Engineering topics
Publications and source records attributed to Jiang, Qing-Dong.
Symmetry-breaking states of matter can transmit symmetry breaking to nearby atoms or molecular complexes, perturbing their spectra. We calculate here one such effect, involving the “axion electrodynamics” relevant to topological insulators, quantitatively, and identify a signature for T violating superconductivity. Furthermore, we offer an operator framework whereby effects of this kind can be analyzed systematically.
Quantum fluctuations in vacuum can exert a dissipative force on moving objects, which is known as Casimir friction. Specifically, a rotating particle in the vacuum will eventually slow down due to the dissipative Casimir friction. Here, we confirm a dissipationless force by examining a rotating particle near a bi-isotropic media that generally breaks parity symmetry or/and time-reversal symmetry. The direction of the dissipationless vacuum force is always parallel with the rotating axis of the particle. We therefore call this dissipationless vacuum force the axial Casimir force.
Both theoretical interest and practical significance attach to the sign and strength of Casimir forces. A famous, discouraging no-go theorem states that “the Casimir force between two bodies with reflection symmetry is always attractive.” In this report, we determine a promising way to avoid the assumptions of the no-go theorem, and propose a universal way to realize repulsive Casimir forces. We show that the sign and strength of Casimir forces can be adjusted by inserting optically active or gyrotropic media between bodies, and modulated by external fields.