2025
- 5th of June 2025, 2:00pm – ‘Light-Matter Interactions in Chiral Media’ by Prof. Paras N. Prasad, Distinguished Professor at the University of Buffalo – The State University of New York (USA) https://www.photonics.buffalo.edu/prasad.html.
Where: 22-32-317, Jussieu campus
Abstract: Chiral photonics dealing with light-matter interaction in Chiral media ,offers, via selective circular polarization (photon spin), spin control of both linear and nonlinear optical functions for applications ranging from optical switching, to negative- and near-zero refractive index metamaterials, to chiral bioimaging. It represents a new direction with substantial opportunity including secure optical communication, beam steering, all optical switching, signature control, quantum computing, bio-detection, subwavelength imaging, and brain wave detection to enhance human effectiveness. However, realization of such applications requires materials with optical activity at visible wavelengths that is orders of magnitude larger than that of any naturally occurring materials. Our theory-guided-design and synthesis of novel chiral polymers has yielded very large linear and multiphoton circular dichroism . We have introduced the concepts of plasmonic, excitonic, and structural enhancement of linear and nonlinear multiphoton optical activities. Some results on polymers and nanocomposites exhibiting chirality derived large magneto-optic effect have also been achieved, which may enable mapping of ultra-weak magnetic fields, like those generated by brain function. We are pursuing multiscale modeling and experimental design of the interaction of structured light endowed with both spin and orbital angular momentum, with nanostructured chiral plasmonic media for adaptive control of effective dielectric function. The seminar will conclude with a discussion of challenges and opportunities in Chiral Photonics.
1. P.N. Prasad “Nanophotonics” John Wiley & Sons, (2004).
2. A. Baev, P.N. Prasad, H. Ågren, M. Samoć, and M. Wegener, »Metaphotonics: An emerging field with opportunities and challenges »; Physics Reports 594, 1-60 (2015).
2024
- 27th of November 2024, 2pm – ‘Quantum Hall physics with photons’, by Prof. Mikael Rechtsman, from Penn State University (USA) – https://leptos.psu.edu/
Where: 22-32-317, Jussieu campus
Abstract: When electrons moving in a two-dimensional plane are subject to a perpendicular magnetic field they move in circles called cyclotron orbits as a result of the Lorentz force. Treated quantum mechanically, these orbits become quantized like the orbitals of an atom, forming highly degenerate states called Landau levels. In this colloquium, I will show how we used strain to make photons « feel » a magnetic field and thus form Landau levels in a photonic crystal, despite the fact that photons carry no charge and thus cannot experience the Lorentz force. This increases the strength of interaction between light and matter, which has implications in quantum optics and integrated photonics. Time permitting, I will discuss the related topic of how edge states in a « Chern insulator » photonic crystal can be used to slow down light in a photonic chip over a wide bandwidth. - 18th of June 2024, 10:45am – ‘Quantum skyrmions’ by Pedro Ornelas, Wits Unviersity (South Africa) – phD student in the Structured light laboratory led by Prof. Andrew Forbes https://structured-light.org/
Where: 22-32-317, Jussieu campus
Abstract: ‘Quantum skyrmions’ i.e. Noise-free Topological Observables of Entangled StatesEntangled states are a promising resource for future quantum technologies such as quantum communication, quantum cryptography and quantum computing, where the approach is to utilize typical entanglement witnesses such as the degree of entanglement and purity as resources for information encoding. However, these features are highly susceptible to noise, thus prompting a search for properties of entangled states that are invariant to realistic noise scenarios. In this talk we will shift our focus to the recently discovered skyrmionic topology of optical systems and propose their existence as a property of a joint non-local system formed by two entangled photons. Furthermore, we will discuss how we can manipulate the non-local topological invariant at will thus revealing the possibility of it being utilized as an information carrier in quantum technologies. Finally, we will discuss the robustness of these topological features by demonstrating their invariance to topical sources of noise and provide an intuitive geometric interpretation to explain the origin of this invariance. - 22th of March 2024 , 10:30am – ‘A brief ride through the field of quantum imaging’ by Prof Markus Graefe, University of Darmstadt (Germany) – https://www.iap.tu-darmstadt.de/efq/experimentelle_festkoerper_quantenoptik/
Where: 22-32-317, Jussieu campus
Abstract: Exploiting the quantum properties of light offers new possibilities for quantum imaging and sensing. As such, one can harness entanglement, correlations, or quantum coherence of photon pairs to circumvent classical limitations in imaging and sensing. This includes super sensitive two-photon absorption, sub-shot noise ghost imaging, and imaging and sensing with undetected light. Besides fundamentals, a brief overview of different concepts of quantum imaging and sensing will be given, with a particular focus on nonlinear interferometers that allow imaging/sensing with undetected light.
