Missions

Theoretical study of quantum fluctuations in the presence of electron-photon interaction

Activities

The aim is to calculate current and charge fluctuations at finite frequency in a nano-device connected to electron reservoirs, and placed in an out-of-equilibrium situation by applying an electrical voltage, in the presence of electron-photon interaction. To do this, the candidate will have to use quantum field theory methods involving out-of-equilibrium Green's functions, and solve the equations of motion verified by these functions.
The calculation of current fluctuations in the absence of electron-photon interaction has already been carried out [1,2,3] and will serve as a basis for the post-doc's work. A relationship between light emission and current fluctuations has been demonstrated experimentally in a tunnel junction [4], confirming the existence of a link between spectral emission power and total noise [5].
We now need to go beyond these preliminary studies to explore the correlations between electromagnetic and electronic modes in nano devices, and fully characterize the relationship between spectral emission power and fluctuations in current, or charge, when interactions are taken into account. This task will be the responsibility of the postdoctoral fellow, who once the analytical calculations done will interact with the IM2NP collaboration partners for the numerical part, and with the LPS and ICB for comparison with experimental results.

[1] R. Zamoum, M. Lavagna, and A. Crépieux, Phys. Rev. B 93, 235449 (2016).
[2] A. Crépieux, S. Sahoo, T.Q. Duong, R. Zamoum, and M. Lavagna, Phys. Rev. Lett. 120, 107702 (2018).
[3] A. Crépieux, T.Q. Duong, and M. Lavagna, J. Phys.: Condens. Matter 37 075302 (2025).
[4] P. Février and J. Gabelli, Nat Commun 9, 4940 (2018).
[5] J.-T. Lü, R.B. Christensen, and M. Brandbyge, Phys. Rev. B 88, 045413 (2013).

Keywords: Non-equilibrium Green's function; Quantum fluctuations; Electrical transport in nano-devices; Second quantization formalism; Dyson equations; Analytical calculations

Skills

The candidate must hold a doctorate in theoretical condensed matter physics, and have competencies in quantum field theory, as well as a high level of rigor in the development of analytical calculations. Numerical computing skills are welcome.

Work Context

The research project is part of the RISOTO collaborative project funded by the ANR (French National Research Agency). The aim is to explore the link between quantum fluctuations in current or charge and light emission in nano-devices (tunnel junction, single and double quantum boxes, STM tip, etc.) with a view to enabling controlled light emission in the optical domain. It brings together two teams of theorists based in Marseille (CPT and IM2NP) and two teams of experimentalists based in Orsay (LPS) and Dijon (ICB). The postdoctoral fellow's home laboratory will be the Centre de Physique Théorique.