Bosonic and fermionic Gaussian states from Kähler structures

We show that bosonic and fermionic Gaussian states (also known as "squeezed coherent states") can be uniquely characterized by their linear complex structure $J$ which is a linear map on the classical phase space. This extends conventional Gaussian methods based on covariance matrices a...

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Main Author: Lucas Hackl, Eugenio Bianchi
Format: Article
Language:English
Published: SciPost 2021-09-01
Series:SciPost Physics Core
Online Access:https://scipost.org/SciPostPhysCore.4.3.025
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author Lucas Hackl, Eugenio Bianchi
author_facet Lucas Hackl, Eugenio Bianchi
author_sort Lucas Hackl, Eugenio Bianchi
collection DOAJ
description We show that bosonic and fermionic Gaussian states (also known as "squeezed coherent states") can be uniquely characterized by their linear complex structure $J$ which is a linear map on the classical phase space. This extends conventional Gaussian methods based on covariance matrices and provides a unified framework to treat bosons and fermions simultaneously. Pure Gaussian states can be identified with the triple $(G,\Omega,J)$ of compatible K\"ahler structures, consisting of a positive definite metric $G$, a symplectic form $\Omega$ and a linear complex structure $J$ with $J^2=-1\!\!1$. Mixed Gaussian states can also be identified with such a triple, but with $J^2\neq -1\!\!1$. We apply these methods to show how computations involving Gaussian states can be reduced to algebraic operations of these objects, leading to many known and some unknown identities. We apply these methods to the study of (A) entanglement and complexity, (B) dynamics of stable systems, (C) dynamics of driven systems. From this, we compile a comprehensive list of mathematical structures and formulas to compare bosonic and fermionic Gaussian states side-by-side.
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spelling doaj.art-8b257af72789442183201362cf1023402022-12-21T21:26:12ZengSciPostSciPost Physics Core2666-93662021-09-014302510.21468/SciPostPhysCore.4.3.025Bosonic and fermionic Gaussian states from Kähler structuresLucas Hackl, Eugenio BianchiWe show that bosonic and fermionic Gaussian states (also known as "squeezed coherent states") can be uniquely characterized by their linear complex structure $J$ which is a linear map on the classical phase space. This extends conventional Gaussian methods based on covariance matrices and provides a unified framework to treat bosons and fermions simultaneously. Pure Gaussian states can be identified with the triple $(G,\Omega,J)$ of compatible K\"ahler structures, consisting of a positive definite metric $G$, a symplectic form $\Omega$ and a linear complex structure $J$ with $J^2=-1\!\!1$. Mixed Gaussian states can also be identified with such a triple, but with $J^2\neq -1\!\!1$. We apply these methods to show how computations involving Gaussian states can be reduced to algebraic operations of these objects, leading to many known and some unknown identities. We apply these methods to the study of (A) entanglement and complexity, (B) dynamics of stable systems, (C) dynamics of driven systems. From this, we compile a comprehensive list of mathematical structures and formulas to compare bosonic and fermionic Gaussian states side-by-side.https://scipost.org/SciPostPhysCore.4.3.025
spellingShingle Lucas Hackl, Eugenio Bianchi
Bosonic and fermionic Gaussian states from Kähler structures
SciPost Physics Core
title Bosonic and fermionic Gaussian states from Kähler structures
title_full Bosonic and fermionic Gaussian states from Kähler structures
title_fullStr Bosonic and fermionic Gaussian states from Kähler structures
title_full_unstemmed Bosonic and fermionic Gaussian states from Kähler structures
title_short Bosonic and fermionic Gaussian states from Kähler structures
title_sort bosonic and fermionic gaussian states from kahler structures
url https://scipost.org/SciPostPhysCore.4.3.025
work_keys_str_mv AT lucashackleugeniobianchi bosonicandfermionicgaussianstatesfromkahlerstructures