1.
Nafria, Vijay; Djordjevic, Ivan B.
Amplified entanglement-assisted communication systems operated in a desert environment and strong atmospheric turbulence regime Journal Article
In: Optics Express, vol. 32, no. 26, pp. 47561–47573, 2024, ISSN: 1094-4087, (Publisher: Optica Publishing Group).
Abstract | Links | BibTeX | Tags: Homodyne detection, Laser communications, Optical properties, Optical transceivers, Rayleigh scattering, Signal processing
@article{nafria_amplified_2024,
title = {Amplified entanglement-assisted communication systems operated in a desert environment and strong atmospheric turbulence regime},
author = {Vijay Nafria and Ivan B. Djordjevic},
url = {https://opg.optica.org/oe/abstract.cfm?uri=oe-32-26-47561},
doi = {10.1364/OE.543021},
issn = {1094-4087},
year = {2024},
date = {2024-12-01},
urldate = {2025-10-08},
journal = {Optics Express},
volume = {32},
number = {26},
pages = {47561–47573},
publisher = {Optica Publishing Group},
abstract = {In this paper, we are presenting results that go against the common belief that entanglement is destroyed by the amplification using an EDFA. Here we demonstrate the quantum advantage of entanglement-assisted communication at 10Gb/s, employing LDPC-coded BPSK, over classical laser communication even after the amplification of signal photons is performed by the EDFA in order to improve the reliability of entanglement-assisted (EA) communication operating in turbulent 1.5 km terrestrial FSO channels. To make the EA system more robust against various atmospheric effects such as scattering, absorption, and turbulence effects we perform the optical phase-conjugation on idler photons rather than turbulence-affected signal photons and use adaptive optics to make additional improvements in terms of the bit-error rate.},
note = {Publisher: Optica Publishing Group},
keywords = {Homodyne detection, Laser communications, Optical properties, Optical transceivers, Rayleigh scattering, Signal processing},
pubstate = {published},
tppubtype = {article}
}
In this paper, we are presenting results that go against the common belief that entanglement is destroyed by the amplification using an EDFA. Here we demonstrate the quantum advantage of entanglement-assisted communication at 10Gb/s, employing LDPC-coded BPSK, over classical laser communication even after the amplification of signal photons is performed by the EDFA in order to improve the reliability of entanglement-assisted (EA) communication operating in turbulent 1.5 km terrestrial FSO channels. To make the EA system more robust against various atmospheric effects such as scattering, absorption, and turbulence effects we perform the optical phase-conjugation on idler photons rather than turbulence-affected signal photons and use adaptive optics to make additional improvements in terms of the bit-error rate.
2.
Nafria, Vijay; Djordjevic, Ivan B.
In: Optics Express, vol. 32, no. 27, pp. 47908–47919, 2024, ISSN: 1094-4087, (Publisher: Optica Publishing Group).
Abstract | Links | BibTeX | Tags: Coupling efficiency, Laser communications, Optical systems, Optical transceivers, Phase conjugation, Signal transmission
@article{nafria_entanglement_2024,
title = {Entanglement assisted free-space optical communication with two-pump-based entanglement generation outperforming classical laser communication in strong turbulence regime at 10 Gb/s},
author = {Vijay Nafria and Ivan B. Djordjevic},
url = {https://opg.optica.org/oe/abstract.cfm?uri=oe-32-27-47908},
doi = {10.1364/OE.544674},
issn = {1094-4087},
year = {2024},
date = {2024-12-01},
urldate = {2025-10-08},
journal = {Optics Express},
volume = {32},
number = {27},
pages = {47908–47919},
publisher = {Optica Publishing Group},
abstract = {A high-speed entanglement assisted communication that operates at 10 Gb/s is proposed, which performs a highly efficient, PPLN-waveguide-based, entanglement generation by making the simultaneous use of S- and L-band pumps. The two-pump-based entanglement generation source satisfies the quasi-phase-matching-condition over the entire C-band. To improve the system reliability, our system performs the phase-conjugation on idler photons in contrast to conventional ways of performing the phase-conjugation on signal photons. To study the performance of the proposed entanglement-assisted system we have developed the 1.5 km long outdoor free-space optical (FSO) link at the University of Arizona campus. Experimental results indicate that the proposed entanglement-assisted system significantly outperforms the classical counterpart at 10 Gb/s, operated in strong turbulence regime. We also demonstrate that the traditional entanglement-assisted system performing the optical phase conjugation on signal photons at the receiver side is not operational at all in strong turbulence regime given that it is extremely difficult to perform the phase-conjugation on weak signal photons when the number of received photons is low. To improve the system performance the adaptive optics is performed on signal photons.},
note = {Publisher: Optica Publishing Group},
keywords = {Coupling efficiency, Laser communications, Optical systems, Optical transceivers, Phase conjugation, Signal transmission},
pubstate = {published},
tppubtype = {article}
}
A high-speed entanglement assisted communication that operates at 10 Gb/s is proposed, which performs a highly efficient, PPLN-waveguide-based, entanglement generation by making the simultaneous use of S- and L-band pumps. The two-pump-based entanglement generation source satisfies the quasi-phase-matching-condition over the entire C-band. To improve the system reliability, our system performs the phase-conjugation on idler photons in contrast to conventional ways of performing the phase-conjugation on signal photons. To study the performance of the proposed entanglement-assisted system we have developed the 1.5 km long outdoor free-space optical (FSO) link at the University of Arizona campus. Experimental results indicate that the proposed entanglement-assisted system significantly outperforms the classical counterpart at 10 Gb/s, operated in strong turbulence regime. We also demonstrate that the traditional entanglement-assisted system performing the optical phase conjugation on signal photons at the receiver side is not operational at all in strong turbulence regime given that it is extremely difficult to perform the phase-conjugation on weak signal photons when the number of received photons is low. To improve the system performance the adaptive optics is performed on signal photons.