Coherent control of superposition of atomic Rydberg states with femtosecond laser pulses

J. PRECLIKOVA; M. KOZÁK; D. FREGENAL; B.T. HJERTAKER; B. HAMRE; O. FRETTE; L. KOCBACH; J.P. HANSEN

Vilna

Conferencia; 11th Nordic Femtochemistry Conference; 2014

We report on experimental and theoretical studies of interaction of Rydberg atoms with sequences of gaussian femtosecond laser pulses in collinear and double-grating arrangements. Sequences of pairs of laser pulses allow the control of the phase between each excited state in a coherent superposition of Rydberg wave packet. Experimentally, westudied populating of the atomic Rydberg states after interaction with a pair of identical femtosecond laser pulses, with a pair of pulses in which one of the pulse was strongly chirped and with two pairs of femtosecond laser pulses. Evolution of superpositions of 20f-30f states of lithium atoms was determined by the selective field ionisation (SFI) method as a function of the time delay between the femtosecond laser pulses and pulse pairs. All our observed results are in excellent agreement with theoretical calculations given by the first order perturbation theory [1,2]. We demonstrate that an excitation of a selected Rydberg state on picosecond timescale can be reached by a pure sequence of four pairs of femtosecond laser pulses with precisely set delays [2]. We proposed a method for characterizing of thermal beam velocity based on observing of Ramsey fringes in double-grating pump and probe setup.