1,860 research outputs found
Probabilistic Super Dense Coding
We explore the possibility of performing super dense coding with
non-maximally entangled states as a resource. Using this we find that one can
send two classical bits in a probabilistic manner by sending a qubit. We
generalize our scheme to higher dimensions and show that one can communicate
2log_2 d classical bits by sending a d-dimensional quantum state with a certain
probability of success. The success probability in super dense coding is
related to the success probability of distinguishing non-orthogonal states. The
optimal average success probabilities are explicitly calculated. We consider
the possibility of sending 2 log_2 d classical bits with a shared resource of a
higher dimensional entangled state (D X D, D > d). It is found that more
entanglement does not necessarily lead to higher success probability. This also
answers the question as to why we need log_2 d ebits to send 2 log_2 d
classical bits in a deterministic fashion.Comment: Latex file, no figures, 11 pages, Discussion changed in Section
Enhancement of Geometric Phase by Frustration of Decoherence: A Parrondo like Effect
Geometric phase plays an important role in evolution of pure or mixed quantum
states. However, when a system undergoes decoherence the development of
geometric phase may be inhibited. Here, we show that when a quantum system
interacts with two competing environments there can be enhancement of geometric
phase. This effect is akin to Parrondo like effect on the geometric phase which
results from quantum frustration of decoherence. Our result suggests that the
mechanism of two competing decoherence can be useful in fault-tolerant
holonomic quantum computation.Comment: 5 pages, 3 figures, Published versio
Comparative study of the electron conduction in azulene and naphthalene
We have studied the feasibility of electron conduction in azulene molecule
and compared with that in its isomer naphthalene. We have used non-equilibrium
Green's function formalism to measure the current in our systems as a response
of the external electric field. Parallely we have performed the Gaussian
calculations with electric field in the same bias window to observe the impact
of external bias on the wave functions of the systems. We have found that, the
conduction of azulene is higher than that of naphthalene inspite of its
intrinsic donor-acceptor property, which leads a system to more insulating
state. Due to stabilization through charge transfer the azulene system can be
fabricated as a very effective molecular wire. Our calculations shows the
possibility of huge device application of azulene in nano-scale instruments.Comment: 6 pages, 8 figure
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