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SUMMARY:Strongly correlated electrons and excitons in moire superlattices
DTSTART;VALUE=DATE-TIME:20210823T090000Z
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UID:indico-contribution-7272-23085@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Atac Imamoglu (ETH Zurich)\nTwisted bilayers of tran
sition metal dichalcogenides offer a wealth of new phenomena\, ranging fro
m dipolar excitons to correlated insulator states. An example of qualitati
vely new phenomena in this system is our recent observation of an electric
ally tunable two-dimensional Feshbach resonance in exciton-hole scattering
[1]\, which allows us to control the strength of interactions between exc
itons and holes located in different layers. Our findings enable hitherto
unexplored possibilities for optical investigation of many-body physics\,
as well as realization of degenerate Bose-Fermi mixtures with tunable inte
ractions.\n\n [1] I. Schwartz\, Y. Shimazaki\, C. Kuhlenkamp. K. Watanabe\
, T. Taniguchi\, M. Kroner\, A. Imamoglu\, arXiv:2105.03997 (2021).\n\nhtt
ps://indico.ijclab.in2p3.fr/event/7272/contributions/23085/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23085/
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SUMMARY:Coexistence and phase separation of pairs and fermions in a one-di
mensional model with pair-hopping
DTSTART;VALUE=DATE-TIME:20210830T090000Z
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UID:indico-contribution-7272-23084@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Guillaume Roux (Université Paris Saclay)\nWe consid
er a simple model of spinless fermions in which the kinetic energy compete
s with a pair-hopping term. We show by means of numerical calculations tha
t there exists a phase in which part of the fermions are paired while the
others remain unpaired. These elementary components makes two mixed Luttin
ger liquids\, one for pairs and one for fermions. A simple two-fluid model
accounts remarkably well for the observed numerical data [1]. Adding near
est-neighbour interaction leads to a rich phase diagram [2] in which we ob
serve a regime in which the two previous Luttinger liquids get phase separ
ated. In the context of impurity physics\, this model on a finite size cha
in allows for the creation of a single pair interacting with a fermionic b
ath or a single fermion interacting with a paired fermions bath.\n\nhttps:
//indico.ijclab.in2p3.fr/event/7272/contributions/23084/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23084/
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SUMMARY:The spatial structure of magnetic polarons in strongly interacting
antiferromagnets
DTSTART;VALUE=DATE-TIME:20210906T090000Z
DTEND;VALUE=DATE-TIME:20210906T100000Z
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UID:indico-contribution-7272-23080@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Georg Bruun (Aarhus University)\nThe properties of m
obile impurities in quantum magnets are fundamental for our understanding
of strongly correlated materials and may play a key role in the physics of
high-temperature superconductivity. Hereby\, the motion of hole-like defe
cts through an antiferromagnet has been of particular importance. It creat
es magnetic frustrations that lead to the formation of a quasiparticle\, w
hose complex structure continues to pose substantial challenges to theory
and numerical simulations. In this article\, we develop a non-perturbative
theoretical approach to describe the microscopic properties of such magne
tic polarons. Based on the self-consistent Born approximation\, which is p
rovenly accurate in the strong-coupling regime\, we obtain a complete desc
ription of the polaron wave function by solving a set of Dyson-like equati
ons that permit to compute relevant spin-hole correlation functions. We ap
ply this new method to analyze the spatial structure of magnetic polarons
in the strongly interacting regime and find qualitative differences from p
redictions of previously applied truncation schemes. Our calculations reve
al a remarkably high spatial symmetry of the polaronic magnetization cloud
and a surprising misalignment between its orientation and the polaron cry
stal momentum. The developed framework opens up a new approach to the micr
oscopic properties of doped quantum magnets and will enable detailed analy
ses of ongoing experiments based on cold-atom quantum simulations of the F
ermi-Hubbard model.\n\nhttps://indico.ijclab.in2p3.fr/event/7272/contribut
ions/23080/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23080/
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SUMMARY:Polaron interactions and bipolarons in one-dimensional Bose gases
in the strong coupling regime
DTSTART;VALUE=DATE-TIME:20210824T080000Z
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UID:indico-contribution-7272-23077@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Grigory Astrakharchik (UPC\, Barcelona\, Spain)\nBos
e polarons\, quasi-particles composed of mobile impurities surrounded by c
old Bose gas\, can experience strong interactions mediated by the many-bod
y environment and form bipolaron bound states. Here we present a detailed
study of heavy polarons in a one-dimensional Bose gas by formulating a non
-perturbative theory and complementing it with exact numerical simulations
. We develop an analytic approach for weak boson-boson interactions and ar
bitrarily strong impurity-boson couplings. Our approach is based on a mean
-field theory that accounts for deformations of the superfluid by the impu
rities and in this way minimizes quantum fluctuations. The mean-field equa
tions are solved exactly in Born-Oppenheimer (BO) approximation leading to
an analytic expression for the interaction potential of heavy polarons wh
ich is found to be in excellent agreement with quantum Monte-Carlo (QMC) r
esults. In the strong-coupling limit the potential substantially deviates
from the exponential form valid for weak coupling and has a linear shape a
t short distances. Taking into account lowest-order BO corrections we calc
ulate bipolaron binding energies and find excellent agreement with QMC res
ults for impurity-boson mass ratios as low as 3.\n\nhttps://indico.ijclab.
