Precision spectroscopy with a single ⁴⁰ Ca ⁺ ion in a Paul trap

Abstract

Precision measurement of the 4s2S1/2–3d2D5/2 clock transition based on 40Ca+ ion at 729 nm is reported. A single 40Ca+ ion is trapped and laser-cooled in a ring Paul trap, and the storage time for the ion is more than one month. The linewidth of a 729 nm laser is reduced to about 1 Hz by locking to a super cavity for longer than one month uninterruptedly. The overall systematic uncertainty of the clock transition is evaluated to be better than 6.5×10−16. The absolute frequency of the clock transition is measured at the 10−15 level by using an optical frequency comb referenced to a hydrogen maser which is calibrated to the SI second through the global positioning system (GPS). The frequency value is 411 042 129 776 393.0(1.6) Hz with the correction of the systematic shifts. In order to carry out the comparison of two 40Ca+ optical frequency standards, another similar 40Ca+ optical frequency standard is constructed. Two optical frequency standards exhibit stabilities of 1×10−14τ−1/2 with 3 days of averaging. Moreover, two additional precision measurements based on the single trapped 40Ca+ ion are carried out. One is the 3d2D5/2 state lifetime measurement, and our result of 1174(10) ms agrees well with the results reported in [Phys. Rev. A 62 032503 (2000)] and [Phys. Rev. A 71 032504 (2005)]. The other one is magic wavelengths for the 4s2S1/2–3d2D5/2 clock transition; λ|mj|=1/2= 395.7992(7) nm and λ|mj|=3/2 = 395.7990(7) nm are reported, and it is the first time that two magic wavelengths for the 40Ca+ clock-transition have been reported.

Relativistic semiempirical-core-potential calculations in Ca+,Sr+ , and Ba+ i

“…Condition (25) drastically simplifies the expressions of the one-body matrix elements calculated with the Gauss quadrature. Radial functions P v (r) and Q v (r) are expanded in regularized Lagrange functions (24) as…”

“…Singly ionized calcium (Ca + ), strontium (Sr + ), and barium (Ba + ) have been proposed as candidates for optical frequency standards due to the long lifetime of their 2 D 3/2,5/2 states [2]. Numerous experiments have been performed in these alkaline-earth-metal ions [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Additionally, several theoretical studies have been carried out using many-body approaches [4,[9][10][11][34][35][36][37].…”

Raman velocity filter as a tool for collinear laser spectroscopy

“…Therefore, we define the time of a πpulse, when m(v = v R ) is saturated after several decay times t π = n/r 0 with n > 1. We choose n by the condition lim η→1− n/r 0 = lim η→1+ t π with t π (η > 1) from equation (37), leading to…”

Parameter estimation in atomic spectroscopy using exceptional points

“…In particular, 40 Ca + has been used in the field of quantum computing and quantum information [28,29,30,31,32,33], for atomic clocks and the frequency standard [34,35,3,2,1,36,37] and recently as a single-atom heat engine [38]. The spectrum of 40 Ca + has been also employed in the quest for drifts of the fine structure constant over a time span of many billion years [39,40].…”