Protected Symmetrical Superconducting Qubit Based on Quantum Flux Parametron

TL;DR

This paper introduces the Degenerium qubit, a symmetrical superconducting qubit based on quantum flux parametron principles, offering improved noise resilience and simplified fabrication for quantum computing.

Contribution

It proposes a novel qubit topology that combines 0-$\\pi$ and flux qubit principles, enhancing symmetry, control, and fabrication robustness.

Findings

Achieves depolarization time of 1.25 seconds.

Attains dephasing time of 90 microseconds.

Demonstrates insensitivity to fabrication variations.

Abstract

Conventional Quantum Flux Parametrons (QFPs) have historically been used for storing classical bits in Josephson junction-based computers. In this work, we propose a novel QFP-based topology dubbed "Degenerium" qubit, to process and compute quantum information. Degenerium combines principles from the 0-$\pi$ qubit and flux qubit to create ideally degenerate quantum ground states, while significantly simplifying the 0-$\pi$ qubit structure. The symmetrical design of Degenerium enables easier qubit control and fabrication. We demonstrate that due to the inherent symmetry of Degenerium, our designed qubit is insensitive to fabrication-induced variations in critical current ($I_c$) of the Josephson junctions. Our calculations of depolarization and dephasing rates due to charge, flux, and critical current noise sources result in depolarization and dephasing times of 1.25 s and 90 $\mu$s, respectively. Further parameter tuning and optimization is possible to meet specific application demands.