Third Relativity

Arthur Stanley Eddington

Richard T. Hammond

Coherent states and a newly developed form of the density operator are used to relate the third-order susceptibility to the first-order susceptibility. The theoretical result is shown to be in fair agreement with the empirical relation.

Masao Nomura

The third and fourth moments of energy spectra in a many-particle configuration are completely related to two-particle matrix elements, so that neither c.f.p. nor explicit diagonalization of any matrix is needed to evaluate these moments. Recah algebra and reduction relations for c.f.p. are well used. We confine ourselves, for simplicity, to jn and j1n1j2n2 configurations of identical particles.

W.-J. Chen, R-Y Lin, W-F Chen +2 more

We investigate generation of the third harmonic (TH; λ = 355 nm) signal by two-colour excitation (λ = 1064 nm and its second harmonic, λ = 532 nm) in argon gas, with emphasis on the influence of relative phases and intensities of the two-colour pump on the third-order nonlinear frequency conversion process. Perturbative nonlinear optics predicts that the TH signal will oscillate periodically with the relative phases of the two-colour driving laser fields due to the interference of TH signals from a direct third-harmonic-generation (THG) channel and a four-wave mixing (FWM) channel. For the first time, we show unequivocal experimental evidence of this effect. A modulation level as high as 0.35 is achieved by waveform control of the two-colour laser field. The modulation also offers a promising way to retrieve the relative phase value of the two-colour laser field.

Alfred Landé, Mendel Sachs