I am a
theoretical physicist with a broad
spectrum of research interests that
includes superconductivity, strongly
correlated systems, mesoscopic physics and
holographic dualities. Two topic of
current interests are quantum two
dimensional superconducting material and
the physics of the SYK model and its
quantum gravity dual: JackiwTeitelboim
gravity.

SUPERCONDUCTIVITY
BY DESIGN

SYK MODEL AND
QUANTUM GRAVITY 
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,
together with Bo Fan we are investigating
differen aspects of the physics of 2D
superconductors on the verge of a
superconductor transition.

The
SachdevYeKitaev (SYK) model, N Majoranas, in
zero spatial dimensions shares the same
lowenergy effective action as quantum
JackiwTeitelboim gravity. Both models are
attracting a lot of attention because they are
simple enough to be tackled analytically while
providing tantalizing insights on
nonperturbative features of quantum gravity
and its field theory dual. Recent research on
this problem, part of which I have coauthored,
has revealed that quantum chaos and randomness
may help solve long standing problems in the
field such as the information paradox or the
factorization problem. I am interesting in
many aspects of this problem from applications
of the SYK model to condensed matter problems
to relations of JT gravity with matrix models.
Currently, I am exploring different aspects of
the physics of single and multi Euclidean
wormholes and it is likely field theory dual:
nonHermitian but PT symmetric SYK model.
Other intriguing problem is the relation
between the quantum gravity path integrals,
and random matrix theory at different levels.
We aim to employ semiclassical trace formula
to express the gravity partition function in
terms of the length of periodic orbits in the
surfaces entering in the partition
function. Another problem of special
interest is to address to address the
information paradox problem by computing out
of equilibrium features of the SYK model such
as the coupling to a reservoir, scattering
process and the dynamics of a Brownian test
particle in a SYK medium.



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.

APPLIED
HOLOGRAPHY

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. Other problems of
current interest is the field theory dual of
blackhole formation, explore holographic dual of
glassy systems and different aspects of vortices
physics in disordered and strongly interacting
systems.

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 geatures, in collaboration
with Lea Santos, of the out of equilibrium
motion which could provide helpful insight on
the conditions for thermalisation.
NOVEL FORMS
OF
QUANTUM MATTER

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 also 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.


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. 

Shuang Wu
Hanteng Wang


PhD
STUDENTS


Jie Ping Zheng
Bo Fan
Yin Can




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





Dario
Rosa

Tomoki
Nosaka

Victor Godet

Lucas
Sa

HaiQing
Zhang, Postdoc, After: Postdoc at Utrecht
University
Pedro Ribeiro, Postdoc, After: Ciencia 2013
Fellow (5 years) at Lisboa University
Paul Matthews, Master Student: After PhD student
at Imperial College, London
Hua Bi Zeng, Postdoc, After: Prof. Bohai
University, China
Jiasheng Chen, Master Student, After: PhD
student, Cavendish Laboratory
Chris Parmee, Master Student, After: PhD
student, Cavendish Laboratory
James Mayoh, PhD Student, After:
Postdoc, Southhampton University
Aurelio Bermudez, PhD Student, After: Postdoc,
Leiden University.
Bruno Murta, PhD Student, After: PhD Student,
Imperial College.
Corentin Bertrand, Master Student, After: PhD
Student, Grenoble University.
Bruno Loureiro, PhD Student, After:Postdoc,
Institute of Theoretical Physics, CEA,
Saclay,Paris.
Vaios Ziogas, Postdoc, After: Postdoc, Centre de
Physique Théorique de l’Ecole Polytechnique,
Paris.



