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touqra
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Can photon form wavepackets? I mean we can't detect the location of a photon right? So this means delta x is infinity, which implies that photon is a plane wave, which is not a wavepacket?
humanino said:Not exactly. You can detect a single photon, with the usual rules for the accuracy in position and momentum. You can actually see a single spot on a screen for instance, if the luminosity of the source is very small. The actual size of the spot is of-course non-zero. It is also true that, before you detect it, the photon with a well defined wavelegth is a plane wave. Depending on how it has been created, the indeterminacy in wavelength can be more or less large. Laser photons have a vanishingly small wavelegth undeterminacy.
A plane wave is a trivial wavepacket.
Fredrick said:Suppose a photon is emitted from a light source inside a box with walls that won't let photons through. This photon obviously doesn't have delta-x equal to infinity.
The answers to your questions are: Yes, photon states can be "wave packets", and no, they aren't always plane waves (=momentum eigenstates).
A plane wave is a momentum eigenstate. A wave packet is a superposition of momentum eigenstates. The state of the photon is never exactly a momentum eigenstate, so I suppose you can say it's always a wave packet, or at least that it's never a plane wave. (Its momentum-space wave function can be "sharp", but never quite as sharp as the Dirac delta function).touqra said:When will they be plane waves? And when will they be wave packets, beside the situation where you mentioned?
I don't think we can detect anything with 100% accuracy. When it comes to measuring positions, the best we can do is to determine a region of space where the particle is. After the measurement, the wave function will be 0 outside that region.touqra said:As in for other particles like electron, that we can detect exactly its position, can we detect a photon's location with 100% accuracy compromising our knowledge on its wavelength? If we can detect it 100% accurate, does this violate the speed of light limit of relativity?
A detector uses electromagnetic wave in some way for any detections. How could you detect a photon with a photon?
Yes, photons can be described as wavepackets. A wavepacket is a localized wave in space and time, and photons behave like waves in certain aspects, such as interference and diffraction. However, they also exhibit particle-like behavior, making it more accurate to describe them as wave-particle duality.
Wavepackets are formed from photons through a process called superposition. In this process, multiple photons with different energy and direction can combine to form a wavepacket with a well-defined energy and momentum. This is similar to how waves in the ocean combine to form larger waves.
No, not all photons form wavepackets. Only photons with a well-defined energy and momentum, such as those emitted from a laser or produced in a particle accelerator, can form wavepackets. Photons from natural sources, such as the sun, have a range of energies and directions and do not form wavepackets.
Wavepackets are significant in quantum mechanics because they can accurately describe the behavior of particles, such as photons, at the quantum level. They allow us to understand and predict the behavior of particles in terms of both wave-like and particle-like properties, which is essential in understanding the behavior of matter and energy at the smallest scales.
Yes, wavepackets of photons can be observed through various experiments, such as the double-slit experiment or diffraction experiments. These experiments show the wave-like behavior of photons, such as interference patterns, which can only be explained by considering them as wavepackets.