Research

Research experiences:

  • BCS and Eliashberg theory of superconductivity.
  • Amplification of superconductivity in superlattices of quantum stripes.
  • Non adiabatic superconductivity: Beyond Migdal theorem.
  • Superconducting fluctuations.
  • Boltzmann equation and transport properties of cuprates.
  • Electronic structure and superconducting properties of MgB2.
  • Crossover between BCS superconductivity and Bose-Einstein condensation.
  • Pseudogap and pair fluctuations in high-Tc superconductors and ultracold fermions.
  • Superfluidity of atomic quantum gases.
  • Multiband and multicomponent superconductivity and superfluidity.
  • Superfluidity of electron-hole pairs in multilayer semiconducting and graphene systems.


Andrea Perali has 15 years of experience in diagrammatic, phenomenological and numerical m
ethods to study the physics of strongly interacting fermions, with skills in parallel computing using fortran compilers.

 

 

Most significant contributions of Andrea Perali to the Physics of Superconductivity and Superfluidity:

1) Correlation between pairing interaction and momentum dependence of the gap parameter in high-Tc

cuprate superconductors. Introduction of the concept and mechanism of momentum decoupling and

local density of states in momentum space [1996-2000; Ref. 11].

2) Stripe Quantum Critical Point Scenario for high-Tc cuprate superconductors:
superconducting properties and phase diagram [1996-2000; Ref. 11].

3) Quantum size effects, shape resonances and Tc enhancement in superconducting stripes:
prediction of shape resonances in the superconducting gaps and in the critical temperature in a single
stripe and in superlattice of stripes [1996-1998; Ref. 12].

After 2004, experimental evidence is accumulating confirming our theoretical predictions, and nowadays

this work is considered pioneering in the scientific community working in superconductivity at the nanoscale.

4) Introduction and development of the multi-patch / multi-gap approach to study superconducting pair

fluctuations and transport properties of strongly interacting fermionic systems, in which the effective interaction

is characterized by a strong momentum dependence and the Fermi surface is broken or anisotropic.

Applications were done for underdoped cuprates. [2000-2002; Ref. 10].

5) Pseudogap: prediction and characterization of the pseudogap in the single-particle excitations of

a system of fermions interacting by an attractive contact potential, caused by strong pair fluctuations

persisting in the normal state above the superconducting / superfluid critical temperature [2002; Ref. 9].
This work was then extended to ultracold trapped fermions and the phase diagram predicted [2004; Ref. 7].

Our results contributed to open the experimental search of the pseudogap in ultracold fermions, and the
first evidence for a normal state pseudogap were reported by the JILA experiment in 2008.

Further experimental evidence for the pseudogap have been reported in 3D [2010-2012; Ref. 2,3] and 2D

trap configurations.

6) Joint theoretical and experimental characterization of the BCS-BEC crossover for ultracold

fermions in the normal state: proposal and first experimental evidence for a crossover boundary between

a pseudogap regime close to unitarity and a molecular regime approaching the BEC limit.
Proposal of the pseudo-Luttinger wave-vector to measure the volume of the remnant Fermi surface [2011-2012; Ref. 2].

Experimental evidence for this boundary has also been reported in very recent ARPES studies of iron-based
chalcogenide superconductors, where our work was taken as a theoretical framework.

7) Theory of the radio-frequency (RF) spectroscopy for ultracold fermions,with and without final

state effects, both in the normal and superfluid states.
Our work set up the diagrammatic theory for the RF response in the BCS-BEC crossover and resulted in several

satisfactor quantitative comparisons between theory and experiments [2008-2010; Ref. 4,5].

8) Atypical BCS-BCS crossover induced by quantum size effects in quasi-1D fermionic condensates

and ultra thin superconductors.
Here we predicted the coexistence of point-like and extended Cooper pairs when a shape resonance occurs

in the system because of the quantum confinement [2012; Ref. 1].