Hg+ Single Ion Spectroscopy

Abstract

A single H g 'ion that is confined in an rf (Paul) trap can be laser cooled so that the amplitude of its motion is much less than a wavelength (the Dicke limit) for optical transitions.cooling to reach the zero point of motion. This realizes for the first time the fundamental limit of laser cooling for a bound atom and the ideal of an isolated atomic particle at rest in space to within the quantum mechanical limits imposed by the surrounding apparatus. all orders, the interrogation time is long and the fundamental shot noise detection limit of a single atom is readily attained.

Experimental issues in coherent quantum-state manipulation of trapped atomic ions

“…In the ion trap experiments discussed here, the ion can spend an appreciable amount of time in the (optically) excited state due to laser excitation; in this case the extra energy due to laser excitation can make an otherwise endothermic reaction become exothermic. For example, in experiments on laser-cooled Hg + ions [ 235 ], when ions were excited to the metastable 5 d 9 6 s 2 2 D 5/2 level (approximately 4.4 eV above the ground state) they reacted with neutral Hg atoms in the background gas to cause loss of the Hg + ions (presumably due to radiative association causing dimer formation). As a second example, in experiments on 9 Be + ions [ 47 , 76 , 211 ], the ions were converted to BeH + upon collision with an H 2 molecule when resonant light was applied to the 2 S 1/2 → 2 P 1/2,3/2 transitions.…”

“…For levels separated by optical energies, very long coherence times are also possible because of the very long radiative lifetimes of particular optical levels. So far however, observed coherence times have been limited by the linewidth of the probing lasers to a few tens of hertz [ 235 , 245 , 246 , 247 ].…”

“…If qubit energy levels are separated by optical energies, the lasers that drive qubit transactions must have the required frequency and phase stability. Given the performance of current stable lasers [ 235 , 245 , 246 , 247 ], this may be a problem for long computations. As discussed in Sec.…”

Optical frequency/wavelength references

“…As accuracy improves, the process becomes increasingly difficult and quadratically more time consuming, thus shortterm stability must be improved. Some alternatives exist for the microwave standards, for example, a UWA-SYRTE collaboration takes advantage of the better short-term stability of and both fibre links were Doppler cancelled [187,188]. The data include the combined instability of the entire system (Hg + , Ca, FLFC and two fibre links) and were measured at the 456 THz Ca frequency.…”

RF-trap apparatus for optical frequency standards

“…Summarv Laser cooled, electromagnetically trapped ions, are an ideal medium for optical frequency standards [ 13, [2], [3]. However, an important source of noise in the optical frequency measurement of such trapped ions is caused by a lack of localization of the trapped ion.…”