Bose Polarons in the Strongly Interacting Regime

Area of Science:

• Quantum physics
• Ultracold atomic gases
• Many-body physics

Background:

• Bose-Einstein condensates (BECs) are quantum states of matter formed by bosons cooled to near absolute zero.
• Impurities interacting with BECs can form quasiparticles known as Bose polarons.
• Understanding these quasiparticles is crucial for exploring many-body quantum phenomena.

Purpose of the Study:

• To experimentally investigate the properties of Bose polarons.
• To characterize the energy, spectral width, and lifetime of Bose polarons in both attractive and repulsive interaction regimes.
• To explore the behavior of Bose polarons in the strongly interacting regime.

Main Methods:

• Superimposing ultracold atomic gases of Rubidium-87 (a BEC) with fermionic Potassium-40 impurities.
• Utilizing Feshbach resonance to control the interaction strength between impurities and bosons.
• Employing radio-frequency spectroscopy to probe polaron properties.

Main Results:

• Successfully created and characterized Bose polarons from fermionic impurities in a BEC.
• Measured the energy, spectral width, and lifetime of polarons on both attractive and repulsive branches.
• Observed a narrow spectral width for polarons on the attractive branch, even with diverging scattering length.

Conclusions:

• The study provides a detailed characterization of Bose polarons in strongly interacting regimes.
• Experimental results offer insights into the nature of quasiparticle formation in quantum gases.
• Findings contribute to the fundamental understanding of impurity-boson interactions in Bose-Einstein condensates.