Christos Gagatsos

Christos Gagatsos studied physics (University of Athens, Greece) and holds a Ph.D. ‚Äúen Sciences de l‚ÄôIng√©nieur et Technologie ‚ÄĚ (ULB, Ecole Polytechnique de Bruxelles, Belgium). He is a former postdoc in the Guha group. He has researched several topics of quantum optics such as noiseless amplification of quantum signals, quantum optics‚Äô problems that involve the calculation of von Neumann entropy, majorization relations, and quantum sensing. His research interests include everything that has to do with continuous variables. These days his research focuses on quantum estimation theory and non-Gaussian cluster states. As of April 2023, Dr. Gagatsos is now an Assistant Professor at the University of Arizona in the department of Electrical and Computer Engineering.

Link to personal homepage: https://ece.engineering.arizona.edu/faculty-staff/faculty/christos-gagatsos

Research:

Keywords: Photonic Quantum Computing, Quantum Sensing, Quantum Communication

Photon subtraction for non-Gaussian states generation which are a resource for optical quantum computation.

Active covert sensing: Unknown parameters’ estimation while an adversary remains unaware of the sensing process.

Covert communications: Communication between parties under the constraint that an eavesdropper is unable to see if information transmission takes place or not.

Quantum enhanced Sagnac interferometer, i.e., angular velocity estimation with application to gyroscopes.

Publications:
Efficient representation of Gaussian states for multi-mode non-Gaussian quantum state engineering via subtraction of arbitrary number of photons. Christos N. Gagatsos, Saikat Guha. Phys. Rev. A 99, 053816 (2019). Photonic Quantum Computing, Mathematical methods of quantum mechanics
Quantum enhanced estimation of diffusion. Dominic Branford, Christos N. Gagatsos, Jai Grover, Alexander J. Hickey, Animesh Datta. arXiv:1901.02497. Quantum Sensing
 Covert sensing using floodlight illumination. Christos N. Gagatsos, Boulat A. Bash, Animesh Datta, Zheshen Zhang, Saikat Guha. arXiv:1812.10743 (accepted to Phys. Rev A). Quantum Sensing
 Bounding the quantum limits of precision for phase estimation with loss and thermal noise. Christos N. Gagatsos, Boulat A. Bash, Saikat Guha, Animesh Datta. Phys. Rev. A 96, 062306 (2017). Quantum Sensing
Fundamental limits of quantum-secure covert optical sensing. Boulat A. Bash, Christos N. Gagatsos, Saikat Guha, Animesh Datta.  https://ieeexplore.ieee.org/document/8007122 (2017). A more detailed version can be found on https://arxiv.org/abs/1701.06206. Quantum Sensing
Gaussian systems for quantum enhanced multiple phase estimation. C. N. Gagatsos, D. Branford, A. Datta. Phys. Rev. A 94, 042342(2016). Quantum Sensing
Entropy generation in Gaussian quantum transformations:
applying the replica method to continuous-variable quantum information theory. C. N. Gagatsos, A. I. Karanikas, G. Kordas, and N. J. Cerf.  npj Quantum Information 2, 15008 (2016) .Heralded noiseless amplification and attenuation of non-Gaussian states of light. C. N. Gagatsos, J. Fiurasek, A. Zavatta, M. Bellini, and N. J. Cerf.  Phys. Rev. A 89, 062311 (2014).
Majorization relations and entanglement generation in a beam splitter. C. N. Gagatsos, O. Oreshkov, N. J. Cerf. Phys. Rev. A 87, 042307 (2013).
 Mutual information and Bose-Einstein condensation.C. N. Gagatsos, A. I. Karanikas and G. I. Kordas Open Syst. Inf. Dyn. 20, 1350008 (2013).
Probabilistic phase-insensitive optical squeezer in compliance with causality. C. N. Gagatsos, E. Karpov and N. J. Cerf. Phys. Rev. A 86, 012324 (2012).  
Complex Time Evolution of Open Quantum Systems. C. N. Gagatsos, A. I. Karanikas and G. I. Kordas Open Syst. Inf. Dyn. 18, 261 (2011).