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g.lemaitre
- 267
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How accurate is this statement:
After the photon passes through the detector, it then passes through the eraser. The eraser is an electronic device that alters the wave-function of the photon, just like the detector is an electronic device that alters the wave-function of the photon.
This guy is claiming that after the photon goes through the detector it then goes through an eraser and the eraser returns it to an interference pattern.
This is from Greene's Fabric of the Cosmos
It seems to me that they are erasing the tagging device above the slits after the photon passes through it, they are not sending a photon through an eraser.
After the photon passes through the detector, it then passes through the eraser. The eraser is an electronic device that alters the wave-function of the photon, just like the detector is an electronic device that alters the wave-function of the photon.
This guy is claiming that after the photon goes through the detector it then goes through an eraser and the eraser returns it to an interference pattern.
This is from Greene's Fabric of the Cosmos
A simple version of the quantum eraser experiment makes use of the double-slit setup, modified in the following way. A tagging device is placed in front of each slit; it marks any passing photon so that when the photon is examined later, you can tell through which slit it passed. The question of how you can place a mark on a photon—how you can do the equivalent of placing an “L” on a photon that passes through the left slit and an “R” on a photon that passes through the right slit—is a good one, but the details are not particularly important. Roughly, the process relies on using a device that allows a photon to pass freely through a slit but forces its spin axis to point in a particular direction. If the devices in front of the left and right slits manipulate the photon spins in specific but distinct ways, then a more refined detector screen that not only registers a dot at the photon’s impact location, but also keeps a record of the photon’s spin orientation, will reveal through which slit a given photon passed on its way to the detector.
When this double-slit-with-tagging experiment is run, the photons do not build up an interference pattern, as in Figure 7.4a. By now the explanation should be familiar: the new tagging devices allow which-path information to be gleaned, and which-path information singles out one history or another; the data show that any given photon passed through either the left slit or the right slit. And without the combination of left-slit and right-slit trajectories, there are no overlapping probability waves, so no interference pattern is generated.
It seems to me that they are erasing the tagging device above the slits after the photon passes through it, they are not sending a photon through an eraser.
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