Long-Range Entangling Operations via Josephson Junction Metasurfaces

TL;DR

This paper introduces a novel method for entangling distant superconducting qubits using a space-time modulated Josephson junction metasurface, enabling high-fidelity operations over centimeter distances.

Contribution

It develops a reconfigurable metasurface platform that facilitates long-range entangling gates by engineering controllable wavevector sidebands, reducing proximity dependence.

Findings

Entangling fidelity exceeds 98% over centimeter-scale distances.

The metasurface enables selective coupling via engineered sidebands.

Long-range two-qubit gates are feasible with high fidelity.

Abstract

We present a framework for implementing two-qubit entangling operations between distant superconducting qubits using a space-time modulated Josephson junction metasurface. By modulating the surface in both space and time, we engineer sidebands with controllable wavevectors that selectively couple target qubits. The metasurface acts as a reconfigurable coupling medium, where the interaction strength is determined by engineered transmission coefficients rather than by exponentially decaying near-field coupling, thus reducing the dependence on physical proximity. We investigated the implementation of two-qubit interactions via iSWAP gates driven resonantly through the metasurface and controlled phase gates via geometric phase accumulation. Simulations show entangling fidelity exceeding 98% maintained over centimeter scale separations.