Quantum control of molecular gas hydrodynamics

Area of Science:

• Physical Chemistry
• Laser Physics
• Fluid Dynamics

Background:

• Controlling gas temperature and hydrodynamics is crucial for various applications.
• Existing methods for gas heating often involve plasma absorption, which can be inefficient or difficult to control.
• Molecular rotational states offer a potential pathway for energy deposition and manipulation.

Purpose of the Study:

• To demonstrate precise control over gas heating and cooling using coherent rotational excitation/deexcitation.
• To investigate the heating mechanisms and compare them to plasma absorption.
• To explore the potential for femtosecond temporal control of gas hydrodynamics.

Main Methods:

• Utilizing sequences of nonionizing laser pulses to achieve coherent rotational excitation/deexcitation of molecular gases.
• Employing collisional decoherence to facilitate energy transfer and gas heating.
• Analyzing gas heating dynamics and hydrodynamic responses under controlled laser focusing conditions.

Main Results:

• Achieved strong impulsive gas heating or heating suppression at standard temperature and pressure.
• Demonstrated gas heating significantly exceeding plasma absorption under identical laser conditions via excitation and decoherence.
• Showcased fine control over macroscopic gas hydrodynamics with approximately 40-fs temporal sensitivity.

Conclusions:

• Coherent rotational excitation/deexcitation provides a powerful mechanism for controlling gas thermodynamics.
• This nonionizing laser-based approach offers superior heating efficiency compared to plasma absorption.
• The demonstrated femtosecond temporal control opens new avenues for manipulating gas dynamics.