B Amplitude of a photon's E and B fields

[slow]

Hi. Please let me know if the question is misplaced in the quantum forum. Is the next. Exist, in quantum terms, the electric and magnetic fields corresponding to a single photon? If yes, add another question. Is there any way to formulate the amplitudes of both fields in electrodynamic terms? That is, in addition to formulating the amplitude in probabilistic terms, formulate it, for example, for $\vec{E}$ with a function whose dimensions are $\frac{volt}{m}$ and for $\vec{H}$ be tesla.

 

[PeterDonis]

Exist, in quantum terms, the electric and magnetic fields corresponding to a single photon?

In quantum electrodynamics, the "electric field" and "magnetic field" are operators. You can apply them to a quantum system in any state, including a state which can reasonably be described as "a single photon". (That simple-looking description hides a multitude of complexities, btw; a "photon" is even less aptly described as a tiny particle than an "electron", for reasons which are too technical to go into in a "B" level thread.) In other words, the "electric field" and "magnetic field" are valid observables in quantum electrodynamics.

Is there any way to formulate the amplitudes of both fields in electrodynamic terms?

As above, the electric and magnetic fields aren't amplitudes, they're operators. As operators, you can pick whatever system of units works for your particular scenario.

 

[slow]

As above, the electric and magnetic fields aren't amplitudes, they're operators. As operators, you can pick whatever system of units works for your particular scenario.

Thank you very much Peter Donis. I will try to indicate better my focus of interest. Does the quantum theory allow calculation of how much the amplitude is worth, expressing the result in a conventional unit system, for example MKS?

 

[PeterDonis]

Does the quantum theory allow calculation of how much the amplitude is worth

I'm not sure what you mean by "how much the amplitude is worth".

expressing the result in a conventional unit system, for example MKS?

This wouldn't make sense. Units like MKS are units of measurement results. Amplitudes are numbers that are used to calculate the probabilities of different possible measurement results. Probabilities are just numbers; they aren't the same as the things they are probabilities of.

 

[slow]

Amplitudes are numbers that are used to calculate the probabilities of different possible measurement results. Probabilities are just numbers; they aren't the same as the things they are probabilities of.

Thank you. We are already at the point that interests me, included in the initial note of the thread. Should I understand that, except for probability, there are no other ways to define or calculate amplitude for a single photon?

 

[PeterDonis]

Should I understand that, except for probability, there are no other ways to define or calculate amplitude for a single photon?

Since amplitudes are defined as quantities used to compute probabilities, I guess the answer would be yes. I'm wondering why you would even think that the answer might be no. What QM textbooks have you studied?

 

[slow]

What QM textbooks have you studied?

It's true, the information in my profile explains it: no background !