OT? Noiseless Single-photon Amplification Demonstrated

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Some regulars here seem to think that physicists never ome up with
anything practical:

http://phys.org/news/2012-11-noiseless-photon-amplifier.html#jCp

"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 quantum state of a single photon
subjected to loss, without adding noise in the process; in fact, their
amplification reduced the noise in the quantum state."

There's a lot of "fancy stuff" involving quantum teleportation and
so on, and it's touted as being applicable to quantum encryption, but
I'm sure some bright boy (or girl) will figure out how to apply the
principle to ordinary photonics and maybe prosaic optics like
microscopes.


Mark L. Fergerson

 

[Mr Stonebeach]

  Some regulars here seem to think that physicists never ome up with
anything practical:

http://phys.org/news/2012-11-noiseless-photon-amplifier.html#jCp

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

There is the theorem by Caves that phase-independent linear
amplification always adds noise, and this has been traditionally
circumvented by parametric amplification which is phase-dependent.
But now this is something different. They claim non-deteministic
noiseless amplification. I would have equated non-determinism
with noise! Apparently they use something more shrewd.
Interesting.

Regards,
Mikko

 

[Les Cargill]

Interesting, thanks.

Of course, strictly speaking an ordinary coherent detection system does
much the same thing, if "noise" is understood as the ratio of the
variance of the amplified signal to the original. The difference is
that the one-photon signal has Poisson statistics (or some squeezed
version) and the amplified one has Gaussian statistics. That just
amounts to a redistribution of variance from the N=1 state to the N=0
state.

Cheers

Phil Hobbs

Does that then mean you can't put two of these in series for more "gain"?

 

[George Herold]

  There is the theorem by Caves that phase-independent linear
amplification always adds noise, and this has been traditionally
circumvented by parametric amplification which is phase-dependent.
But now this is something different. They claim non-deteministic
noiseless amplification. I would have equated non-determinism
with noise!

First I didn't know that about parametric amps, so thanks.

In quantum things the amount of noise can depend on the coupling.
(I'm thinking of this paper by Rolf Landauer on noise.)

Say does a maser add noise?

George H.

Apparently they use something more shrewd.

 

[George Herold]

Interesting, thanks.

Of course, strictly speaking an ordinary coherent detection system does
much the same thing, if "noise" is understood as the ratio of the
variance of the amplified signal to the original.  The difference is
that the one-photon signal has Poisson statistics (or some squeezed
version) and the amplified one has Gaussian statistics.   That just
amounts to a redistribution of variance from the N=1 state to the N=0state.

Ouch, Phil, you lost me on the last part. I got the Poisson/ Gaussian
bit,
(some averaging can turn Poisson to Gaussian, no?)
But what's N?

George H.