3 research outputs found
Information capacity analysis of fully correlated multi-level amplitude damping channels
The primary objective of quantum Shannon theory is to evaluate the capacity
of quantum channels. In spite of the existence of rigorous coding theorems that
quantify the transmission of information through quantum channels,
superadditivity effects limit our understanding of the channel capacities. In
this paper, we mainly focus on a family of channels known as multi-level
amplitude damping channels. We investigate some of the information capacities
of the simplest member of multi-level Amplitude Damping Channel, a qutrit
channel, in the presence of correlations between successive applications of the
channel. We find the upper bounds of the single-shot classical capacities and
calculate the quantum capacities associated with a specific class of maps after
investigating the degradability property of the channels. Additionally, the
quantum and classical capacities of the channels have been computed in
entanglement-assisted scenarios
Preservation and enhancement of quantum correlations under Stark effect
We analyze the dynamics of quantum correlations by obtaining the exact
expression of Bures distance entanglement, trace distance discord, and local
quantum uncertainty of two two-level atoms. Here, the atoms undergo two-photon
transitions mediated through an intermediate virtual state where each atom is
separately coupled to a dissipative reservoir at zero temperature in the
presence of the Stark shift effect. We have investigated the dynamics of this
atomic system for two different initial conditions of the environment. In the
first case, we have assumed the environment's state to be in ground state and
in the other case, we have assumed the state to be in first excited state. The
second initial condition is significant as it shows the role played by both the
Stark shift parameters in contrast to only one of the Stark shift parameters
for the first initial condition. Our results demonstrate that quantum
correlations can be sustained for an extended period in the presence of Stark
shift effect in the case of both Markovian and non-Markovian reservoirs. The
effect in the non-Markovian reservoir is more prominent than the Markovian
reservoir, even for a very small value of the Stark shift parameter. We observe
that among the correlation measures considered, only local quantum uncertainty
is accompanied by a sudden change phenomenon, i.e., an abrupt change in the
decay rate of a correlation measure. Our findings are significant as preserving
quantum correlations is one of the essential aspects in attaining optimum
performance in quantum information tasks