This preview shows pages 1–2. Sign up to view the full content.
Today’s class:
• Finish our discussion on
‘measurements’
• Schrödinger's cat!
• Quantum computer
• Schrödinger in 3D
What does the probability density of the particle
look like immediately
after you measure its
position
? (assuming you have a nondestructive
way of measuring particle – don’t destroy it, just
measure where it is)

Ψ
(
x
,
t
)
2

Ψ
(
x
,
t
)
2
A
B
Q1

Ψ
(
x
,
t
)
2

Ψ
(
x
,
t
)
2
C
D
E
Could be B, C, or D, depending on where you found it.
Measurement
changes
wave function: particle localized where you measured it,
so if you measure it again, will probably find it in the same place.
x
x
x
x
Electron in
free space
e

in free space after
position measurement
Second
detector
finds particle
most likely
Measurement changes
wave function!
e

in free space
after double slit
Detector array finds
e

at specific
location
b
change
wave function
Double slit:
localizes electron
b
changes
wave function
Detector
array#1
Detector
array#2
at same
location as
detector#1
QT sim
Measuring energy
Suppose you have a particle in the state:
where
Ψ
1
(x,t)
and
Ψ
2
(x,t)
are the ground state and first excited
state of the infinite square well.
What does the probability
density, P(x,t),
of this particle look like immediately after you
measure its ENERGY?
)
,
(
)
,
(
)
,
(
2
2
1
1
2
1
t
x
t
x
t
x
Ψ
+
Ψ
=
Ψ
Ψ
)
2
Ψ x
)
2
Or another graph
like this but shifted
to left or right,
Or similar but
Q2

(
x
,
t
)

Ψ
(
x
,
t
)

Ψ
(
x
,
t
)
2

Ψ
(
x
,
t
)
2
A
C
B
D
E
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 08/24/2010 for the course PHYS 2130 taught by Professor Staff during the Spring '08 term at Colorado.
 Spring '08
 staff
 Physics

Click to edit the document details