A common thread of my research effort is the study and engineering of cooperative mechanisms. I study superradiance and other *emergent phenomena* arising in solid-state cavity quantum electrodynamics (QED). I also develop scientific software, focusing on ways in which the research community can cooperatively contribute, empowering science* at scale*.

More precisely, I actively pursue three main lines of research: open quantum systems out of equilibrium, solid-state electronic photonics and polaritonics, and open-source scientific software for numerical methods in quantum optics and quantum information science.

## Open-source quantum software

I develop and maintain open-source software that implements numerical methods with applications in “quantum technology” and quantum optics research. Since 2018, I am lead developer and community leader for QuTiP, the quantum toolbox in Python, for which I co-developed the PIQS module.

I see open-source software development more as a method than a proper theme of research, but on the other side, the numerical perspective it provides does affect the way one can see a problem. For example, the Liouvillian superoperator describing an open quantum system dynamics can be seen not only as a linear functional but also represented with a concrete matrix, whose properties can be numerically studied, such as its spectrum and eigenstates.

R. LaRose *et al.,* arXiv:2009.04417, Mitiq

H. Silvério & S. Grijalva *et al., Quantum* **6**, 629 (2022) Link, Pulser

B. Li *et al., Quantum* **6**, 630 (2022) Link, QuTiP-QIP

N. Shammah *et al.*, *Physical Review A ***98**, 063815 (2018), PIQS

More info in the Code page.

## Out-of-equilibrium quantum systems

I am interested in the emerging dynamics of many-body quantum systems out of equilibrium. While at-equilibrium physics is well described by standard thermodynamics, out-of equilibrium systems, under external drive and undergoing dissipation, represent a much less characterized system model. I am interested in particular in macroscopic quantum effects, such as light emission induced by quantum vacuum instabilities in cavity QED, spin squeezing, superradiance, and chaos.

To tackle these problems I exploit symmetries of the models that can allow a feasible numerical approach by representing the dynamics with more compact algebraic operators and superoperators.

G.-Q. Zhang *et al.*, *PRX Quantum* **2**, 020307 (2021).

G. Piccitto *et al.*, *Physical Review B ***104**, 014307 (2021)

D. Huybrechts *et al.*, *Physical Review B ***101**, 214302 (2020)

N. Shammah *et al.*, *Physical Review A ***98**, 063815 (2018)

N. Shammah *et al.* Physical Review A **96**, 023863 (2017)

## Solid-state photonics and polaritonics

There has been considerable advancement in optoelectronic solid-state devices where light and matter hybridize to form quasiparticles known as polaritons. The same heterostructure technology has been used to engineer artificial quantum atoms with broken inversion symmetry, which opens up the possibility for unconventional light emission. Applications include Terahertz light emission, a range where there is a “technology gap” in our capability of detecting and emitting electromagnetic waves.

I use analytical techniques in perturbation theory and with non-perturbative approaches to treat the many-body physics of these electronic and photonic systems, which can often be described as a two-dimensional electron gas (2DEG) interacting with a photonic field.

M. Cirio *et al., *Physical Review Letters 122, 190403 (2019)

N. Shammah and S. De Liberato, Physical Review B **92**, 201402 Rapid Comm. (2015)

N. Shammah *et al., *Physical Review B **89**, 235309 (2014)