Introduction To Quantum Mechanics
3rd Edition
ISBN: 9781107189638
Author: Griffiths, David J., Schroeter, Darrell F.
Publisher: Cambridge University Press
expand_more
expand_more
format_list_bulleted
Question
Chapter 11, Problem 11.36P
(a)
To determine
The classical position of the oscillator, assuming it started from rest at the origin
(b)
To determine
Show that the solution to the time-dependent Schrodinger equation for this oscillator can be written as
(c)
To determine
Show that the eigenfunctions and eigenvalues of
(d)
To determine
Show that in the adiabatic approximation the classical position reduces to
(e)
To determine
Show that
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
4. Consider a harmonic oscillator in two dimensions described by the Lagrangian
т
mw?
L
2
2
where (r, ø) are the polar coordinates, m > 0 is the mass, and w > 0 the oscillation
frequency of the oscillator.
(a) Find the canonical momenta p, and pø, and show that the Hamiltonian is given by
mw?
H(r, 0, Pr; Po) =
2m
2mr?
2
(b) Show that p is a constant of motion.
(c) In the following we will perform a variable transformation (r, 6, p,, Pa) → (Q,,Qo, Pr, Pg
defined by
Q, = 7.
lp,
P,
Pg = Pe
Qo = 20,
%3D
%3D
2r
2
where l is an arbitrary constant length that just ensures that Q, has also the dimension
of length. Show that this transformation is canonical.
(d) The Hamiltonian becomes in the new variables
2P?
mw?l
2
H(Q..Qo» Pr, Pa) = Q,P; +
mlQ,
-Qr.
2
ml
Show that the fact that energy E is conserved and H = E allows us to introduce a new
Hamiltonian HK and a new energy EK such that HK
with
%3D
Ek is equivalent to H = E,
P2
P?
Hg(Qr.Qá, Pr, Pa) =
|
2m
2mQ? Q,
Determine the constant a and the…
A particle of mass m is suspended from a support by a light string of length which passes
through a small hole below the support (see diagram below). The particle moves in a vertical
plane with the string taut. The support moves vertically and its upward displacement (measured
from the ring) is given by a function z = h(t). The effect of this motion is that the string-particle
system behaves like a simple pendulum whose length varies in time.
I
[Expect to use a few lines to answer these questions.]
a) Write down the Lagrangian of the system.
b) Derive the Euler-Lagrange equations.
z=h(t)
c) Compute the Hamiltonian. Is it conserved?
The time-evolution of a physical system with one coordinate q is described by the La-
grangian
1
L
ģ² + aġ sin q sin t + b cos q,
2
where a and b are constants.
(a) Show that the corresponding Hamiltonian is
1
(p – a sin q sin t)² – b cos q.
2
H
Is H a constant of the motion?
(b) Obtain a type 2 generating function, F2(q, P,t), for the canonical transformation
Q = q,
P = p – a sin q sin t.
ƏF2
dq
Q=
OF2
Definition of a type 2 generating function:
(c) Use K = H + ƏF2/ðt to find the new Hamiltonian, K(Q, P,t), obtained by applying
the transformation from part (b) to the Hamiltonian given in part (a).
(d) Using your result from part (c), or otherwise, derive the equation of motion
Q
= -(a cos t + b) sin Q.
Chapter 11 Solutions
Introduction To Quantum Mechanics
Ch. 11.1 - Prob. 11.1PCh. 11.1 - Prob. 11.2PCh. 11.1 - Prob. 11.3PCh. 11.1 - Prob. 11.4PCh. 11.1 - Prob. 11.5PCh. 11.1 - Prob. 11.6PCh. 11.1 - Prob. 11.7PCh. 11.1 - Prob. 11.8PCh. 11.1 - Prob. 11.9PCh. 11.3 - Prob. 11.10P
Ch. 11.3 - Prob. 11.11PCh. 11.3 - Prob. 11.12PCh. 11.3 - Prob. 11.13PCh. 11.3 - Prob. 11.14PCh. 11.3 - Prob. 11.15PCh. 11.3 - Prob. 11.16PCh. 11.4 - Prob. 11.17PCh. 11.5 - Prob. 11.18PCh. 11.5 - Prob. 11.19PCh. 11.5 - Prob. 11.20PCh. 11.5 - Prob. 11.21PCh. 11.5 - Prob. 11.22PCh. 11 - Prob. 11.23PCh. 11 - Prob. 11.24PCh. 11 - Prob. 11.25PCh. 11 - Prob. 11.26PCh. 11 - Prob. 11.27PCh. 11 - Prob. 11.28PCh. 11 - Prob. 11.29PCh. 11 - Prob. 11.30PCh. 11 - Prob. 11.31PCh. 11 - Prob. 11.33PCh. 11 - Prob. 11.35PCh. 11 - Prob. 11.36PCh. 11 - Prob. 11.37P
Knowledge Booster
Similar questions
- Consider the Lagrangian for a bead on a rotating horizontal wire:L = m/2 ( ̇q2 + ω2q2).(a) What is H? Is it constant?(b) What if angular speed of rotation ω were not a constant? If ω = ω(t)what is H? Would it be constant?(c) In either case does H = E, the total energy.arrow_forwardConsider the schematic of the single pendulum. M The kinetic energy T and potential energy V may be written as: T = ²m²²8² V = -gml cos (0) аас dt 80 The Lagrangian L is given by L=T-V, and the Euler-Lagrange equations for the motion of the pendulum are given by the following second order differential equation in : ас 80 = 11 = 0 Write down the second order ODE using the specific T and V defined above. Please write this ODE in the form = f(0,0). Notice that this ODE is not linear! Now you may assume that l = m = g = 1 for the remainder of the problem. You may still suspend variables to get a system of two first order (nonlinear) ODEs by writing the ODE as: w = f(0,w) What are the fixed points of this system where all derivatives are