Chapter 3: Q20P (page 118)
Show that the energy-time uncertainty principle reduces to the "your name" uncertainty principle (Problem 3.14), when the observable in question is x.
Short Answer
The energy-time uncertainty principle reduces to .
Chapter 3: Q20P (page 118)
Show that the energy-time uncertainty principle reduces to the "your name" uncertainty principle (Problem 3.14), when the observable in question is x.
The energy-time uncertainty principle reduces to .
All the tools & learning materials you need for study success - in one app.
Get started for free(a) Check that the eigenvalues of the hermitian operator in Example 3.1 are real. Show that the eigenfunctions (for distinct eigenvalues) are orthogonal.
(b) Do the same for the operator in Problem 3.6.
(a) Write down the time-dependent "Schrödinger equation" in momentum space, for a free particle, and solve it. Answer:
(b) Find role="math" localid="1656051039815" for the traveling gaussian wave packet (Problem 2.43), and construct for this case. Also construct , and note that it is independent of time.
(c) Calculaterole="math" localid="1656051188971" androle="math" localid="1656051181044" by evaluating the appropriate integrals involving, and compare your answers to Problem 2.43.
(d) Show thatrole="math" localid="1656051421703" (where the subscript denotes the stationary gaussian), and comment on this result.
Consider the wave function
whereis some positive integer. This function is purely sinusoidal (with wavelength)on the interval, but it still carries a range of momenta, because the oscillations do not continue out to infinity. Find the momentum space wave function. Sketch the graphs ofand, and determine their widths,and(the distance between zeros on either side of the main peak). Note what happens to each width as. Usingandas estimates ofand, check that the uncertainty principle is satisfied. Warning: If you try calculating, you're in for a rude surprise. Can you diagnose the problem?
Is the ground state of the infinite square well an eigenfunction of momentum? If so, what is its momentum? If not, why not?
Prove the famous "(your name) uncertainty principle," relating the uncertainty in position to the uncertainty in energy:
For stationary states this doesn't tell you much-why not?
What do you think about this solution?
We value your feedback to improve our textbook solutions.