Superconducting qubit without Josephson junctions manipulated by the orbital angular momentum of light

TL;DR

This paper proposes a new type of superconducting qubit that uses the orbital angular momentum of light for control, eliminating the need for Josephson junctions and enabling faster, more reliable quantum operations.

Contribution

It introduces a superconducting qubit design without Josephson junctions, utilizing light's orbital angular momentum for control, simplifying fabrication and improving qubit lifetime.

Findings

Qubit lifetime is extended due to absence of junction resistance.

Sub-nanosecond single- and two-qubit gate operations are achieved.

Fabrication process is simplified, reducing device variability.

Abstract

Conventional superconducting qubits have used Josephson junctions as an essential part to provide anharmonicity for well-separated energy-level spacings. However, because a superconducting ring without Josephson junctions has intrinsically well-separated energy-level spacings, Josephson junctions are not necessary as long as one can achieve single-qubit operations. We show that the orbital angular momentum of light can be adopted as a qubit-control means and can eliminate the need for Josephson junctions. The feasibility study reveals that the proposed qubit has many advantages over the previous ones. The lifetime of the qubit is extended due to the lack of the junction resistance. Very fast (sub-nanosecond) qubit manipulation in both single- and two-qubit gate is achieved. Without Josephson junctions, the fabrication process is simple and the deviations in the characteristics of each qubit can be improved.