Nonclassical suppression of conductance fluctuation in a double stadium quantum system - art. no. 081307

A double stadium quantum network of two quantum cavity stadiums with a tuna ble coupling by a ballistic quantum point contact in between was studied on universal properties of conductance fluctuation (CF) and weak localization (WL). Our experimental data of CF(Var(G)) and WL(deltaG) are best fitted b y Var(G)/Var(G(U))=0.25(n/N)(alpha) and deltaG/deltaG(U)=0.42(n/N)(beta), r espectively, with alpha =1.2 and beta = 1.8, where Var(G(U)) and deltaG(U) represent the universal magnitudes, n is a variable mode number at the poin t contact, and N is a fixed mode number at both the entrance and the exit g ates. Our best fit exponents of alpha = 1.2 and beta = 1.8 are closer to th ose of quantum-mechanical theories (alpha = 1 and beta = 2) than those of O hm's law analysis (alpha = beta = 2). This nonclassical suppression of cond uctance fluctuation in a simplest network of mesoscopic electronic elements suggests a quantum-mechanical importance in the network construction betwe en mesoscopic quantum structures.