Information Propagating through a Dispersive Medium—Observation of Optical Precursors

Jaak Aaviksoo, J. Kühl, Klaus Ploog

The appearance of precursors at pulse propagation in a dispersive medium was predicted in 1914.1 Precursors were detected experimentally for the propagation of microwave pulses in waveguides,2 whereas observation of optical precursors has not been reported so far. Experimental pulse propagation studies in the optical domain have revealed severe pulse velocity reduction near the material resonances, which has been interpreted in the framework of group velocity.3

Chao-Guang Huang, Yuan‐Zhong Zhang

Daniel J. Gauthier, Michael D. Stenner, Mark Allen Neifeld

B. Macke, Bernard Ségard

We show that the optical transients recently read as "Sommerfeld-Brillouin precursors" by Jeong, Dawes and Gauthier are not identifiable with optical precursors (unless one considers that any coherent transient propagating in a dilute medium at the velocity c is an optical precursor) and that they can be interpreted in very simple physical terms.

Shengwang Du

Silvia Cardenas-Lopez, Pablo Solano, Luis A. Orozco +1 more

When a broadband signal propagates through a dispersive medium, some frequency components move faster than the center of the pulse. This leads to the appearance of precursors, transient signals that emerge from the medium earlier than the main part of the pulse and seem to propagate superluminally. Here, we investigate the microscopic origin of precursors in a minimal setup: an array of qubits coupled to a waveguide. The linear transmission function only converges to that of a continuous medium for large qubit numbers. Nevertheless, the dispersion produced by only two qubits is enough to produce oscillatory transients. Precursors are best observed under conditions of electromagnetically induced transparency, as the center of the pulse is significantly delayed. Under these conditions, just a single qutrit is enough to generate a precursor. Our results pave the way towards dispersion engineering of light with just a few qubits and can be realized with superconducting qubits coupled to transmission lines or atoms coupled to optical waveguides.