Circuit theory for decoherence in superconducting charge qubits

TL;DR

This paper develops a comprehensive quantum circuit theory for superconducting charge qubits, incorporating circuit elements and dissipation to accurately analyze decoherence and leakage rates.

Contribution

It introduces a circuit-based quantum theory that accounts for full Hilbert space and circuit inductances, extending beyond traditional spin-boson models.

Findings

Calculates decoherence and leakage rates considering dissipative circuit elements.

Includes effects of self and mutual inductances in the analysis.

Provides a dual theory to flux qubit circuit models.

Abstract

Based on a network graph analysis of the underlying circuit, a quantum theory of arbitrary superconducting charge qubits is derived. Describing the dissipative elements of the circuit with a Caldeira-Leggett model, we calculate the decoherence and leakage rates of a charge qubit. The analysis includes decoherence due to a dissipative circuit element such as a voltage source or the quasiparticle resistances of the Josephson junctions in the circuit. The theory presented here is dual to the quantum circuit theory for superconducting flux qubits. In contrast to spin-boson models, the full Hilbert space structure of the qubit and its coupling to the dissipative environment is taken into account. Moreover, both self and mutual inductances of the circuit are fully included.