6 research outputs found
Interpolation of recurrence and hashing entanglement distillation protocols
We construct new entanglement distillation protocols by interpolating between
the recurrence and hashing protocols. This leads to asymptotic two-way
distillation protocols, resulting in an improvement of the distillation rate
for all mixed Bell diagonal entangled states, even for the ones with very high
fidelity. We also present a method how entanglement-assisted distillation
protocols can be converted into non-entanglement-assisted protocols with the
same yield
Entanglement distillation by dissipation and continuous quantum repeaters
Even though entanglement is very vulnerable to interactions with the
environment, it can be created by purely dissipative processes. Yet, the
attainable degree of entanglement is profoundly limited in the presence of
noise sources. We show that distillation can also be realized dissipatively,
such that a highly entanglement steady state is obtained. The schemes put
forward here display counterintuitive phenomena, such as improved performance
if noise is added to the system. We also show how dissipative distillation can
be employed in a continuous quantum repeater architecture, in which the
resources scale polynomially with the distance
Distillability via protocols respecting the positivity of partial transpose
We show that all quantum states that do not have a positive partial transpose
are distillable via channels, which preserve the positivity of the partial
transpose. The question whether NPT bound entanglement exist is therefore
closely related to the connection between the set of separable superoperators
and PPT-preserving maps.Comment: 3 pages, REVTeX, remark on complete positivity and reference adde
Activating NPPT distillation with an infinitesimal amount of bound entanglement
We show that bipartite quantum states of any dimension, which do not have a
positive partial transpose, become 1-distillable when one adds an infinitesimal
amount of bound entanglement. To this end we investigate the activation
properties of a new class of symmetric bound entangled states of full rank. It
is shown that in this set there exist universal activator states capable of
activating the distillation of any NPPT state.Comment: 4 pages, revtex4, 1 figure, references correcte