Entangled photons to produce better quantum images

A while back, we saw how quantum imaging had been put on a firmer theoretical footing, thanks to some new thinking by Seth Lloyd at MIT.

Quantum imaging involves sending one of a pair of entangled photons towards an object while holding on to the other.

For a long while nobody was quite sure what benefit you might get from this entanglement. Some physicists speculated that it could be possible to produce reflection-free images by measuring the entangled twin that you hang on to, even if the other photon never returns.

What Lloyd calculated was that illuminating an object with entangled photons can increase the signal to noise ratio of the reflected signal by a factor of 2^e, where e is the number of bits of entanglement. That’s an exponential improvement.

Now he and a few pals have filled in a few details in the scheme that make it more realistic. done the experiment and shown that Lloyd was right on the money. They sent photons towards an object and used the reflection to determine whether the object was present or absent.

When they used entangled photons, this process was much more efficient.

The result is effectively the first quantum image taken with entangled photons .

Now all we’re waiting for is experimental proof of the scheme which, if I’m not mistaken, won’t be long in coming. The work was part funded by DARPA’s Quantum Sensor Program so it’ll be interesting to see what plans the organisation has for this technique.

Ref: arxiv.org/abs/0810.0534: Quantum illumination with Gaussian states

2 Responses to “Entangled photons to produce better quantum images”

  1. counterfly says:

    it’s a theory paper, yo

  2. KFC says:

    Ahem, apologies. Just shows what a bit of wishful thinking and a late night at the computer can do. Never post after midnight. Corrected as above.