Coupled mode theory for superconducting bosons: from Josephson harmonics to charge saturation

  • date:

    Dienstag, 05.08.2025, 11:00 Uhr

  • speaker:

    Thomas Maldonado
    Princeton University, USA

  • Abstract: In this talk, I'll explore the consequences of modeling Cooper pairs in superconducting circuits as non-relativistic spin-0 bosons. I'll outline a simple derivation of circuit quantum electrodynamics (QED) from scalar QED by applying coupled mode theory to the Josephson junction (JJ), thereby reproducing the standard circuit-geometric dependence of all relevant quantum computing parameters. Notable departures from prevailing theoretical treatments of the JJ include (1) a second harmonic in the Josephson current phase relation due to the nonlinear Coulomb interaction and (2) a voltage-induced redshift in the transmon spectrum due to charge saturation in finite-island geometries.