Capacitance and charge relaxation resistance of chaotic cavities – Joint distribution of two linear statistics in the Laguerre ensemble of random matrices

Aurélien Grabsch 1 Christophe Texier 2

Europhysics letters – EPL, Association européenne de physique, 2015, 109, pp.50004

We consider the AC transport in a quantum RC circuit made of a coherent chaotic cavity with a top gate. Within a random matrix approach, we study the joint distribution for the mesoscopic capacitance $C_\mu=(1/C+1/C_q)^{-1}$ and the charge relaxation resistance $R_q$, where $C$ is the geometric capacitance and $C_q$ the quantum capacitance. We study the limit of a large number of conducting channels $N$ with a Coulomb gas method. We obtain $\langle R_q\rangle\simeq h/(Ne^2)=R_\mathrm{dc}$ and show that the relative fluctuations are of order $1/N$ both for $C_q$ and $R_q$, with strong correlations $\langle \delta C_q\delta R_q\rangle/\sqrt{\langle \delta C_q^2\rangle\,\langle \delta R_q^2\rangle}\simeq+0.707$. The detailed analysis of large deviations involves a second order phase transition in the Coulomb gas. The two dimensional phase diagram is obtained.

  • 1. ENS Cachan – École normale supérieure – Cachan
  • 2. LPTMS – Laboratoire de Physique Théorique et Modèles Statistiques
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