675 research outputs found
Entanglement in a fermionic spin chain containing a single mobile boson under decoherence
The concurrence between first and the last sites of a fermionic spin chain
containing a single boson is rigorously investigated at finite low temperature
in the vicinity of a weak homogeneous magnetic field. We consider the boson as
a mobile spin-1 particle through the chain and study concurrence without/under
decoherence and express some interesting phase flip and bit flip reactions of
the pairwise entanglement between first and the last half-spins in the chain.
Our investigations show that the concurrence between two considered half-spins
has different behavior for various positions of the single boson along the
chain. Indeed, we realize that the single boson mobility has an essential role
to probe the pairwise entanglement intensity between two spins located at the
opposite ends of a fermionic chain. Interestingly, the entanglement remains
alive for higher temperatures when the boson is the nearest neighbor of the
first fermion. When the boson is at the middle of chain, it is demonstrated
that the threshold temperature (at which the concurrence vanishes) versus
decoherence rate can be considered as a threshold temperature boundary. These
results pave the way to set and interpret the numerical and analytical
expressions for utilizing quantum information in realistic scenarios such as
quantum state transmission, quantum communication science and quantum
information processing, where the both fermion-fermion and fermion-boson
correlations should be taken in to account.Comment: 6 pages, 7 figure
Numerical Radius Bounds via the Euclidean Operator Radius and Norm
In this paper, we begin by showing a new generalization of the celebrated
Cauchy-Schwarz inequality for the inner product. Then, this generalization is
used to present some bounds for the Euclidean operator radius and the Euclidean
operator norm.
These bounds will be used then to obtain some bounds for the numerical radius
in a way that extends many well-known results in many cases.
The obtained results will be compared with the existing literature through
numerical examples and rigorous approaches, whoever is applicable. In this
context, more than 15 numerical examples will be given to support the advantage
of our findings.
Among many consequences, will show that if is an accretive-dissipative
bounded linear operator on a Hilbert space, then , where and denote, respectively, the numerical
radius, the Euclidean norm, the real part and the imaginary part
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