Circuit quantization with time-dependent magnetic fields for realistic geometries

npj Quantum Information, vol. 8

Abstract

Abstract Quantum circuit theory has become a powerful and indispensable tool to predict the dynamics of superconducting circuits. Surprisingly however, the question of how to properly account for a time-dependent driving via external magnetic fields has hardly been addressed so far. Here, we derive a general recipe to construct a low-energy Hamiltonian, taking as input only the circuit geometry and the solution of the external magnetic fields. We find that the interplay of geometry and field distribution leads to a much richer circuit dynamics than commonly anticipated, already in devices as simple as the superconducting quantum interference device (SQUID). These dynamics can be captured by assigning negative, time-dependent or even momentarily singular capacitances to the Josephson junctions. Negative capacitances give rise to a strong enhancement of the qubit relaxation rates, while time-dependent capacitances lead to a finite Berry phase.

Authors 2

1. Roman-Pascal Riwar

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich, Germany

   Peter Grünberg Institute, Theoretical Nanoelectronics, Jülich, Germany

   Peter Grünberg Institute, Theoretical Nanoelectronics, D-52425, Jülich, Germany

2. David Peter Divincenzo Aachen Institute for Quantum Information

   RWTH Aachen University · Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Institute for Quantum Information, RWTH Aachen University, Aachen, Germany

   Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich, Germany

   Peter Grünberg Institute, Theoretical Nanoelectronics, Jülich, Germany

   Peter Grünberg Institute, Theoretical Nanoelectronics, D-52425, Jülich, Germany