Deterministic entanglement between a propagating photon and a singlet--triplet qubit in an optically active quantum dot molecule

Abstract

Two-electron charged self-assembled quantum dot molecules exhibit a decoherence-avoiding singlet-triplet qubit subspace and an efficient spin-photon interface. We demonstrate quantum entanglement between emitted photons and the spin-qubit after the emission event. We measure the overlap with a fully entangled state to be $69.5\pm 2.7\%$, exceeding the threshold of $50\%$ required to prove the non-separability of the density matrix of the system. The photonic qubit is encoded in two photon states with an energy difference larger than the timing resolution of existing detectors. We devise a novel heterodyne detection method, enabling projective measurements of such photonic color qubits along any direction on the Bloch sphere.

References in corpus (2)

• Ultrafast optical control of entanglement between two quantum dot spins
• Quantum interface between photonic and superconducting qubits

Cited by in corpus (9)

• Optical spin locking of a solid-state qubit
• Quantum dot molecule devices with optical control of charge status and electronic control of coupling
• Second-order photon correlation measurement with picosecond resolution
• Generation of frequency sidebands on single photons with indistinguishability from quantum dots
• Multipartite entanglement generation in coupled microcavity arrays
• NOON state generation with phonons in acoustic wave resonators assisted by a nitrogen-vacancy-center ensemble
• Coherence limitations in the optical control of the singlet-triplet qubit in a quantum dot molecule
• Precision of the acoustic control of single photon scattering with semiconductor quantum dots
• Hybrid acousto-optical spin control in quantum dots