The strongly driven Fermi polaron

Abstract

Quasiparticles are emergent excitations of matter that underlie much of our understanding of quantum many-body systems. Therefore, the prospect of manipulating their properties with external fields -- or even destroying them -- has both fundamental and practical implications. However, in solid-state materials it is often challenging to understand how quasiparticles are modified by external fields owing to their complex interplay with other collective excitations, such as phonons. Here, we take advantage of the clean setting of homogeneous quantum gases and fast radio-frequency control to manipulate Fermi polarons -- quasiparticles formed by impurities interacting with a non-interacting Fermi gas -- from weak to ultrastrong drives. Exploiting two internal states of the impurity species, we develop a steady-state spectroscopy, from which we extract the energy of the driven polaron. We measure the decay rate and the quasiparticle residue of the driven polaron from the Rabi oscillations between the two internal states. At large drive strengths, the so-extracted quasiparticle residue exceeds unity, raising intriguing questions on the relationship between the Rabi oscillations and the impurity's spectral functions. Our experiment establishes the driven Fermi polaron as a promising platform for studying controllable quasiparticles in strongly driven quantum matter.

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Cited by in corpus (11)

• Universal Efimov Scaling in the Rabi-Coupled Few-Body Spectrum
• Universal quantum dynamics of Bose polarons
• Mass-gap description of heavy impurities in Fermi gases
• Scattering resonances and pairing in a Rabi-coupled Fermi gas
• Two-Body Contact Dynamics in a Bose Gas near a Fano-Feshbach Resonance
• Hybrid-pair superfluidity in a strongly driven Fermi gas
• Medium-enhanced polaron repulsion in a dilute Bose mixture
• An efficient high-current circuit for fast radio-frequency spectroscopy in cold atomic gases
• Dimer-projection contact and the clock shift of a unitary Fermi gas
• Efficient variational approach to the Fermi polaron problem in two dimensions, both in and out of equilibrium
• Emergence of Fermi's Golden Rule in the Probing of a Quantum Many-Body System