Impact of turbulence in long range quantum and classical communications

The study of the free-space distribution of quantum correlations is necessary for any future application of quantum as classical communication aiming to connect two remote locations. Here we study the propagation of a coherent laser beam over 143 Km (between Tenerife and La Palma Islands of the Canary archipelagos). By attenuating the beam we also studied the propagation at the single photon level. We investigated the statistic of arrival of the incoming photons and the scintillation of the beam. From the analysis of the data, we propose the exploitation of turbulence to improve the SNR of the signal.Comment: 5 Pages, 5 figures, 1 Table, revtex

Advanced Techniques in Free Space Quantum Communication

The main argument of this thesis is the application of advanced techniques for the optimization of single photon communication and in general of single photon applications. The work is inserted in the contest of various projects that involve the departments of Information Engineering and Astronomy of the University of Padua. In particular my contribution has been the development of a quantum cryptography setup that we called QuAKE. The system has been designed and implemented in our labs and include in the hardware some advanced temporal and spatial filtering techniques. These features has been realized respectively with an ad hoc electronics and with an adaptive optics system, the latter developed entirely in our department. The high level software for quantum cryptography has been also implemented and many optimizations have been realized both in the logical design and in the single algorithms. The last part of this thesis describes an astronomical instrument, called AquEYE, developed by our group and capable of time tagging single photons coming from celestial sources. In particular a description of the time and frequency distribution unit is given since this has been my contribution to the AquEYE instrument so far. The thesis is organized as follows: after an introduction to quantum cryp- tography (chapter 1), the QuAKE system is presented (chapter 2), the electronics and the optical setup are described (chapter 3) as well as the adaptive optics system (chapter 4), it follows a description of the results obtained testing the adaptive optics system outdoor and on the QuAKE system (chapter 5) and the description of the high level software and the related results (chapter 6), last a description on the timing and frequency unit of AquEYE is presented as well as some of the early results of the instrument (chapter 7)

Session VI. Industrybreakthroughs.-Adaptica: products outline and technology developments

Abstract Adaptica is a Spin-off company of the University of Padova (incorporated in February 2009). It is composed by six young scientists and three collaborators. The background expertise of Adaptica’s R&D division is in adaptive optics for ultrashort pulses laser technology, astronomy, non linear optics and embedded systems for digital electronics. Moreover Adaptica CEO is a thirty years experienced manager in the field of technologies for automation and ophthalmic diagnostic system productions. This vertical approach is fostering new technologies, very compact and with friendly interfaces with the goal to make Adaptive Optics a technology for many optical applications. The mixture of academic and company organization maximizes both productivity and innovation, with high quality in the components. The same approach brought consequently to the submission of two patents in the first 8 months of activity. The products of Adaptica are based on adaptive optics systems composed by a highly embedded digital electronic system, deformable optics and aberration sensors. On this base, Adaptica is presenting on the market state of the art membrane deformable mirrors, electronic control units based on embedded PC, Shack Hartmann wavefront sensors and LCD/LCOS spatial light modulators. By means of these standard laboratory products, Adaptica produces also a series which is internationally distributed by Edmund Optics Inc (USA). Moreover Adaptica is recently producing and distributing a tool for teaching Adaptive Optics to universities courses and R&D industry division. In this talk it will be presented a description of Adaptica's product line with particular attention on the specifications, constraints and typical applications. In the conclusions we will outline a summary of some recent results and future developments

Aqueye Plus: a very fast single photon counter for astronomical photometry to quantum limits equipped with an Optical Vortex coronagraph

In recent years, we developed two very high speed single photon photometers, Aqueye and Iqueye, as prototypes for \u201cquantum\u201d photometers for the Extremely Large Telescopes of the next decade. These instruments, based on single photon avalanche photodiodes and a 4-fold split-pupil concept, have been successfully used to obtain data of the highest quality on optical pulsars. Subsequently, we performed an attempt to utilize the Orbital Angular Momentum and associated Optical Vorticity to achieve high performance stellar coronagraphy. Presently, we are making a synergic effort in building Aqueye Plus, a new instrument for the 1.8 m telescope of the Asiago - Cima Ekar Observatory, which combines both functions, namely high speed simultaneous multicolor photon counting photometry and stellar coronagraphy. The innovative capability of Aqueye Plus is to take advantage of the two parallel outputs (NIM and TTL) of the four high time accuracy photon counting sensors. The NIM output preserves the best timing capability, while the TTL output drives a deformable 32-element mirror in a sort of quadrant detector to correct for defocus and tip/tilt aberrations of the stellar image on the phase mask discontinuity. This paper describes the Aqueye Plus instrument main characteristics and its foreseen performance

Aqueye+: a wavefront sensorless adaptive optics system for narrow field coronagraphy

We have designed Aqueye+, an instrument for the Copernicus 182 cm Asiago Telescope, with two channels, one devoted to ultrafast photometry based on four single photon avalanche photodiodes, the second dedicated to stellar coronagraphy based on innovative optical vortex coronagraph system. The OVC requires a very good image quality, therefore an adaptive optic system AO was designed for the instrument. The peculiarity of this AO system is that there is no wavefront sensors, but the feedback for the deformable mirror is instead given by the photometric channel of Aqueye+