TY - JOUR

T1 - Light shift mitigation in microcell-based coherent-population-trapping atomic clocks in the field of two circularly polarized light beams

AU - Brazhnikov, D. V.

AU - Ignatovich, S. M.

AU - Skvortsov, M. N.

N1 - The work was supported by the Russian Science Foundation (Grant No. 22-12-00279).

PY - 2024/5

Y1 - 2024/5

N2 - State-of-the-art miniature atomic clocks (MACs) are based on the phenomenon of coherent population trapping (CPT) in alkali-metal atomic vapors (Rb or Cs). Improving the stability of the clock frequency is a crucial issue; resolving it would result in significant progress in numerous applications. Here, we examine the configuration of the light field, which is composed of two bichromatic beams with opposing handedness of circular polarization. The beams are in resonance with optical transitions in the Cs D1 line (λ≈895 nm). This configuration has previously been shown to produce observed CPT resonances with higher contrast than a standard single-beam scheme; however, our scheme implements pump and probe beams that operate independently, with the transmission of the probe beam being monitored separately. This approach differs from previous studies. The experiments are carried out using a cubic 5×5×5mm3 vapor cell filled with buffer gas. It is shown that the line shape of the resonance acquires an asymmetry that can be efficiently controlled by a microwave (Raman) phase between the beams. As a proof of concept, we study the way in which this asymmetry can help to mitigate the influence of the ac Stark (light) shift on the long-term frequency stability of CPT clocks based on vapor microcells (V≪1cm3). Experimental verification is performed with both a distributed-Bragg-reflector laser and a vertical-cavity surface-emitting laser. The latter is of particular importance for the development of MACs. The experimental results are in qualitative agreement with the analytical theory based on a double-Λ scheme of atomic energy levels.

AB - State-of-the-art miniature atomic clocks (MACs) are based on the phenomenon of coherent population trapping (CPT) in alkali-metal atomic vapors (Rb or Cs). Improving the stability of the clock frequency is a crucial issue; resolving it would result in significant progress in numerous applications. Here, we examine the configuration of the light field, which is composed of two bichromatic beams with opposing handedness of circular polarization. The beams are in resonance with optical transitions in the Cs D1 line (λ≈895 nm). This configuration has previously been shown to produce observed CPT resonances with higher contrast than a standard single-beam scheme; however, our scheme implements pump and probe beams that operate independently, with the transmission of the probe beam being monitored separately. This approach differs from previous studies. The experiments are carried out using a cubic 5×5×5mm3 vapor cell filled with buffer gas. It is shown that the line shape of the resonance acquires an asymmetry that can be efficiently controlled by a microwave (Raman) phase between the beams. As a proof of concept, we study the way in which this asymmetry can help to mitigate the influence of the ac Stark (light) shift on the long-term frequency stability of CPT clocks based on vapor microcells (V≪1cm3). Experimental verification is performed with both a distributed-Bragg-reflector laser and a vertical-cavity surface-emitting laser. The latter is of particular importance for the development of MACs. The experimental results are in qualitative agreement with the analytical theory based on a double-Λ scheme of atomic energy levels.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85194382581&origin=inward&txGid=5138f6522ada225a1a23cac9ad7a2b35

UR - https://www.mendeley.com/catalogue/6a4e406d-9293-3c5f-b995-bbc2c4e30941/

U2 - 10.1103/PhysRevApplied.21.054046

DO - 10.1103/PhysRevApplied.21.054046

M3 - Article

VL - 21

JO - Physical Review Applied

JF - Physical Review Applied

SN - 2331-7019

IS - 5

M1 - 054046

ER -