TITOLO CONFERENZA

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TITOLO CONFERENZA

• Phase diagram of Josephson junction arrays with
  capacitive disorder
• Phys. Rev. B 67,014518 (2003)

F.P.Mancini, P. Sodano, and A. Trombettoni
Dipartimento di Fisica and Sezione I.N.F.N.,
Università di Perugia, Via A. Pascoli, I-06123
Perugia, Italy
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CAPACITIVE DISORDER

• (RANDOM) OFFSET CHARGE DEFECTS
• IN THE JUNCTIONS OR IN THE SUBSTRATE
• IMPERFECTIONS IN THE COSTRUCTION OF DEVICES

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Phase diagrams for the diagonal model without
charge frustration (a) and with half-integer
uniform charge frustration (b). From Grignani et
al., Phys. Rev. B 61, 11676 (2000).
(a)
(b)
,
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MEAN FIELD THEORY
FUNCTIONAL APPROACH NEAR TRANSITION POINT
Ginzburg-Landau free energy
coordination number Matsubara
frequencies vectors of the reciprocal
lattice
defined by Fourier transform of the phase
correlator
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AVERAGE OVER THE DISORDER  RANDOM OFFSET CHARGES
Diagonal capacitance matrix
Gaussian distribution Uniform distribution    
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Phase diagram for random offset charges with
Gaussian distribution. The bold line is for se
and it represents the case of large variance. To
the left (right), we plot qe (q0). We use s
/2e0.1(red line) and 0.25 (blue line)
Phase diagram with diagonal capacitance and
random offset charges with Gaussian (a) and
uniform (b) distribution. Top (bottom) of the
figures kB T / EC1 (0.1). We plot the cases
s/2e 0.1 (black lines), 0.25 (red lines). For
large s/2e the phase boundary line is flat and it
is the same for both distributions (blue lines).
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Non diagonal capacitance matrix with weak
nearest-neighbor interaction. s /2e is
respectively 0 (black line), 0.015 (red line) and
0.03 (blue line).
Phase diagram at T0 for random offset charges
with uniform distribution.
Diagonal capacitance matrix. s /2e is
respectively 0.1 (black line), 0.25 (red line)
and 0.4 (blue line).