Coherent control of localization in phase-modulated quasiperiodic lattices

We report experiments demonstrating reversible coherent control of a localization phase transition by phasonic modulation. As background, we recently reported phasonic spectroscopy of a quantum gas in an artificial quasicrystal realized by a bichromatic optical lattice [1]. In this work we study a different frequency regime where excitation into higher bands is not significant, and the modulation frequency is high enough to avoid intraband excitations [2]. In this regime, the phase modulation allows us to control the sign and magnitude of the effective lattice depth of the phase-modulated secondary lattice [1]. By monitoring expansion of a Bose-Einstein Condensate in the modulated bichromatic lattice, we observed that the effective variation of the secondary lattice depth causes a number of localization-delocalization transitions as the phason drive amplitude is increased. These results open a new path to dynamical coherent control of the transport properties of quantum matter.



[1] S. Rajagopal et al., Phys. Rev. Lett. 123, 223201 (2019)

[2] G.Sun and A. Eckardt, Phys. Rev. Res. 2, 013241 (2020)