Quantum control via chirped coherent anti-Stokes Raman spectroscopy

TL;DR

This paper introduces a chirped-pulse quantum control scheme called C-CARS that enhances vibrational coherence in molecules during CARS spectroscopy by using adiabatic passage techniques with chirped pulses.

Contribution

It presents a novel chirped-pulse control method for CARS spectroscopy, improving robustness, selectivity, and efficiency in vibrational excitation.

Findings

Enhanced vibrational coherence in molecules.

Improved spectral selectivity through chirp rate control.

Robustness against experimental variations.

Abstract

A chirped-pulse quantum control scheme applicable to Coherent Anti-Stokes Raman Scattering spectroscopy, named as C-CARS, is presented aimed at maximizing the vibrational coherence in molecules. It implies chirping of three incoming pulses in the four-wave mixing process of CARS, the pump, the Stokes and the probe, to fulfil the conditions of adiabatic passage. The scheme is derived in the framework of rotating wave approximation and adiabatic elimination of excited state manifold simplifying the four-level model system into a ``super-effective'' two level system. The robustness, spectral selectivity and adiabatic nature of this method are helpful in improving the existing methods of CARS spectroscopy for sensing, imaging and detection. We also show that the selectivity of excitation of vibrational degrees of freedom can be controlled by carefully choosing the spectral chirp rate of the pulses.