Manipulating Fermi Polarons by Strong Driving*

The nature of quasiparticles determines many thermodynamic and transport properties of quantum systems. We report on the control of the Fermi polaron - a paradigmatic quasiparticle emerging from contact interactions between impurities and a Fermi sea - by driving the impurity between two internal states using a radio-frequency (RF) field of tunable strength and detuning. Using the effective magnetization of the impurity as our observable, we find that the polaron energy approaches zero as the drive strength increases, and the decay rate increases by an order of magnitude, indicating the polaron's properties are widely tunable by the RF drive. The behavior is qualitatively well captured by the T-matrix theory.