6 research outputs found
The Structure and Quantum Capacity of a Partially Degradable Quantum Channel
The quantum capacity of degradable quantum channels has been proven to be
additive. On the other hand, there is no general rule for the behavior of
quantum capacity for non-degradable quantum channels. We introduce the set of
partially degradable (PD) quantum channels to answer the question of additivity
of quantum capacity for a well-separable subset of non-degradable channels. A
quantum channel is partially degradable if the channel output can be used to
simulate the degraded environment state. PD channels could exist both in the
degradable, non-degradable and conjugate degradable family. We define the term
partial simulation, which is a clear benefit that arises from the structure of
the complementary channel of a PD channel. We prove that the quantum capacity
of an arbitrary dimensional PD channel is additive. We also demonstrate that
better quantum data rates can be achieved over a PD channel in comparison to
standard (non-PD) channels. Our results indicate that the partial degradability
property can be exploited and yet still hold many benefits for quantum
communications.Comment: 59 pages, 13 figures, Journal-ref: IEEE Acces
Quantum Information Transmission over a Partially Degradable Channel
We investigate a quantum coding for quantum communication over a PD
(partially degradable) degradable quantum channel. For a PD channel, the
degraded environment state can be expressed from the channel output state up to
a degrading map. PD channels can be restricted to the set of optical channels
which allows for the parties to exploit the benefits in experimental quantum
communications. We show that for a PD channel, the partial degradability
property leads to higher quantum data rates in comparison to those of a
degradable channel. The PD property is particular convenient for quantum
communications and allows one to implement the experimental quantum protocols
with higher performance. We define a coding scheme for PD-channels and give the
achievable rates of quantum communication.Comment: 7 pages, 2 figures, Journal-ref: IEEE Acces
Resonant Multilevel Amplitude Damping Channels
We introduce a new set of quantum channels: resonant multilevel amplitude
damping (ReMAD) channels. Among other instances, they can describe energy
dissipation effects in multilevel atomic systems induced by the interaction
with a zero-temperature bosonic environment. At variance with the already known
class of multilevel amplitude damping (MAD) channels, this new class of maps
allows the presence of an environment unable to discriminate transitions with
identical energy gaps. After characterizing the algebra of their composition
rules, by analyzing the qutrit case, we show that this new set of channels can
exhibit degradability and antidegradability in vast regions of the allowed
parameter space. There we compute their quantum capacity and private classical
capacity. We show that these capacities can be computed exactly also in regions
of the parameter space where the channels aren't degradable nor antidegradable
A Survey on Quantum Channel Capacities
Quantum information processing exploits the quantum nature of information. It
offers fundamentally new solutions in the field of computer science and extends
the possibilities to a level that cannot be imagined in classical communication
systems. For quantum communication channels, many new capacity definitions were
developed in comparison to classical counterparts. A quantum channel can be
used to realize classical information transmission or to deliver quantum
information, such as quantum entanglement. Here we review the properties of the
quantum communication channel, the various capacity measures and the
fundamental differences between the classical and quantum channels.Comment: 58 pages, Journal-ref: IEEE Communications Surveys and Tutorials
(2018) (updated & improved version of arXiv:1208.1270