Quantum Imaging

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I've found this Zeilinger quantum imaging experiment from 2014 to be a more intuitive way for people to grasp some of the the significance of quantum mechanics.

This experiment uses the phenomena of quantum coherent interference to show that information can be obtained about an object (in this case a tiny cardboard cut out of a cat) without detecting the photons that interacted with the object.


[Image: quantum-imaging-cat.jpg]


Quote:Information is central to quantum mechanics. In particular, quantum interference occurs only if there exists no information to distinguish between the superposed states. The mere possibility of obtaining information that could distinguish between overlapping states inhibits quantum interference (1,2). Here we introduce and experimentally demonstrate a quantum imaging concept based on induced coherence without induced emission (3,4). Our experiment uses two separate down-conversion nonlinear crystals (numbered NL1 and NL2), each illuminated by the same pump laser, creating one pair of photons (denoted idler and signal). If the photon pair is created in NL1, one photon (the idler) passes through the object to be imaged and is overlapped with the idler amplitude created in NL2, its source thus being undefined. Interference of the signal amplitudes coming from the two crystals then reveals the image of the object. The photons that pass through the imaged object (idler photons from NL1) are never detected, while we obtain images exclusively with the signal photons (from NL1 and NL2), which do not interact with the object. Our experiment is fundamentally different from previous quantum imaging techniques, such as interaction-free imaging (5) or ghost imaging (6–9), because now the photons used to illuminate the object do not have to be detected at all and no coincidence detection is necessary. This enables the probe wavelength to be chosen in a range for which suitable detectors are not available. To illustrate this, we show images of objects that are either opaque or invisible to the detected photons. Our experiment is a prototype in quantum information—knowledge can be extracted by, and about, a photon that is never detected.

Quote:We have shown that information can be obtained about an object without detecting the photons that interacted with the object. Knowing the two-photon state, one can obtain information about an object. It has not escaped our attention that, on the other hand, by knowing the object, one could obtain information about the quantum state without detecting it.

https://thinkingdeeper.files.wordpress.c...maging.pdf
We shall not cease from exploration
And the end of all our exploring 
Will be to arrive where we started
And know the place for the first time.
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In this way... we can see that an image can be recovered from the quantum state... and the quantum state can be recovered from the image...

this allows a continuous process of:

...quantum state recovers image recovers quantum state recovers image recovers quantum state...


One might speculate, that awareness and acknowledgement that one does not know an answer, and holding that state of unknowing open by refusing to close it, and by remaining in that state, one can recover answers from interference?

Contrast that state to these examples:

1) unawareness and/or refusal to acknowledge that one does not know an answer ("It's caused by this or that"),

2) closing ones state of unknowing by a trick or other method ("it's just a 'coincidence'", "it's just a 'hallucination'", "that's just the way the world is", "I will never be able to understand that")

3) closing ones state of unknowing due to distraction.
We shall not cease from exploration
And the end of all our exploring 
Will be to arrive where we started
And know the place for the first time.
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