Sub-ns timing accuracy for satellite quantum communications

Abstract

Satellite quantum communications have rapidly evolved in the past few years, culminating in the proposal, development and deployment of satellite missions dedicated to Quantum Key Distribution and the realization of fundamental tests of quantum mechanics in space. However, in comparison with the more mature technology based on fiber optics, several challenges are still open, such as the capability of detecting with high temporal accuracy single photons coming from orbiting terminals. Satellite Laser Ranging, commonly used to estimate satellite distance, could also be exploited to overcome this challenge. For example, high repetition rates and low background noise can be obtained by determining the time-of-flight of faint laser pulses that are retro-reflected by geodynamics satellites and then detected on Earth at the single-photon level. Here we report on a experiment achieving a temporal accuracy of about 230 ps in the detection of an optical signal of few photons per pulse reflected by satellites in medium Earth orbit, at a distance exceeding 7500 km by using commercially available detectors. Lastly, the performance of the Matera Laser Ranging Observatory are evaluated in terms of detection rate and signal to noise ratio for satellite quantum communications.

Simulation of Silicon Waveguide Single-Photon Avalanche Detectors for Integrated Quantum Photonics

“…Long tails in the timing distribution can adversely affect applications requiring high timing accuracies, e.g. satellite-based quantum communications [39]. Therefore, we present the full-width-half-maximum (FWHM) and fullwidth-tenth-maximum (FWTM) timing jitter, both extracted from timing histograms with 1 ps bin size, to better describe the timing performance of the SPADs.…”

The Deep Space Quantum Link: Prospective Fundamental Physics Experiments using Long-Baseline Quantum Optics

“…The photon temporal superposition state along the space channel may be kept in a single polarization by exploiting suitable corner cube technology for the retroreflectors, as demonstrated for space quantum communications [43], thus allowing for a large parameter space for the observables under test; the latter use was pivotal in the test in space of the Wheeler "delayed choice Gedankenexperiment", addressing the well-known wave-particle duality of quantum physics [44,45]. We note that the scheme proposed in [41,42] exploits classical light in order to test the Einstein Equivalence Principle in the optical domain.…”

“…Finally, the temporal resolution for the discrimination of the interference is a sensible parameter for the experimental design. Present limits in the case of a link to a MEO satellite are of order of a quarter of nanosecond [45].…”

Quantum key distribution and beyond: introduction

“…This feature issue on QKD and beyond has a collection of work that addresses the above challenges. Agnesi et al demonstrate some new techniques for subnanosecond timing accuracy for satellite communications [1]. This will enable high-rate low-noise long-distance satellite QKD links to be established.…”