Contributor info: Prof. Gianluca Gregori

Ian Bailey, Bhaswati Chakraborty, Gemma Chapman, Edward J. Daw, John Gallop, Gianluca Gregori, Edward Hardy, Ling Hao, Edward Laird, Peter Leek, John March-Russell, Phil Meeson, Seaárbhan Ó Peatáin, Yuri Pashkin, Mitchell G. Perry, Michele Piscitelli, Edward Romans, Subir Sarkar, Paul J. Smith, Ningqiang Song, Mahesh Soni, Boon K. Tan, Stephen West, Stafford Withington

SciPost Phys. Proc. 12, 040 (2023) · published 4 July 2023 | Toggle abstract · pdf

In 2021 the Quantum Sensors for the Hidden Sector (QSHS) collaboration was founded in the UK and received funding to develop and demonstrate quantum devices with the potential to detect hidden sector particles in the $\mu$eV to 100 $\mu$eV mass window. The collaboration has been developing a range of devices. It is building a high-field, low-temperature facility at the University of Sheffield to characterise and test the devices in a haloscope geometry. This paper introduces the collaboration's motivation, aims, and progress.

Z. A. Moldabekov, T. Dornheim, G. Gregori, F. Graziani, M. Bonitz, A. Cangi

SciPost Phys. 12, 062 (2022) · published 16 February 2022 | Toggle abstract · pdf

Correlated many-fermion systems emerge in a broad range of phenomena in warm dense matter, plasmonics, and ultracold atoms. Quantum hydrodynamics (QHD) complements first-principles methods for many-fermion systems at larger scales. We illustrate the failure of the standard Bohm potential central to QHD for strong perturbations when the density perturbation is larger than about $10^{-3}$ of the mean density. We then extend QHD to this regime via the \emph{many-fermion Bohm potential} from first-principles. This may lead to more accurate QHD simulations beyond their common application domain in the presence of strong perturbations at scales unattainable with first-principles methods.

Srishty Aggarwal, Banibrata Mukhopadhyay, Gianluca Gregori

SciPost Phys. 11, 093 (2021) · published 18 November 2021 | Toggle abstract · pdf

We investigate the two-dimensional motion of relativistic cold electrons in the presence of ‘strictly’ spatially varying magnetic fields satisfying, however, no magnetic monopole condition. We find that the degeneracy of Landau levels, which arises in the case of the constant magnetic field, lifts out when the field is variable and the energy levels of spin-up and spin-down electrons align in an interesting way depending on the nature of change of field. Also the varying magnetic field splits Landau levels of electrons with zero angular momentum from positive angular momentum, unlike the constant field which only can split the levels between positive and negative angular momenta. Exploring Landau quantization in non-uniform magnetic fields is a unique venture on its own and has interdisciplinary implications in the fields ranging from condensed matter to astrophysics to quantum information. As examples, we show magnetized white dwarfs, with varying magnetic fields, involved simultaneously with Lorentz force and Landau quantization affecting the underlying degenerate electron gas, exhibiting a significant violation of the Chandrasekhar mass-limit; and an increase in quantum speed of electrons in the presence of a spatially growing magnetic field.