NUCLEAR PHYSICS; DATA ON NUCLEAR PHYSICS REPORTED BY RESEARCHERS AT YEREVAN STATE UNIVERSITY

Science Letter
July 22, 2008

"We develop a variational many-body approach within a second quantized
formulation for a few-electron system in a parabolic two-dimensional
quantum dot (QD). By way of application, the nature of the ground
state of a two-electron system in a parabolic QD in a broad range of
magnetic fields is theoretically investigated," researchers in Yerevan,
Armenia report (see also Nuclear Physics).

"Various phase transitions on the basis of the resulting analytical
expressions for energy of the system have been investigated:
First, the well-known transition from a maximum density droplet
to a Wigner phase in a magnetic field is obtained, provided that
the QD is in conditions of weak confinement. Furthermore, in the
case of relatively strong QD confinement and weak magnetic fields,
a rotationally symmetric spin-singlet state is the ground state of
the system. However, in a strong magnetic field and for the same
QD confinement, a broken-symmetry spin-singlet state appears to be
energetically favored over the symmetric spin-singlet state," wrote
A.A. Avetisyan and colleagues, Yerevan State University.

The researchers concluded: "A first investigation of such a
broken-symmetry spin-singlet phase in a QD in a magnetic field is
shown to be an important application of the proposed technique."

Avetisyan and colleagues published their study in Physics of Atomic
Nuclei (Phase transitions in a few-electron quantum dot in a magnetic
field: Wigner phases and broken-symmetry spin-singlet states. Physics
of Atomic Nuclei, 2008;71(5):800-806).

For additional information, contact A.A. Avetisyan, Yerevan State
University, Dept. of Physics, Yerevan 375049, Armenia.

From: Emil Lazarian | Ararat NewsPress