Subir Sachdev (Yale)

1
Universal conductance of nanowires near the
superconductor-metal quantum transition
Subir Sachdev (Yale) Philipp Werner
(ETH) Matthias Troyer (ETH)
cond-mat/0402431
Talk online Sachdev
2
T0 Superconductor-metal transition
Repulsive BCS interaction
Attractive BCS interaction
R
Superconductor
Metal
R
Rc
M.V. Feigel'man and A.I. Larkin, Chem. Phys. 235,
107 (1998) B. Spivak, A. Zyuzin, and M. Hruska,
Phys. Rev. B 64, 132502 (2001).
3
T0 Superconductor-metal transition
yi
R
4
Continuum theory for quantum critical point
5
Consequences of hyperscaling
T
No transition for Tgt0 in d1
Normal
Superconductor
R
Rc
Sharp transition at T0
6
Consequences of hyperscaling
Quantum Critical Region
T
No transition for Tgt0 in d1
Normal
Superconductor
R
Rc
Sharp transition at T0
7
Consequences of hyperscaling
Quantum Critical Region
8
Consequences of hyperscaling
Quantum Critical Region
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Effect of the leads
10
Large n computation of conductance
11
Quantum Monte Carlo and large n computation of
d.c. conductance
12

• Conclusions
• Universal transport in wires near the
  superconductor-metal transition
• Theory includes contributions from thermal and
  quantum phase slips ---- reduces to the classical
  LAMH theory at high temperatures
• Sensitivity to leads should be a generic feature
  of the coherent transport regime of quantum
  critical points.