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Metastable level lifetimes from electron-shelving measurements with ion clouds and single ions  [PDF]
Martina Knoop,Caroline Champenois,Ga?tan Hagel,Marie Houssin,Caroline Lisowski,Michel Vedel,Fernande Vedel
Physics , 2003, DOI: 10.1140/epjd/e2004-00022-6
Abstract: The lifetime of the 3d^2D_5/2-level in singly-ionized calcium has been measured by the electron-shelving technique on different samples of rf trapped ions. The metastable state has been directly populated by exciting the dipole-forbidden 4S_1/2 - 3D_5/2 transition. In ion clouds, the natural lifetime of this metastable level has been measured to be (1095+-27) ms. For the single-ion case, we determined a lifetime of (1152+-20) ms. The 1sigma-error bars at the 2%-level have different origins for the two kinds of experiments: data fitting methods for lifetime measurements in an ion cloud and control of experimental parameters for a single ion. De-shelving effects are extensively discussed. The influence of differing approaches for the processing of the single-ion quantum jump data on the lifetime values is shown. Comparison with recent measurements shows excellent agreement when evaluated from a given method.
Shelving and Probe Efficiency in Trapped Ion Experiments  [PDF]
M. Schacht,M. M. Schauer
Physics , 2014, DOI: 10.1088/0953-4075/47/16/165002
Abstract: A generalized probe sequence typical of trapped ion experiments using shelving is studied. Detection efficiency is analyzed for finite shelved state lifetimes and using multi-modal count distributions. Multi-modal distributions are more appropriate for measurements that use a small number of ions than the simple Poisson counting statistics usually considered and have a larger variance that may be significant in determining uncertainties and in making weighted fits. Optimal probe times and the resulting state detection efficiency and sensitivity are determined for arbitrary cooling rates, initial states and shelved state lifetimes, in terms of a probe coherence time {\tau}p. A universal optimal probe time of tp ~ 0.43{\tau}p is shown to give an almost optimal probe sensitivity for most systems.
Three-Dimensional Array for 40Ca+ Ion Trapping

WAN Jin-Yin,LIU Liang,

中国物理快报 , 2009,
Abstract: We present a three-dimensional scalable linear ion trap scheme for ion trapping and discuss its applications for the optical frequency standard and scalable quantum information processing with its parallel strings of trapped 40Ca+ ions. The geometry here contains nine equal-distance parallel rods driven by rf, which form trapping potentials for radial confinement and two end ring electrodes biased at a few volts for axial confinement. Its feasibility is calculated by using the finite element analysis method.
Experimental Improvement of Signal of a Single Laser-Cooled Trapped 40Ca+ Ion
Experimental Improvement of Signal of a Single Laser-Cooled Trapped ^40Ca^+ Ion

SHU Hua-Lin,GUO Bin,GUAN Hua,LIU Qu,HUANG Xue-Ren,GAO Ke-Lin,

中国物理快报 , 2007,
Abstract: A single 40Ca+ ion is loaded in a miniature Paul trap and the probability of directly loading a single ion is above 50%. The signal-to-noise ratio and the storage time for a single ion have been improved by minimizing the ion micromotion and locking a 397nm cooling laser to a Fabry--Perot interferometer and optogalvanic signal. From the fluorescence spectrum, the ion temperature is estimated to be about 5mK.
Optical frequency standard based on a single 40Ca+
KeLin Gao
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5646-5
Abstract: Research on the development of the optical frequency standard based on trapped and cold 40Ca+ with the 4s 2S1/2-3d 2D5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10 16. The absolute frequency of the clock transition was measured at 10 15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.
Control of a Cloud of Laser-Cooled 40Ca+ in a Linear Ion Trap

ZHOU Fei,XIE Yi,XU You-Yang,LI Jiao-Mei,HUANG Xue-Ren,FENG Mang,

中国物理快报 , 2010,
Abstract: A cloud of laser-cooled 40Ca+ is successfully trapped and manipulated under well control in our home-built linear ion trap, which is designed and constructed solely for studying quantum information processing. By exploring the variation of the ion cloud with respect to the trap parameters, we have optimized the trapping condition and obtained very good fluorescence spectra. We observe the dynamics of the ion cloud, and estimate the temperature of the ion cloud to be of the order of milli-Kelvin.
Hertz-level Measurement of the 40Ca+ 4s 2S1/2-3d 2D5/2 Clock Transition Frequency With Respect to the SI Second through GPS  [PDF]
Y. Huang,J. Cao,P. Liu,K. Liang,B. Ou,H. Guan,X. Huang,T. Li,K. Gao
Physics , 2011, DOI: 10.1103/PhysRevA.85.030503
Abstract: We report a frequency measurement of the clock transition of a single ^40Ca^+ ion trapped and laser cooled in a miniature ring Paul trap with 10^-15 level uncertainty. In the measurement, we used an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the Global Positioning System (GPS). Two rounds of measurements were taken in May and June 2011, respectively. The frequency was measured to be 411 042 129 776 393.0(1.6) Hz with a fractional uncertainty of 3.9{\times}10^-15 in a total averaging time of > 2{\times}10^6 s within 32 days.
A cloud of laser cooled 40Ca+ in a linear ion trap
Fei Zhou,YouYang Xu,Yi Xie,Bin Guo,HuaLin Shu,JiaoMei Li,XueRen Huang,Mang Feng
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-4072-9
Abstract: A cloud of 40Ca+ is successfully trapped and cooled using the radiation of a red-detuned 397 nm laser beam and a resonant 866 nm laser beam in our prototype linear ion trap, which was designed and constructed for studying quantum information processing. We have characterized the size of the ion cloud, estimating the temperature to be in the order of milli-Kelvins.
A diode laser stabilization scheme for 40Ca+ single ion spectroscopy  [PDF]
F. Rohde,M. Almendros,C. Schuck,J. Huwer,M. Hennrich,J. Eschner
Physics , 2009, DOI: 10.1088/0953-4075/43/11/115401
Abstract: We present a scheme for stabilizing multiple lasers at wavelengths between 795 and 866 nm to the same atomic reference line. A reference laser at 852 nm is stabilized to the Cs D2 line using a Doppler-free frequency modulation technique. Through transfer cavities, four lasers are stabilized to the relevant atomic transitions in 40Ca+. The rms linewidth of a transfer-locked laser is measured to be 123 kHz with respect to an independent atomic reference, the Rb D1 line. This stability is confirmed by the comparison of an excitation spectrum of a single 40Ca+ ion to an eight-level Bloch equation model. The measured Allan variance of 10^(-22) at 10 s demonstrates a high degree of stability for time scales up to 100 s.
Optical Shelving: Suppressed Fluorescence  [PDF]
Richard A Mould
Physics , 2007,
Abstract: The shelving phenomenon of quantum optics, originally observed by Dehmelt, is analyzed in terms of the qRules that are given in another paper. The heuristic value of these rules is apparent because they not only describe the dark period during shelving, but they reveal the mechanism that enforces the suppression of fluorescence during that time.
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