Cavity polariton blockade for non-local entangling gates with trapped atoms
Vineesha Srivastava, Sven Jandura, Gavin K. Brennen, Guido Pupillo · Quantum Science and Technology · 2025
Abstract We propose a scheme for realizing multi-qubit entangled W-state and non-local CZ and C 2 Z gates via a cavity polariton blockade mechanism with a system of atomic qubits coupled to a common cavity mode. The polariton blockade is achieved by tuning the system, an N − qubit register, such that no two atoms are simultaneously excited to the qubit excited state, and there is an effective coupling only between the ground state and a singly-excited W state of the qubit register. The control step requires only an external drive of the cavity mode and a global qubit pulse and no individual qubit addressing. We analytically obtain the state preparation error upper bound for an N − qubit W state which scales as ( 1 − 1 / N ) / C where C is the single particle cooperativity. We additionally show the application of the polariton blockade mechanism in realizing a non-local CZ and C 2 Z gate by using a different set of computational qubit states, and characterize the gate infidelity upper bounds which scale as ∼ 1 / C .