Structural instability of driven Josephson circuits prevented by an inductive shunt

TL;DR

This paper demonstrates that adding an inductive shunt to driven Josephson circuits enhances their stability under strong parametric drives, enabling better control for quantum applications.

Contribution

The authors introduce an inductively shunted transmon design and a new numerical method to predict and prevent instabilities in driven superconducting circuits.

Findings

Inductive shunt extends stable pump power range.

Novel numerical approach avoids perturbative limitations.

Enhanced stability for strong drives in superconducting circuits.

Abstract

Superconducting circuits are a versatile platform to implement a multitude of Hamiltonians which perform quantum computation, simulation and sensing tasks. A key ingredient for realizing a desired Hamiltonian is the irradiation of the circuit by a strong drive. These strong drives provide an in-situ control of couplings, which cannot be obtained by near-equilibrium Hamiltonians. However, as shown in this paper, out-of-equilibrium systems are easily plagued by complex dynamics leading to instabilities. Predicting and preventing these instabilities is crucial, both from a fundamental and application perspective. We propose an inductively shunted transmon as the elementary circuit optimized for strong parametric drives. Developing a novel numerical approach that avoids the built-in limitations of perturbative analysis, we demonstrate that adding the inductive shunt significantly extends the range of pump powers over which the circuit behaves in a stable manner.