Plasmon Intrinsic Dipole Moment*

Plasmons are usually described by macroscopic objects such as electric fields and currents. They are nevertheless quantum objects with internal structure. We show [1] this can include an intrinsic, static dipole moment that is tied to the quantum geometry of the Hilbert space in which the plasmon states reside.  This quantum geometric dipole offers a unique handle for controlling plasmon dynamics, via density modulation and electric fields. We demonstrate that a nonvanishing plasmon quantum geometric dipole gives rise to nonreciprocal skew scattering for plasmons from impurities in a valley dependent way.  This skew scattering can be directly observed in near field optical microscopy.