Modern methods of detecting single photons and their application in quantum communications

Single-photon frequency conversion for quantum interface plays an important role in quantum communications and networks, which is crucial for the realization of quantum memory, faithful entanglement swapping and quantum teleportation. In this chapter, we will present our recent experiments about single-photon frequency conversion based on quadratic nonlinear processes. Firstly, we demonstrated spectrum compression of broadband single photons at the telecom wavelength to the near-visible window, marking a critical step towards coherent photonic interface. Secondly, we demonstrated the nonlinear interaction between two chirped broadband single-photon-level coherent states, which may be utilized to achieve heralding entanglement at a distance. Finally, we theoretically introduced and experimentally demonstrated single-photon frequency conversion in the telecom band, enabling switching of single photons between dense wavelength-division multiplexing channels. Moreover, quantum entanglement between the photon pair is maintained after the frequency conversion. Our researches have realized three significant quantum interfaces via single-photon frequency conversion, which hold great promise for the development of quantum communications and networks.

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High-brightness source of heralded single photons for quantum communications from microstructured fibre

31st European Conference on Optical Communications (ECOC 2005) ◽

10.1049/cp:20050836 ◽

2005 ◽

Author(s):

O. Alibart

Keyword(s):

Single Photons ◽

Quantum Communications ◽

High Brightness ◽

Microstructured Fibre

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Indistinguishable Photons from a Single Molecule under Pulsed Excitation

EPJ Web of Conferences ◽

10.1051/epjconf/202125506002 ◽

2021 ◽

Vol 255 ◽

pp. 06002

Author(s):

Pietro Lombardi ◽

Maja Colautti ◽

Rocco Duquennoy ◽

Ghulam Murtaza ◽

Prosenjit Majumder ◽

...

Keyword(s):

Single Molecule ◽

Single Photon ◽

Low Cost ◽

Photon Emission ◽

Light Sources ◽

Single Photons ◽

Quantum Communications ◽

Ideal Quantum ◽

On Chip ◽

Key Resources

Quantum light sources are crucial for the future of quantum photonic technologies and, among them, single photons on-demand are key resources in quantum communications and information processing. Ideal quantum emitters providing indistinguishable photons in a clocked manner, negligible decoherence and spectral diffusion, and with potential for scalability are today still a major challenge. We report on photostable and indistinguishable single photon emission from dibenzoterrylene molecules isolated in anthracene nanocrystals (DBT:Ac NCs) at 3K. The visibility of two-photon interference is preserved even when they are separated more than thirty times the excited-state lifetime, or ten fluorescence cycles. One of the advantages of organic molecules is the low-cost mass production of nominally identical emitters, that also allow for on-chip integration. These aspects combined with high spectral stability and coherence make them promising for applications and future quantum technologies.

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Real-time shaping of entangled photons by classical control and feedback

Science Advances ◽

10.1126/sciadv.abb6298 ◽

2020 ◽

Vol 6 (37) ◽

pp. eabb6298 ◽

Cited By ~ 1

Author(s):

Ohad Lib ◽

Giora Hasson ◽

Yaron Bromberg

Keyword(s):

Real Time ◽

Quantum Correlations ◽

Great Promise ◽

Single Photons ◽

Entangled Photons ◽

Quantum Communications ◽

Recent Developments ◽

Wavefront Shaping ◽

Classical Control ◽

And Control

Quantum technologies hold great promise for revolutionizing photonic applications such as cryptography. Yet, their implementation in real-world scenarios is challenging, mostly because of sensitivity of quantum correlations to scattering. Recent developments in optimizing the shape of single photons introduce new ways to control entangled photons. Nevertheless, shaping single photons in real time remains a challenge due to the weak associated signals, which are too noisy for optimization processes. Here, we overcome this challenge and control scattering of entangled photons by shaping the classical laser beam that stimulates their creation. We discover that because the classical beam and the entangled photons follow the same path, the strong classical signal can be used for optimizing the weak quantum signal. We show that this approach can increase the length of free-space turbulent quantum links by up to two orders of magnitude, opening the door for using wavefront shaping for quantum communications.

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Broadband on-chip single-photon spectrometer

Nature Communications ◽

10.1038/s41467-019-12149-x ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 13

Author(s):

Risheng Cheng ◽

Chang-Ling Zou ◽

Xiang Guo ◽

Sihao Wang ◽

Xu Han ◽

...

Keyword(s):

Single Photon ◽

Astronomical Observation ◽

Single Element ◽

Single Photons ◽

Quantum Communications ◽

Wavelength Division ◽

Wavelength Division Multiplexed ◽

Small Device ◽

On Chip ◽

Wavelength Detection

Abstract Single-photon counters are single-pixel binary devices that click upon the absorption of a photon but obscure its spectral information, whereas resolving the color of detected photons has been in critical demand for frontier astronomical observation, spectroscopic imaging and wavelength division multiplexed quantum communications. Current implementations of single-photon spectrometers either consist of bulky wavelength-scanning components or have limited detection channels, preventing parallel detection of broadband single photons with high spectral resolutions. Here, we present the first broadband chip-scale single-photon spectrometer covering both visible and infrared wavebands spanning from 600 nm to 2000 nm. The spectrometer integrates an on-chip dispersive echelle grating with a single-element propagating superconducting nanowire detector of ultraslow-velocity for mapping the dispersed photons with high spatial resolutions. The demonstrated on-chip single-photon spectrometer features small device footprint, high robustness with no moving parts and meanwhile offers more than 200 equivalent wavelength detection channels with further scalability.

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