First noiseless single photon amplifier

November 12, 2012

Research physicists have demonstrated the first device capable of amplifying the information in a single particle of light without adding noise.

The research collaboration, involving Griffith University, The University of Queensland and University of Science and Technology of China, was able to amplify the noisy of a single photon subjected to loss, without adding noise in the process; in fact, their amplification reduced the noise in the quantum state.

The results have been published today in "Heralded noiseless amplification of a photon polarization qubit", on the Nature Physics website.

Team leader, Professor Geoff Pryde from Griffith University's Centre for said the breakthrough would provide a new tool for all sorts of new .

"This is the first time the information stored in a single photon has been amplified," Professor Pryde said.

"The technique works by combining the noisy quantum state with a 'clean' single photon in the amplifier, and using 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."

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 technology applications.

Research into such applications is being pursued in Australia's Centre of Excellence for Quantum Computation and Communication Technology, as well as around the world. ​

Fellow team member Professor Tim Ralph from the University of Queensland said this breakthrough was the culmination of years of research.

"We have been developing the ideas and experimental techniques that led to this breakthrough for the past 4 years," Professor Ralph said.

"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."

Explore further: Observing a Photon no Longer a Seek-and-Destroy Mission

More information: Heralded noiseless amplification of a photon polarization qubit, Nature Physics, DOI:10.1038/nphys2469

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1 / 5 (1) Nov 12, 2012
This sounds more like a filter and a buffer.

So there is a new photon, what only one (?), then if it has more energy ie If it has been 'amplified' then it must be higher frequency which destroys or rather loses the initial information level, so that makes it more like a schmitt trigger but not an amplifier.

How is transferring the state of one photon (presumably absorbed) into another photon - an amplifier ?

Has the definition of 'amplifier' changed perhaps ?

not rated yet Nov 13, 2012
How is transferring the state of one photon (presumably absorbed) into another photon - an amplifier ?

Has the definition of 'amplifier' changed perhaps ?

Hi Mike

They are not amplifying the photon but the quantum information. When transmitting qubits they're prone to outside influences that might disturb and destroy the quantum information that's carried by the photon, so you have to amplify it to keep the data quality.

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