Dephasing-induced leakage in multi-level superconducting quantum circuits

TL;DR

This paper investigates how dephasing causes leakage into non-computational states in superconducting qubits, analyzing the phenomenon through both analytical and numerical methods to understand its impact on quantum operations.

Contribution

It provides a detailed analysis of dephasing-induced leakage in multi-level superconducting circuits, highlighting its significance beyond ideal control scenarios.

Findings

Dephasing leads to leakage during quantum operations.

Leakage is analytically characterized for common gates.

Numerical simulations confirm the analytical predictions.

Abstract

Superconducting quantum circuits, such as the transmon, have multiple quantum states beyond the computational subspace. These states can be populated during quantum logic operations; residual population in such states is known as leakage. While control methods can eliminate this error in ideal systems, leakage will arise from transient population in the presence of dephasing. This dephasing-induced leakage effect is analyzed, both analytically and numerically, for common single and two-qubit operations used in transmon-based approaches to quantum information processing.