Fast generation of Schr\"odinger cat states in a Kerr-tunable superconducting resonator

TL;DR

This paper introduces a fast, scalable method to generate and store Schr"odinger cat states in a superconducting circuit by modulating Kerr nonlinearity, achieving high fidelity in a short time.

Contribution

The authors demonstrate a novel Kerr-tuning approach for rapid cat state generation and passive preservation in a chip-based superconducting resonator.

Findings

Achieved 89.1% fidelity in 96 ns

Successfully generated 2-component cat states

Passive preservation at Kerr-free point

Abstract

Schr\"odinger cat states, quantum superpositions of macroscopically distinct classical states, are an important resource for quantum communication, quantum metrology and quantum computation. Especially, cat states in a phase space protected against phase-flip errors can be used as a logical qubit. However, cat states, normally generated in three-dimensional cavities, are facing the challenges of scalability and controllability. Here, we present a novel strategy to generate and store cat states in a coplanar superconducting circuit by the fast modulation of Kerr nonlinearity. At the Kerr-free work point, our cat states are passively preserved due to the vanishing Kerr effect. We are able to prepare a 2-component cat state in our chip-based device with a fidelity reaching 89.1% under a 96 ns gate time. Our scheme shows an excellent route to constructing a chip-based bosonic quantum processor.