Search for: All records

The central topic of this letter is to show that light-matter hybridization not only gives rise to novel dynamic responses but can also modify intermolecular interactions and induce new structural order. Using the van der Waals (vdW) system in an optical cavity as an example, we predict the effects of quantum interference and collectivity in cavity-induced many-body dispersion forces. Specifically, the leading order correction due to cavity-induced quantum fluctuations leads to 3-body and 4-body vdW interactions, which can align intermolecular vectors and are not pairwise additive. In addition, the cavity-induced dipole leads to a single-molecule energy shift that aligns individual molecules, and a pairwise interaction that scales as R–3 instead of the standard R–6 distance scaling. The coefficients of all these cavity-induced interactions depend on the cavity frequency and are renormalized by the effective Rabi frequency, which in turn depends on the particle density. Finally, we study the interaction of the vdW system in a cavity with an external object and find a significant enhancement in the interaction range due to modified distance scaling laws. These theoretical predictions suggest the possibility of cavity-induced nematic or smectic order and may provide an essential clue to understand intriguing phenomena observed in optical cavities, such as strongly modified ground-state reactivity, ion transport and charge mobility. 

Ninety years ago, Wigner derived the leading order expansion term in ℏ 2 for the tunneling rate through a symmetric barrier. His derivation included two contributions: one came from the parabolic barrier, but a second term involved the fourth-order derivative of the potential at the barrier top. He left us with a challenge, which is answered in this paper, to derive the same but for an asymmetric barrier. A crucial element of the derivation is obtaining the ℏ 2 expansion term for the projection operator, which appears in the flux-side expression for the rate. It is also reassuring that an analytical calculation of semiclassical transition state theory (TST) reproduces the anharmonic corrections to the leading order of ℏ 2 . The efficacy of the resulting expression is demonstrated for an Eckart barrier, leading to the conclusion that especially when considering heavy atom tunneling, one should use the expansion derived in this paper, rather than the parabolic barrier approximation. The rate expression derived here reveals how the classical TST limit is approached as a function of ℏ and, thus, provides critical insights to understand the validity of popular approximate theories, such as the classical Wigner, centroid molecular dynamics, and ring polymer molecular dynamics methods.