Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE Access

Low-Complexity Degenerate Entanglement-Assisted Detection, Radars, LiDARs, and Triple-Function Radar-Communication-LiDAR System

Ivan B. Djordjević

Published Jan 1, 2026• 0 citations
Publisher

Abstract

We propose a low-complexity degenerate entanglement-assisted (DEA) system suitable for radar, communication, and LiDAR applications. The proposed DEA system employs on transmitter side a continuous wave (CW) dual-pump-based approach, a type-0 periodically poled lithium niobate (PPLN) waveguide, an optical bandpass filter, and a proposed single-drive Mach-Zehnder modulator. On receiver side, for communication and radar applications, the proposed balanced receiver is used as the entanglement-assisted detector. For LiDAR applications, on the other hand, the DEA detector array is used on receiver side. Two independent CW pump lasers operated at telecom wavelengths are employed in the dual-pump-based approach. For radar and LiDAR applications, the portion of degenerate entangled photons is employed as the reference signal and the rest to transmit the probe signal. We also propose a DEA triple-function radar-communication-LiDAR system. To demonstrate the quantum advantage, we conducted 1 Gb/s DEA radar and communication experiments over terrestrial free-space optical (FSO) link at the University of Arizona campus, between ECE Dept. and Optical Sciences Meinel buildings. We demonstrate that in the presence of the atmospheric turbulence in the saturation regime the proposed low-complexity DEA quantum radar and communication system outperform significantly corresponding classical counterparts.

DOI
10.1109/access.2026.3727001

Related papers

Low-Complexity Degenerate Entanglement- Assisted Communication Systems for Strong Atmospheric Turbulence Channels

Ivan B. Djordjević

We propose a low-complexity degenerate entanglement-assisted free-space optical (FSO) communication system employing a two-pumps approach, a type-0 periodically poled lithium niobate (PPLN) waveguide, a multistage WDM demultiplexer, and a properly biased Mach-Zehnder modulator on transmitter side and, for binary phase-shift keying (BPSK) signaling, a single PIN photodetector or avalanche photodetector (APD) on a receiver side. Two-pumps-based approach utilizes two independent pump lasers operating at telecom wavelengths. The portion of degenerate entangled photons is used as the unmodulated carrier and the rest to transmit the modulated PSK/quadrature amplitude modulation (QAM) signal. The unmodulated portion of entangled photons is selected by properly choosing the bias voltage and phase representing the transmitted bits. In BPSK signaling, the unmodulated carrier photons are used on receiver side to reconstruct the transmitted symbol by beating them with modulated signal photons on either PIN photodetector or APD. We also describe how to implement the M-ary PSK and QAM transmitters for the degenerate entanglement assisted communications. Further, we propose a low-complexity PSK/QAM demodulator compatible with the proposed degenerate entanglement assisted communication concept. To demonstrate the quantum advantage, we conducted 1 Gb/s degenerate entanglement assisted BPSK experiments over a 1.5 km terrestrial FSO link we have developed previously at the University of Arizona, between ECE Dept. and Optical Sciences Meinel buildings. We demonstrate that in the strong atmospheric turbulence regime the proposed low-complexity degenerate entanglement assisted communication system performs significantly better compared to corresponding classical laser and thermal source-based communications counterparts.

IEEE Access•Jan 1, 2026•2 citations

On the Degenerate Entanglement-Assisted Free-Space Optical Communication With SLM-Based Beam Steering Using Dual-Pump Lasers

Ivan B. Djordjević, Ignacio A. Rojas

We propose a degenerate entanglement-assisted (EA) free-space optical (FSO) communication system employing spatial light modulator (SLM)-based beam steering and a novel dual-pump configuration. The system utilizes a type-0 periodically poled lithium niobate (PPLN) waveguide to generate signal and idler photon pairs at 1570 nm, using two independent low-cost C- and L-band pump lasers. To enable homodyne detection, unmodulated idler photons are transmitted alongside modulated signal photons thus avoiding the need for phase conjugation and quantum memories. We demonstrate 1 Gb/s degenerate entanglement assisted transmission over a 1.5 km terrestrial FSO link at the University of Arizona campus, operating in the L-band. Experimental results show that the proposed degenerate EA system significantly outperforms its classical counterpart, particularly under strong atmospheric turbulence conditions.

