David J. Dean, Oak Ridge Nat. Lab.
Phases: From Nuclei to Quantum Dots
Physics Division Colloquium - 7 Apr 2000

Thermal properties of, and transitions in, strongly correlated quantum mechanical systems have been studied in various contexts. Perhaps the most obvious are the normal-conducting to super-conducting transitions in condensed matter systems. Many nuclear systems exhibit an intrinsic deformation in their ground states, and deformed-to-spherical transitions have been studied in many models. As a result, observable consequences, such as enhanced moments of inertia, decreasing quadrupole transition moments, and decreasing correlated pair-transfer amplitudes may be investigated.

In studies of many-body phenomena in quantum dots, experimental efforts have focused on mapping the magnetic field dependence of their ground-state structure by measuring the chemical potential via capacitance spectroscopy. Cusps and steps in the chemical potential were found to clearly separate different ranges of magnetic fields. These features were identified with phase transitions in the charge density of the quantum dot. Unique structures that break rotational symmetry within a quantum dot and develop as a function of increasing magnetic field were also reported in theoretical investigations and associated with experimental observations of charge-density redistribution. Thermal characteristics of the broken symmetry phase have also recently been investigated.

In this talk, I will compare the transitions that occur in nuclei as a function of increasing neutron number, temperature, and cranking frequency (an ``external field'') to those that occur in semi-conductor quantum dots as a function of electron number, increasing temperature, and increasing external magnetic field.

ANL Physics Division Colloquium Schedule