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What is the Fourier transform (x) ? Using Plancherel鈥檚 theorem shows that(x)=12eikxdk.

Short Answer

Expert verified

The Fourier transform for the given function is

(x)=12eikxdk

Step by step solution

01

Define the Schrodinger equation

A differential equation that describes matter in quantum mechanics in terms of the wave-like properties of particles in a field. Its answer is related to a particle's probability density in space and time.

02

Determine the Fourier transform

By using the Fourier transform,

F(k)=12f(x)eikxdx

Substitute f(x)=(x) into equation

F(k)=12(x)eikxdx

(x)eikxdx=1

F(k)=12

f(x)=(x)鈥夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌=1212eikxdk鈥夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌夆赌=12eikxdk

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Most popular questions from this chapter

In this problem we explore some of the more useful theorems (stated without proof) involving Hermite polynomials.

a. The Rodrigues formula says thatHn()=(1)ne2(d诲尉)ne2

Use it to derive H3 and H4 .

b. The following recursion relation gives you Hn+1 in terms of the two preceding Hermite polynomials: Hn+1()=2尉贬n()2nHn1()

Use it, together with your answer in (a), to obtain H5 and H6 .

(c) If you differentiate an nth-order polynomial, you get a polynomial of

Order (n-1). For the Hermite polynomials, in fact,

dHn诲尉=2nHn1()

Check this, by differentiatingH5and H6.

d. Hn()is the nth z-derivative, at z = 0, of the generating function exp(z2+2z)or, to put it another way, it is the coefficient ofznn! in the Taylor series expansion for this function: ez2+2尉锄=n=0znn!Hn()

Use this to obtain H0,H1and H2.

A particle of mass m in the harmonic oscillator potential (Equation 2.44) starts (x,0)=A(1-2mx)2e-m2x2out in the state for some constant A.
(a) What is the expectation value of the energy?
(c) At a later time T the wave function islocalid="1658123604154" (x,T)=B(1+2mx)2e-m2x2
for some constant B. What is the smallest possible value of T ?

Delta functions live under integral signs, and two expressions (D1xandD2x)involving delta functions are said to be equal if

-+f(x)D1(x)dx=-+f(x)D2(x)dxfor every (ordinary) function f(x).

(a) Show that

(cx)=1|c|(x)(2.145)

where c is a real constant. (Be sure to check the case where c is negative.)

(b) Let (x) be the step function:

(x){1,x>00,x>0(2.146).

(In the rare case where it actually matters, we define (0) to be 1/2.) Show that dldx=

A particle is in the ground state of the harmonic oscillator with classical frequency , when suddenly the spring constant quadruples, so '=2, without initially changing the wave function (of course, will now evolve differently, because the Hamiltonian has changed). What is the probability that a measurement of the energy would still return the value 2? What is the probability of getting ?

Prove the following three theorem;

a) For normalizable solutions the separation constant E must be real as E0+iand show that if equation 1.20 is to hold for all t, must be zero.

b) The time - independent wave function localid="1658117146660" (x) can always be taken to be real, This doesn鈥檛 mean that every solution to the time-independent Schrodinger equation is real; what it says is that if you鈥檝e got one that is not, it can always be expressed as a linear combination of solutions that are . So, you might as well stick to 鈥檚 that are real

c) If is an even function then (x)can always be taken to be either even or odd

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