Progress on indium and barium single ion optical frequency standards

Abstract

Abstract-We report progress on 115 In + and 137 Ba + single ion optical frequency standards using all solid-state sources. Both are free from quadrupole field shifts and together enable a search for drift in fundamental constants.

Electron impact excitation of the 6s 2S1/2 state of In atom at small scattering angles

“…The 115 In + stored in a radio-frequency trap and laser cooled has been investigated as a possible optical frequency standard with high stability and accuracy. The narrow 5s 21 S 0 -5s5p 3 P 0 transition in In + at a wavelength of 236.5 nm could be used as a reference clock transition [3,4].…”

Frequency stabilization of a 650 nm laser to an I2 spectrum for trapped Ba138+ ions

“…In the field of quantum computation [20,21], quantum communication [22] and precision measurement of parity non-conservation [23] with trapped ions, the Ba + ion has been an attractive choice. A single Ba + ion has low-lying and long-lived D states [24] and a lambda structure of cooling cycle [25], which are all in the visible wavelength range. A 493 nm laser drives the S 1/2 -P 1/2 transition, which performs as the main circulation of Doppler cooling and since the branching ratios of the P 1/2 -S 1/2 and P 1/2 -D 3/2 transitions are comparable, as 0.73 and 0.27 [26] respectively, a 650 nm laser bridging the D 3/2 -P 1/2 transition is in need to pump the population in D 3/2 state back to the cooling cycle.…”

Calculation of the magnetic hyperfine structure constant of alkali metals and alkaline-earth-metal ions using the relativistic coupled-cluster method

“…Currently, the hyperfine transition of Cs atom [[Xe]6S( 2 S 1/2 , F = 3, m F = 0) ↔ [Xe]6S( 2 S 1/2 , F = 4, m F = 0)] is used as frequency standard which is accurate up to 1 per 10 15 [2]. Singly ionized alkaline earth metal ions are insensitive to the perturbation of the environment arising form collisions and Doppler shift and thus, have been considered for the potential candidates for optical frequency standard [3][4][5][6]. The 2 S 1/2 ground state of these ions are regarded for quantum information processing studies to encode quantum-bit into hyperfine levels because of their long phase coherence due to their small energy gap and relatively large spontaneous decay lifetime [7,8].…”