Year: 2010
Type: article
Abstract: We have extracted information about real time dynamics of $^{4}\text{H}\text{e}$ systems from noisy imaginary-time correlation functions $f(\ensuremath{\tau})$ computed via quantum Monte Carlo (QMC): production and falsification of model spectral functions $s(\ensuremath{\omega})$ are obtained via a survival-to-compatibility with $f(\ensuremath{\tau})$ evolutionary process, based on genetic algorithms. Statistical uncertainty in $f(\ensuremath{\tau})$ is promoted to be an asset via a sampling of equivalent $f(\ensuremath{\tau})$ within the noise, which give rise to independent evolutionary processes. In the case of pure superfluid $^{4}\text{H}\text{e}$ we have recovered from exact QMC simulations sharp quasiparticle excitations with spectral functions displaying also the multiphonon branch. As further applications, we have studied the impuriton branch of one $^{3}\text{H}\text{e}$ atom in liquid $^{4}\text{H}\text{e}$ and the vacancy-wave excitations in hcp solid $^{4}\text{H}\text{e}$ finding an unexpected rotonlike feature.
Source: Physical Review B
Authors: E. Vitali, M. Rossi, L. Reatto, D. E. Galli
Institution: University of Milan
Language: Latvian
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2060953054