Physica Scripta

Precise Optical Spectroscopy with Ion Traps

Wayne M. Itano, Jonas Bergquist, Randall G. Hulet, David J. Wineland

Published Jan 1, 1988• 21 citations

Abstract

We have used stored ion methods to improve resolution and sensitivity in optical spectroscopy. Single atomic ions have been confined by electric and magnetic fields, cooled by laser radiation pressure to temperatures on the order of 1 mK, and probed spectroscopically with narrowband lasers. The absorption resonance of a single Hg + ion has been observed by a decrease in the transmitted light intensity. An ultraviolet transition in Hg + has been observed with a linewidth of only 30 kHz. Quantum jumps to and from metastable levels of Hg + have been observed and used to determine radiative decay rates and to infer the existence of photon antibunching. Quantum jumps have also been observed in single Mg + ions.

DOI: 10.1088/0031-8949/1988/t22/011

Related papers

Single ion optical frequency standard

Jonas Bergquist, Wayne M. Itano, David J. Wineland +3 more

Experimental research toward the realization of an optical frequency standard of high accuracy is briefly reviewed. The studies concentrated on single, laser-cooled ions since they offer several attractive features for the achievement of high accuracy. These features include long storage time which eliminates transit-time broadening, confinement that is nearly nonperturbative to the internal level structure of the ion, laser-cooling that reduces motional shifts to small values, and electron-shelving whereby transitions to long-lived states can be detected with unit probability. The authors studied spectroscopically the electric-quadrupole allowed transition at 282 nm in a single, laser-cooled /sup 199/Hg/sup +/ ion stored in an RF Paul trap with extremely high resolution. The measured linewidth is limited by the spectral purity of the laser to about 80 Hz. Possible improvements and future directions are discussed.>

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)Jan 1, 19918 citations

Spectroscopy of Single Trapped Ions and Application to Frequency Standards

HERBERT WALTHER

Single ions trapped and laser cooled provide ideal objects for high resolution spectroscopy and frequency standards. For the latter purpose we are investigating the 5s2 1S0 → 5s5p 3P0 transition of In+. With a natural linewidth of only 1.1 Hz this resonance offers very high resolution and is highly immune to frequency shifts due to external electromagnetic fields, because it connects two levels with vanishing electronic magnetic momenta [1]. The wavelength of this clock transition is 236.5 nm and is technically very convenient, since it coincides with the fourth harmonic of the 946 nm Nd:YAG laser line. So this intrinsically frequency stable solid-state laser can be used to excite the transition [2]. For laser cooling and fluorescence detection of the indium ion the 5s2 1So -> 5s5p 3P1 transition at 230.6 nm can be employed. The use of the relatively narrow intercombination line for laser cooling allows us to study optical sideband cooling in the strong binding regime, where the oscillation frequencies of the ion in the trap (around 1 MHz) are larger than the optical linewidth of 360 kHz. In this parameter range laser cooling is possible to the quantum ground state of the vibrational motion in the trap corresponding to a temperature of roughly 100 μK. The same low temperature was obtained with sideband cooling of a small Coulomb crystal consisting of two ions, creating an interesting new quantum few-particle system.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Jan 1, 19980 citations

Optical spectroscopy of a single ion at the Dicke limit

Jonas Bergquist, F. Diedrich, Wayne M. Itano +1 more

A single Hg+ ion that is confined in an rf (Paul) trap can be laser cooled so that the amplitude of its motion is much less than an optical wavelength (the Dicke limit for optical transitions).1 More recently, we used the technique of sideband cooling to reach the zero point of motion.2 This realizes for the first time, we believe, the fundamental limit of laser cooling and the ideal of an isolated atomic particle at rest in free space to within the quantum mechanical limits imposed by the surrounding apparatus. In both limits, Doppler effects to all orders become negligible, the interrogation time is arbitrarily long, and the fundamental shot noise limit of a single atom is readily attained. We report these results and our progress toward the 2S1/2—2D5/2 282-nm transition with a resolution approaching the 2-Hz natural linewidth.

Annual Meeting Optical Society of AmericaJan 1, 19880 citations

Single ion spectroscopy for optical clocks

Chr. Tamm, E. Peik, T. Schneider +5 more

The 435 mum171Yb+transition is a good candidate for an atomic clock based on an optical transition. We have stored single171Yb ions for several months in RF traps. The ions are cooled, repumped and the clock transition is interrogated by (frequency-doubled) diode lasers. The interrogation laser linewidth was 30 Hz determining the resolvable linewidth of the Yb+transition interrogated. The absolute frequency of this transition was measured using an optical comb generator, self referenced by broadening the spectrum to above one octave, with respect to a Cs fountain clock. Of all systematic frequency shifts to which this transition is subject an estimate indicates that the electric quadruple shift appears is the largest. To obtain a magnitude of the quadruple shift (and the quadruple moment) the clock frequencies of two independently stored and cooled171Yb ions were compared while varying the static electric field in one trap. The measured frequency shift amounting to ~1 Hz/V. This result would seem to permit clocks with much higher accuracy than the clocks based on microwave transition, particularly if the technique of aligning the ions with respect to the electric field were applicable. Anticipating even more precise clocks, we are presently investigating a blue nuclear transition in229Th. Such a nuclear transition should be even better shielded from environmental influences than transitions in the electron shell. This nuclear transition has not yet been directly optically observed. We are presently investigating the luminescence after incoherent broad band optical excitation. The triply ionized223Th is then a suitable system for trapped single ion spectroscopy. The cooling transition lies conveniently in the near infrared and the nuclear clock transition can be read out by nuclear/electron shell double resonance

CAOL . International Conference on Advanced Optoelectronics and LasersJul 8, 20041 citation

Trapped atomic particles in action

Konstantin N. Drabovich

A review of recent papers on research on trapped ions cooled by laser radiation is given. Experiments are described on observing quantum jumps in atoms and on investigating antibunching and sub-Poisson statistics of photons of fluorescence radiation from single atoms. Experiments on phase transitions in a system of cold ions are discussed.

Soviet Physics UspekhiJul 31, 19890 citations

Absorption spectroscopy at the limit: detection of a single atom

D. J. Wineland, Wayne M. Itano, Jonas Bergquist

We investigate the sensitivity limit of absorption spectroscopy. An experiment is described in which the decrease in transmitted light intensity that is due to absorption by a single, electromagnetically confined atomic ion is observed.

Optics LettersJun 1, 198793 citations