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NEST Scientific Report 2007-2009 Evidence for a first-order quantum phase transition of excitons
 

Summary: NEST Scientific Report 2007-2009
Evidence for a first-order quantum phase transition of excitons
in semiconductor bilayers
29
W
hen dominated by quantum-mechanical fluctuations, ground state
transformations display a tendency towards quantum criticality associated with
collapse of the characteristic energy scale expressed by softening of low-lying
excitation modes. In the presence of competing interactions and weak residual disorder the
nature of the quantum phase transition is predicted to become discontinuous as the critical
point is approached. The observation of these elusive effects require a fine tuning of the
impact of the interaction terms that is difficult to achieve in experiments. We demonstrated
that coupled electron bilayers realized in double quantum wells display excitonic and
metallic ground states stabilized by different terms of electron interactions that can be tuned
with high precision. This competition drives this soft-mode system to undergo a first-order
quantum phase transition
In coupled electron bilayers confined in
modulation-doped GaAs double quantum
wells, the energy levels split into symmetric
and anti-symmetric combinations

  

Source: Abbondandolo, Alberto - Scuola Normale Superiore of Pisa

 

Collections: Mathematics