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naima
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I know that the electric field can be expressed in term of creation and annihilation operators; Is it the same for the magnetic field B ?
Matterwave said:Most of the time the Electro-magnetic field is quantized in QFT using path integral formalisms. This is far simpler I hear than with canonical quanization methods. As such, I never read about E and B commuting or not. However, for specific instances, like the E&M field inside a cavity, it might be easier to quantize it via canonical quantization as was done in your link.
f95toli said:The derivation in the link is pretty much the "standard" way of deriving the quantization in both textbooks on quantum optics and cavity- and circuit-QED (the latter is as it happens the field the authors work in). Path integral formalism is virtually never used in CQED (at least I've never seen in done) and it is not something you would come across in a normal textbook.
Note also that these field are quite different than e.g. particle and sub-atomic physics in that you have a fairly obvious connection to the macroscopic word (the cavity) meaning it is often quite convenient to be able to switch from "classical" EM theory in the many photon limit, to 2nd quantization when looking at pure quantum effects.
I do this all the time.
naima said:I realize (for the first time) that E and B do not commute. have you read that in a textbook?
A magnetic field is a region of space where a magnet or electric current can exert a force on other magnets or moving electric charges. It is represented by lines of force that point from north to south.
A magnetic field is created by moving electric charges, such as in a current-carrying wire, or by the spin of electrons in an atom. The strength of the magnetic field depends on the magnitude and direction of the current or spin.
Magnetic field operators are mathematical tools used to describe the behavior of a magnetic field. They can be used to calculate the strength and direction of the field at a given point, as well as to predict how the field will change in response to different conditions.
Magnetic fields are typically measured using a device called a magnetometer. This instrument can detect the strength and direction of a magnetic field and display the information on a scale or graph.
Magnetic fields have many practical applications, such as in generators and motors, which use the force of a magnetic field to produce electricity and mechanical motion. They are also used in medical imaging techniques like MRI, as well as in compasses, speakers, and magnetic storage devices like hard drives.