High harmonic generation in heavy fermion systems

Shohei Imai, Atsushi Ono, Sumio Ishihara

High harmonic generation in crystalline solids has been examined so far on the basis of one-body energy-band structures arising from electron itineracy in a periodic potential. Here, we show the emergence of high harmonic generation signals which are attributed to the dynamics of many-body states in a low-dimensional correlated electron system. An interacting fermion model and its effective pseudospin model on a one-dimensional dimer-type lattice are analyzed. Observed high harmonic generation signals in a spontaneously symmetry-broken state, where charge densities are polarized inside of dimer units, show threshold behavior with respect to light amplitude and are interpreted in terms of tunneling and recombination of kink-antikink excitations in an electric field.

Jayne Wilkins

Benedikt Fauseweh, Jian‐Xin Zhu

Fast and dynamical control of quantum phases is highly desired in the application of quantum phenomena in devices. On the experimental side, ultrafast laser pulses provide an ideal platform to induce femtosecond dynamics in a variety of materials. Here we show that a laser pulse driven heavy fermion system can be tuned to dynamically evolve into a phase, which is not present in equilibrium. Using the state-of-the-art time-dependent variational Monte Carlo method, we perform numerical simulations of realistic laser pulses applied to the Kondo lattice model. By tracking spin and charge degrees of freedom we identify a dynamical phase transition, within the partially Kondo screened phase, from a charge ordered into a metallic state, while preserving the spin order of the system. We propose using high-harmonic generation and nonequilibrium optical conductivity to identify the dynamical phase transition in an ultrafast experiment.

H. Schweitzer, G. Czycholl

Joel Feldman, Eugene Trubowitz B

Javier Rivera-Dean, H. B. Crispin, Philipp Stammer +6 more

High-harmonic generation (HHG) has recently emerged as a promising method for generating nonclassical states of light with frequencies spanning from the infrared up to the extreme ultraviolet regime. In this work, we theoretically investigate the generation of squeezed states of light through HHG processes in atomic systems that were initially driven to their first excited state. Our study reveals significant single-mode squeezing in both the driving field and low-order harmonic modes. Additionally, we characterize two-mode squeezing features in the generated states, both between fundamental and harmonic modes, and among the harmonic modes themselves. Using these correlations, we demonstrate the generation of optical Schr\"odinger kitten states through heralding measurements, specifically via photon subtraction in one of the modes influenced by two-mode squeezing.