IEEE Access•Jan 1, 2025•5 citations

Entanglement assisted free-space optical communication with two-pump-based entanglement generation outperforming classical laser communication in strong turbulence regime at 10 Gb/s

Vijay Nafria, Ivan B. Djordjević

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.

Optics Express•Dec 4, 2024•7 citations

Entanglement Based Detection, Networking, Sensing, and Radars

Ivan B. Djordjević, Vijay Nafria

Entanglement based (EB) communication, networking, and sensing represent excellent alternatives to corresponding classical counterparts in particular in either lowbrightness or high-attenuation regime and when the signal photons are buried in noise. In EB applications idler photons are stored in memory while the signal photons, carrying information, are transmitted over lossy, noisy, and for communication/networking over free-space optical (FSO) channels signal photons are also affected by the atmospheric turbulence and scattering effects. In optical phase conjugation (OPC)-based EB receiver, the OPC operation is performed on signal photons, which are severely affected by FSO channel impairments, with many signal photons being either absorbed or scattered by the FSO channel. Here we propose to perform the OPC operation on idler photons instead. The OPC operation is performed using low-cost, C-band components including tunable laser, periodically polled lithium niobate (PPLN) waveguides, tunable filter, and WDM demultiplexer; and this implementation is suitable for the photonic integrated circuit (PIC) realization. A similar approach is applied to implement the C-band devicesbased entanglement source. Given that the idler photons are brighter compared to the signal photons transmitted over either FSO channel or fiber-optics channel, the OPC operation is much more efficient. In the OPC-based receiver for FSO communications, we need to couple the signal photons to the single-mode fiber (SMF) before the OPC takes place, making the OPC process sensitive to the FSO-to-SMF coupling inefficiency. By performing the OPC on the idler photons instead, the OPC process is insensitive to poor coupling efficiency. In addition to being superior in terms of spectral efficiency compared to classical counterparts, in particular in highly lossy and noisy environment, the proposed EB scheme with the phaseconjugation on idler photons is superior to the corresponding scheme performing the phase-conjugation on signal photons in terms of receiver sensitivity making it an attractive option for radar applications. To validate the proposed concept at the University of Arizona campus we have developed a terrestrial FSO testbed. For detection probability of 0.99 the proposed EB radar outperforms the classical counterpart by 6.7 dB. We experimentally demonstrate that the target detection probability of the proposed entanglement based radar over turbulent FSO channel is significantly better than that of corresponding classical detection scheme.

IEEE photonics journal•Jan 25, 2024•18 citations

Entanglement Assisted Radars Operated over Strong Atmospheric Turbulence Channels

Ivan B. Djordjević, Vijay Nafria

In this invited paper we review our recent research activities on experimental demonstration of entanglement based (EB) radars, operated over strong atmospheric turbulence channels. In conventional EB communications, sensing, and radars the phase-conjugation, required before homodyne detection takes place, is performed on received signal photons. In atmospheric turbulent channels, the signal photons are affected by diffraction, absorption, scattering, and atmospheric turbulence effects so that only limited number of weak target probe returned signal photons reach the receiver side in EB radars. Moreover, it is extremely difficult to perform any phase-conjugation on weak signal photons when the average number of received photons is <<1. To solve this problem, we have recently proposed to perform phase-conjugation on bright idler photons instead. Namely, we perform the wavelength conversion by the PPLN waveguide on bright idler photons, so that the idler photons will have the same wavelength as the signal photons, and after that we use a classical homodyne balanced detector as an entanglement assisted detector. To generate entangled photon pairs, we use C-/L-band tunable laser, EDFA, the PPLN waveguide, and WDM demultiplexers. To demonstrate the high-potential of the proposed EB radar concept, we developed an experimental outdoor free-space optical (FSO) testbed at the University of Arizona campus. Using this FSO testbed we experimentally demonstrate that the proposed EB radar significantly outperforms the corresponding classical counterpart and can operate in strong turbulence regime. To improve the detection probabilities further, we use deformable mirror-based adaptive optics.

