We will discuss recent results: (i) on the theory of the Casimir torque between two gratingsrotated by an angle θ with respect to each other [1]; and (ii) on the theory and experimenton the Casimir force between interpenetrating gratings [2]. These findings pave the way tothe design of contactless quantum vacuum torsional spring and sensors with possiblerelevance to micro and nanomechanical devices.References[1] Mauro Antezza, H. B. Chan, Brahim Guizal, V.N. Marachevsky, Riccardo Messina,Mingkang Wang, Phys. Rev. Lett. 124, 013903 (2020)[2] Mingkang Wang, L. Tang, C.Y. Ng, Riccardo Messina, Brahim Guizal, J. A. Crosse,Mauro Antezza, C.T. Chan, H.B. Chan, Nature Communication 12, 600 (2021)

The presence of interlayer interactions in twisted bilayer graphene(TBG) enhances several characteristics, including the optical and electronic properties. We theoretically investigate the magic angle of TBG according to the vanishing of Fermi velocity and find double magic angles in a series. Thermal radiation from TBG can be tuned to the far infrared range by changing twist angles. The peculiar radiation spectrum is out of atmospheric window, which can be of great use in invisibility and keeping warm. The total radiation of TBG is slightly more than twice of a single layer graphene.

We will discuss some recent numerical results on the Casimir interaction between metallic gratings [1, 2, 3] . These findings pave the way to the design of a contactless quantum vacuum torsional spring, and sensors with possi- ble relevance to micro and nanomechanical devices.

We present a numerical approach for the solution of EM scattering from a dielectric cylinder partially covered with graphene. It is based on a classical Fourier-Bessel expan- sion of the fields inside and outside the cylinder to which we apply the ad-hoc boundary conditions in the presence of graphene. Due to the singular nature of the electric field at the ends of the graphene sheet, we introduce auxiliary boundary conditions to better take this reality into account. The result is a very simple and very efficient method allow- ing the study of diffraction from such structures.

Kirchhoff’s law is one of the most fundamental law in thermal radiation. The violation of traditional Kirchhoff’s law provides possibilities for achieving energy conversion with higher efficiency. Various micro-structures have been designed to realize single-band nonreciprocal thermal emitters. However, dual-band nonreciprocal thermal radiations are still rarely studied. Here, we introduce magneto-optical material into a cascading one-dimensional (1-D) magnetophotonic crystal (MPC) heterostructure composed of two 1-D MPCs and a metal layer. Assisted by the nonreciprocity of the magneto-optical material and the coupling effect of two optical Tamm states (OTSs), a dual-band nonreciprocal lithography-free thermal emitter is achieved. The emitter exhibits near-complete dualchannel nonreciprocal thermal radiation at the wavelengths of 15.337 μm and 15.731 μm for an external magnetic field of 3T and an incident angle of 56 degrees. Besides, the magnetic field distribution is also calculated to confirm that the dual-band nonreciprocal radiation originates from the coupling effect between two OTSs. Our work may pave the way for constructing dual-band and multi-band nonreciprocal thermal emitters.

A primary motivation for studying topological matter regards the protection of topological order from its environment. In this work, we study a topological emitter array coupled to an electromagnetic environment. The photon-emitter coupling produces nonlocal interactions between emitters. Using periodic boundary conditions for all ranges of environment-induced interactions, the chiral symmetry inherent to the emitter array is preserved. This chiral symmetry protects the Hamiltonian and induces parity in the Lindblad operator. A topological phase transition occurs at a critical photon-emitter coupling related to the energy spectrum width of the emitter array. Interestingly, the critical point nontrivially changes the dissipation rates of edge states, yielding a dissipative topological phase transition. In the protected topological phase, edge states suffer from environment-induced dissipation for weak photon-emitter coupling. However, strong coupling leads to robust dissipationless edge states with a window at the emitter spacing. Our work shows the potential to manipulate topological quantum matter with electromagnetic environments.

We present a numerical approach for the solution of EM scattering from a dielectric cylinder partially covered with graphene. It is based on a classical Fourier-Bessel expansion of the fields inside and outside the cylinder to which we apply the ad-hoc boundary conditions in the presence of graphene. Due to the singular nature of the electric field at the ends of the graphene sheet, we introduce auxiliary boundary conditions to better take this reality into account. The result is a very simple and very efficient method allowing the study of diffraction from such structures.