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CATEGORIES:Theoretical Physics Seminars
SUMMARY:Theory of classical metastability in open quantum
systems - Katarzyna Macieszczak\, University of Ca
mbridge
DTSTART:20200730T120000Z
DTEND:20200730T130000Z
UID:TALK4245AT
URL:/talk/index/4245
DESCRIPTION:Abstract: Metastability is a large separation in t
imescales in the\ndynamics\, manifesting as the ex
istence of a regime when states of the\nsystem app
ear stationary\, before eventual relaxation toward
s a true\nstationary state at much larger times. I
n this talk\, I will focus on the\nemergence of cl
assical metastability\, i.e.\, the case when metas
table\nstates can be approximated as probabilistic
mixtures of a finite number\nof states. I will sh
ow that a number of classical features follow from
\nthis approximation. First\, metastable states ar
e mixtures of\napproximately disjoint states which
can be distinguished with negligible\nerror and t
hus play the role of metastable phases. Second\, s
ymmetries of\nthe dynamics correspond to approxima
te permutations of metastable phases\nand thus are
necessarily discrete. Third\, the long-time dynam
ics – the\nfinal relaxation towards the stationary
state – is approximated by a\nclassical stochasti
c dynamics between the metastable phases.\nImporta
ntly\, the classical dynamics is observed not only
on average\, but\nalso at the level of individual
quantum trajectories: coarse-grained\ncontinuous
measurement records can be viewed as noisy classic
al\ntrajectories\, while their statistics can be a
pproximated by that of the\nclassical dynamics. Fi
nally\, I will also briefly explain how to\nnumeri
cally verify the presence of classical metastabili
ty in a given\nopen quantum system. Since the prox
imity to a first-order dissipative\nphase transiti
on manifests as metastability\, the presented resu
lts can\nbe used to investigate such transitions –
which occur in the\nthermodynamic limit – already
at moderate sizes accessible to numerics.\n\nRefe
rence: arXiv:2006.01227
LOCATION:https://bham-ac-uk.zoom.us/j/9115054257?pwd=UWJqaG
ZpZitLUVZHQkJGby9xU2dXQT09
CONTACT:
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