Heralded noiseless amplification of a photon polarization qubit

By S. Kocsis, G. Xiang, Timothy C. Ralph, G. Pryde. Nature Physics, 2012

133 citations recorded by the source corpus.

Long-distance quantum communication is limited by optical absorption and scattering. A noiseless amplifier for photonic qubits coherently encoded across two optical modes is now demonstrated, which could combat this negative effect. The method enabled a fivefold increase in the transmission fidelity of the polarization state of a single photon. Photons are the best long-range carriers of quantum information, but the unavoidable absorption and scattering in a transmission channel places a serious limitation on viable communication distances. Signal amplification will therefore be an essential feature of quantum technologies, with direct applications to quantum communication, metrology and fundamental tests of quantum theory. Non-deterministic noiseless amplification of a single mode1,2,3,4,5 can circumvent the challenges related to amplifying a quantum signal, such as the no-cloning theorem6 and the minimum noise cost for deterministic quantum state amplification7. However, existing devices are not suitable for amplifying the fundamental optical quantum information carrier: a qubit coherently encoded across two optical modes. Here, we construct a coherent two-mode amplifier to demonstrate the first heralded noiseless linear amplification of a qubit encoded in the polarization state of a single photon. In doing so, we increase the transmission fidelity of a realistic qubit channel by up to a factor of five. Qubit amplifiers promise to extend the range of secure quantum communication8,9 and other quantum information science and technology protocols.

Subfields: Artificial Intelligence

View Paper: https://www.semanticscholar.org/paper/a2587d92c3aa03d6926c33b04062eb2b03e252d6