in2p3.fr/event/7272/contributions/23077/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23077/
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BEGIN:VEVENT
SUMMARY:Thermal instability\, evaporation\, and thermodynamics of one-dime
nsional liquids in weakly interacting Bose-Bose mixtures. Important perspe
ctives for impurities.
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UID:indico-contribution-7272-23076@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Giulia De Rosi (UPC – Universitat Politècnica de
Catalunya)\nWe study the low-temperature thermodynamics of weakly interact
ing uniform liquids in one-dimensional attractive Bose-Bose mixtures. The
Bogoliubov approach is used to simultaneously describe quantum and thermal
fluctuations. First\, we investigate in detail two different thermal mech
anisms driving the liquid-to-gas transition\, the dynamical instability\,
and the evaporation\, and we draw the phase diagram. Then\, we compute the
main thermodynamic quantities of the liquid\, such as the chemical potent
ial\, the Tan's contact\, the adiabatic sound velocity\, and the specific
heat at constant volume. The strong dependence of the thermodynamic quanti
ties on the temperature may be used as a precise temperature probe for exp
eriments on quantum liquids. \n\nThe liquid-to-gas transition should also
occur by reducing the concentration of one component in the mixture. By re
aching the highly unbalanced mixture limit of our theory\, one can explore
the Bose polaron problem with attractive impurity-bath interaction\, at f
inite temperature and in one spatial dimension where quantum and thermal f
luctuations\, which are both consistently taken into account in our theory
\, are strongly enhanced.\n\nhttps://indico.ijclab.in2p3.fr/event/7272/con
tributions/23076/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23076/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anderson localization of composite particles
DTSTART;VALUE=DATE-TIME:20210830T080000Z
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UID:indico-contribution-7272-23074@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Fumika Suzuki (IST Austria)\nWe investigate the effe
ct of coupling between translational and internal degrees of freedom of co
mposite quantum particles on their localization in a random potential. We
show that entanglement between the two degrees of freedom weakens localiza
tion due to the upper bound imposed on the inverse participation ratio by
purity of a quantum state. We perform numerical calculations for a two-par
ticle system bound by a harmonic force in a 1D disordered lattice and a ri
gid rotor in a 2D disordered lattice. We illustrate that the coupling has
a dramatic effect on localization properties\, even with a small number of
internal states participating in quantum dynamics.\n\nhttps://indico.ijcl
ab.in2p3.fr/event/7272/contributions/23074/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23074/
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BEGIN:VEVENT
SUMMARY:Quantum Impurities coupled to Markovian and Non-Markovian Environm
ents
DTSTART;VALUE=DATE-TIME:20210901T090000Z
DTEND;VALUE=DATE-TIME:20210901T100000Z
DTSTAMP;VALUE=DATE-TIME:20210805T200713Z
UID:indico-contribution-7272-23072@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Marco Schiro (CNRS and College de France)\nTBA\n\nht
tps://indico.ijclab.in2p3.fr/event/7272/contributions/23072/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23072/
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BEGIN:VEVENT
SUMMARY:Electric and heat transport in a charge two-channel Kondo device
DTSTART;VALUE=DATE-TIME:20210903T080000Z
DTEND;VALUE=DATE-TIME:20210903T090000Z
DTSTAMP;VALUE=DATE-TIME:20210805T200713Z
UID:indico-contribution-7272-23071@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Lars Fritz (Utrecht University)\nMotivated by the ex
perimental realization of a multi-channel charge Kondo device [Iftikhar et
al.\, Nature 526\, 233 (2015)]\, we study generic charge and heat transpo
rt properties of the charge two-channel Kondo model. We present a comprehe
nsive discussion of the out-of-equilibrium and time-dependent charge trans
port\, as well as thermal transport within linear response theory. The tra
