ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

nov. 12. péntek 10h15,

online
<https://teams.microsoft.com/l/meetup-join/19%3a21ec60c6162141b288b58744ae2db5b3%40thread.tacv2/1636571303445?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>
a Microsoft Teamsben
Horváth Dávid (SISSA and INFN Sezione di Trieste):

Inhomogeneous quantum quenches in the sine-Gordon theory

In this talk I review our recent results [1] on inhomogeneous quantum
quenches in the attractive regime of the sine--Gordon quantum field theory.
The system is prepared in an inhomogeneous initial state in finite volume
by coupling the topological charge density operator to a Gaussian external
field. After switching off the external field, time evolution is governed
by the homogeneous sine-Gordon Hamiltonian. Varying either the interaction
strength of the sine-Gordon model or the amplitude of the external source
field, an interesting transition is observed in the expectation value of
the soliton density. This affects both the initial profile of the density
and its time evolution and can be summarised as a steep transition between
behaviours reminiscent of the Klein-Gordon, and the free massive Dirac
fermion theory with initial external fields of high enough magnitude. The
transition in the initial state is also displayed by the classical
sine-Gordon theory and hence can be understood by semi-classical
considerations in terms of the presence of small amplitude field
configurations and the appearance of soliton excitations, which are
naturally associated with bosonic and fermionic excitations on the quantum
level, respectively. Features of the quantum dynamics are also consistent
with this correspondence and comparing them to the classical evolution of
the density profile reveals that quantum effects become markedly pronounced
during the time evolution.
These results suggest a crossover between the dominance of bosonic and
fermionic degrees of freedom whose precise identification in terms of the
fundamental particle excitations can be rather non-trivial. Nevertheless,
their interplay is expected to influence the sine-Gordon dynamics in
arbitrary inhomogeneous settings.


[1] D. X. Horváth, M. Kormos, S. Sotiriadis, G. Takács, arXiv:2109.06869

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Asbóth János
szemináriumi koordinátor