Deterministic generation of entanglement between a quantum-dot spin and a photon

We propose a method for deterministic generation of entanglement between a quantum-dot spin and a photon. Entanglement is established by an elastic scattering event from a cavity that is strongly coupled to a singly charged quantum dot. Due to the elastic nature of the interaction, the energy of the photon does not become entangled with the quantum dot, eliminating the need for temporal postselection. We derive an analytical expression for fidelity of the generated entangled state and investigate its behavior under realistic experimental conditions. We show that entanglement fidelities exceeding 0.974 can be realized using currently achievable quantum-dot cavity quantum electrodynamics systems.

Figure 1

(a) Proposed scheme for entangling a quantum-dot spin and a photon. (b) Energy-level structure for a singly charged quantum dot.

Figure 2

(a) Entanglement fidelity as a function of the cooperativity $C_{\uparrow }$ for several different values of the magnetic field magnitude $B$. (b) Optimal fidelity as a function of the magnetic field magnitude $B$.

Figure 3

Entanglement fidelity as a function of the photon pulse width (blue solid line). The red dashed line indicates the fidelity in the quasimonochromatic limit.

Figure 4

Entanglement fidelity as a function of the polarization misalignment angle θ for several different values of the magnetic field magnitude $B$.