Footprints of impurity quantum phase transitions in quantum Monte Carlo statistics

0547690 - FZÚ 2022 RIV US eng J - Journal Article
Pokorný, Vladislav - Novotný, T.
Footprints of impurity quantum phase transitions in quantum Monte Carlo statistics.
Physical Review Research. Roč. 3, č. 2 (2021), č. článku 023013. E-ISSN 2643-1564
R&D Projects: GA ČR GA19-13525S; GA MŠMT LTC19045
Research Infrastructure: e-INFRA CZ - 90140
Institutional support: RVO:68378271
Keywords : quantum Monte Carlo * quantum phase transition * hybridization expansion * statistical moments
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Method of publishing: Open access

Interacting single-level quantum dots connected to BCS superconducting leads represent a well-controllable system to study the interplay between the correlation effects and the electron pairing that can result in a 0−π (singlet-doublet) quantum phase transition (QPT). The physics of this system can be well described by the impurity Anderson model. We present an analysis of the statistics of the perturbation expansion order of the continuous-time hybridization expansion quantum Monte Carlo algorithm in the vicinity of such a first-order impurity QPT. By calculating the moments of the histograms of the expansion order which deviate from the ideal Gaussian shape, we provide an insight into the thermodynamic mixing of the two phases at low but finite temperatures, which is reflected in the bimodal nature of the histograms.
Permanent Link: http://hdl.handle.net/11104/0323940