Invention:
Contrary to the common belief that quantum entanglement is destroyed by amplification, in entanglement-assisted communication systems dominated by attenuation effects rather than noise, the signal photons can be amplified by the erbium-doped fiber amplifier (EDFA) without destroying the entanglement. The inventors developed a terrestrial free-space optical (FSO) testbed at the University Arizona campus by establishing 1.5 km long FSO link. They demonstrated that an amplified entanglement assisted communication system at 10 Gb/s operated in strong turbulence regime significantly outperforms amplified classical laser communication link operated in medium turbulence regime. This demonstration validated entanglement assisted communication over long-range terrestrial FSO links.
Background:
Entanglement represents a unique quantum information property that enables quantum sensing approaching the Heisenberg limit, the communication beating the Shannon limit, and secure communications with security guaranteed by the quantum mechanics laws rather than computational complexity. The quantum communication over terrestrial free-space optical (FSO) channels is severely affected by absorption, diffraction, scattering, and atmospheric turbulence effects. It is widely believed that entangled photons cannot be amplified by a classical amplifier, such as the EDFA, without destroying the quantum entanglement. However, the inventors' demonstration has shown that in highly noisy and lossy environments, the entanglement assisted communication systems dominated by attenuation effects rather than noise, the signal photons can be amplified by the EDFA without destroying the entanglement.
Applications:
- Quantum communications
- Long-range terrestrial FSO communications
- Covert communication
Advantages:
- Outperforms the classical communication system in medium turbulence regime
- Demonstrated viability
- Can modify signal photons without destroying the entanglement
