Detection of a plasmon-polariton quantum wave packet

Higher-Order Multidimensional and Pump–Probe Spectroscopies

“…15,16 2D nanoscopy allowed us to detect a plasmon-polariton quantum wave packet. 130 In this example, we observed aliased 3Q coherences in an eighth-order nonlinear process that could be assigned to multiple excitations of the plasmon. This example demonstrates that higher-order signals also play an important role in plasmonic systems.…”

“…An obvious extension of higher-order spectroscopy beyond bulk measurements is its combination with spatial resolution. Multidimensional spectroscopy has already been combined with fluorescence microscopy. , Another variant combines action-detected phase-cycling 2D spectroscopy with photoemission electron microscopy (PEEM), providing spatial resolution down to ∼3 nm, which is why we named it “2D nanoscopy”. , 2D nanoscopy allowed us to detect a plasmon-polariton quantum wave packet . In this example, we observed aliased 3Q coherences in an eighth-order nonlinear process that could be assigned to multiple excitations of the plasmon.…”

Ultrafast photoemission electron microscopy: A multidimensional probe of nonequilibrium physics

“…[229] A unique aspect of multiphoton PEEM experiments is that it allows the extraction of the quantum pathways of the photoemission involving plasmon quasiparticles, as well as the interaction between the plasmon-assisted intermediate states, [58] which are beyond the classical wave analysis. Pres et al [63] reported a quantum mechanical model for plasmonelectron interaction in a multiphoton PEEM experiment. In this case, the plasmon polariton state is considered as a quantum harmonic oscillator represented by occupation number state |ψ⟩, and the classical polarization, which is recorded by PEEM, is described as ⟨ψ|b + b † |ψ⟩, where b and b † are the plasmon lowering and raising operators, respectively.…”

“…Therefore, it allows ultrafast imaging of surface parallel fields along both x and y directions (E x and E y ); the 038703-16 surface-normal (E z ) field is thus obtained based on the constitution relation of the Maxwell's equations. [284] It is important to note that because ITR-PEEM is a nonlinear microscopy technique, additional Fourier filtering was required to quantitatively extract the field amplitude; photoemission signals due to cross-polarized excitation pathways, [58,63] however, may affect quantitative analysis of the E-field amplitude.…”

“…Since then, timeresolved (TR-) PEEM, and particularly interferometric time resolved (ITR-) PEEM have been improved to adapt broadly tunable femtosecond and attosecond light sources, normal incident excitation schemes, full-vectorial imaging method, etc., making them the prevailing technique in resolving plasmon dynamics. [14,15,[48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] More importantly, besides their success in imaging of electromagnetic modes, ultrafast PEEM has also been widely applied to imaging the evolutions of magnetic domains and textures in magnetic materials, [65][66][67][68][69][70] as well as hot carrier and exciton dynamics in metals and semiconductors. [32,[71][72][73][74][75][76][77][78][79][80] With the implementation of MM, the corresponding studies have been extended to the reciprocal space, allowing multidimensional probing of the corresponding excited states physics.…”