scholarly journals Observing quantum coherence from photons scattered in free-space

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Shihan Sajeed ◽  
Thomas Jennewein
Keyword(s):  
Free Space ◽  
Quantum Coherence ◽  
Quantum Communication ◽  
Single Photon ◽  
Detector Array ◽  
Line Of Sight ◽  
Background Suppression ◽  
Single Photon Detector ◽  
High Background ◽  
Non Line Of Sight

AbstractQuantum channels in free-space, an essential prerequisite for fundamental tests of quantum mechanics and quantum technologies in open space, have so far been based on direct line-of-sight because the predominant approaches for photon-encoding, including polarization and spatial modes, are not compatible with randomly scattered photons. Here we demonstrate a novel approach to transfer and recover quantum coherence from scattered, non-line-of-sight photons analyzed in a multimode and imaging interferometer for time-bins, combined with photon detection based on a 8 × 8 single-photon-detector-array. The observed time-bin visibility for scattered photons remained at a high 95% over a wide scattering angle range of −450 to +450, while the individual pixels in the detector array resolve or track an image in its field of view of ca. 0.5°. Using our method, we demonstrate the viability of two novel applications. Firstly, using scattered photons as an indirect channel for quantum communication thereby enabling non-line-of-sight quantum communication with background suppression, and secondly, using the combined arrival time and quantum coherence to enhance the contrast of low-light imaging and laser ranging under high background light. We believe our method will instigate new lines for research and development on applying photon coherence from scattered signals to quantum sensing, imaging, and communication in free-space environments.

scholarly journals A low-noise single-photon detector for long-distance free-space quantum communication

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Elena Anisimova ◽  
Dmitri Nikulov ◽  
Simeng Simone Hu ◽  
Mark Bourgon ◽  
Sebastian Philipp Neumann ◽  
...  
Keyword(s):  
Free Space ◽  
Quantum Communication ◽  
Detection Efficiency ◽  
Single Photon ◽  
Avalanche Photodiode ◽  
Low Noise ◽  
Photon Detector ◽  
Single Photon Detector ◽  
Long Distance ◽  
Communication Links

AbstractWe build and test a single-photon detector based on a Si avalanche photodiode Excelitas 30902SH thermoelectrically cooled to −100∘C. Our detector has dark count rate below 1 Hz, $500\ \mu\mathrm{m}$ 500 μ m diameter photosensitive area, photon detection efficiency around 50%, afterpulsing less than 0.35%, and timing jitter under 1 ns. These characteristics make it suitable for long-distance free-space quantum communication links, which we briefly discuss. We also report an improved method that we call long-time afterpulsing analysis, used to determine and visualise long trap lifetimes at different temperatures.

scholarly journals Fast-Gated 16 × 1 SPAD Array for Non-Line-of-Sight Imaging Applications

Instruments ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 14
Author(s):  
Marco Renna ◽  
Ji Hyun Nam ◽  
Mauro Buttafava ◽  
Federica Villa ◽  
Andreas Velten ◽  
...  
Keyword(s):  
Single Photon ◽  
Photon Counting ◽  
Complementary Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Line Of Sight ◽  
Single Photon Detector ◽  
Single Photon Counting ◽  
Timing Resolution ◽  
Fast Gating ◽  
Non Line Of Sight

In this paper we present a novel single-photon detector specifically designed for Non-Line-Of-Sight (NLOS) imaging applications within the framework of the DARPA REVEAL program. The instrument is based on a linear 16 × 1 Complementary Metal-Oxide-Semiconductor (CMOS) Single-Photon Avalanche Diode (SPAD) array operated in fast-gated mode by a novel fast-gating Active Quenching Circuit (AQC) array, which enables the detectors with sub-ns transitions thanks to a SPAD-dummy approach. The detector exhibits a timing resolution better than 50 ps (Full Width at Half Maximum - FWHM) at a measurement repetition rate up to 40 MHz, and provides 16 independent outputs compatible with commercial Time-Correlated Single-Photon Counting (TCSPC) instrumentation. The instrument has been experimentally characterized and operated in preliminary NLOS imaging acquisitions where a 40 × 60 cm hidden object is successfully reconstructed by scanning over a grid of 150 × 150 positions.

scholarly journals Photon-counting distributed free-space spectroscopy

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Saifen Yu ◽  
Zhen Zhang ◽  
Haiyun Xia ◽  
Xiankang Dou ◽  
Tengfei Wu ◽  
...  
Keyword(s):  
Spectrum Analysis ◽  
Free Space ◽  
Single Photon ◽  
Photon Counting ◽  
Wide Band ◽  
Atmospheric Environment ◽  
Molecular Spectra ◽  
Single Photon Detector ◽  
Range Resolution ◽  
Biomedical Diagnostics

AbstractSpectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances, from quantum descriptions to chemical and biomedical diagnostics. Challenges exist in accurate spectrum analysis in free space, which hinders us from understanding the composition of multiple gases and the chemical processes in the atmosphere. A photon-counting distributed free-space spectroscopy is proposed and demonstrated using lidar technique, incorporating a comb-referenced frequency-scanning laser and a superconducting nanowire single-photon detector. It is suitable for remote spectrum analysis with a range resolution over a wide band. As an example, a continuous field experiment is carried out over 72 h to obtain the spectra of carbon dioxide (CO2) and semi-heavy water (HDO, isotopic water vapor) in 6 km, with a range resolution of 60 m and a time resolution of 10 min. Compared to the methods that obtain only column-integrated spectra over kilometer-scale, the range resolution is improved by 2–3 orders of magnitude in this work. The CO2 and HDO concentrations are retrieved from the spectra acquired with uncertainties as low as ±1.2% and ±14.3%, respectively. This method holds much promise for increasing knowledge of atmospheric environment and chemistry researches, especially in terms of the evolution of complex molecular spectra in open areas.

scholarly journals Long-range depth imaging using a single-photon detector array and non-local data fusion

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Susan Chan ◽  
Abderrahim Halimi ◽  
Feng Zhu ◽  
Istvan Gyongy ◽  
Robert K. Henderson ◽  
...  
Keyword(s):  
Data Fusion ◽  
Long Range ◽  
Single Photon ◽  
Detector Array ◽  
Photon Detector ◽  
Local Data ◽  
Single Photon Detector ◽  
Depth Imaging ◽  
Non Local

scholarly journals A Single-Shot Non-Line-of-Sight Range-Finder

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4820 ◽  
Author(s):  
James Brooks ◽  
Daniele Faccio
Keyword(s):  
Autonomous Vehicles ◽  
Arrival Time ◽  
Single Photon ◽  
Photon Counting ◽  
Line Of Sight ◽  
Single Shot ◽  
Single Photon Counting ◽  
Range Finding ◽  
Finding Method ◽  
Non Line Of Sight

The ability to locate a target around a corner is crucial in situations where it is impractical or unsafe to physically move around the obstruction. However, current techniques are limited to long acquisition times as they rely on single-photon counting for precise arrival time measurements. Here, we demonstrate a single-shot non-line-of-sight range-finding method operating at 10 Hz and capable of detecting a moving human target up to distances of 3 m around a corner. Due to the potential data acquisition speeds, this technique will find applications in search and rescue and autonomous vehicles.

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