Tackling the Blackbody Shift in a Strontium Optical Lattice Clock (original) (raw)

Blackbody-radiation shift in the Sr optical atomic clock

Physical Review A, 2013

We evaluated the static and dynamic polarizabilities of the 5s 2 1 S0 and 5s5p 3 P o 0 states of Sr using the high-precision relativistic configuration interaction + all-order method. Our calculation explains the discrepancy between the recent experimental 5s 2 1 S0 − 5s5p 3 P o 0 dc Stark shift measurement ∆α = 247.374(7) [Middelmann et. al, arXiv:1208.2848] and the earlier theoretical result of 261(4) a.u. [Porsev and Derevianko, Phys. Rev. A 74, 020502R (2006)]. Our present value of 247.5 a.u. is in excellent agreement with the experimental result. We also evaluated the dynamic correction to the BBR shift with 1% uncertainty; -0.1492(16) Hz. The dynamic correction to the BBR shift is unusually large in the case of Sr (7%) and it enters significantly into the uncertainty budget of the Sr optical lattice clock. We suggest future experiments that could further reduce the present uncertainties.

Observation and cancellation of the dc Stark shift in strontium optical lattice clocks

2011

We report on the observation of a dc Stark frequency shift at the 10−1310^{-13}10−13 level by comparing two strontium optical lattice clocks. This frequency shift arises from the presence of electric charges trapped on dielectric surfaces placed under vacuum close to the atomic sample. We show that these charges can be eliminated by shining UV light on the dielectric surfaces,

Blackbody radiation shifts in optical atomic clocks

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000

A review of recent theoretical calculations of blackbody radiation (BBR) shifts in optical atomic clocks is presented. We summarize previous results for monovalent ions that were obtained by a relativistic all-order single-double method, where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. A recently developed method for accurate calculations of BBR shifts in divalent atoms is then presented. This approach combines the relativistic all-order method and the configuration interaction method, which provides for accurate treatment of correlation corrections in atoms with two valence electrons. Calculations of the BBR shifts in B + , Al + , and In + have enabled us to reduce the present fractional uncertainties in the frequencies of their clock transitions as measured at room temperature: to 4 × 10 −19 for Al + and 10 −18 for B + and In + . These uncertainties approach recent estimates of the limits of precision of currently proposed optical atomic clocks. We discuss directions of future theoretical developments for reducing clock uncertainties due to blackbody radiation shifts.

Accurate Optical Lattice Clock with Sr87 Atoms

Physical Review Letters, 2006

We report a frequency measurement of the 1 S0 − 3 P0 transition of 87 Sr atoms in an optical lattice clock. The frequency is determined to be 429 228 004 229 879 (5) Hz with a fractional uncertainty that is comparable to state-of-the-art optical clocks with neutral atoms in free fall. Two previous measurements of this transition were found to disagree by about 2 × 10 −13 , i.e. almost four times the combined error bar, instilling doubt on the potential of optical lattice clocks to perform at a high accuracy level. In perfect agreement with one of these two values, our measurement essentially dissipates this doubt. PACS numbers: 06.30.Ft,32.80.-t,42.50.Hz,42.62.Fi 1 S 0 1 P 1 4 6 1 n m / = 3 2 M H z 3 S 1 3 P 0 6 8 9 n m / = 7 , 6 k H z 6 8 8 n m 7 0 7 n m 6 7 9 n m 6 9 8 n m / = 1 m H z 3 P 1 3 P 2 FIG. 1: Relevant energy levels of 87 Sr.

Precision spectroscopy of cold strontium atoms, towards optical atomic clock

This report concerns the experiment of precision spectroscopy of cold strontium atoms in the Polish National Laboratory of Atomic, Molecular and Optical Physics in Toruń. The system is composed of a Zeeman slower and magneto-optical traps (at 461 nm and 689 nm), a frequency comb, and a narrow-band laser locked to an ultra-stable optical cavity. All parts of the experiment are prepared and the first measurements of the absolute frequency of the 1 S0-3 P1, 689 nm optical transition in 88 Sr atoms are performed.

Sr Lattice Clock at 1 × 10 –16 Fractional Uncertainty by Remote Optical Evaluation with a Ca Clock

Science, 2008

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over kilometer-scale urban distances, a key step for development, dissemination, and application of these optical standards. Through this remote comparison and a proper design of lattice-confined neutral atoms for clock operation, we evaluate the uncertainty of a strontium (Sr) optical lattice clock at the 1 × 10 –16 fractional level, surpassing the current best evaluations of cesium (Cs) primary standards. We also report on the observation of density-dependent effects in the spin-polarized fermionic sample and discuss the current limiting effect of blackbody radiation–induced frequency shifts.

Systematic Study of the Sr87 Clock Transition in an Optical Lattice

Physical Review Letters, 2006

With ultracold 87 Sr confined in a magic wavelength optical lattice, we present the most precise study (2.8 Hz statistical uncertainty) to date of the 1 S 0-3 P 0 optical clock transition with a detailed analysis of systematic shifts (19 Hz uncertainty) in the absolute frequency measurement of 429 228 004 229 869 Hz. The high resolution permits an investigation of the optical lattice motional sideband structure. The local oscillator for this optical atomic clock is a stable diode laser with its hertz-level linewidth characterized by an octave-spanning femtosecond frequency comb.

Development of a Strontium optical lattice clock

The ESA mission "Space Optical Clock" project aims at operating an optical lattice clock on the ISS in approximately 2023. The scientific goals of the mission are to perform tests of fundamental physics, to enable space-assisted relativistic geodesy and to intercompare optical clocks on the ground using microwave and optical links. The performance goal of the space clock is less than 1 × 10-17 uncertainty and 1 × 10-15 τ-1/2 instability. Within an EU-FP7-funded project, a strontium optical lattice clock demonstrator has been developed. Goal performances are instability below 1 × 10-15 τ-1/2 and fractional inaccuracy 5 × 10-17. For the design of the clock, techniques and approaches suitable for later space application are used, such as modular design, diode lasers, low power consumption subunits, and compact dimensions. The Sr clock apparatus is fully operational, and the clock transition in 88 Sr was observed with linewidth as small as 9 Hz.