State flip at exceptional points in atomic spectra

Abstract

We study the behavior of the non-adiabatic population transfer between resonances at an exceptional point in the spectrum of the hydrogen atom. It is known that, when the exceptional point is encircled, the system always ends up in the same state, independent of the initial occupation within the two-dimensional subspace spanned by the states coalescing at the exceptional point. We verify this behavior for a realistic quantum system, viz. the hydrogen atom in crossed electric and magnetic fields. It is also shown that the non-adiabatic hypothesis can be violated when resonances in the vicinity are taken into account. In addition, we study the non-adiabatic population transfer in the case of a third-order exceptional point, in which three resonances are involved.

Extremely broadband, on-chip optical nonreciprocity enabled by mimicking nonlinear anti-adiabatic quantum jumps near exceptional points

“…These adiabatic interaction properties have been confirmed by tracking the instantaneous eigenstates in the quasi-stationary limit. The complete dynamics of state evolution in non-Hermitian systems with significant imaginary eigenvalue splitting in general involve highly non-adiabatic behaviour associated with an anti-adiabatic state jump occurring under appropriate initial-state and parametric conditions21222324. The anti-adiabatic state jump is a key interaction leading to the time-asymmetric state-evolution passages in our proposed system.…”

Optically anisotropic media: New approaches to the dielectric function, singular axes, microcavity modes and Raman scattering intensities

“…A simplified discussion how exceptional points arise mathematically can be found in Appendix A1. Exceptional points have been found in coupled dissipative dynamical systems [54], mechanical problems [55], electronic circuits [56], microwave cavities [57], gyrokinetics of plasmas [58], coupled fiber-ring resonators [59], atomic spectra [60,61], coupled quantum cascade microdisk lasers [62], photonic crystals [63], inhomogeneous gain media [64], optical lattices of driven cold atoms [65] and plasmonic waveguides [66]. We also point to literature on exceptional points with a degeneracy larger than two [63,[67][68][69].…”

Exceptional Points and Asymmetric Mode Switching in Plasmonic Waveguides

“…So far many interesting phenomena have been observed in the presence of EPs, such as unidirectional reflection or transmission [6], revival of lasing [7], and loss-induced transparency [8]. The EPs have been also widely investigated in atomic spectra [9], optical and acoustic cavities [10]- [12], photonic crystals [13], multilayer structures [14], and optical waveguides [3].…”

“…The state exchange for slowly encircling EP relies on adiabatic evolution and it has been reported in quasi-static experiments in non-Hermitian system [9], [10]. However, when considering a dynamical encircling, that is, the system parameters changes in time, the evolution of system states don't follow the adiabatic expectation [19]- [21].…”