Scattering of accelerated wave packets

Abstract

Wave-packet scattering from a stationary potential is significantly modified when the wave packet is subject to an external time-dependent force during the interaction. In the semiclassical limit, wave-packet motion is simply described by Newtonian equations, and the external force can, for example, cancel the potential force, making a potential barrier transparent. Here we consider wave-packet scattering from reflectionless potentials, where in general the potential becomes reflective when probed by an accelerated wave packet. In the particular case of the recently introduced class of complex Kramers-Kronig potentials we show that a broad class of timedependent forces can be applied without inducing any scattering, while there is a breakdown of the reflectionless property when there is a broadband distribution of initial particle momentum, involving both positive and negative components.

Non-Hermitian invisibility in tight-binding lattices

“…However, the most amazing effects, such as invisibility, could be realized only when considering NH potentials. Recently, wave reflection and scattering from complex potentials has sparked a great interest with the prediction of intriguing phenomena, such as unidirectional or bidirectional invisibility of the potential [8][9][10][11][12][13][14][15][16][17][18][19][20][21], asymmetric scattering [22][23][24], constant-intensity wave transmission across suitably engineered NH scattering landscapes [25][26][27][28][29][30], reflectionless transmission based on the spatial Kramers-Kronig relations [31][32][33][34][35][36][37][38][39][40][41][42][43][44]46,47], and NH transparency [48].…”

A Miniaturized Anechoic Chamber: Omnidirectional Impedance Matching Based on Truncated Spatial Kramers–Kronig Medium

“…demonstrated theoretically that a class of isotropic, inhomogeneous 1D susceptibility profiles can be used to achieve omnidirectionally reflectionless absorption without any gain region, as long as they satisfy the spatial Kramers–Kronig (KK) relations. [ 23–28 ] Recent studies demonstrated experimentally that such spatial KK media can be implemented in a broadband frequency range by constructing passive gradient mesoscopic structures. [ 29,30 ] However, it is still difficult to use these KK media to absorb radiated waves in free space background due to the impedance mismatching at the truncation boundaries.…”

“…Kramers-Kronig (KK) relations. [23][24][25][26][27][28] Recent studies demonstrated experimentally that such spatial KK media can be implemented in a broadband frequency range by constructing passive gradient mesoscopic structures. [29,30] However, it is still difficult to use these KK media to absorb radiated waves in free space background due to the impedance mismatching at the truncation boundaries.…”