Light shift in an optically pumped caesium-beam frequency standard

Abstract

An evaluation of the light shift in an optically pumped caesium-beam frequency standard is presented. We show that the light shift can be accurately estimated by taking into account the angular anisotropy of the spontaneous photon emission, the neglect of which is shown to give rise to an error comparable to the value of the shift. Our data refer to a complete set of optical transitions for the caesium D2 line relevant to the KRISS-1 caesium-beam frequency standard.

Accuracy evaluation of an optically pumped caesium beam frequency standard KRISS-1

“…The stray light can come from fluorescent light emitted by either excited atoms or mechanically scattered beams. The fluorescence light shift is calculated to be less than the type-A uncertainty of KRISS-1 based on the theoretical works of Shirley [31], Hisadome [32] and Jun et al [33] . The mechanical light scattering inside the atomic beam tube has been recently minimized by the insertion of the graphite beam flight tube along the drift region of the cavity.…”

Improvement of Frequency Locking Algorithm for Atomic Frequency Standards

“…7,8,11) In this paper we propose a new algorithm and compare it with the old one that had been used for the optically pumped cesium atomic beam frequency standards such as NIST-7 8) and KRISS-1. [10][11][12][13][14][15][16] The new algorithm exploiting twice as frequent feedback as the old one can reduce the frequency noise transformed from special types of signal noise such as flicker noise and random-walk noise. To characterize the two methods we first check how fast the servos can find the center frequency of the Ramsey signal from an initial guess.…”

Optimization of frequency shifts in optically detected magnetic-state-selection cesium beam atomic clocks

“…, where Δν F =g (v) (g = 3, 4) is the LS of the ground state |g . We have [9] Δν where the summation is for all laser polarizations q and all possible dipole transitions from the ground state |g to the excited state |e ; I s is the stray light intensity; d q eg is the spherical components of the dipole matrix element; ν and λ are the frequency and wavelength of the light; νeg and γ e are the frequency and half-width of the transition |e -|g , respectively. Neglecting other frequency shifts, the Ramsey resonance curve is expressed as…”

“…where ρ(v) is the atomic velocity distribution after the magnetic state selection (we have considered that slow atoms have a greater contribution to the Ramsey signal [9]); ν 0 is the unperturbed frequency of the clock transition; ν d is the frequency of the microwave field; b is the Rabi frequency; L is the microwave-free distance and l is the length of each interaction region. The microwave frequency is locked by the slow square wave frequency modulation with the modulation depth ν sw .…”