A device capable of amplifying the information in a single particle of light without adding noise has been created.  The researchers were able to amplify the noisy quantum state of a single photon subjected to loss, without adding noise in the process - their amplification actually reduced the noise in the quantum state. 

It is expected the results will stimulate further interest in the fundamental laws that govern how well amplifiers can work and in developing uses of noiseless amplification techniques for other quantum information technology applications.

Professor Geoff Pryde from Griffith University's Centre for Quantum Dynamics said the breakthrough would provide a new tool for all sorts of new quantum technologies. "This is the first time the information stored in a single photon has been amplified.  The technique works by combining the noisy quantum state with a 'clean' single photon in the amplifier, and using quantum teleportation to transfer the information onto the new photon. The most obvious application for this work is in improved quantum cryptography; secret messaging which is guaranteed secure by the laws of physics."

"We have been developing the ideas and experimental techniques that led to this breakthrough for the past 4 years," said Professor Tim Ralph from the University of Queensland. "Quantum information is useful but very fragile and normal amplification techniques destroy it. The key feature of our photon amplifier is that it preserves the quantum information and may help overcome the current distance limitations of quantum communication." 

"Heralded noiseless amplification of a photon polarization qubit" published in Nature Physics