nsport properties are calculated at\, and also in the vicinity of\, the ex
actly solvable Emery-Kivelson point\, which has the form of a Majorana fer
mion resonant level model. We focus on regimes where our solution gives ex
act results for the physical quantum dot device\, and highlight new predic
tions relevant to future experiments.\n\nhttps://indico.ijclab.in2p3.fr/ev
ent/7272/contributions/23071/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23071/
END:VEVENT
BEGIN:VEVENT
SUMMARY:High-order diagrammatic expansion around BCS: polarized superfluid
phase of the attractive Hubbard model
DTSTART;VALUE=DATE-TIME:20210831T090000Z
DTEND;VALUE=DATE-TIME:20210831T100000Z
DTSTAMP;VALUE=DATE-TIME:20210805T200713Z
UID:indico-contribution-7272-23070@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Félix Werner (LKB\, ENS)\nIn contrast to convention
al QMC methods\, expansions of intensive quantities in series of connected
Feynman diagrams can be formulated directly in the thermodynamic limit. O
ver the last decade\, diagrammatic Monte Carlo algorithms made it possible
to reach large expansion orders and to obtain state-of-the-art results fo
r various models of interacting fermions in 2 and 3 dimensions\, mostly in
the normal phase.\n\nWe obtained first results inside a superconducting p
hase\, for the 3D attractive Hubbard model [1]. Spontaneous symmetry break
ing is implemented by expanding around a BCS Hamiltonian. All diagrams up
to 12 loops are summed thanks to the connected determinant algorithm [2] w
ith anomalous propagators. Working on the BCS side of the strongly correla
ted regime\, we observe convergence of the expansion\, and benchmark the r
esults against determinant diagrammatic Monte Carlo [3]. In presence of a
polarizing Zeeman field (where unbiased benchmarks are unavailable due to
the fermion sign problem) we observe a first-order superconducting-to-norm
al phase transition\, and a thermally activated polarization of the superc
onducting phase well described by a dilute gas of quasiparticles. We also
discuss the large-order behavior of the expansion and its relation to Gold
stone and instanton singularities.\n\n\n[1] G. Spada\, R. Rossi\, F. Simko
vic\, R. Garioud\, M. Ferrero\, K. Van Houcke\, F. Werner\, arXiv:2103.120
38\n[2] R. Rossi\, PRL 119\, 045701 (2017)\n[3] E. Burovski\, N. Prokof'ev
\, B. Svistunov\, M. Troyer\, PRL 96\, 160402 (2006)\n\nhttps://indico.ijc
lab.in2p3.fr/event/7272/contributions/23070/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23070/
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BEGIN:VEVENT
SUMMARY:Local dynamic control of spin impurities using chiral molecules
DTSTART;VALUE=DATE-TIME:20210902T080000Z
DTEND;VALUE=DATE-TIME:20210902T090000Z
DTSTAMP;VALUE=DATE-TIME:20210805T200713Z
UID:indico-contribution-7272-23069@indico.ijclab.in2p3.fr
DESCRIPTION:Speakers: Yossi Paltiel (The Hebrew University of Jerusalem)\n
Using the chiral induced spin selectivity (CISS) effect we were able to in
duce local spin impurities on magnetic and superconducting material. Dynam
ic control of spin impurities was also achieved. The CISS is an electronic
phenomenon in which electron transmission through chiral molecules depend
s on the direction of the electron spin. Thus charge displacement and tran
smission in chiral molecules generates a spin-polarized electron distribut
ion. This effect is metastable and may generate local magnetic defect that
can be enhanced or removed by electric dipole. Also selective process may
organize the molecules adsorption.In my talk I will present the CISS effe
ct and its importance\, both for applications and basic science. I will sh
ow that when chiral molecules are adsorbed on the surface of thin ferromag
netic film\,they induce magnetization perpendicular to the surface\, witho
ut the application of current or external magnetic field. On superconducto
rs chiral molecules generate Shiba like states\, as well as change the ord
er parameter of the superconductor. Lastly\, I will also point to open que
stions regarding dynamic control of skyrmions\, and the CISS effect.\n\nht
tps://indico.ijclab.in2p3.fr/event/7272/contributions/23069/
LOCATION:
URL:https://indico.ijclab.in2p3.fr/event/7272/contributions/23069/
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