Fast nonadiabatic dynamics of many-body quantum systems

Modeling many-body quantum systems with strong interactions is one of the core challenges of modern physics. A range of methods has been developed to approach this task, each with its own idiosyncrasies, approximations, and realm of applicability. However, there remain many problems that are intractable for existing methods. In particular, many approaches face a huge computational barrier when modeling large numbers of coupled electrons and ions at finite temperature. Here, we address this shortfall with a new approach to modeling many-body quantum systems. On the basis of the Bohmian trajectory formalism, our new method treats the full particle dynamics with a considerable increase in computational speed. As a result, we are able to perform large-scale simulations of coupled electron-ion systems without using the adiabatic Born-Oppenheimer approximation.

Dynamics of heavy quarkonia in memory-dependent dissipative environment from Bohmian trajectory perspective

In this work, we study the dynamics of particles coupled to a dissipative environment from Bohmian trajectory perspective. The dissipation is modeled using the concept of memory-dependent derivative (MDD), which is characterized by its time-delay constant [Formula: see text] and nonsingular kernel [Formula: see text] of two parameters [Formula: see text], [Formula: see text]. By assuming a Gaussian packet wave function, we derived a MDD-Langevin equation (MDDLE). The general behavioral solution [Formula: see text] of the MDDLE is investigated for the case of Gaussian fluctuation force. Based on the miscellaneous choices of [Formula: see text], [Formula: see text], [Formula: see text], the findings are that [Formula: see text] can exhibit distinct behaviors, such as monotonic and nonmonotonic decay without zero crossings, oscillatory-like without zero and with zero crossing. Therefore, we have either diffusion or oscillatory dominate based on the problem parameters. For a harmonically bound heavy quarkonium, characterized by the angular frequency [Formula: see text], the position correlation function [Formula: see text] is then obtained and analyzed numerically. The analysis shows that this correlation function is also sensitive to the various choices of [Formula: see text] and kernel parameters. Based on these choices, the correlation function exhibits distinct behaviors: oscillation without damping, damping, and enhanced. This wide range of behavior coverage increases the versatility to fit nonlinear or memory-dependent experimental findings. The results are compared with the fractional Langevin equation.

When Photons Are Lying about Where They Have Been

The history of photons in a nested Mach–Zehnder interferometer with an inserted Dove prism is analyzed. It is argued that the Dove prism does not change the past of the photon. Alonso and Jordan correctly point out that an experiment by Danan et al. demonstrating the past of the photon in a nested interferometer will show different results when the Dove prism is inserted. The reason, however, is not that the past is changed, but that the experimental demonstration becomes incorrect. The explanation of a signal from the place in which the photon was (almost) not present is given. Bohmian trajectory of the photon is specified.