Optical Clocks Based on Ultranarrow Three-Photon Resonances in Alkaline Earth Atoms

Abstract

A sharp resonance line that appears in three-photon transitions between the 1 S 0 and 3 P 0 states of alkaline earth and Yb atoms is proposed as an optical frequency standard. This proposal permits the use of the even isotopes, in which the clock transition is narrower than in proposed clocks using the odd isotopes and the energy interval is not affected by external magnetic fields or the polarization of trapping light. The method has the unique feature that the width and rate of the clock transition can be continuously adjusted from the M Hz level to sub-mHz without loss of signal amplitude by varying the intensities of the three optical beams. Doppler and recoil effects can be eliminated by proper alignment of the three optical beams or by point confinement in a lattice trap. The three beams can be mixed to produce the optical frequency corresponding to the 3 P 0 -1 S 0 clock interval.

Multipolar theory of blackbody radiation shift of atomic energy levels and its implications for optical lattice clocks

“…Ft, 32.10.Dk, Atomic clocks based on ultranarrow [6,7]. In addition, various schemes of probing the highlyforbidden nsnp 3 P 0 − ns 2 1 S 0 clock transition have been proposed: three-photon transition, electromagneticallyinduced transparency, and transition assisted by external magnetic field [6,7,8].Considering advantages of optical lattice clocks, here we investigate an important systematic effect of the black-body radiation (BBR) on the frequency of the 3 P 0 − 1 S 0 clock transition. Indeed, the SI definition of the second explicitly involves atomic clock operating at the absolute zero of temperature.…”

“…Ft, 32.10.Dk, Atomic clocks based on ultranarrow [6,7]. In addition, various schemes of probing the highlyforbidden nsnp 3 P 0 − ns 2 1 S 0 clock transition have been proposed: three-photon transition, electromagneticallyinduced transparency, and transition assisted by external magnetic field [6,7,8].…”

Ultrahigh-resolution spectroscopy with atomic or molecular dark resonances: Exact steady-state line shapes and asymptotic profiles in the adiabatic pulsed regime

“…Since such quantum superposition states are radiatively stable, the associated Raman coherence production leads to extremely narrow Dark Resonances allowing high-resolution frequency measurements [11]. Such coherences were explored for single trapped ions [12,13], microwave clocks [14], microwave chips [15,16], optical lattice clocks [17], multi-photon excitations [18,19], or nuclear clocks [20]. Similar coherent superpositions are used in solid-state physics for quantum information [21], in super-conducting circuits [22,23], in a single impurity ion inserted into a crystal [24], in quantum dots [25] with protection against random nuclear spin interactions [26], and in opto-mechanical systems [27,28].…”

<title>Laser sources for precision spectroscopy on atomic strontium</title>

“…These studies open the way to the realization of a new optical frequency standard with unprecedented stability and accuracy. Proposals based on different interrogation schemes have been put forward (optical lattice clock [6], engineered atom clock [7,8]) suggesting the possibility to reach the 10 −17 level of overall accuracy. Indeed, thanks to the higher oscillator frequency, a clock in the optical domain could potentially reach a stability level of 10 −18 at 1 s [6] which represents a factor of 10 4 improvement with respect to the best microwave standards [9].…”