What is a probability amplitude?

[Carnot]

Hi

What is a probability amplitude - I have read the article on wikipedia and I still don't get it.
Hope someone out there can explain it to me..

Thanks

 

[mathman]

The probability amplitude is the solution of some equation, such as the wave equation. When it is squared (absolute value) it is interpreted as a probability. Don't try to look for a deeper meaning.

 

[JesseM]

The probability amplitude is the solution of some equation, such as the wave equation. When it is squared (absolute value) it is interpreted as a probability. Don't try to look for a deeper meaning.

Would be a bit more accurate to say the probability amplitude function is a solution to the Schrodinger equation (the probability amplitude function is the system's "quantum state"), but this function gives a set of different probability amplitudes for different possible eigenstates of some observable quantity, like different position eigenstates. For each possible position (or set of positions for a collection of multiple particles), the function would assign a complex number (say, 2 + 3i) to that position(s) which would be the "probability amplitude" for that particular position(s). And if you make a position measurement, the square of the probability amplitude for any particular position eigenstate (really the complex conjugate of the probability amplitude, like [2 + 3i]*[2 - 3i]) gives the probability the particle (or collection of particles) will be found in that position(s). No one knows why you have to go through this arcane procedure of finding the time evolution of the probability amplitude and taking the complex conjugate at the moment of measurement to get the probabilities of different measurement results, it's just that this procedure seems to be the correct way to predict real-world probabilities.

 

[Carnot]

That made it a bit clearer :-)

Thanks a lot both of you