P1246990921YxRUi

1
The Fit and the PendulumQuantum Mechanics and
New Clocks
M. Crescimanno Department of Physics and
Astronomy Youngstown State University R.
Walsworth , D. Phillips, Irina Novikova and
Christine Wang Harvard -Smithsonian Center for
Astrophysics
2
ONR, NASA, Research Corporation, Cluster
Ohio Program, YSU PACER funds
3
"No one can serve two masters for a slave will
either hate one and love the other or be devoted
to the one and despise the other."
4
IDEAL CLOCK
Based on regularity of periodic behavior must be
Bright need good SNR to "split" the line.
Dark period needs to be immune from environment.
5
Gerard David "Rest on the Flight into Egypt"
1512(?)
6
A Brief History of Time......Measurement
Mercury Ion
Stability
1014
104-6
103-4
107-10
Size/Cost
Rooms
Quarter
Table
?
7
Why Small Atomic Clocks?

• Cell Phone Repeaters

• GPS System

8
Rb Atomic Clock
Optical table lasers, optics and magnetic shields

• QL 15,000
• split endplate design for double bulb
• mechanical tuning
• access for fiber optical detector

(Source D. Phillips)
9
Level Scheme
Level Scheme Simplified
What the experimentalist knows...
What the theorist thinks...
10
Atomic Clock Traditional Maser
Light
RF Pickup
Shield
Microwave Cavity
Good
Simple , Bright
Bad
Light shifts, environment couplings large, bulky
11
Need to shine some dark on this clock...
Fountain Clocks
CPT Clock
(Reduce time atoms spend in cavity)
(Use interference)
12
Coherent Population Trapped Clock
optical pumping to a superposition hyperfine
ground states
Atomic population's dipole vanishes
"Dark State"
No microwave cavity
Small Size
Simple construction
Low light readout
13
CPT Electromagnetically Induced Transparency
o1
Collisions, ...
Light
RWA
14
CPT Electromagnetically Induced Transparency
Static Solution (exact)
Im(rho_01) probe beam absorption
Dispersion Large index of refraction slow- and
stopped light
Little spike of transparency in middle...
15
EIT window
CPT clock lock to center of EIT window
16
CPT clock
Elements
2 Lasers
Photodetector
Shield
17
Schematic of "All-Optical" Atomic Clock
cell oven solenoid shields
cell oven solenoid shields
12 GHz photodetector
3.42 GHz EOM

laser diode
isolator
3.42 GHz drive
x
2

M
u
l
t
p
l
i
e
r
6.84 GHz LO
p
o
w
e
r

l
e
v
e
l




1
7

d
B
m
f
r
e
q

6
.
8
3
4

G
H
z
DC feedback signal
VCXO
(Source D. Phillips, R. Walsworth)
18
Why so good?
(Data from I. Novikova)

• Medium Term stability at the 1012 Level

• Environmental susceptibility

19
Simulation
calculations performed in C/GSL/IDL
parameters chosen to match experimental
conditions
output lineshapes
Detection
from literature and our measurements
20
Simulation
Includes...
Analytic solution for steady state
Doppler effect Motional Averaging (Lamb-Dicke)
AC Stark Effect due to carrier
Lockin detection modulation dependent effects -
(EIT line asymmetry)
21
Preliminary Comparisons
So many knobs to twist !
THEORY
DATA
22
Detuning Slope
DATA
w1/w0 10 mHz/MHZ
Slope is negative !
THEORY
23
Dependence on Modulation
DATA
THEORY
24
Carrier Intensity Stark Effect
THEORY
DATA
25
CONCLUSIONS
CPT clock may be promising
Experiment and QO theory are converging
QO theory informing design compromises
26
(No Transcript)