Experimental demonstration of ultrahigh-precision transport and acceleration of single ions

A basic performance test of a novel ion source is carried out to attain an extremely narrow beam for pinpoint irradiation of single ions onto an intended target. In principle, the normalized root-mean-squared emittance of the beam can reach a sub-femtometer level, which makes a transverse spot size of nanometer order available. The system is based on a compact linear Paul trap equipped with a Doppler-cooling device. The trap is the most popular, economical type consisting simply of a few metal plates and rods. Among several possible choices of ion species, we picked <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msup> <a:mmultiscripts> <a:mi>Ca</a:mi> <a:mprescripts/> <a:none/> <a:mn>40</a:mn> </a:mmultiscripts> <a:mo>+</a:mo> </a:msup> </a:math> for the present investigation. A small number of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msup> <c:mmultiscripts> <c:mi>Ca</c:mi> <c:mprescripts/> <c:none/> <c:mn>40</c:mn> </c:mmultiscripts> <c:mo>+</c:mo> </c:msup> </c:math> ions are first laser cooled to near absolute zero where they form a spatially ordered configuration called a . The axial-potential well provided by dc bias voltages on two planar electrodes is then deformed gradually to eject the ions from the trap along the design orbit. We demonstrate that it is possible to launch the ultracold ions one by one at arbitrary timing with no serious radio-frequency heating. These ions are accelerated to 1 keV immediately after the extraction. The effectiveness of a few different ion-ejection schemes is experimentally verified and supported by three-dimensional molecular dynamics simulations.