I am a
theoretical physicist with a broad
spectrum of research interests that
include low dimensional superconducitvity,
strongly correlated systems and mesoscopic
physics with a special emphasis on novel
two dimensional superconducting materials,
and holographic dualities. Two topic of
current interests are the nanoengineering
of novel disordered two dimensional
superconductors and the physics of the SYK
model and its quantum gravity dual:
JackiwTeitelboim gravity.

SUPERCONDUCTIVITY
BY DESIGN

NOVEL FORMS
OF QUANTUM MATTER 
Recent
technological advances in both growth and
measurement of nano/hetero structures
have put the basis to study quantitatively
nanoscale superconductivity. One particular
area of interest is the identification of
materials, physical
mechanisms and geometrical arrangements which
lead to an enhancement of superconductivity in
the nanoscale. Examples of interest include copper
oxides heterostructures, LAO/STO
and FeSe/STO interfaces and granular
conventional superconductors. Together with
James Mayoh and Aurelio Bermudez, I have proposed
a novel method to engineer more robust
superconductivity by controlled
nanogranularity and also investigated
the role of the substrate in the enhancement
of superconductivity in thin films. Together
with Lara Benfatto et al. we have recently
verifed that coherence effects related to
nanogranularity help explain the enhancement
of Tc observed in granular Al. Currently we
are investigating whether similar mechanism
could enhance superconductivity in novel
engineered two dimensional superconductors
such as FeSe/STO.

The
ground state of all forms of superconductivity
is a superposition of dimers, either
spinsinglet or spintriplet, which for
sufficiently low temperature condensate.
However the Efimov effect, that predicts the
existence of bound states of three
distinguishable particles even in the limit of
no bound states for two particles, suggests
the possibility of a richer phenomenology.
Together with Pascal Naidon in Riken and
Shimpei Endo in Paris, we have
found that Efimov physics can induce
novel forms of stable quantum matter,
more specifically a trimer Fermi liquid.
Topologically non trivial quantum matter also
offers a promising arena to discover
nonconventional superconductors. We
have recently studied
the distinctive features of a supercurrent in
a dissipative topological Josephson junction.
Currently we are working on condensed matter
realisations of Efimov physics and its
potential to realise novel forms of
superconductivity.



It is now possible to
control and measure the size and shape of a
superconducting nanograin. This paves the
way for a quantitative understanding of nanoscale
superconductivity. Figure from Nature
Materials,
9,
550
(2010).

It is possible to
substantially enhance the critical temperature of
bulk superconductors by granular
nanoengineering. Figure from Phys.
Rev. B 90, 134513 (2014) for grain size
~5nm and, from top to bottom, FCC, BCC and
cubic packings.

HOLOGRAPHIC
DUALITIES & QUANTUM GRAVITY

OUT OF
EQUILIBRIUM DYNAMIC & THERMALIZATION

The
AdS/CFT correspondence, also referred to as the
holographic principle, is arguably he most
important theoretical development in high energy
physics of the last decade. It conjectures that
certain strongly coupled field theories are dual
of weakly coupled gravity theories in a
different dimension. The application of the
holographic duality in condensed matter systems
is rapidly emerging as a forefront research
field. Problems of special interest are those in
which some sort of universality is expected. For
instance, together with Hong Liu and P. Chesler,
I have reported
novel aspects of the physics of out of
equilibrium defect generation by holography
techniques and scaling ideas. More recently I am
working with Jac Verbaarschot and other
collaborators on the physics of the
SachdevYeKitaev which has attracted a lot of
recent attention as a toy model of holography
with a (quantum) gravity dual: JackiwTeitelboim
gravity.

The
conditions leading to thermalization in a closed
system after a quatum quench is being
intensively investigated in recent years. I am
interested on the role of spatial
inhomogeneities and topological fluctuations
(vortices and phase slips) in this
process. In two dimension this is closely
related to the physics of the Kosterlitz
Thouless transition out of equilibrium. I have
recently investigated
this problem by studying the out of
equilibirum dynamics resulting from a quench in
the spatial dimensionality of a strongly
correlated system. Currently I am also
interested in the study of transport properties
of strongly correlated systems, especially
universal aspects such as the existence of
dynamical bounds, in collaboration
with David Berenstein, or generic
features, in collaboration
with Lea Santos, of the out of equilibrium
motion which could provide helpful insight on
the conditions for thermalisation.


Time evolution of the order
parameter of a two dimensional holographic
superlfuid, from PRX
5 021015
(2015) , as
it is cooled from the disordered to the ordered
phase. According to the KibbleZurek
mechnanism the number vortices, generated at tfreeze,
scale with the quench speed. We have found that
only at a later time teq vortices
are formed and that the scaling with the
quench speed breaks down for sufficiently
fast quenches. 

Vaios Ziogas
Shuang Wu
Salomon
Zacarias


PhD
STUDENTS


Jie Ping Zheng
Bo
Fan




Nimrod
Bachar
Geneve University

Guy
Deutscher
TelAviv

Uwe S.
Pracht
Stuttgart U.

Martin
Dressel
Stuttgart U.





Aurelio
Bermudez
Leiden University

Lara
Benfatto
laSapienza, Rome

Lea Santos
Yeshiva U. NYC

Claudio
Castellani
laSapienza, Rome





Pedro
Ribeiro
Lisboa University

HaiQing
Zhang
Utrecht University

James
Mayoh
Southampton
U

Hua Bi
Zeng
Bohai University





Carmen
Verdu
Columbia

Miguel
Ugeda
DIPC

ZhiXun
Shen
Stanford

José
Ignacio Pascual
DIPC

 