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Scientific Report 2007-2009
Condensed matter physics and biophysics
C29. Quantum phenomena in complex matter
Our interest has been to study the role of quantum
interference between different scattering channels driven
by exchange interaction. This mechanism was introduced
by Ugo Fano in the paper published in Nuovo
Cimento in 1935 following a proposal of Sergio Segrè
and Enrico Fermi. The topic was previously of interest
to Ettore Majorana but he did not publish the work,
that was left in his unpublished manuscripts. This resonance
due to quantum interference was called Risonanza
di Forma by Enrico Fermi, the Shape Resonance, that
manifest itself in a negative and positive quantum interference
between open and closed scattering channels.
In 1955, the work of Fano was extended by Feshbach to
many body systems for interpretation of interference between
open and closed scattering channels in the nuclear
physics.
Cooperative quantum phenomena have been proposed
by some authors to be needed for understanding the cooperative
phenomena observed in living matter and in
its evolution. The key physical problem is that a quantum
macroscopic condensate of interest for understanding
cooperativity in living matter should occur at room
temperature. This hypothesis is in contrast with all our
knowledge. In fact, in a standard homogenous system it
is known that the Bose-Einstein condensation for bosons,
or the BCS condensation for fermions should appear only
near the absolute zero temperature. It has been noted
in 1993 by our group that this type of interference in a
many body fermionic system, made of two distinguishable
particles with attractive interaction between similar
particles and repulsive interaction between different
particles, could increase the critical temperature for the
formation of superfluid condensates. This phenomenon
could allow the formation of a superfluid like condensate
at room temperature. In the same year it was independently
proposed by Stoof in Leiden that an atomic Feshabach
resonance for atomic association ad dissociation
in a bosonic gas could increase the critical temperature
for the Bose-Einstein condensation.
The work we have been doing these last 3 years focus
on the fact that the Fano-Feshbach resonance take place
a phase separation regime between the distinguishable
particles in the proximity of a quantum critical point.
We have investigated, first, how this type of phase separation
can be manipulated by illumination, studying the
simple case where photo-illumination induces a disorder
to order phase transition [1]; second, the simple case of
phase separation between a liquid and a striped-liquid
driving in the presence of anisotropic interaction [2]. We
have studied the Fano-Feshbach resonance and nanoscale
phase separation in a polaron liquid near the quantum
critical point for a polaron Wigner crystal [3]. Finally
we have presented a scenario where the emergence of life
in our universe is related with the onset a the mechanism
based on Feshbach Resonance for association and
I (a.u.)
a)
b)
c)
P(R) (a.u.)
P(R) (a.u.)
P(R) (a.u.)
0 2 4 6 8 101214
radius (nm)
0 2 4 6 8 101214
radius (nm)
0 2 4 6 8 101214
radius (nm)
1 2 3 4
q (nm -1 )
Figure 1: I(q) vs q for an apoferritin solution incubated in
different concentration of Al(III) and Fe(II). a: apoferritin;
b: apoferritin in Fe(II), c: apoferritin in Al/Fe. In the insets
are distribution functions from the SAXS.
dissociation of biological molecules [4].
Recently we are working on two projects. The first
concerns the conformation landscape of a protein without
secondary structure: τ-protein where the dynamic
fluctuations are expected to be fast and to control the
biological function. The second project concerns the
study of the ferritin , the main iron storage protein in
living systems. Ferritin is a stable complex forming an
hollow sphere (apoferritin) filled with a Fe(II) oxide
core. The ferritin core composition differs between
pathological and physiological conditions. In particular
clinical conditions, plasma ferritin can be filled with
metal other then Fe, such as Al. We are studying the
shape and metal content variations of plasma ferritin
extracted from different clinical patients, by means of
small angle X-ray scattering (SAXS), mass spectroscopy
and light scattering techniques. Moreover we are
developing an in-vitro model of the aluminium uptake
in ferritin. Fig. 1 an example of the pair distributions
obtained from the SAXS, an effective technique to
detect ferritin core variations.
References
1. M. Fratini, et al., J. Sup. Nov. Mag. 20, 551 (2007).
2. D. Innocenti, et al., J. Sup. Nov. Mag. 22, 529 (2009).
3. M. Fratini, et al., J. Phys: Conf. Ser. 108, 012036 (2008).
4. N. Poccia, et al., Int. J. Mol. Sci. 10, 2084 (2009).
Authors
A. Bianconi, N.Poccia, A. Ricci, G. Ciasca, D. Innocenti, G.
Campi,V. Palmisano, L. Simonelli, M. Fratini, N.L. Saini
http://superstripes.com/
Sapienza Università di Roma 82 Dipartimento di Fisica