-
Notifications
You must be signed in to change notification settings - Fork 2
/
M1L1h.txt
71 lines (69 loc) · 2.68 KB
/
M1L1h.txt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
#
# File: content-mit-8422-1x-captions/M1L1h.txt
#
# Captions for 8.422x module
#
# This file has 62 caption lines.
#
# Do not add or delete any lines. If there is text missing at the end, please add it to the last line.
#
#----------------------------------------
But finally, if you pulse on an optical standing wave
and your object are not individual atoms,
noninteracting atoms, your object
is the Bose-Einstein condensate or atoms which strongly
interact, then you're not transferring
recoil to individual atoms.
You are transferring momentum to a complicated many-body system.
This means what we are measuring is the dynamic structure
factor.
If you have atoms, you want to do spectroscopy.
You want to know what energy levels are there,
and then you know your atom.
If you have a strongly interacting system,
you also want to know what energy levels are there.
But each energy level in a homogeneous system
or in a periodic potential is associated with momentum
and quasimomentum.
So in other words, if you have a more complicated system,
you want to figure out what are the possible states in terms
of momentum and energy.
And the optical standing wave, the pulsed optical standing
wave, is the way how we impart momentum and energy
to a system.
What I actually just told you is a story
in my own research career.
I was a post-doc with Dave Pritchard.
He had trained at MIT in the '90s
by a pioneer in laser cooling.
And then we had Bose-Einstein condensates
in the late '90s, Professor Pritchard and myself,
we teamed up.
I was the expert on Bose-Einstein condensation.
He was the expert on atom interferometry.
So just by sort of exploring things,
we took Bose-Einstein condensates,
and we pulsed on the standing wave.
What was on our mind was, hey, let's build an interferometer.
But I'm more the many-body physics person.
I suddenly said, yes, but if we now
change the momentum and the frequency of this standing
wave, what happens?
And I suddenly realized that this
is a way to measure properties of a Bose-Einstein condensate
in a way which hadn't been done before.
So I realized, since this is maybe
the last thing I want to tell you today--
I realized sort of in my own research and my collaboration
with Dave Pritchard that we had build an experiment,
and we just turned one knob at our experiment.
And the following day, we were no longer
doing atom interferometry.
We were doing many-body physics.
So this is, I think, what makes our field exciting.
We are using the tools, the precision, and the control
of a atomic physics, which leads to the most
accurate atomic clocks in the world--
atomic clocks, which are the most accurate in the world.
And we are using those tools to do entanglement and many-body
physics.