Lovett, B., & Ferguson, A. (2017). Microwave irradiation and quasiparticles in a superconducting double dot. Physical Review B, 95 (23)https://doi.org/10.1103/PhysRevB.95.235413
© 2017 American Physical Society. We study the interaction of the charge states of a superconducting double dot, comprising two superconducting islands coupled by a Josephson junction, with microwaves between 2 and 55 GHz. We observe resonant transitions between even-parity charge states at relatively low frequencies and breaking of Cooper pairs under higher-frequency irradiation, allowing our device to act as a click detector for microwave photons. By applying a magnetic field and tuning the pair-breaking energy, we perform spectroscopy on the environment in our cryostat and determine the temperature of a nonequilibrium photon bath. Finally, we exploit the band structure of our device to break Cooper pairs dependent on the symmetry of the initial Cooper pair state.
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External DOI: https://doi.org/10.1103/PhysRevB.95.235413
This record's URL: https://www.repository.cam.ac.uk/handle/1810/269728