2023
- 1st of December 2024 , 10am – ‘Quantum microscopy using spatially correlated photons’ by Prof. Bienvenu Ndagano, iNRS (Canada) – https://inrs.ca/la-recherche/professeurs/bienvenu-irenge-ndagano/
Where: 22-32-317, Jussieu campus
Abstract: Exploiting spatial correlations between photons is fundamental in quantum imaging. Correlation-based imaging, a scheme whereby one photon from a pair interacts with an object before reaching the detection system. The joint measurement of the two photons then reveals the image of the object. Though the image reconstruction was initially implemented using computational techniques that employ a single pixel with no spatial resolution on its own, modern implementations can make use of arrays of single-photon sensitive detectors. Novel imaging sensors such as arrays of single photon avalanche diodes (SPADs) have enabled two- and three-dimensional imaging, the latter being enabled by the high temporal resolution. Furthermore, their high-frame rate, compared to rival technology, dramatically reduces the acquisition time required to spatially characterise quantum states and form a correlation image. In this talk, I will provide an overview recent research work in 2D, and 3D correlation-based imaging using photon pairs. Particularly, I will focus on optical designs geared towards applications in microscopy. - 18th of September 2024 , 11am – ‘Orbital Angular momentum entanglement’ by Prof. Anand Kumar Jha, IIT Kanpur (India) – https://home.iitk.ac.in/~akjha/
Where: 22-32-426, Jussieu campus
Abstract: The fact that a photon in a light beam can carry orbital angular momentum (OAM) in the integer multiples of ℏ has made OAM a very important degree of freedom for quantum information and quantum metrology. However, the efficient techniques for generating and detecting high-dimensional OAM entangled states have been lacking, which severely limits the potential applicability of such states for real-world applications. In this talk, I will present our recently-developed techniques for efficiently generating and detecting OAM-entangled states with dimensionalities up to 200. - 12th of July 2023 , 2pm – ‘Quantum Interference in Transverse-Spatial Modes’ by Markus Hiekkamäki, Tampere University (Finland) – phD student in Robert Fickler’s group
Where: 22-32-426, Jussieu campus
Abstract: Since classical interference has become ubiquitous in our modern optical devices and experiments, it is reasonable to assume that its quantum counterparts could become as prevalent in the next wave of technologies. The first signs of this can already be seen in the plethora of potential quantum technological applications that heavily rely on non-classical multi-photon interference effects. One degree of freedom where multi-photon interference has not been extensively studied yet is the transverse-spatial degree of freedom. This lack of studies is surprising when considering the potential benefits this degree of freedom has demonstrated in many other technological applications. Hence, our work aimed to increase our understanding of quantum interference in transverse spatial modes. We do this by investigating two-photon interference effects in this degree of freedom and by exploring some of their applications in metrology. The quantum interference experiments we performed utilized arbitrary unitary devices built using multi-plane light conversion devices and a simplified system that allowed us to create single-beam N00N states. - 15th June 2023 – Quantum imaging symposium
Where: Batiment Esclangon, Jussieu campus
Invited speakers:
– Prof. Miles Padgett, University of Glasgow
Single-fibre imaging
– Prof. Nicolas Treps, Sorbonne University
Separation estimation of optical sources using modal decomposition
– Prof. Sara Ducci, Université Paris Cité
Generation and engineering of quantum states of light with semiconductor chips
– Prof. Edoardo Charbon, Ecole Polytechnique Fédérale de Lausanne
Photon-counting and Single-photon Sensors for Quantum Imaging Applications
– Dr. Valentina Parigi, Sorbonne University
Continuous variable entangled networks
– Prof. Andrew Forbes, University of the Witwatersrand
Towards teleporting images
– Prof. Daniele Faccio, University of Glasgow
Hong Ou Mandel microscopy
– Prof. Agnès Maitre, Sorbonne University
Emission of single quantum dot under confined environment and high excitation
– Prof. Eric Lantz, University of Franche-Comté
Highly multimode and multiphoton quantum interferences
quantumimagingparis.fr 