

Physicists Take Low-Light Images Using Less Than One Photon per Pixel - markfenton
https://medium.com/the-physics-arxiv-blog/researchers-take-low-light-images-using-less-than-one-photon-per-pixel-22f03c391235

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WhoBeI
You don't even need to capture a photon coming from the object.

Shoot a red laser at a couple of non-linear crystals to split the photons into
a red/infrared entangled pair. Now, send the infrared ones through the object
and into the other crystal while you divert the red ones to a screen without
touching the object. As you can no longer determine which infrared photon
belongs to what entangled pair the information they ones had is now contained
in the red photons instead - and an image of the object appears on the screen.

[http://medienportal.univie.ac.at/presse/aktuelle-
pressemeldu...](http://medienportal.univie.ac.at/presse/aktuelle-
pressemeldungen/detailansicht/artikel/quantenphysik-ermoeglicht-
revolutionaeres-abbildungsverfahren-kopie-1/)

Who the hell needs magic when there's quantum physics.

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Retric
That's not quite what happens. Based on your description information about an
object could travel faster than light.

You send light from cristal A to the object and then on to cristal B. You then
construct the image using light from both cristals. The specific spookiness is
only apparent when you try and track an individual photon.

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ahaefner
This is similar to nuclear gamma-ray imaging, such as in medical application,
where the number of counts is inherently low because the high energy photons
are more penetrating and thus escape the camera.

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tlb
Heralded imaging is explained here:
[https://en.wikipedia.org/wiki/Ghost_imaging](https://en.wikipedia.org/wiki/Ghost_imaging)

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simcop2387
I wonder if this could be used to boost resolution of SEM and similar devices
with electrons instead of photons. It'd make imaging non-metallic objects a
lot easier since you won't have to bombard it with as many electrons,
potentially destroying the object you want to examine.

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tjradcliffe
Unlikely. Resolution limits are determined by aperture and wavelength, which
is unrelated to photon number. There may be other tricks that can get around
those limits, but they will be quite different from this sort of photon-number
stuff.

Photon number is conjugate to phase, whereas to improve resolution you need to
know phase very precisely, so the uncertainty in (and therefore the number of)
photons goes up.

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quarterwave
"Photon number is conjugate to phase' \- I'd like to understand that better,
is it the same as saying photon counting destroys phase information? Would it
also hold true for gated counting?

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jrapdx3
Maybe it's just my eyeballs, but it looks like the <1 photon/pixel result was
kind of fuzzy vs. the higher photon count image (cf. wasp wing).

If the idea is getting targeted bits of information about an object, as in
whether a feature is present or absent, the very low photon image might meet
the need.

However, with photography as art, the requirements for image resolution would
be much higher, much more similar to the multi-photon image examples.

So it would appear mileage varies: the minimal photon images suit the
minimalist domain, but an ordinary high-resolution image would require many
more photons/pixel to get the expected result.

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nullc
The paper on "heralded imaging" seems to be only available as a paywalled
abstract, so I have no idea what that is. :(

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frozenport
Without seeing the visibility curve, these results could be purely classical.

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mrfusion
Could this be used for telescopes?

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jerf
No. This requires you to be in full control of the photons illuminating the
image so you can properly entangle and detect them.

