Quantum dots with a large Thouless number g embody a regime where both disorder and interactions can be treated nonperturbatively using large-N techniques (with N=g) and quantum phase transitions can be studied. Here we focus on dots where the noninteracting Hamiltonian is drawn from a crossover ensemble between two symmetry classes, where the crossover parameter introduces a tunable energy scale independent of and much smaller than the Thouless energy. We show that the quantum critical regime, dominated by collective critical fluctuations, can be accessed at this energy scale. The nonperturbative physics of this regime can only be described by the large-N approach, as we illustrate with two experimentally relevant examples.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 2004|
Bibliographical noteFunding Information:
It is a pleasure to thank R. Shankar and Y. Alhassid for illuminating conversations, and the NSF for partial support under Contract No. DMR-0311761.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics