4 ms·

It's not enough to do crazy quantum stuff in the camera, the light source would have to be similarly manipulated in a quantum way as well. My understanding is

It's not enough to do crazy quantum stuff in the camera, the light source would have to be similarly manipulated in a quantum way as well. My understanding is that the human eye has a surprisingly high quantum efficiency (about 12 to 30 % of photons are detected), and that the reason night looks dark is because there really aren't that many visible spectrum photons around. My guess is that this camera is physically enormous. Edit: Apparently, it's really small! I am dumbfounded. Then again, I guess it could have a hundred times the area of a human pupil and still be pretty small.

twelvechairs 10y ago
Humans can actually see well in the dark once adjusted but generally without colour (due to using rods rather than cones in the eye). The colour is probably what makes this video appear incredible to us as its not how we are used to percieving darkness (even with eg night vision). As to the technical question according to this you need 90 photons for a 60% chance at a human response http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.html http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.h...
amluto 10y ago
> It's not enough to do crazy quantum stuff in the camera, the light source would have to be similarly manipulated in a quantum way as well. Not entirely true. Assuming an incoherent source, conventional optics, and a well-defined frame (i.e. you measure for a time t and the source is unchanging for the whole time), you have a bunch of modes of incoming light that would hit each pixel. Measuring these modes in the photon number basis isn't optimal. The ideal measurement is probably something quite different. It may also depend on your exact assumptions avoid the source.
- deleted 10y ago
  [deleted]
- doubleunplussed 10y ago
  Ultimately you want to count photons to produce an image. And if it's an incoherent source, I don't think there's anything else you can do with it. With coherent light it can be useful to have the light interact with matter in a way that depends on the phase of the light. But if the light is incoherent then that won't yield anything useful. And this still doesn't beat the shot noise limit - your phase measurements still come from counting photons subject to shot noise. Then there's polarisation. Two polarisation states. But really that's just like saying there are two kinds of photons. Both polarisation states are subject to number-phase uncertainty principle. I think that's it. There's the number and phase, which are conjugate variables. You can make number more accurate by squeezing phase, but only if you control the light source. And then there's the two polarisation states. And the EM field simply doesn't have any more degrees of freedom than that, so I think that's it unfortunately. It's number-phase squeezing or nothing if you want to count photons more accurately than shot noise.
  - krastanov 10y ago
    You are missing something though: Using entangled detectors you can surpass the diffraction limit. Googling "quantum internet and diffraction limit" would bring up some more information. Either way, this would apply to resolution, not to sensitivity (which is what you seem to be covering)

twelvechairs 10y ago

Humans can actually see well in the dark once adjusted but generally without colour (due to using rods rather than cones in the eye). The colour is probably what makes this video appear incredible to us as its not how we are used to percieving darkness (even with eg night vision). As to the technical question according to this you need 90 photons for a 60% chance at a human response http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.html http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.h...

amluto 10y ago

> It's not enough to do crazy quantum stuff in the camera, the light source would have to be similarly manipulated in a quantum way as well. Not entirely true. Assuming an incoherent source, conventional optics, and a well-defined frame (i.e. you measure for a time t and the source is unchanging for the whole time), you have a bunch of modes of incoming light that would hit each pixel. Measuring these modes in the photon number basis isn't optimal. The ideal measurement is probably something quite different. It may also depend on your exact assumptions avoid the source.

deleted 10y ago
[deleted]
doubleunplussed 10y ago
Ultimately you want to count photons to produce an image. And if it's an incoherent source, I don't think there's anything else you can do with it. With coherent light it can be useful to have the light interact with matter in a way that depends on the phase of the light. But if the light is incoherent then that won't yield anything useful. And this still doesn't beat the shot noise limit - your phase measurements still come from counting photons subject to shot noise. Then there's polarisation. Two polarisation states. But really that's just like saying there are two kinds of photons. Both polarisation states are subject to number-phase uncertainty principle. I think that's it. There's the number and phase, which are conjugate variables. You can make number more accurate by squeezing phase, but only if you control the light source. And then there's the two polarisation states. And the EM field simply doesn't have any more degrees of freedom than that, so I think that's it unfortunately. It's number-phase squeezing or nothing if you want to count photons more accurately than shot noise.
- krastanov 10y ago
  You are missing something though: Using entangled detectors you can surpass the diffraction limit. Googling "quantum internet and diffraction limit" would bring up some more information. Either way, this would apply to resolution, not to sensitivity (which is what you seem to be covering)