Quantum repeater without Bell measurements in double-quantum-dot systems

We propose a Bell measurement-free scheme to implement a quantum repeater in GaAs/AlGaAs double-quantum-dot systems. We prove that four pairs of double quantum dots compose an entanglement unit, given that the initial state is singlet states. Our scheme differs from the famous Duan–Lukin–Cirac–Zoller (DLCZ) protocol in that Bell measurements are unnecessary for the entanglement swapping, which provides great advantages and conveniences in experimental implementations. Our scheme significantly improves the success probability of quantum repeaters based on solid-state quantum devices.