Exploring QM's Theory on Photon Creation and Annihilation

In summary, photons can be created from the annihilation of an electron and a positron, but a single photon cannot spontaneously turn into an electron and positron. However, two colliding photons can create an electron and positron, and in the presence of a nucleus, a single photon with enough energy can also create an electron and positron through pair production. The electric field of the nucleus plays a role in this process, as the electromagnetic force is involved. The threshold for pair production is 1.022 Mev.
  • #1
Agnostic
110
0
Does QM tell us that photons are actually electrons and positrons goign through a cycle of annilation and creation?
 
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  • #2
can an electron and positron annhilate each other without the presence of a neutron?
 
  • #3
No, but an electron and a positron can annihilate to create a photon. this is not a statement about ALL photons.

Electron positron annihilation not have to happen in the presence of a neutron.
 
  • #4
Is that to say there is a 0 probabilty of a photon going to a positron and electron?
 
  • #5
A single photon cannot spontaneously become an electron and a positron, as it would be unable to simultaneously conserve energy and momentum. For the same reason, an electron and a positron cannot annihilate into a single photon.

However, two colliding photons (if they have sufficient energy) can form and electron and a positron; and, an electron and positron can annihilate to form two photons.
 
  • #6
According to the path integral formulation of QM, a photon has a non-zero probability of spending time as a (virtual ?) e+/e- pair.
 
  • #7
In addition to the 2 photon into electron-positron pair, it is possible for a single photon (of enough energy >1.22 Mev) to form a pair when in the presence of a nucleus to get the required energy and momentum balance. This reaction is quite common in nuclear reactors and in lead shielding.
 
  • #8
Mathman, with the single photon near a nucleus, does the electric field of the nucleus play a part ? Presumably a 1.22 Mev photon is a gamma-ray type .
 
  • #9
The electric field plays a role, since (I presume) the electromagnetic force is the only force involved. As far as the photon energy, yes it is a gamma ray. Gamma rays from nuclear reactors can be as high as 10 Mev (maybe even higher).

P.S. Error (by me) - threshold for pair production is 1.022 Mev, not 1.22.
 
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1. What is Quantum Mechanics (QM)?

Quantum Mechanics is a branch of physics that studies the behavior of particles at the atomic and subatomic level. It is based on the principles of wave-particle duality, uncertainty, and superposition, and is essential for understanding the behavior of photons.

2. How are photons created and annihilated according to QM?

According to QM, photons are created when an excited atom emits energy in the form of a particle. This process is called photon emission. Conversely, photons can be annihilated when they interact with matter and their energy is absorbed, causing them to disappear.

3. What is the significance of photon creation and annihilation in QM?

Photon creation and annihilation are significant in QM because they provide insights into the fundamental nature of light and its interactions with matter. These processes also play a crucial role in many technological applications, such as laser technology and quantum computing.

4. How does QM explain the behavior of photons?

QM explains the behavior of photons through the principles of wave-particle duality and superposition. Photons exhibit properties of both waves and particles, and their behavior can be described by a probability wave function that determines the likelihood of their position and momentum at any given time.

5. What are some experiments that support QM's theory on photon creation and annihilation?

There have been numerous experiments that support QM's theory on photon creation and annihilation. Examples include the double-slit experiment, which demonstrates the wave-like behavior of photons, and the photoelectric effect, which shows the particle-like nature of photons. Additionally, the observation of quantum entanglement in photon pairs supports the concept of superposition and the instantaneous creation and annihilation of photons.

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