SummaryThe ion microwave frequency standard is a candidate for the next generation of practical microwave frequency standards, which has a very wide application potential. Tsinghua University has continuously been working on the research and development of ion microwave frequency standards. A demonstration experiment of two laser-cooled cadmium ion microwave clocks with zero dead time shows a short-term stability of τ-0.95averaging. Besides, a microwave frequency standard based on cadmium ions sympathetically cooled by ytterbium ions has been realized, and the clock signal has been obtained. In addition, two new laser-cooled ytterbium ion microwave clocks are also being built.SummaryThe ion microwave frequency standard is a candidate for the next generation of practical microwave frequency standards, which has a very wide application potential. Tsinghua University has continuously been working on the research and development of ion microwave frequency standards. A demonstration experiment of two laser-cooled cadmium ion microwave clocks with zero dead time shows a short-term stability of τ-0.95averaging. Besides, a microwave frequency standard based on cadmium ions sympathetically cooled by ytterbium ions has been realized, and the clock signal has been obtained. In addition, two new laser-cooled ytterbium ion microwave clocks are also being built.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)May 15, 20230 citations

Development of Atomic Frequency Standards Using Laser-Cooled Atoms (invited)

H. Lee, T. M. Kwon, S. Park

aprsJan 1, 20010 citations

Optical frequency standard based upon single laser-cooled indium ion

Warren Nagourney, Justin R. Torgerson, HANS G. DEHMELT

The current state of our single indium ion work will be presented, with emphasis on the construction of a narrow, solid-state source of tunable UV radiation which will serve as a “clock” laser for the single-ion standard. Indium is shown to be a favorable candidate for a standard with a long term inaccuracy of less than one part in 1017. Its advantages are small systematic errors which are well-understood and relatively straightforward generation of the cooling and “clock” radiation. The stringent requirements on the long term stability of the “flywheel” clock laser and the difficulty in coherently relating the optical clock laser frequency to a convenient microwave source are problems which should soon be overcome.The current state of our single indium ion work will be presented, with emphasis on the construction of a narrow, solid-state source of tunable UV radiation which will serve as a “clock” laser for the single-ion standard. Indium is shown to be a favorable candidate for a standard with a long term inaccuracy of less than one part in 1017. Its advantages are small systematic errors which are well-understood and relatively straightforward generation of the cooling and “clock” radiation. The stringent requirements on the long term stability of the “flywheel” clock laser and the difficulty in coherently relating the optical clock laser frequency to a convenient microwave source are problems which should soon be overcome.

AIP conference proceedingsJan 1, 19992 citations

Application of Laser Cooling to the Atomic Frequency Standards

F. Strumia

Springer eBooksJan 1, 198812 citations

Laser Cooling of Atomic Beams and its Application to Frequency Standards

N. Beverini, F. Strumia

NATO ASI series. Series B : PhysicsJan 1, 19900 citations

Blackbody thermometry with cold molecular ions and application to ion-based frequency standards

Jeroen C. J. Koelemeij, Bernhard Roth, Stephan Schiller

We have used laser spectroscopy to measure the rotational level distribution of trapped molecular $\mathrm{H}{\mathrm{D}}^{+}$ ions at translational temperatures in the millikelvin range. The $\mathrm{H}{\mathrm{D}}^{+}$ ions are loaded into an ion trap by electron-impact ionization, and sympathetically cooled using laser-cooled ${\mathrm{Be}}^{+}$ ions which are already stored in the trap. Under our experimental conditions, the internal (rotational) degrees of freedom turn out to be independent of the translational degrees of freedom, and an effective rotational temperature close to room temperature is found. The near absence of background-gas collisions allows the rotational temperature to be related directly to the temperature of the ambient blackbody radiation (BBR). This feature suggests the use of molecular ions for BBR thermometry, which may help to improve the accuracy of frequency standards based on trapped atomic ions. For the spectroscopic measurement of the rotational populations, we propose a nondestructive technique.We have used laser spectroscopy to measure the rotational level distribution of trapped molecular $\mathrm{H}{\mathrm{D}}^{+}$ ions at translational temperatures in the millikelvin range. The $\mathrm{H}{\mathrm{D}}^{+}$ ions are loaded into an ion trap by electron-impact ionization, and sympathetically cooled using laser-cooled ${\mathrm{Be}}^{+}$ ions which are already stored in the trap. Under our experimental conditions, the internal (rotational) degrees of freedom turn out to be independent of the translational degrees of freedom, and an effective rotational temperature close to room temperature is found. The near absence of background-gas collisions allows the rotational temperature to be related directly to the temperature of the ambient blackbody radiation (BBR). This feature suggests the use of molecular ions for BBR thermometry, which may help to improve the accuracy of frequency standards based on trapped atomic ions. For the spectroscopic measurement of the rotational populations, we propose a nondestructive technique.

Physical Review AAug 17, 200762 citations

We have used laser spectroscopy to measure the rotational level distribution of trapped molecular

\mathrm{H}{\mathrm{D}}^{+}

ions at translational temperatures in the millikelvin range. The

\mathrm{H}{\mathrm{D}}^{+}

ions are loaded into an ion trap by electron-impact ionization, and sympathetically cooled using laser-cooled

{\mathrm{Be}}^{+}

ions which are already stored in the trap. Under our experimental conditions, the internal (rotational) degrees of freedom turn out to be independent of the translational degrees of freedom, and an effective rotational temperature close to room temperature is found. The near absence of background-gas collisions allows the rotational temperature to be related directly to the temperature of the ambient blackbody radiation (BBR). This feature suggests the use of molecular ions for BBR thermometry, which may help to improve the accuracy of frequency standards based on trapped atomic ions. For the spectroscopic measurement of the rotational populations, we propose a nondestructive technique.