The dynamics of three-level Λ\Lambda-type system driven by the trains of ultrashort laser pulses

We study the dynamics of a tree-level $\Lambda$-type atoms driven by a coherent train of short, non-overlapping laser pulses.We derive analytical non-perturbative expressions for density matrix by approximating pulses by delta-function.We demonstrate that depending on train parameters several scenarios of system dynamics are realized. We show the possibility of driving Raman transitions between the two ground states of $\Lambda$-system avoiding populating excited state by using the pulses with effective area equal to $2\pi$.The number of $2\pi$-pulses needed to transfer the entire population from one ground state to another depends on the ratio between the Rabi frequencies of two allowed transitions. In the case of equal Rabi frequencies, the system can be transferred from one ground state to another with a single $2\pi$ pulse. When the total pulse area differs from $2\pi$ and the two-photon resonance condition is fullfilled, the system evolves into a "dark" state and becomes transparent to subsequent pulses. We derive analytical expression for the density matrix in the quasi-steady-state regime. We analyze the dependence of the post-pulse excited state population in the quasi-steady-state regime on the train parameters. We find the optimal values for train parameters corresponding to the maximimum of the excited state population. The maximum of the excited state population in the steady state regime is reached at the effective single pulse area equal to $\pi$ and is equal to 2/3 in the limiting case when its radiative lifetime is much shorter then the pulse repetition period

Feasibility of the optical fiber clock

We explore the feasibility of a compact high-precision Hg atomic clock based on a hollow core optical fiber. We evaluate the sensitivity of the $^1S_0$-$^3P_0$ clock transition in Hg and other divalent atoms to the fiber inner core surface at non-zero temperatures. The Casimir-Polder interaction induced $^1S_0$-$^3P_0$ transition frequency shift is calculated for the atom inside the hollow capillary as a function of atomic position, capillary material, and geometric parameters. For $^{199}\mathrm{Hg}$ atoms on the axis of a silica capillary with inner radius $\geq 15 \,\mu \mathrm{m}$ and optimally chosen thickness $d\sim 1 \,\mu \mathrm{m}$, the atom-surface interaction induced $^1S_0$-$^3P_0$ clock transition frequency shift can be kept on the level $\delta\nu/\nu_{\mathrm{Hg}} \sim10^{-19}$. We also estimate the atom loss and heating due to the collisions with the buffer gas, lattice intensity noise induced heating, spontaneous photon scattering, and residual birefringence induced frequency shifts.Comment: 8 pages, 5 figures, submitte

Doppler cooling with coherent trains of laser pulses and tunable "velocity comb"

We explore the possibility of decelerating and Doppler cooling of an ensemble of two-level atoms by a coherent train of short, non-overlapping laser pulses. We develop a simple analytical model for dynamics of a two-level system driven by the resulting frequency comb field. We find that the effective scattering force mimics the underlying frequency comb structure. The force pattern depends strongly on the ratio of the atomic lifetime to the repetition time and pulse area. For example, in the limit of short lifetimes, the frequency peaks of the optical force wash out. We show that laser cooling with pulse trains results in a "velocity comb", a series of narrow peaks in the velocity space

Doppler cooling of three-level Λ\Lambda-systems by coherent pulse trains

We explore the possibility of decelerating and Doppler cooling an ensemble of tree-level $\Lambda$-type atoms by a coherent train of short, non-overlapping laser pulses. We show that $\Lambda$-atoms can be Doppler cooled without additional repumping of the population from the intermediate ground state. We derive analytical expression for the scattering force in the quasi-steady-state regime and analyze its dependence on pulse train parameters. Based on this analysis we propose a method of choosing pulse train parameters to optimize the cooling process.Comment: 22 pages, 6 figure

Spectral dynamics of high power 1.8 µm laser-pulse generated by Raman conversion of a picosecond Yb-laser in hydrogen-filled Kagome HC-PCF

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Spectral-temporal dynamics of high power Raman picosecond pulse using H2-filled Kagome HC-PCF

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Atom-surface Van der Waals potential induced sub-Doppler transparencies in Rb vapor filled Kagome HC-PCF

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Progress towards atomic vapor photonic microcells : coherence and polarization relaxation measurements in coated and uncoated HC-PCF

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