Quantum coherence dispersion

Xue Mei Su, Byoung Seung HAM, Z. C. Zhuo +1 more

We propose a scheme in a four level atomic system to enhance group velocity dispersion and nonlinearity for a weak field using photonic bandgap created by quantum coherence with standing fields, where weak probe pulse propagates fast or slowly controlled by interaction between atoms and coherent fields.

裕也 中尾, Hiroya Nakao

José Tito Mendonça, Hugo Terças

Fernando Parisio

We investigate how quantum coherence can be distributed among the several off-diagonal elements of an arbitrary density matrix. An easily computable quantity that captures this variability notion is proposed and it is argued that it presents marked features of complexity quantifiers. It turns out that this coherence dispersion ($Δ_{\rm c}$) is maximized for intermediate values of an appropriate entropy (the relative entropy of coherence), a prevalent signature of complexity quantifiers across different fields, from evolutionary biology to linguistics and information science. The final part of the manuscript is dedicated to the connection between the proposed framework and non-equilibrium systems in the quantum regime.

Guoli Ma, Baoguo Shi, Yanli Yao +2 more

We study the effects of quantum coherence induced by permanent dipole moments in a three-level dipolar molecule. We find that the absorption and dispersion properties can be significantly modified by this coherence under different conditions. It is shown that electromagnetically induced transparency, enhancement of the index of refraction, lasing without population inversion, and anomalous dispersion are all dependent on this interference.

W. Pötz, Ulrich Hohenester, Jaroslav Fabian