Pattern Formation In One-Dimensional Polaron Systems And Temporal Orthogonality Catastrophe

Recent Studies Have Demonstrated That Higher Than Two-Body Bath-Impurity Correlations Are Not Important For Quantitatively Describing The Ground State Of The Bose Polaron. Motivated By The Above, We Employ The So-Called Gross Ansatz (GA) Approach To Unravel The Stationary And Dynamical Properties Of The Homogeneous One-Dimensional Bose-Polaron For Different Impurity Momenta And Bath-Impurity Couplings. We Explicate That The Character Of The Equilibrium State Crossovers From The Quasi-Particle Bose Polaron Regime To The Collective-Excitation Stationary Dark-Bright Soliton For Varying Impurity Momentum And Interactions. Following An Interspecies Interaction Quench The Temporal Orthogonality Catastrophe Is Identified, Provided That Bath-Impurity Interactions Are Sufficiently Stronger Than The Intraspecies Bath Ones, Thus Generalizing The Results Of The Confined Case. This Catastrophe Originates From The Formation Of Dispersive Shock Wave Structures Associated With The Zero-Range Character Of The Bath-Impurity Potential. For Initially Moving Impurities, A Momentum Transfer Process From The Impurity To The Dispersive Shock Waves Via The Exerted Drag Force Is Demonstrated, Resulting In A Final Polaronic State With Reduced Velocity. Our Results Clearly Demonstrate The Crucial Role Of Non-Linear Excitations For Determining The Behavior Of The One-Dimensional Bose Polaron

Radiofrequency spectroscopy of one-dimensional trapped Bose polarons: crossover from the adiabatic to the diabatic regime

We investigate the crossover of the impurity-induced dynamics, in trapped one-dimensional Bose polarons subject to radio frequency (rf) pulses of varying intensity, from an adiabatic to a diabatic regime. Utilizing adiabatic pulses for either weak repulsive or attractive impurity-medium interactions, a multitude of polaronic excitations or mode-couplings of the impurity-bath interaction with the collective breathing motion of the bosonic medium are spectrally resolved. We find that for strongly repulsive impurity-bath interactions, a temporal orthogonality catastrophe manifests in resonances in the excitation spectra where impurity coherence vanishes. When two impurities are introduced, impurity-impurity correlations, for either attractive or strong repulsive couplings, induce a spectral shift of the resonances with respect to the single impurity. For a heavy impurity, the polaronic peak is accompanied by a series of equidistant side-band resonances, related to interference of the impurity spin dynamics and the sound waves of the bath. In all cases, we enter the diabatic transfer regime for an increasing bare Rabi frequency of the rf field with a Lorentzian spectral shape featuring a single polaronic resonance. The findings in this work on the effects of external trap, rf pulse and impurity-impurity interaction should have implications for the new generations of cold-atom experiments.Comment: 23 pages, 11 figure

Pump Probe Spectroscopy of Bose Polarons: Dynamical Formation and Coherence

We propose and investigate a pump-probe spectroscopy scheme to unveil the time-resolved dynamics of fermionic or bosonic impurities immersed in a harmonically trapped Bose-Einstein condensate. In this scheme a pump pulse initially transfers the impurities from a noninteracting to a resonantly interacting spin-state and, after a finite time in which the system evolves freely, the probe pulse reverses this transition. This directly allows to monitor the nonequilibrium dynamics of the impurities as the dynamical formation of coherent attractive or repulsive Bose polarons and signatures of their induced-interactions are imprinted in the probe spectra. We show that for interspecies repulsions exceeding the intraspecies ones a temporal orthogonality catastrophe occurs, followed by enhanced energy redistribution processes, independently of the impurity's flavor. This phenomenon takes place over the characteristic trap timescales. For much longer timescales a steady state is reached characterized by substantial losses of coherence of the impurities. This steady state is related to eigenstate thermalization and it is demonstrated to be independent of the system's characteristics.Comment: 17 pages, 8 figure

Quench Dynamics and Orthogonality Catastrophe of Bose Polarons

We monitor the correlated quench induced dynamical dressing of a spinor impurity repulsively interacting with a Bose-Einstein condensate. Inspecting the temporal evolution of the structure factor three distinct dynamical regions arise upon increasing the interspecies interaction. These regions are found to be related to the segregated nature of the impurity and to the ohmic character of the bath. It is shown that the impurity dynamics can be described by an effective potential that deforms from a harmonic to a double-well one when crossing the miscibility-immiscibility threshold. In particular, for miscible components the polaron formation is imprinted on the spectral response of the system. We further illustrate that for increasing interaction an orthogonality catastrophe occurs and the polaron picture breaks down. Then a dissipative motion of the impurity takes place leading to a transfer of energy to its environment. This process signals the presence of entanglement in the many-body system.Comment: 14 pages, 7 figure

Many-Body Dissipative Flow of a Confined Scalar Bose-Einstein Condensate Driven by a Gaussian Impurity

The many-body dissipative flow induced by a mobile aussian impurity harmonically oscillating within a cigar-shaped Bose-Einstein condensate is investigated. For very {small and large driving frequencies} the superfluid phase is preserved. Dissipation is identified, for intermediate driving frequencies, by the non-zero value of the drag force whose abrupt increase {signals the spontaneous downstream emission of an array of gray solitons. After each emission event, typically each of the solitary waves formed decays and splits into two daughter gray solitary waves that are found to be robust propagating in the bosonic background for large evolution times.} In particular, a smooth transition towards dissipation is observed, with the {\it critical} velocity for solitary wave formation depending on both the characteristics of the obstacle, namely its driving frequency and width as well as on the interaction strength. The variance of a sample of single-shot simulations indicates the fragmented nature of the system; here it is found to increase during evolution for driving frequencies where the coherent structure formation becomes significant. Finally, we demonstrate that for fairly large particle numbers in-situ single-shot images directly capture the gray soliton's decay and splitting.Comment: 14 pages, 7 figure