1. No category

CNISM
Fisica Teorica della Materia,
Fotonica & Nanostrutture
Dario Gerace
Dipartimento di Fisica, Università di Pavia
Giornata di orientamento L.M. in Scienze Fisiche - 19 Maggio 2015
Groups and People
Ø  Computational Statistical Mechanics
Prof. S. Romano
Prof. L. C. Andreani
Ø  Photonics &
Nanostructures
Prof. D. Gerace
Prof. M. Liscidini
Post-Docs: A. Bozzola, P. Kowalczewski, S. W. Flores
PhD students: F. Alpeggiani, S. Del Sorbo, M. Menotti, S. Rafizadeh
Master students: V. Introini, D. Kos, M. Passoni, L. Redorici
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
COMPUTATIONAL
STATISTICAL
MECHANICS
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Statistical Mechanics
Ø  Computational research on liquid phases of matter
(nematic phases of liquid crystals)
Ø  Statistical mechanics of spin lattices
(also exact demonstrations)
Ø  Study of thermodynamic and structural properties of
systems of interacting many particles
RELATED COURSES (L.M. Chimica):
Statistical Thermodynamics
Theoretical and Computational Chemistry
WEBSITE: http://www2.pv.infn.it/~romano/
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
PHOTONICS
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Photonic crystals
electrons in crystalline
solids
Schrödinger equation
photons in periodic
dielectric media
2nd-order Maxwell eqs.
for harmonic fields
“Photonic bands” and energy gaps, as in solids!
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Photonic crystal nanocavities
Ø  Trapping light at the nanoscale
SEM of a fabricated device
Theoretical modeling
Q ~ 106 à τ~1 ns
V~(λ/n)3 à |E|2 ~1/V
Ø  Several applied and fundamental works on enhanced optical
nonlinearities in collaboration with optical spectroscopy group
(see Guizzetti)
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Photonic crystals in silicon photonics:
grating couplers for telecom applications
Our task: optimizing the
coupling efficiency from a
single-mode optical fiber (longdistance communication) into
a silicon optical integrated
circuit
UGent (2002-)
EU project Fabulous
Project goal: realizing an
Optical Network Unit in silicon
photonics à optical modem on
a silicon chip!
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Photovoltaics
Ø  Photovoltaic conversion in solar cells = optical problem (light trapping)
+ electronic problem (carrier collection)
⇒  both fundamental aspects (efficiency limits) and applied ones
⇒  cultural opportunities, as well as funding and career ones
Ø  Projects: public + industrial
EU FP7 Marie Curie ITN Network “PROPHET”
ENI S.p.A. “Photonics for PV systems based on fluorescent concentrators”
Nanophotonics meets Photovoltaics !
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Bloch surface waves
Ø  Theoretical study of optical surface waves in periodic media.
M. Menotti and M. Liscidini
(a)
(b)
z
nPMMA,h
⇒  e.g., Biosensing applications
x
y
w
nTiO2,dfirst
nSiO2,dSiO2
Fisica teorica della materia, fotonica e nanostrutture
n – Dip.
,d Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
TiO2
TiO2
Quantum Nonlinear Photonics
Ø  Theorertical studies on the generation and characterization of
nonclassical states of light (i.e., entangled, squeezed …), in
connection with experiments (see Guizzetti)
Ø  Connections to Quantum Mechanics, Quantum Computation
and Quantum Information (see D’Ariano)
A CLASSIC NEVER GETS OLD
MARCO LISCIDINI1, J. E. SIPE2
1
2
Department of Physics, University of Pavia, Pavia, Italy
Department of Physics, University of Toronto, Toronto; Ontario, Canada
Fig. 1 Artistic represe
the resolution enhan
the characterization o
pairs by stimulated e
picture is a combinat
results of two JSD me
of photons generated
in an integrated wave
The less resolved par
by means of a quantu
based on coincidence
the more resolved im
magnifier is obtained
classical analog of SD
limit of classical mechanics. In this view, when we arrive at the
divide between classical and quantum, we are in truly foreign
territory. The fundamental concepts we use in physics on a
day-to-day basis, such as the presumed separation between
experimenter and experimental system [10], are in need of
in time, and if this classical-like oscillation is couple
electromagnetic field in the usual way emission or
can result, depending on the relative phase of the
moment and the applied field. Classical-like calcula
here mirror the results of full quantum calculations
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Single-photon sources
|e>
!ω 0
Ø  An ideal single-photon source à
| n = 1〉
|g>
ω0
Ø  Our interest: realizing
single-photon sources
integrated in silicon chips
Ultimately: single-photon devices (transitors, diodes…)
Fundamental physics today…applications tomorrow ?
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
ELEMENTARY
MATERIAL
EXCITATIONS
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Elementary excitations as quasi-particles
Ø  Solids are complex systems…but their
low-energy excitations can be described
in terms of collective degrees of freedom,
which can be considered actual particles
phonons, excitons, polaritons, plasmons,
magnons, …
Ø  Quantum theories of elementary excitations à QFT
e.g. à a Cooper pair
phonon
Teoria dei solidi, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Plasmonics
dielectric
PLASMONS: collective excitations of free
electrons in a metal
They can LOCALIZE à surface plasmons
+
-
+
They can COUPLE TO RADIATION
(surface plasmon polaritons)
-
+
metal
Vibrant field of research, with many fundamental aspects (control of radiative
processes, sub-wavelength optics, classical and quantum phenomena) and
applied ones (biosensors…)
Electronic
systems
PLASMONICS
Photonics
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Quantum simulators
Ø  Digital simulators: Directly computing the time evolution of
complex manybody models
Elementary unit (qubit): collective spin
ensemble in a microwave resonator à
MIUR – FIRB project in
collaboration with Univ. Parma
Ø  Analog simulators: Studying systems with formal analogies
with models in theoretical physics
e.g.: relativistic electrons in graphene,
strongly correlated photonic lattices,
analog dynamics in curved space-time
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Research in Condensed Matter Theory
FUNDAMENTAL RESEARCH
APPLIED RESEARCH
Theoretical
Physics
Statistical
Physics
Energetics
Quantum
Mechanics
CM theory
Quantum optics
Quantum electronics
Information and
Communication
Technologies
Materials sciences
Quantum information
processing
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics
Research in Condensed Matter Theory
Ø  Problem solving à trained at developing numerical and/or
analytic skills
Ø  Collaborative works, international environment
Fisica teorica della materia, fotonica e nanostrutture – Dip. Fisica, Università di Pavia – http://fisica.unipv.it/nanophotonics