Wednesday, March 8, 2017

quantum mechanics - What is a coherent state?



In quantum mechanics, what exactly is a coherent state, and how does it differ from other states?



Answer



A coherent state is a state that is not an energy eigenstate, so the observables vary in time, but the uncertainty of the canonical conjugates (position and momentum) stays constant - unlike, for instance, in an ordinary wave packet moving in free space: this "floats away", the position uncertainty gets ever bigger and bigger.


-

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)

classical mechanics - Moment of a force about a given axis (Torque) - Scalar or vectorial?

I am studying Statics and saw that: The moment of a force about a given axis (or Torque) is defined by the equation: $M_X = (\vec r \times \...

  • IQ test sample patterns
    I was solving the sample problems for my school's IQ society and there are some I don't get. Since all I get is a final score, I wan...
  • homework and exercises - Parallel or series connection?
    Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23? Btw it appeared as a question in the basic physics...
  • A real star riddle
    500 are at my end, 500 are at my start, but at my heart there are only 5. The first letter and the first number make me complete: Some consi...