Libration of Strongly-Oriented Polar Molecules inside a Superfluid.

Area of Science:

• Quantum mechanics
• Condensed matter physics
• Molecular physics

Background:

• Polar molecules in superfluid environments (e.g., helium nanodroplets, Bose-Einstein condensates) are subjects of interest.
• The behavior of molecules in such systems is influenced by interactions with the surrounding many-particle bath and external fields.

Purpose of the Study:

• To investigate the behavior of a polar molecule in a superfluid environment under a strong electrostatic field.
• To understand the formation and properties of novel quasiparticles, termed "pendulons."
• To explore the impact of external fields on molecular rotational spectra and many-particle excitations.

Main Methods:

• Theoretical study of a polar molecule coupled to a superfluid bath.
• Analysis of molecular pendular motion induced by an electrostatic field.
• Investigation of the resulting "pendulon" quasiparticle and its spectral properties.

Main Results:

• Coupling of molecular pendular motion to the bath forms "pendulons" (librators dressed by excitations).
• Pendulon spectra exhibit instabilities absent in the field-free "angulon" quasiparticle.
• External fields allow fine-tuning of these spectral instabilities.

Conclusions:

• The formation of pendulons offers a new perspective on molecule-superfluid interactions.
• External electrostatic fields provide a mechanism to control and study spectral instabilities.
• This research paves the way for experimental investigations into angular momentum redistribution in many-particle systems.