Adjustable entanglement enhancement via approaching to higher-order exceptional points in non-Hermitian network system

Abstract

We propose an enhanced entanglement generation scheme in the non-Hermitian system by introducing an ancillary qubit with adjustable driven field to control the target entanglement, making this model more suitable for the switch operation at the quantum interface. Moreover, through adiabatic elimination, the mode of the qubit has been eliminated, and direct coupling between the cavities has been realized. The effective coupling strength between two non-Hermitian microwave cavities can be adjusted as an optimal value to satisfy a specific phase condition that realizes the maximally entangled state on a timescale. To prove the ability of our scheme to improve the performances of entanglement generation in the non-Hermitian system, the numerical simulations are performed based on a model where two microwave cavities are indirectly coupled through a superconducting qubit. It is evident that non-Hermitian cavities can be entangled significantly faster than Hermitian cavities, with the relative speedup increasing significantly as the perturbation is decreased, and the fourth-order exceptional points at J=0 are approached. Last but not least, our scheme has good robustness against parameter errors, crosstalk, and Gaussian white noise and is a feasible scheme for enhanced entanglement generation via approaching to higher-order exceptional points in a non-Hermitian network system.