TY - JOUR

T1 - Theory of nonlinear sub-Doppler spectroscopy taking into account atomic-motion-induced density-dependent effects in a gas

AU - Yudin, V. I.

AU - Taichenachev, A. V.

AU - Basalaev, M. Yu

AU - Prudnikov, O. N.

AU - Pal'Chikov, V. G.

AU - Zanon-Willette, T.

AU - Bagayev, S. N.

N1 - We thank I. M. Sokolov, V. L. Velichansky, and S. A. Zibrov for useful discussions. This research was supported by the Russian Science Foundation (Grant No. 22-72-10096). V.I.Y. was supported by the Ministry of Science and Higher Education of the Russian Federation (Grant No. FSUS-2020-0036).

PY - 2024/4

Y1 - 2024/4

N2 - We develop a field-nonlinear theory of sub-Doppler spectroscopy in a gas of two-level atoms, based on a self-consistent solution of the Maxwell-Bloch equations in the mean-field and single-atom density-matrix approximations. This makes it possible to correctly take into account the effects caused by the free motion of atoms in a gas, which lead to a nonlinear dependence of the spectroscopic signal on the atomic density even in the absence of a direct interatomic interaction (e.g., dipole-dipole interaction). Within the framework of this approach, analytical expressions for the light field were obtained for an arbitrary number of resonant waves and arbitrary optical thickness of a gas medium. Sub-Doppler spectroscopy in the transmission signal for two counterpropagating and copropagating waves has been studied in detail. A previously unknown redshift of a narrow sub-Doppler resonance is predicted in a counterpropagating waves scheme, when the frequency of one wave is fixed and the frequency of the other wave is varied. The magnitude of this shift depends on the atomic density and can be more than an order of magnitude greater than the known shift from the interatomic dipole-dipole interaction (Lorentz-Lorenz shift). The found effects, caused by the free motion of atoms, require a significant revision of the existing picture of spectroscopic effects depending on the density of atoms in a gas. Apart from the fundamental aspect, obtained results are important for precision laser spectroscopy and optical atomic clocks.

AB - We develop a field-nonlinear theory of sub-Doppler spectroscopy in a gas of two-level atoms, based on a self-consistent solution of the Maxwell-Bloch equations in the mean-field and single-atom density-matrix approximations. This makes it possible to correctly take into account the effects caused by the free motion of atoms in a gas, which lead to a nonlinear dependence of the spectroscopic signal on the atomic density even in the absence of a direct interatomic interaction (e.g., dipole-dipole interaction). Within the framework of this approach, analytical expressions for the light field were obtained for an arbitrary number of resonant waves and arbitrary optical thickness of a gas medium. Sub-Doppler spectroscopy in the transmission signal for two counterpropagating and copropagating waves has been studied in detail. A previously unknown redshift of a narrow sub-Doppler resonance is predicted in a counterpropagating waves scheme, when the frequency of one wave is fixed and the frequency of the other wave is varied. The magnitude of this shift depends on the atomic density and can be more than an order of magnitude greater than the known shift from the interatomic dipole-dipole interaction (Lorentz-Lorenz shift). The found effects, caused by the free motion of atoms, require a significant revision of the existing picture of spectroscopic effects depending on the density of atoms in a gas. Apart from the fundamental aspect, obtained results are important for precision laser spectroscopy and optical atomic clocks.

UR - https://www.mendeley.com/catalogue/4ba0bd73-c789-3da3-a037-7ba8e25ee091/

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85189356746&origin=inward&txGid=8e661932424832f986d9dc5662d274e3

U2 - 10.1103/PhysRevA.109.043504

DO - 10.1103/PhysRevA.109.043504

M3 - Article

VL - 109

JO - Physical Review A

JF - Physical Review A

SN - 2469-9926

IS - 4

M1 - 043504

ER -