Current Research

The research pursued by the Experimental Quantum Photonics Group at LSU explores the fundamental and applied aspects of optical physics and quantum optics. We investigate novel properties of light and their potential for developing quantum technologies. This is a fast-developing research field with tremendous potential to impact different areas of science and engineering, such as quantum metrology, quantum communications, and quantum information science. Some of the research that we pursue includes (i) the development of quantum measurement schemes that allow amplification of small physical parameters and characterization of photonic states, (ii) the demonstration of highly efficient sources of entangled photons and engineering of complex high-dimensional states of light, (iii) the implementation of quantum protocols that utilize optimization algorithms to effectively use the information content in each photon, and (iv) the exploration of physical conditions under which light is forced to manifest new surprising properties.

Currently, our research efforts are concentrated mainly in following areas:

An important part of our research has been devoted to the development of efficient sources of correlated photons. In the low-photon regime, the Quantum Photonics team has developed sources of spontaneous parametric down-conversion with overall system efficiencies of the order of 80%. In the mesoscopic domain, we have demonstrated complete control of photon statistics, mean photon numbers and degree of correlations of multiphoton entangled states with up to twelve photons. In addition, we have demonstrated engineering and characterization of high-dimensional states that exploit various degrees of freedom of light, such as polarization, time, energy, position, linear momentum, angular position and orbital angular momentum.

We are currently investigating multiple paths to develop the next generation of quantum protocols for metrology and imaging, in our opinion, these technologies should be smart. Motivated by recent progress in the field of artificial intelligence and machine learning, we are developing a unique family of technologies that utilize quantum properties of light to learn and to make decisions. Our research is aimed at developing smart quantum metrology and imaging techniques that utilize quantum properties of light such as quantum statistical fluctuations, entanglement, and photonic high-dimensional states to boost self-learning and self-evolving features of machine learning. We exploit these properties to force optimization algorithms for machine learning to unambiguously converge to unique solutions, with small uncertainties in rapid fashion.

We are currently developing quantum protocols that utilize spatial modes of light and entanglement to increase the channel capacity and the level of security of communication protocols. We are developing communications schemes inspired in the Ekert protocol. Here, the polarization and spatial degree of freedom of entangled photons are used to encode multiple bits of information in a single photon. The robustness of these hybrid states under realistic conditions of atmospheric turbulence is being investigated by our group. Furthermore, we are developing new metrics to characterize entanglement in these complex communication modes.

We are using our bright sources of spontaneous parametric down-conversion to explore fundamental physics that can only be studied in multiparticle systems. We are using waveguide lattices to explore multiphoton Hong-Ou-Mandel effects. The unique nonclassical features produced by quantum interference among photons prepared in exotic quantum superpositions have important implications for quantum random walks and boson sampling. The Quantum Photonics Group is performing research along this direction. We are also exploring the possibility of using exceptional points to protect multiphoton states and to increase the sensitivity of protocols that rely on multiphoton interference.

We are developing new platforms to control multiphoton quantum processes using optical near-field effects. We achieve an exquisite level of control through novel light-matter interactions that have not been accounted for in traditional quantum optics. Our experimental protocols offer the possibility of suppressing decoherence in multiphoton systems through the manipulation of dissipative quantum near-fields. We are using simple metallic nanostructures, such as slits and gratings to build complex multiphoton networks. These photonic nanostructures allow us to control multiphoton quantum dynamics through the manipulation of multiphoton interference and scattering processes. We are interested in the potential of dissipative quantum near-fields to control trajectories of multiphoton wavepackets, decoherence, and multiphoton scattering in photonic networks. The control of quantum systems at this fundamental level enable us to use photonic networks to demonstrate classical-to-quantum transitions in the propagation dynamics of photons.