International Conference on Transparent Optical Networks•Jul 14, 2024•1 citation

Two-Pumps-Based Degenerate Entanglement Assisted Communication with SLM-Based Beam Pointing

Ivan B. Djordjević, Ignacio A. Rojas

We successfully demonstrate two-pumps-based degenerate entanglement assisted free-space optical communication system at 1 Gb/s operating in L-band with SLM-based beam pointing by employing type-0 PPLN waveguide to generate signal and idler photons at 1570 nm.

Frontiers in Optics•Jan 1, 2025•0 citations
We propose a low-complexity degenerate entanglement-assisted (DEA) system suitable for radar, communication, and LiDAR applications. The proposed DEA system employs on transmitter side a continuous wave (CW) dual-pump-based approach, a type-0 periodically poled lithium niobate (PPLN) waveguide, an optical bandpass filter, and a proposed single-drive Mach-Zehnder modulator. On receiver side, for communication and radar applications, the proposed balanced receiver is used as the entanglement-assisted detector. For LiDAR applications, on the other hand, the DEA detector array is used on receiver side. Two independent CW pump lasers operated at telecom wavelengths are employed in the dual-pump-based approach. For radar and LiDAR applications, the portion of degenerate entangled photons is employed as the reference signal and the rest to transmit the probe signal. We also propose a DEA triple-function radar-communication-LiDAR system. To demonstrate the quantum advantage, we conducted 1 Gb/s DEA radar and communication experiments over terrestrial free-space optical (FSO) link at the University of Arizona campus, between ECE Dept. and Optical Sciences Meinel buildings. We demonstrate that in the presence of the atmospheric turbulence in the saturation regime the proposed low-complexity DEA quantum radar and communication system outperform significantly corresponding classical counterparts.
We propose a low-complexity degenerate entanglement-assisted free-space optical (FSO) communication system employing a two-pumps approach, a type-0 periodically poled lithium niobate (PPLN) waveguide, a multistage WDM demultiplexer, and a properly biased Mach-Zehnder modulator on transmitter side and, for binary phase-shift keying (BPSK) signaling, a single PIN photodetector or avalanche photodetector (APD) on a receiver side. Two-pumps-based approach utilizes two independent pump lasers operating at telecom wavelengths. The portion of degenerate entangled photons is used as the unmodulated carrier and the rest to transmit the modulated PSK/quadrature amplitude modulation (QAM) signal. The unmodulated portion of entangled photons is selected by properly choosing the bias voltage and phase representing the transmitted bits. In BPSK signaling, the unmodulated carrier photons are used on receiver side to reconstruct the transmitted symbol by beating them with modulated signal photons on either PIN photodetector or APD. We also describe how to implement the M-ary PSK and QAM transmitters for the degenerate entanglement assisted communications. Further, we propose a low-complexity PSK/QAM demodulator compatible with the proposed degenerate entanglement assisted communication concept. To demonstrate the quantum advantage, we conducted 1 Gb/s degenerate entanglement assisted BPSK experiments over a 1.5 km terrestrial FSO link we have developed previously at the University of Arizona, between ECE Dept. and Optical Sciences Meinel buildings. We demonstrate that in the strong atmospheric turbulence regime the proposed low-complexity degenerate entanglement assisted communication system performs significantly better compared to corresponding classical laser and thermal source-based communications counterparts.
We propose a degenerate entanglement-assisted (EA) free-space optical (FSO) communication system employing spatial light modulator (SLM)-based beam steering and a novel dual-pump configuration. The system utilizes a type-0 periodically poled lithium niobate (PPLN) waveguide to generate signal and idler photon pairs at 1570 nm, using two independent low-cost C- and L-band pump lasers. To enable homodyne detection, unmodulated idler photons are transmitted alongside modulated signal photons thus avoiding the need for phase conjugation and quantum memories. We demonstrate 1 Gb/s degenerate entanglement assisted transmission over a 1.5 km terrestrial FSO link at the University of Arizona campus, operating in the L-band. Experimental results show that the proposed degenerate EA system significantly outperforms its classical counterpart, particularly under strong atmospheric turbulence conditions.
