Biomedical Engineering Reference
In-Depth Information
2.7
Magnetization of Mn 12 as a function of magnetic field at six
different temperatures. The stepped magnetic hysteresis shows
relaxation of the field due to magnetization (spin) tunneling.
high-T c superconductors, 2-d metal-insulator transition at large r s (ratio of
Coulomb to kinetic energy) and Kondo systems.
The Kondo effect in the fully controllable semiconducting double-
quantum-dot (DQD) system is described below. In particular, this section
addresses the following two areas of interest.
.
The DQDs presented represent the first experimental realization of the
two-impurity Kondo system, which has been studied theoretically for
nearly two decades.
.
Direct evidence for the controlled entanglement of quantum dot spins is
presented, one on each dot, into a spin-singlet state.
￿ ￿ ￿ ￿ ￿ ￿
These findings have important implication for quantum computation
applications. Similar studies and results have been reported recently in the
work of Craig et al. [156], though with a different coupled quantum dot
scheme.
In the past decade, the semiconducting quantum dot system has proven to
be a versatile and ideal system for studying correlated effects involving the
spin degree of freedom. Under appropriate conditions, an isolated spin on a
quantum dot closely models an isolated spin impurity and, through its
coupling to conduction electrons in the leads connected to the dot, can give
rise to a rich variety of correlated behaviors. As a result of the tunability of
the semiconducting quantum dot system, it is possible to continuously vary
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