Near-field radiative heat transfer (NFRHT) has received growing attention because of its high intensity far beyond the Planck's black-body limit. Insertion of a third object in proximity of the two particles can significantly influence and manipulate its NFRHT. However, for the system composed of many particles, the effect of many-body interaction (MBI) on NFRHT between arbitrary two particles is still not well understood. In this work, the MBI is studied for two particles with three typical proximate ensembles: particle chain, plane and grating. With the increasing of proximate particle size, the MBI on NFRHT will experience a radical change from inhibition to enhancement. The polarizability of the proximate particle increases with particle radius, which enhances the interaction between the proximate particles and the main particle, and then results in enhancement of NFRHT between the main particles. When twisting the proximate particle ensemble, the proximate MBI accounts for a smooth and non-oscillated twisting angle dependence of NFRHT, and it is different from the oscillation phenomenon of NFRHT for particle gratings. This work deepens the understanding of NFRHT in dense particulate systems.

We report on transport measurements in monolayer MoS2 devices, close to the bottom of the conduction band edge. These devices were annealed in situ before electrical measurements. This allows us to obtain good ohmic contacts at low temperatures, and to measure precisely the conductivity and mobility via four-probe measurements. The measured effective mobility up to μ eff = 180 cm 2 V −1 s −1 is among the largest obtained in CVD-grown MoS2 monolayer devices. These measurements show that electronic transport is of the insulating type for σ ≤ 1.4 e 2 / h and n ≤ 1.7 × 10 12 cm −2 , and a crossover to a metallic regime is observed above those values. In the insulating regime, thermally activated transport dominates at high temperature ( T > 120 K). At lower temperatures, conductivity is driven by Efros–Schklovkii variable range hopping in all measured devices, with a universal and constant hopping prefactor, that is a clear indication that hopping is not phonon-mediated. At higher carrier density, and high temperature, the conductivity is well modeled by the Boltzmann equation for a non-interacting Fermi gas, taking into account both phonon and impurity scatterings. Finally, even if this apparent metal-insulator transition can be explained by phonon-related phenomena at high temperature, the possibility of a genuine 2D MIT cannot be ruled out, as we can observe a clear power-law diverging localization length close to the transition, and a one-parameter scaling can be realized.

We propose a scheme for a quantum thermal machine made by atoms interacting with a single nonequilibrium electromagnetic field. We show that these machines can deliver all thermodynamic tasks (cooling, heating, and population inversion) by establishing quantum coherence with the body on which they act. Remarkably, this system allows these machines to reach efficiencies at maximum power very close to the Carnot limit, which is much more than in existing models [1]. REFERENCES 1. Leggio, B., B. Bellomo, and M. Antezza, Phys. Rev. A, Vol. 91, 012117 (2015)

I will discuss recent results: (i) on the Casimir torque between two metallic onedimensional gratings rotated by an angle θ with respect to each other [1]; and (ii) on the quantitative effect of the presence of the metallic contact grid at the front side of thermophotovoltaic cells, based on a rigorous approach [2]. This effect can be tremendous both in terms of optical and electrical (resistive) losses. However, it has been theoretically either discarded or studied by means of extremely simplified models (like shadowing methods, consisting in just ignoring the fraction of the cell surface covered by metal). 1. Antezza, M., H. B. Chan, B. Guizal, V. N. Marachevsky, R. Messina, and M. Wang, Phys. Rev. Lett., Vol. 12, 013903, 2020. 2. Austry, K., Y. Jeyar, M. Luo, B. Guizal, R. Messina, R. Vaillon, and M. Antezza, 2023 (in preparation).

We explore the impact of three water-soluble polyelectrolytes (PEs) on the flow of concentrated suspensions of poly(N-isopropylacrylamide) (PNIPAm) microgels with thermoresponsive anionic charge density. By progressively adding the PEs to a jammed suspension of swollen microgels, we show that the rheology of the mixtures is remarkably influenced by the sign of the PE charge, PE concentration and hydrophobicity only when the temperature is raised above the microgel volume phase transition temperature Tc, namely when microgels collapse, they are partially hydrophobic and form a volume-spanning colloidal gel. We find that the original gel is strengthened close to the isoelectric point, attained when microgels are mixed with cationic PEs, while PE hydrophobicity rules the gel strengthening at very high PE concentrations. Surprisingly, we find that polyelectrolyte adsorption or partial embedding of PE chains inside the microgel periphery occurs also when anionic polymers of polystyrene sulfonate with high degree of sulfonation are added. This gives rise to colloidal stabilization and to the melting of the original gel network above Tc. Contrastingly, the presence of polyelectrolytes in suspensions of swollen, jammed microgels results in a weak softening of the original repulsive glass, even when an apparent isoelectric condition is met. Our study puts forward the crucial role of electrostatics in thermosensitive microgels, unveiling an exciting new way to tailor the flow of these soft colloids and highlighting a largely unexplored path to engineer soft colloidal mixtures.

We use numerical simulations to study the dynamics of dense assemblies of self-propelled particles in the limit of extremely large, but finite, persistence times. In this limit, the system evolves intermittently between mechanical equilibria where active forces balance interparticle interactions. We develop an efficient numerical strategy allowing us to resolve the statistical properties of elastic and plastic relaxation events caused by activity-driven fluctuations. The system relaxes via a succession of scale-free elastic events and broadly distributed plastic events that both depend on the system size. Correlations between plastic events lead to emergent dynamic facilitation and heterogeneous relaxation dynamics. Our results show that dynamical behaviour in extremely persistent active systems is qualitatively similar to that of sheared amorphous solids, yet with some important differences.