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Abstract:

We present a framework for implementing two-qubit entangling operations between distant superconducting qubits using a space-time modulated Josephson junction (JJ) 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 $T_{\mu}\left(\mathrm{k}_{\mu} \cdot \mathrm{r}\right)$ 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.