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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 ?

Short Answer

Expert verified

(a) The expectation value of energy can be written as H=7350.

(b) Smallest possible value, T=.

Step by step solution

01

Harmonic oscillator potential

The harmonic oscillator is an essential concept of quantum mechanics. The oscillator oscillates about an equilibrium point, and the system's total energy is always constant. The potential that can represent the system is harmonic oscillator potential.

02

Solving the first three stationary states

a)

Since,

=m/x=m/1/4

The wave function is:

x,0=A1-22e-2/2x,0=A1-42e-2/2

鈥︹赌︹赌︹赌︹赌(1)

Now,

0x=e-2/2

localid="1658127827170" 1x=2e-2/21x=222-1e-2/2So,x,0=c00+c11+c22

Substitute values in the above expression, and we get,x,0=c0+2c1+22c2-12c2e-2/2 鈥︹赌︹赌︹赌︹赌..(2)

Comparing equations 1 and 2 as:

2c2=4Ac2=22A/2c1=-4Ac1=-22A/c0=c22=Ac0=A+c22

03

Normalizing

1+2A=3A1=c02+c12+c22

Substitute values in the above expression, and we get,

1=8+8+9A2A=5

Therefore, the values will be:

c0=35

04

Expectation value of energy

H=cn2n+12H=c121+12+c222+12+c323+12

Substitute values in the above expression, and we get,

role="math" localid="1658127161820" H=92512+82532+82552H=7350

Thus, the expectation value of energy can be written as: H=7350.

05

finding T for the lowest value

x,t=350e-it/2-2251e-3it/2+2251e-5it/2x,t=e-it/2350-2251e-it/2+2252e-2it/2

Since for the lowest value, we need,

e-iT=-1e-2iT=1T=T=

The smallest possible value of T can be written as: T=.

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