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.
Entanglement based (EB) communication, networking, and sensing represent excellent alternatives to corresponding classical counterparts in particular in either lowbrightness or high-attenuation regime and when the signal photons are buried in noise. In EB applications idler photons are stored in memory while the signal photons, carrying information, are transmitted over lossy, noisy, and for communication/networking over free-space optical (FSO) channels signal photons are also affected by the atmospheric turbulence and scattering effects. In optical phase conjugation (OPC)-based EB receiver, the OPC operation is performed on signal photons, which are severely affected by FSO channel impairments, with many signal photons being either absorbed or scattered by the FSO channel. Here we propose to perform the OPC operation on idler photons instead. The OPC operation is performed using low-cost, C-band components including tunable laser, periodically polled lithium niobate (PPLN) waveguides, tunable filter, and WDM demultiplexer; and this implementation is suitable for the photonic integrated circuit (PIC) realization. A similar approach is applied to implement the C-band devicesbased entanglement source. Given that the idler photons are brighter compared to the signal photons transmitted over either FSO channel or fiber-optics channel, the OPC operation is much more efficient. In the OPC-based receiver for FSO communications, we need to couple the signal photons to the single-mode fiber (SMF) before the OPC takes place, making the OPC process sensitive to the FSO-to-SMF coupling inefficiency. By performing the OPC on the idler photons instead, the OPC process is insensitive to poor coupling efficiency. In addition to being superior in terms of spectral efficiency compared to classical counterparts, in particular in highly lossy and noisy environment, the proposed EB scheme with the phaseconjugation on idler photons is superior to the corresponding scheme performing the phase-conjugation on signal photons in terms of receiver sensitivity making it an attractive option for radar applications. To validate the proposed concept at the University of Arizona campus we have developed a terrestrial FSO testbed. For detection probability of 0.99 the proposed EB radar outperforms the classical counterpart by 6.7 dB. We experimentally demonstrate that the target detection probability of the proposed entanglement based radar over turbulent FSO channel is significantly better than that of corresponding classical detection scheme.
In this invited paper we review our recent research activities on experimental demonstration of entanglement based (EB) radars, operated over strong atmospheric turbulence channels. In conventional EB communications, sensing, and radars the phase-conjugation, required before homodyne detection takes place, is performed on received signal photons. In atmospheric turbulent channels, the signal photons are affected by diffraction, absorption, scattering, and atmospheric turbulence effects so that only limited number of weak target probe returned signal photons reach the receiver side in EB radars. Moreover, it is extremely difficult to perform any phase-conjugation on weak signal photons when the average number of received photons is <<1. To solve this problem, we have recently proposed to perform phase-conjugation on bright idler photons instead. Namely, we perform the wavelength conversion by the PPLN waveguide on bright idler photons, so that the idler photons will have the same wavelength as the signal photons, and after that we use a classical homodyne balanced detector as an entanglement assisted detector. To generate entangled photon pairs, we use C-/L-band tunable laser, EDFA, the PPLN waveguide, and WDM demultiplexers. To demonstrate the high-potential of the proposed EB radar concept, we developed an experimental outdoor free-space optical (FSO) testbed at the University of Arizona campus. Using this FSO testbed we experimentally demonstrate that the proposed EB radar significantly outperforms the corresponding classical counterpart and can operate in strong turbulence regime. To improve the detection probabilities further, we use deformable mirror-based adaptive optics.