Indistinguishable Entangled Photons Generated by a Light-Emitting Diode

Abstract

A linear optical quantum computer relies on interference between photonic qubits for logic, and entanglement for near-deterministic operation. Here we measure the interference and entanglement properties of photons emitted by a quantum dot embedded within a light-emitting diode. We show that pairs of simultaneously generated photons are entangled, and indistinguishable from subsequently generated photons. We measure entanglement fidelity of 0.87 and two-photon-interference visibility of 0.60 ± 0.05. The visibility, limited by detector jitter, could be improved by optical cavity designs.

Optimal excitation conditions for indistinguishable photons from quantum dots

“…In 2013, Gazzano et al showed that good indistinguishability can be achieved in a high brightness source [25]. Stevenson et al [26] showed that a diode structure can produce indistinguishable and entangled photons with electrical pumping. The first to show indistinguishable photons from the biexciton state were Müller et al in 2014 [13].…”

The role of phonon scattering in the indistinguishability of photons emitted from semiconductor cavity QED systems

“…The generation of indistinguishable single photons using continuous optical or electrical excitation [22][23][24][25] and pulsed electrical [26,27] excitation has been demonstrated. A relatively high two-photon interference visibility was achieved in electrically driven SPSs [27], despite the system being incoherently pumped and the absence of cavity QED effects in the experiment.…”

On-Demand Semiconductor Source of Entangled Photons Which Simultaneously Has High Fidelity, Efficiency, and Indistinguishability

“…To this end, tremendous progress has been reported in eliminating the fine structure splitting of neutral excitons [16][17][18], improving the extraction efficiency using double-micropillar structures [19] or broadband antennas [20][21][22], and enhancing the entanglement fidelity and photon indistinguishability using resonant excitation [23,24]. Encouragingly, the entanglement fidelity (A) and the photon indistinguishability (D) (for 2 ns separation) has reached 0.978(5) and 0.93 (7), respectively [18,24]. Very recently, the entanglement fidelity of 0.9 (A) was combined with a record-high pair efficiency of 0.37 per pulse, which is the product of the pair generation rate of 0.88 (B) and the extraction efficiency of 0.42 (C), on the same device [22].…”