zero? Write down the linearized equations in a neighborhood of each fixed point and determine the linear stability. You may formally linearize the nonlinear ODE or you may use a small angle approximation for sin(0); the two approaches are equivalent.arrow_forward(a) What does the quadrupole formula (P) = = = (Qij Q³ ³) compute? Reason the answer. (b) A point mass m undergoes a harmonic motion along the z-axis with frequency w and amplitude L, x(t) = y(t) = 0, z(t) = L cos(wt). Show that the only non-vanishing component of the quadrupole moment tensor is = Im L² cos² (wt). (c) Use the quadrupole formula to compute the power radiated by the emission of gravitational waves. (Hint: recall that (cos(t)) = (sin(t)) = 0 and (cos² (t)) = (sin² (t)) = ½½ for a given frequency 2.)arrow_forward
- Let a two-degree-of-freedom system be described by the Hamiltonian 1 H =(P +P)+ V(x, y) and suppose the potential energy V is a homogenous function of degree -2: V(xx, ày) = 2-2v(x,y) VÀ > 0. Show that $ = (xpy – yp.)² +2(x² + y²)V(x, y) is a second constant of the motion independent of the Hamiltonian (Yoshida, 1987). Therefore, this system is integrable.arrow_forwardOur unforced spring mass model is mx00 + βx0 + kx = 0 with m, β, k >0. We know physically that our spring will eventually come to rest nomatter the initial conditions or the values of m, β, or k. If our modelis a good model, all solutions x(t) should approach 0 as t → ∞. Foreach of the three cases below, explain how we know that both rootsr1,2 =−β ± Sqrt(β^2 − 4km)/2mwill lead to solutions that exhibit exponentialdecay.(a) β^2 − 4km > 0. (b) β^2 − 4km =0. (c) β^2 − 4km >= 0.arrow_forward: The Hamiltonian for the one-dimensional simple harmonic oscillator is: mw? 1 ÎĤ =- + 2m Use the definition of the simple harmonic oscillator lowering operator 1 -î + iv mwh mw V2 and its Hermitian conjugate to: (a) Evaluate (â', â] (b) Show that = Vi e n = Vmwh () and Ĥ = ħw(âtâ + }) à ât %3D (c) Evaluate [âtâ, â] (d) Find (î),(f), (x²) and (p2) for the nth stationary state of the harmonic oscillator. Check that the uncertainty principle is satisfied.arrow_forward
- The equations of motion of the orbits of the planets due to their gravitational force with the sun are given as follows (in polar coordinates): [attached to the figure]. With M solar mass, m planetary mass, E energy of the planetary incident, l angular momentum system, and G is the universal gravitational constant. Find the solution of the above differential equation and express it in r as a function θ, r = r(θ). This solution depicts an elliptical curve (conical wedge) as the shape the orbits of the planets around the sun.arrow_forwardTwo springs of force constants k1 and k2 are attached to a block of mass m and to fixed supports as shown in Fig. 2. The table surface is frictionless. (a) If the block is displaced from its equilibrium position and is then released, show that its motion will be simple harmonic with angular frequency w = √(k1 + k2)/m. (b) Suppose the system is now submersed in a liquid with damping coefficient b , what is the condition that the block will return to itsequilibrium position without oscillation?Sketch a graph to show the behavior of the system in this case.arrow_forwardConsider a uniformly charged ring in the xy plane, centered at the origin. The ring has radius a and positive charge q distributed evenly along its circumference. A small metal ball of mass m and negative charge −q0 is released from rest at the point (0,0,d) and constrained to move along the z axis, with no damping. At 0<d≪a, the ball's subsequent trajectory is oscillating along the z axis between z=d and z=−d. The ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. What will be the angular frequency ω of these oscillations? Use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. Express your answer in terms of given charges, dimensions, and constants.arrow_forward
- As an illustration of why it matters which variables you hold fixed when taking partial derivatives, consider the following mathematical example. Let w = xy and x = yz. Write w purely in terms of x and z, and then purely in terms of y and z.arrow_forwardFor motion in a plane with the HamiltonianH = |p|n − a r−n,where p is the vector of the momenta conjugate to the Cartesian coordinates,show that there is a constant of the motionD = (p . r) / n − H t.arrow_forwardEmploying the power expansion to the solution of the equation of motion, show that for a one-dimensional harmonic oscillator with a Hamiltonian that p2 H mw? 2m the solution is given by x(t) = x0 coS wt + Ро sin wt , where xo = x(t = 0) and po = p(t = 0) represent the initial conditions.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Classical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage Learning
Classical Dynamics of Particles and Systems
Physics
ISBN:9780534408961
Author:Stephen T. Thornton, Jerry B. Marion
Publisher:Cengage Learning