Analysis of arbitrary superconducting quantum circuits accompanied by a Python package: SQcircuit
Abstract
Superconducting quantum circuits are a promising hardware platform for realizing a faulttolerant quantum computer. Accelerating progress in this field of research demands general approaches and computational tools to analyze and design more complex superconducting circuits. We develop a framework to systematically construct a superconducting quantum circuit's quantized Hamiltonian from its physical description. As is often the case with quantum descriptions of multicoordinate systems, the complexity rises rapidly with the number of variables. Therefore, we introduce a set of coordinate transformations with which we can find bases to diagonalize the Hamiltonian efficiently. Furthermore, we broaden our framework's scope to calculate the circuit's key properties required for optimizing and discovering novel qubits. We implement the methods described in this work in an opensource Python package SQcircuit. In this manuscript, we introduce the reader to the SQcircuit environment and functionality. We show through a series of examples how to analyze a number of interesting quantum circuits and obtain features such as the spectrum, coherence times, transition matrix elements, coupling operators, and the phase coordinate representation of eigenfunctions.
 Publication:

Quantum
 Pub Date:
 September 2023
 DOI:
 10.22331/q202309251118
 arXiv:
 arXiv:2206.08319
 Bibcode:
 2023Quant...7.1118R
 Keywords:

 Quantum Physics;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Physics  Applied Physics
 EPrint:
 23 pages, 6 figures. Accompanying SQcircuit package on https://sqcircuit.org/