15 research outputs found
Heralded Noiseless Amplification of a Photon Polarization Qubit
Non-deterministic noiseless amplification of a single mode can circumvent the
unique challenges to amplifying a quantum signal, such as the no-cloning
theorem, and the minimum noise cost for deterministic quantum state
amplification. 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
communication and other quantum information science and technology protocols.Comment: 6 pages, 3 figure
A high-fidelity noiseless amplifier for quantum light states
Noise is the price to pay when trying to clone or amplify arbitrary quantum
states. The quantum noise associated to linear phase-insensitive amplifiers can
only be avoided by relaxing the requirement of a deterministic operation. Here
we present the experimental realization of a probabilistic noiseless linear
amplifier that is able to amplify coherent states at the highest level of
effective gain and final state fidelity ever reached. Based on a sequence of
photon addition and subtraction, and characterized by a significant
amplification and low distortions, this high-fidelity amplification scheme may
become an essential tool for quantum communications and metrology, by enhancing
the discrimination between partially overlapping quantum states or by
recovering the information transmitted over lossy channels.Comment: 5 pages, 4 figure