Stanford PNT hollberg Nov07 b - Stanford Center for Position ...
Stanford PNT hollberg Nov07 b - Stanford Center for Position ...
Stanford PNT hollberg Nov07 b - Stanford Center for Position ...
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Advantages of Optical Clocks Quantum Projection Noise<br />
Fractional Frequency instability ~<br />
1 P<br />
Cooling/<br />
detection<br />
transition<br />
S<br />
f<br />
3 P or D<br />
Clock<br />
transition<br />
0<br />
f optical<br />
microwave<br />
! = observation time<br />
N = number of atoms<br />
10<br />
!<br />
10<br />
0 !<br />
15<br />
10<br />
5<br />
10<br />
• Large number of atoms 10 6 or more<br />
• High signal/noise<br />
• Possibility of lattices<br />
# =<br />
One atomic clock is always “perfect”<br />
Two similar clocks -- hard to detect systematic errors<br />
Different types of clocks can determine most accurate and stable<br />
y<br />
K<br />
$ "<br />
"<br />
T<br />
N<br />
cycle<br />
atoms<br />
!<br />
Candidate neutral atoms<br />
Ca, Sr, Yb, Mg, H, Ag, Hg…<br />
0<br />
Δν<br />
ν 0<br />
ν
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