Robust excitation of C-band quantum dots for quantum communication

Abstract

Building a quantum internet requires efficient and reliable quantum hardware, from photonic sources to quantum repeaters and detectors, ideally operating at telecommunication wavelengths. Thanks to their high brightness and single-photon purity, quantum dot (QD) sources hold the promise to achieve high communication rates for quantum-secured network applications. Furthermore, it was recently shown that excitation schemes such as longitudinal acoustic phonon-assisted (LA) pumping provide security benefits by scrambling the coherence between the emitted photon-number states. In this work, we investigate further advantages of LA-pumped quantum dots with emission in the telecom C-band as a core hardware component of the quantum internet. We experimentally demonstrate how varying the pump power and spectral detuning with respect to the excitonic transition can improve quantum-secured communication rates and provide stable emission statistics regardless of network-environment fluctuations. These findings have significant implications for general implementations of QD single-photon sources in practical quantum communication networks.

High-rate intercity quantum key distribution with a semiconductor single-photon source

“…For convenience, we assume balanced efficiencies of the receiver ports and SNSPD channels for each polarisation basis. f E C describes the error correction inefficiency of the algorithm, p c indicates the total detection probability of the photon number states 43 , 44 .…”

“…In this experiment, the MTL for both the asymptotic and finite-key block cases are limited by the blinking-corrected g 2 (0), since the multi-photon emission probability is detrimental for generating high SKRs with single-photon states in the high-loss regime. The SKR and MTL can be improved by employing adequate pre-attenuation 46 and employing time gating on the histograms of second-order correlation and truth table during post-processing 44 , 50 .…”

“…In SPS-based QKD, the average photon number per pulse and single-photon purity are two essential parameters that must be considered in the QKD algorithm to calculate the secret key rate and the maximum tolerated loss. For the non-blinking SPS, the single-photon purity is typically assessed as 44 . However, the regular definition of g (2) (0) with blinking effect will be higher than the non-blinking g (2) (0), and this results in the underestimation of the single photon purity with .…”

Coherently and Incoherently Pumped Telecom C-Band Single-Photon Source with High Brightness and Indistinguishability

“…Contrary to coherent pumping by resonance fluorescence that typically requires cross-polarization-based filtering with intrinsic losses, the SUPER scheme allows for straightforward spectral filtering, making it appealing for high-efficiency single-photon sources. Incoherent operation of the source is achieved via longitudinal-acoustic phonon-assisted (LA) pumping with a blue-detuned laser that is, hence, again compatible with straightforward spectral filtering. , Thus, SUPER and LA act as complementary coherent and incoherent pumping schemes while the latter serves, furthermore, as a benchmark for the SUPER scheme that is novel for these telecom C-band QDs. Figure depicts the spectral relation between the addressed QD transition and the pump lasers for the employed pumping schemes schematically, showing the possibility of straightforward spectral filtering in both cases.…”