The Kramers-Kronig relations are derived for the permittivity of the usual plasma model which neglects dissipation and of a generalized model which takes into account the interband transitions. The generalized plasma model is shown to be consistent with all precision experiments on the measurement of the Casimir force.

Titanium carbide (TiC) nanocrystals were recently proposed as the carrier of the mysterious 21 mm emission feature observed in post–asymptotic giant branch stars, based on their close spectral match and the presolar nature of meteoritic TiC nanograins (which reveals their stellar ejecta origin). But we show in this Letter that the KramersKronig dispersion relations, which relate the wavelength-...

We establish a fundamental relationship between the averaged local density of states and the extinction mean free path of waves propagating in random media. From the principle of causality and the Kramers-Kronig relations, we show that both quantities are connected by dispersion relations and are constrained by a frequency sum rule. The results should be helpful in the analysis of wave transpor...

Phase measurements are of paramount importance in quantum optical sensing. However, the promise a advantage, celebrated Heisenberg scaling, is severely curtailed presence noise and loss. Here we investigate systems which phase absorption profiles linked by Kramers–Kronig relations show that, limit large photon number, their use connects uncertainties on attainable optimal probes for loss phase....

As previous theoretical results recently revealed, a Kramers-Kronig transform of multiphoton absorption rates allows for a precise prediction on the dispersion of the nonlinear refractive index n2 in the near IR. It was shown that this method allows to reproduce recent experimental results on the importance of the higher-order Kerr effect. Extending these results, the current manuscript provide...

Using the principle of causality as expressed in the Kramers-Kronig relations, we derive a generalized criterion for a negative refractive index that admits imperfect transparency at an observation frequency omega. It also allows us to relate the global properties of the loss (i.e., its frequency response) to its local behavior at omega. However, causality-based criteria rely on the group veloc...