Pulse-train control of branching processes: Elimination of background and intruder state population

Abstract

The authors introduce and describe pulse train control (PTC) of population branching in strongly coupled processes as a novel control tool for the separation of competing multiphoton processes. Control strategies are presented based on the different responses of processes with different photonicities and/or different frequency detunings to the pulse-to-pulse time delay and the pulse-to-pulse phase shift in pulse trains. The control efficiency is further enhanced by the property of pulse trains that complete population transfer can be obtained over an extended frequency range that replaces the resonance frequency of simple pulses. The possibility to freely tune the frequency assists the separation of the competing processes and reduces the number of subpulses required for full control. As a sample application, PTC of leaking multiphoton resonances is demonstrated by numerical simulations. In model systems exhibiting sizable background (intruder) state population if excited with single pulses, PTC leading to complete accumulation of population in the target state and elimination of background population is readily achieved. The analysis of the results reveals different mechanisms of control and provides clues on the mechanisms of the leaking process itself. In an alternative setup, pulse trains can be used as a phase-sensitive tool for level switching. By changing only the pulse-to-pulse phase shift of a train with otherwise unchanged parameters, population can be transferred to any of two different target states in a near-quantitative manner.

Rovibrational manipulation of molecular quantum state by a train of ultrashort pulses

“…The population transfer process is steered by a single laser pulse with hx ¼ 28 946:93 cm À1 and sp ¼ 0:2 ps. population transfer process can be treated as a two-level model [34,35]. However, when I 0 > 1:4 Â 10 10 W=cm 2 , the difference between the population of the target state jv 0 ¼ 9; J 0 ¼ 1i and the total population of the electronic state A 1 R þ becomes large with the increase of pulse peak intensity, which means that a part of population is transferred to other rovibrational states.…”

Maximum coherent superposition state achievement using a non-resonant pulse train in non-degenerate three-level atoms

“…Since the invention of the mode-locked lasers, pulse trains have been used in many areas such as in the measurement of spectroscopy [1][2][3][4][5][6][7] for a long time. In recent years, much interest has been devoted to the quantum dynamics of atoms and molecules [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. As to the generation of the pulse train, the technique also develops rapidly.…”