Quantum Mechanics for Mathematicians

(lily) #1

What is the initial wavefunctionψ(q,0)?
Show that at later times|ψ(q,t)|^2 is peaked about a point that moves with
velocity~mk.


Problem 3:
Show that the limit asT→0 of the propagator


U(T,qT−q 0 ) =


m
i 2 πT

e−
i 2 mT(qT−q^0 )^2

is aδ-function distribution.


Problem 4:
Use the Cauchy integral formula method of section 12.6 to derive equation
12.9 for the propagator from equation 12.13.


Problem 5:
In chapter 10 we described the quantum system of a free non-relativistic
particle of massminR^3. Using tensor products, how would you describe a
system of two identical such particles? Find the Hamiltonian and momentum
operators. Find a basis for the energy and momentum eigenstates for such a
system, first under the assumption that the particles are bosons, then under the
assumption that the particles are fermions.


B.7 Chapters 14 to 16


Problem 1:
Consider a particle moving in two dimensions, with the Hamiltonian function


h=

1

2 m

((p 1 −Bq 2 )^2 +p^22 )


  • Find the vector fieldXhassociated to this function.

  • Show that the quantities


p 1 and p 2 −Bq 1

are conserved.


  • Write down Hamilton’s equations for this system and find the general
    solutions for the trajectories (q(t),p(t)).


This system describes a particle moving in a plane, experiencing a magnetic
field orthogonal to the plane. You should find that the trajectories are circles
in the plane, with a frequency called the Larmor frequency.


Problem 2:
Consider the action of the groupSO(3) on phase spaceR^6 by simultaneously
rotating position and momentum vectors.

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