2 research outputs found
Two-impurity-entanglement generation by electron scattering in zigzag phosphorene nanoribbons
In this paper, we investigate how two on-side doped impurities with net
magnetic moments in an edge chain of a zigzag phosphorene nanoribbon~(zPNR) can
be entangled by scattering of the traveling edge-state electrons. To this end,
in the first step, we employ the Lippmann-Schwinger equation as well as the
Green's function approach to study the scattering of the free traveling
electrons from two magnetic impurities in a one-dimensional tight-binding
chain. Then, following the same formalism, that is shown that the behavior of
two on-side spin impurities in the edge chain of a zPNR in responding to the
scattering of the edge-state traveling electrons is very similar to what
happens for the one-dimensional chain. In both cases, considering a known
incoming wave state, the reflected and transmitted parts of the final wave
state are evaluated analytically. Using the obtained results, the related
partial density matrices and the reflection and transmission probabilities are
computable. Negativity as a measure of the produced entanglement in the final
state is calculated and the results are discussed. Our theoretical model
actually proposes a method, which is perhaps experimentally performable to
create the entanglement in the state of the impurities
Local Temperatures Out of Equilibrium
The temperature of a physical system is operationally defined in physics as
"that quantity which is measured by a thermometer" weakly coupled to, and at
equilibrium with the system. This definition is unique only at global
equilibrium in view of the zeroth law of thermodynamics: when the system and
the thermometer have reached equilibrium, the "thermometer degrees of freedom"
can be traced out and the temperature read by the thermometer can be uniquely
assigned to the system. Unfortunately, such a procedure cannot be
straightforwardly extended to a system out of equilibrium, where local
excitations may be spatially inhomogeneous and the zeroth law of thermodynamics
does not hold. With the advent of several experimental techniques that attempt
to extract a single parameter characterizing the degree of local excitations of
a (mesoscopic or nanoscale) system out of equilibrium, this issue is making a
strong comeback to the forefront of research. In this paper, we will review the
difficulties to define a unique temperature out of equilibrium, the majority of
definitions that have been proposed so far, and discuss both their advantages
and limitations. We will then examine a variety of experimental techniques
developed for measuring the non-equilibrium local temperatures under various
conditions. Finally we will discuss the physical implications of the notion of
local temperature, and present the practical applications of such a concept in
a variety of nanosystems out of equilibrium.Comment: Corrected version to Physics Report