MOSCOW -- The co-founder of the first successful quantum technology company claimed this week to have demonstrated macroscopic quantum entanglement, a breakthrough that could be help to develop quantum communications networks.
In a presentation at International Conference on Quantum Technologies (ICQT) here this week, Nicolas Gisin, a board member at Geneva-based quantum key distribution system vendor ID Quantique, showed quantum entanglement involving two macroscopic optically distinct states that render a quantum phenomenon visible to the naked eye. He also showed how the technique can be automated with simple non-quantum detectors which are sensitive only to the number of photons present as opposed to the exotic quantum measurement techniques necessary today.
In his talk, he began by describing a new quantum memory technology, developed at ID Quantique to facilitate long-distance communications of quantum-bits (q-bits), which make use of quantum-entanglement and -teleportation in order to transfer q-bits from photons to ultra-cool atoms trapped inside a photonic crystal.
"To make a quantum communications network, you need the quantum equivalent of repeater nodes, which require coherent and reversibly mapped quantum entanglement with a quantum memory," said Gisin.
Nicolas Gisin, the co-founder of the first successful company based on quantum technologies, ID Quantique, reveals the first macroscopic example of quantum entanglement.
Gisin's quantum memory works using an ensemble of up to 10 billion super cooled rare-earth ions inside a photonic crystal, which have been forced into a huge superposition state. The technique was able to demonstrate an entanglement-reserving quantum memory transferred the q-bits to the ions using light-to-crystal quantum teleportation that transferred the quantum state with a fidelity of 93 percent.
The technique enabled what Gisin called "large entanglment" of thousands of photons trapped inside a photonic crystal large enough to hold in your hand. The entangled bits (e-bits) were thus large enough to be viewed with the naked eye, and could be automatically detecting using non-quantum "classical" detectors to determine their state.
In experiments, Gisin's showed how single-photon entanglement could be transferred to the large ensemble of photons using an optical fiber coupler, which was verified by separating out a single photon from the ensemble and using an analyzer with an interferometer that measured their entanglement. And by combining with the quantum memory at telecommunications wavelengths, Gisim's set-up allowed the temporary storage of thousands of e-bits in a solid state quantum memory.