Ph.D. Thesis - Physics

Figure 9-2: Left: Level diagram for the 40 Ca + ion, showing the Doppler cooling transition
at 397 nm, the repumper at 866 nm, and the sideband cooling and coherent operations laser
at 729 nm. The spontaneous emission rate from the 4P 1/2 state is 23 MHz, with the ion
decaying to 3D 3/2 ≈ 1/16 of the time. The lifetime of the 3D 5/2 state is ≈ 1.2 s. Right:
Photoionization transitions for 40 Ca. A 422 nm photon pumps the atom from the 4s4s state
to the excited 4s4p state, then a 370 nm photon takes the atom into an autoionizing level,
resulting in the loss of a single electron.
at 422 and 370 nm, are generated from extended cavity diode lasers. A schematic of the
two-photon PI process is also given in Fig. 9-2.
The laser system was furnished by Toptica. The 397 nm Doppler cooling beam is pro-
duced by frequency-doubling a 794 nm laser diode, while the 866 nm radiation is produced
from an extended cavity diode laser directly. Photographs of these lasers are presented in
Fig. 9.1.1 and Fig. 9-4.
The lasers are locked using the Pound-Drever-Hall (P-D-H) method to a four-hole ULE
cavity under vacuum, with an approximate pressure of 10 −8 mbar. 1 The control electronics
for current and temperature stabilization, as well as the P-D-H lock are furnished by Toptica.
The frequencies are then monitored using a Toptica wavemeter.
9.1.2 The microfabricated trap
The trap is manufactured using standard microfabrication techniques. The credit for the
design and manufacture of the traps goes to Nikos Daniilidis, a post-doc in the Innsbruck
group who collaborated on this project with Andreas Wallraff at ETH Zürich. The trap
1 In this chapter we shall use mbar rather than torr to describe vacuum pressures. Fortunately, 1 mbar
= 0.75 torr, so that they are on the same order of magnitude.
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