Generation of a Maximally Entangled State Using Collective Optical Pumping

We propose and implement a novel scheme for dissipatively pumping two qubits into a singlet Bell state. The method relies on a process of collective optical pumping to an excited level, to which all states apart from the singlet are coupled. We apply the method to deterministically entangle two trapped Ca-40(+) ions. Within 16 pumping cycles, an initially separable state is transformed into one with 83(1)% singlet fidelity, and states with initial fidelity of >= 70% converge onto a fidelity of 93(1)%. We theoretically analyze the performance and error susceptibility of the scheme and find it to be insensitive to a large class of experimentally relevant noise sources.

Automated summary

This study proposes and implements a novel scheme for converting two qubits into a singlet Bell state through dissipative pumping. The method utilizes collective optical pumping to an excited level, allowing for deterministic entanglement of two trapped ions. The results show that a high fidelity singlet state can be achieved within a certain number of pumping cycles.