PROJECT PREPRINT AND PUBLICATIONS 

G. Calajo, D. E Chang, Few-and many-body photon bound states in quantum nonlinear media: a spin-model approach, arXiv:2110.00050 (2021). https://arxiv.org/abs/2110.00050
In this work we study the emergence of multi-photon bound states in generic quantum nonlinear such as arrays of quantum emitters coupled to photonic waveguides and Rydberg nonlinear media. We propose and utilize a spin-model formulation of quantum atom-light interactions as a general, unified framework to study bound states in several distinct systems. We study the few- and many-body excitation dynamics showing that these bound states manifest themselves as spatio-temporal correlations at the output. Interestingly, for all the specific systems studied, we find that the large-photon number limit always coincides with the well-known semi-classical soliton phenomenon of self-induced transparency or immediate generalizations thereof.

F. Roccati, S. Lorenzo, G. Calajò, G. M. Palma, A. Carollo, F. Ciccarello, Exotic interactions mediated by a non-Hermitian photonic bath, arXiv:2109.13255 (2021). https://arxiv.org/pdf/2109.13255.pdf
We study the exotic interaction between emitters mediated by the photonic modes of a lossy pho- tonic lattice described by a non-Hermitian Hamiltonian. Here due to structured losses photons can mediate dissipative, fully non-reciprocal, interactions between the emitters with range critically dependent on the loss rate. When this loss rate corresponds to a bare-lattice exceptional point, the effective couplings are exactly nearest-neighbour, implementing a dissipative, fully non-reciprocal, Hatano-Nelson model irrespective of the lattice boundary conditions.

M. Scigliuzzo, G. Calajò, F. Ciccarello, D. Perez Lozano, A. Bengtsson, P. Scarlino, A.Wallraff, D. Chang, P. Delsing, S. Gasparinetti, "Extensible quantum simulation architecture based on atom-photon bound states in an array of high-impedance resonators",  arXiv:2107.06852 (2021). https://arxiv.org/pdf/2107.06852.pdf
In this work we present an implementation of a novel microwave architecture consisting of an array of compact, high-impedance superconducting resonators forming a 1 GHz-wide pass band, in which we have embedded two frequency-tuneable artificial atoms. We study the atom-field interaction and access previously unexplored coupling regimes, in both the single- and double-excitation subspace. The presented architecture holds promise for quantum simulation with tuneable-range interactions and photon transport experiments in nonlinear regime.

QUANLUX OUTREACH 

4 February 2022
I met 30 students of the Liceo Classico Meli in Palermo and I explained the research of the QuanLux project trough an interactive activity: the ICFO decide game.


24-27 January 2022
I gave a lecture series of 8 hours in total on "Modern platforms for Quantum Nonlinear Optics" at the University of Palermo. Here the link for the program https://www.unipa.it/dipartimenti/difc/.content/documenti/Seminari/calajo.pdf.

25 November 2021
Unfortunately due to new Covid outbreak I had to cancel my visit to Vienna. Anyway I  gave an Alumni online talk on  "New directions in Quantum Nonlinear Optics"  at ITP Vienna seminar.

10-15 October 2021
I gave a live talk on  "Many-body bound states in Quantum Nonlinear media"  at the Italian quantum information conference IQIS2021.
Here the conference link https://indico.unina.it/event/52/

5-11 September 2021
I finally came back to attend a conference in presence presenting a poster on  "Many-body bound states in Quantum Nonlinear media"  at the Quantum Optics X in Torun, Poland.
Here the conference link http://quantumoptics.faj.org.pl

21-25 June 2021
I gave an online talk on "Many-body bound states in Quantum Nonlinear media" at the WQED20 conference.
Here the conference website https://wqed20.weebly.com/invited-speakers.html

17/5/2021
I virtually met the students  of the Liceo calini of Brescia participating to the ICFO decide game.

27/11/2020
In the following link  you can find my micro-talk on photon molecules done for the European research night. Enjoy!
Link to the video.