scholarly journals NUMERICAL CHARACTERIZATION OF ATMOSPHERIC EFFECTS ON AN EARTH–SPACE QUANTUM COMMUNICATION CHANNEL

2007 ◽  
Vol 05 (01n02) ◽  
pp. 241-248 ◽  
Author(s):  
N. ANTONIETTI ◽  
M. MONDIN ◽  
G. BRIDA ◽  
M. GENOVESE
Keyword(s):  
Free Space ◽  
Communication Channel ◽  
Quantum Communication ◽  
Single Photon ◽  
Atmospheric Effects ◽  
Single Photons ◽  
Atmospheric Conditions ◽  
Numerical Characterization ◽  
Simulation Results

Quantum communication in free space is the next challenge of telecommunications. Since we want to determine the outcome of a quantum communication by means of single photons, we must understand how a single photon interacts with the atmosphere. In this brief article, some simulation results for realistic and generic atmospheric conditions are reported and discussed.

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.

Performance characterization of Pauli channels assisted by indefinite causal order and post-measurement

2020 ◽  
Vol 20 (15&16) ◽  
pp. 1261-1280
Author(s):  
Francisco Delgado ◽  
Carlos Cardoso-Isidoro
Keyword(s):  
Quantum Channel ◽  
Communication Channel ◽  
Quantum Communication ◽  
Quantum Channels ◽  
Causal Order ◽  
Combined Process ◽  
Performance Characterization ◽  
Output State ◽  
Transmission Of Information

Indefinite causal order has introduced disruptive procedures to improve the fidelity of quantum communication by introducing the superposition of { orders} on a set of quantum channels. It has been applied to several well characterized quantum channels as depolarizing, dephasing and teleportation. This work analyses the behavior of a parametric quantum channel for single qubits expressed in the form of Pauli channels. Combinatorics lets to obtain affordable formulas for the analysis of the output state of the channel when it goes through a certain imperfect quantum communication channel when it is deployed as a redundant application of it under indefinite causal order. In addition, the process exploits post-measurement on the associated control to select certain components of transmission. Then, the fidelity of such outputs is analysed to characterize the generic channel in terms of its parameters. As a result, we get notable enhancement in the transmission of information for well characterized channels due to the combined process: indefinite causal order plus post-measurement.

scholarly journals Ultrabright single-photon sources

Photoniques ◽  
2017 ◽  
pp. 23-26
Author(s):  
Pascale Senellart ◽  
Valérian Giesz ◽  
Loic Lanco
Keyword(s):  
Communication Network ◽  
Quantum Dots ◽  
Solid State ◽  
Quantum Communication ◽  
Single Photon ◽  
Single Photons ◽  
Cryogenic Temperatures ◽  
Optical Microcavity ◽  
Photon Sources ◽  
Lithography Technique

The development of a quantum communication network will require sources that efficiently emit single photons. Now, using a new lithography technique that garnered a silver CNRS medal in 2014, it has recently proved possible to fabricate these sources using quantum dots (QDs), that is, artificial solid-state atoms. Performed at cryogenic temperatures, this technique makes it possible to position a single QD in the middle of an optical microcavity with nanometric precision.

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 Single-Photon Single-Ion Interaction in Free Space Configuration in Front of a Parabolic Mirror

2012 ◽  
Vol 19 (04) ◽  
pp. 1250023 ◽  
Author(s):  
Magdalena Stobińska ◽  
Robert Alicki
Keyword(s):  
Free Space ◽  
Emission Rate ◽  
Single Photon ◽  
Polarization Degree ◽  
Single Photons ◽  
Parabolic Mirror ◽  
Mode Structure ◽  
Spontaneous Emission Rate ◽  
Parabolic Boundary ◽  
Metallic Mirror

The efficient interaction between single photons and single matter objects in free space is of key importance for quantum technologies. An experimental setup for testing this possibility involves single two-level ion trapped at the focus of a parabolic metallic mirror. We study the conditions for the setup, under which the assumption about the free-space mode structure of the radiation field in the vicinity of the atom is justified. In our analysis we apply vectorial properties of light by including the polarization degree of freedom. We look for possible changes in the spontaneous emission rate of the atom resulting from the presence of the parabolic boundary conditions.

scholarly journals MQC-MB: Multiphoton Quantum Communication Using Multiple-Beam Concept in Free Space Optical Channel

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 66
Author(s):  
Nur Ziadah Harun ◽  
Zuriati Ahmad Zukarnain ◽  
Zurina Mohd Hanapi ◽  
Idawaty Ahmad ◽  
Majed F. Khodr
Keyword(s):  
Free Space ◽  
Quantum Communication ◽  
Single Photon ◽  
Optical Channel ◽  
Quantum Model ◽  
Secret Key ◽  
Quantum Bit ◽  
Single Beam ◽  
Multiple Beam ◽  
The Impact

Multiphoton Quantum Key Distribution (QKD) has recently been proposed to exchange the secret keys using the rotational of polarization over a multi-stage protocol. It has the ability to outperform the weaknesses of a single photon QKD by improving the generation of key rate and distance range. This paper investigates the theoretical aspects of multiphoton QKD protocol’s performance over free space optic (FSO) networks. The most common setup for quantum communication is the single-beam approach. However, the single-beam setup has limitations in terms of high geometrical loss. In this paper, the symmetry multiple-beam for quantum communication which is called as Multiphoton Quantum Communication-Multiple Beam (MQC-MB) is proposed to transmit the multiphoton from the sender to the receiver in order to minimize the impact of geometrical loss that is faced by the single-beam setup. The analysis was carried out through mathematical analysis by establishing the FSO quantum model with the effects of atmospheric and geometrical loss as well as considering atmospheric turbulence modeled by log-normal distribution. The design criteria of FSO, such as the transmitter, receiver, beam divergence, and diameter of apertures, are analytically investigated. The numerical results demonstrate that the MQC-MB outperforms the single-beam in terms of reducing channel loss by about 8 dB and works well under strong turbulence channel. Furthermore, the MQC-MB reduces the quantum bit error rate (QBER) and improves the secret key rate (SKR) as compared to the single-beam system even though the distance between the sender and receiver increases.

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