Abstract
Entangled photons are an integral part in quantum optics experiments and a key resource in quantum imaging, quantum communication, and photonic quantum information processing. Making this resource available on-demand has been an ongoing scientific challenge with enormous progress in recent years. Of particular interest is the potential to transmit quantum information over long distances, making photons the only reliable flying qubit. Entangled photons at the telecom C-band could be directly launched into single-mode optical fibers, enabling worldwide quantum communication via existing telecommunication infrastructure. However, the on-demand generation of entangled photons at this desired wavelength window has been elusive. Here, we show a photon pair generation efficiency of 69.9 ± 3.6% in the telecom C-band by an InAs/GaAs semiconductor quantum dot on a metamorphic buffer layer. Using a robust phonon-assisted two-photon excitation scheme we measure a maximum concurrence of 91.4 ± 3.8% and a peak fidelity to the Φ+ state of 95.2 ± 1.1%, verifying on-demand generation of strongly entangled photon pairs and marking an important milestone for interfacing quantum light sources with our classical fiber networks.
Highlights
Entangled photons are an integral part in quantum optics experiments and a key resource in quantum imaging, quantum communication, and photonic quantum information processing
In recent years semiconductor quantum dots have emerged as strong competitors due to their promise of deterministic qubit generation, based on their unrivaled emission of on-demand single photons[15−18] and entangled photon pairs.[17−23] These outstanding properties hinge on the emission of photons via the radiative biexciton−exciton cascade, emitting polarization-entangled photon pairs.[24]
We have demonstrated on-demand emission of polarization entangled photon pairs from an InAs/GaAs quantum dot in the telecom C-band
Summary
We have demonstrated on-demand emission of polarization entangled photon pairs from an InAs/GaAs quantum dot in the telecom C-band. The high-quality entanglement that we are generating with our source is based on the state preparation via the phonon-assisted two-photon excitation scheme, combined with a good enough time resolution of our detection system compared to the fine-structure splitting of our quantum dot. The industrygrade growth technique of the used quantum dots allows for wide availability of entangled photon emitters in the telecom C-band in the future and is, a promising candidate for providing feasible sources for deployment in fiber-based quantum networks. The high level of concurrence in combination with the resilient phonon-assisted excitation scheme has strong potential for any application relying on remote sources of entangled photons.
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