Everyone said it was a delayed experiment. It must be the two-way experiment. The double-slit interference experiment of the single light path is a pre-experiment (the interpretation of the misunderstood “observation” is worthy of recognition). This experiment studies the photon-pair entanglement state, and the wave-particle duality is the tool of this experiment. The full name of this experiment is called the quantum erase experiment, and some people call it the quantum erase delay experiment. This method is misleading and should be called the quantum erase selection experiment.
The horror of it is that it seems intuitively that the fact that happens after one light path determines the fact that it happens first on another light path. In fact, this is just an intuitive shock to people, you have to look carefully at their experimental design, there is no so-called delay. The purpose of this experiment is to prove that the photon has an entangled state. Once the interference photon is detected, the quantum state collapses immediately, the volatility disappears, and the superdomain of the entangled photon collapses. The so-called “choice” means that one optical path chooses whether to collapse or not, and it also chooses whether to collapse on another optical path. Again, there is only choice and no delay.
Many explanations do not indicate that there is a computer behind the two light screens. The role of this computer is to detect photon pairs. Only when the entangled photons are detected at the same time, the images produced by the pair of photons are recorded. Other photons are not recorded. So it can be understood as follows: both interference images and non-interference images are superimposed.
When one optical path chooses to view the interference image, the image on the other optical path displays the corresponding image, and the other images are filtered by the computer behind.
Add some important points: 1. After the quantum state collapses, the current trajectory of the photon is determined.
1.1. Detect behind the double slit and collect the image formed by the detected photons, which is equivalent to a point light source appearing at the detector. If there is no double slit in front of the light source, there will be no interference fringes.
- The information obtained when the quantum state collapses is never possible to reverse the trajectory before the collapse, that is, it is not known from which double slit it entered before the detection, and there is fluctuation before the detection. It is clear that these two points can basically be understood by most seemingly brain-burning double-slit experiments, and “delay” hallucinations can find flaws.
The discussion is very lively, and it has reached a level where it can only give basic intuition. Please believe only half. Supplementary note: For the single light path experiment, it is not a terrible thing to eliminate interference fringes by “observing”. After the double slit in the double slit, use the detector to observe the photons and record the images formed by these photons. These photons must have passed through the detector. Then this is equivalent to putting a point light source behind the double slit.
Put a light bulb behind the double slit, the light bulb does not show interference fringes. What’s so shocking? To add: Wheeler delayed experiment Copenhagen school gave an explanation, local operation led to changes in the entire system. Take the antireflection coating of the lens as an example: the photon seems to know in advance that the photon reflected by the lens wants to disappear if it reflects in front of the film, so the photon is forced to penetrate directly without reflection because of what happened later.
In fact, the photon will still be reflected at the moment when it is put into the AR coating. After a period of time, the system becomes stable and will not be reflected but directly incident. Wheeler’s delayed selection experiment only assumed the state of the system after it stabilized, and considered that the cause and effect were reversed. When the mirror is inserted, the photons that have passed through the double slit will not be affected, and the photons that have passed through will begin to adapt to new systems (such as antireflection coatings). The photons that pass through after the system stabilizes appear to choose only one optical path.
The moment the mirror is inserted does not affect the photons that have passed through, and subsequent events do not interfere with the events that have occurred. After the insertion, after the system is stable, the later events interfere with the later events, which is not scary at all.