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zdcyclops
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A single electron is fired at a detector, what do we know about the electron after it reaches the detector that we did not know before.
Strilanc said:It depends on the experiment. What does the detector detect? Is the fired electron being prepared in a known state? A mixed state?
For example, suppose the detector records the spin of the electron along the Z axis and the electron's spin is prepared in the state ##\left| \uparrow \right\rangle##. Then we don't really learn much at all about the spin by firing the electron at the detector. The detector is going to say it's upward... but we already knew the electron's spin was being prepared that way.
If we're instead preparing the electron's spin to be in the state ##\frac{1}{\sqrt{2}} \left| \uparrow \right\rangle + \frac{1}{\sqrt{2}} \left| \downarrow \right\rangle##, and we have two Z-axis-spin detectors one after another. Before the electron passes the first detector we don't know what the second detector will read. But after the electron passes through the first detector, we do know what the second detector will read: whatever the first detector just output.
So that's one important thing that detectors can tell you about: information about what the next detector will say.
naima said:When you say that an electron carries information it looks like a local property of a particle. When you have two maximally entangled particles the information is not localized in each of them.
We know that the electron was in the general neighborhood of the detector and we know approximately when the state change happened. That reduces our uncertainty about the position of the electron, but it commensurately increases our uncertainty as to the momentum.zdcyclops said:When there is a change in the detector you know where the electron is and when it arrived, and from this from this other things can be calculated.
A quantum object is an entity that exhibits quantum properties, such as superposition and entanglement, at the subatomic level. This includes particles like photons, electrons, and atoms.
Information is carried by single quantum objects through their quantum states, which describe their properties and behavior. These states can be manipulated and measured to encode and retrieve information, similar to how 0s and 1s are used in classical computing.
Single quantum objects can carry various types of information, including classical data, quantum data, and even combinations of both. This makes them useful for applications in communication, computation, and cryptography.
The information carried by single quantum objects is fundamentally different from classical information because it is encoded in quantum states rather than classical bits. This allows for properties like superposition and entanglement, which can lead to faster and more secure communication and computation.
There are several challenges in using single quantum objects for information processing, including the fragile nature of quantum states, the difficulty in controlling and measuring them accurately, and the need for specialized equipment and techniques. However, advancements in quantum technology are helping to overcome these challenges and make quantum information processing a reality.