Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum phase transition in a realistic double-quantum-dot system   Observing quantum phase transitions in mesoscopic systems is a daunting task,
thwarted by the difficulty of experimentally varying the magnetic interactions,
the typical driving force behind these phase transitions. Here we demonstrate
that in realistic coupled double-dot systems, the level energy difference
between the two dots, which can be easily tuned experimentally, can drive the
system through a phase transition, when its value crosses the difference
between the intra- and inter-dot Coulomb repulsion. Using the numerical
renormalization group and the semi-analytic slave-boson mean-field theory, we
study the nature of this phase transition, and demonstrate, by mapping the
Hamiltonian into an even-odd basis, that indeed the competition between the dot
level energy difference and the difference in repulsion energies governs the
sign and magnitude of the effective magnetic interaction. The observational
consequences of this transition are discussed.

1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph