(1996). [50] I. Bˆ aldea, H. K¨ oppel, and L. S. Cederbaum, Phys. Rev. B 55 , 1481 (1997). [51] I. Bˆ aldea and L. S. Cederbaum, Phys. Rev. B 77 , 165339 (2008). [52] I. Bˆ aldea, L. S. Cederbaum, and J. Schirmer, Eur. Phys. J. B 69 , 251 (2009). [53] I. Bˆ aldea and L. S. Cederbaum, Quantum-dot nanorings, in Handbook of Nanophysics , edited by K. Sattler, chapter 42, Boca Raton: Taylor & Francis, 2010 (to appear). [54] A. A. Abrikosov, L. P. Gorkov, and I. E. Dzyaloshinski, Methods of Quantum Field Theory in Statistical Physics , Dover, New York, 1963. [55] J. Schirmer (private communication). [56] D. V. Averin and Y. V. Nazarov, Phys. Rev. Lett. 65 , 2446 (1990). [57] A. Groshev, T. Ivanov, and V. Valtchinov, Phys. Rev. Lett. 66 , 1082 (1991). [58] S. De Franceschi et al., Phys. Rev. Lett. 86 , 878 (2001). [59] Strictly, we would have to take N = 1 but then we would miss the Coulomb contact interac- tions. [60] S. Ho Choi, B. Kim, and C. D. Frisbie, Science 320 , 1482 (2008). [61] See Ch. 13 in Ref. 1. [62] P. Lucignano, R. Mazzarello, A. Smogunov, M. Fabrizio, and E. Tosatti, Nature Materials 8 , 563 (2009). 26