Quantum key distribution with localized photons

Information is usually extracted from a photon when a photodetector clicks. On the other hand, a single particle encloses part of the information it is carrying in its wavefunction which is usually lost in a single click. The wavefunction shape may be recovered reconstructing it with many detections, but there is no way to reconstruct it with a single detector’s click….

….in all but one case : when the wavefunction is localized.

If a photon wavefunction is localized the click on the detector also pinpoints the photon location so that much more information may be extracted.

AL_quantum_13_06_2016.dvi

In a recently published paper we demonstrate how to exploit this additional information in an optical fiber supporting transverse localization. Moreover by exploiting position and momentum complementarity we are able to encrypt information with a quantum key distribution protocol.

 

Annunci

LOCALITIS project financed!

Fiber_Light_3

The fundation “Con il sud” announced that the LOCALITIS project will be financed for 360K euros. It seems that my activity on Anderson localization will receive quite a boost   at CNR-Nanotech!

The aim of the project is to encode up to 14 bits of information in a single photon traveling in a localized wavefunction.

Stay tuned!

Enhanced adaptive focusing through semi-transparent media

Semi_trasparent

Adaptive focusing enables to focus light through opaque curtains. The maximum resolution of this process is limited by the effective numerical aperture of the system: the span of angles which contribute to the focusing. In a recent paper , we demonstrate, by exploiting a custom spatial filter, how it is possible to select, between the many light paths contributing to the adaptive focusing, the ones which provide the higher numerical aperture. This optical selection effectively improves the resolution of the adaptive focusing in the weak scattering regime.

Read more on the Scientific Reports Article

or on the web paper.

 

Inhomogeneity-driven optical rogue waves through obstacles

RW

 

In a speckle pattern, light is organized in disordered fashion with maxima and minima of intensity. The multiple wave components underlying  an inhomogeneous  optical rogue wave may give rise to exceptional maxima of intensity which are similar to unpredictable rogue waves appearing from nowhere in the ocean. Here, we demonstrate that the inhomogeneity-driven optical rogue waves may be fully tailored through adaptive optics and that may be also activated behind fully reflective obstacles.

Disorder Induced Self-Focusing

Focusing

 

In photonics, disorder is usually seen as a bad feature decreasing the efficiency of optical elements and driving light far from your target.

In this paper we demonstrate that the reverse is possible: disorder transforms two de focusing-plastics into a self-focusing metamaterial.

By exploiting a phenomenon named Transversal Anderson localization it is possible to exploit scattering events to constrain light into a tiny space, and exploit very cheap disordered optical to bring information at large distances.

By putting together Transverse localization and Nonlinearity it si possible to achieve complete control of a light beam, defining the degree of localization and its position.

“Light Localisation and Lasing” out in January

L_LOC

I’have been happy to part of the “Light Localisation and Lasing”  team: a comprehensive book on light, lasing and disorder.

Out in January 2015!

“The properties of quasi-random and random photonic systems have been extensively studied over the last two decades, but recent technological advances have opened new horizons in the field, providing better samples and devices. New optical characterization techniques have enhanced understanding of the novel and fundamental properties of these systems. This book examines the full hierarchy of these systems, from 1D to 2D and 3D, from photonic crystals and random microresonator chains to quasi crystals.”

Disorder Induced Self Focusing


Disorder induced_focusing

In a nonlinear optical material, the refractive index varies with the optical intensity. In general thermal nonlinearity produces a de-focusing effect. In this paper  we demonstrate that disorder changes the terms around and transform a de-focusing nonlinearity into a focusing one. When the thermal nonlinearity is activated, the two materials composing the optical fiber respond differently and the refractive index mismatch increases, enhancing the strength of the transversal Anderson localization. In a nutshell we demonstrate a nonlinearly enhanced transverse Anderson localization.