2 research outputs found
Correspondence between maximally entangled states in discrete and Gaussian regimes
We study a general corresponding principle between discrete-variable quantum
states and continuous-variable (especially, restricted on Gaussian) states via
quantum purification method. In the previous work, we have already investigated
an information-theoretic correspondence between the Gaussian maximally mixed
states (GMMSs) and their purifications known as Gaussian maximally entangled
states (GMESs) in [Phys. Lett. A {\bf 380}, 3607 (2016)]. We here compare an
-dimensional maximally entangled state to the GMES we proposed
previously, through an explicit calculation of quantum fidelity between those
entangled states. By exploiting the results, we naturally conclude that our
GMES is more suitable to the concept of \emph{maximally entangled} state in
Gaussian quantum information, and thus it might be useful or applicable for
quantum information tasks than the two-mode squeezed vacuum (TMSV) state in the
Gaussian regime.Comment: 5 pages, 2 figures; Minor changed and references update
Approximate private quantum channels on fermionic Gaussian systems
The private quantum channel (PQC) maps any quantum state to the maximally
mixed state for the discrete as well as the bosonic Gaussian quantum systems,
and it has fundamental meaning on the quantum cryptographic tasks and the
quantum channel capacity problems. In this paper, we introduce a notion of
approximate private quantum channel (-PQC) on fermionic Gaussian
systems (i.e., -FPQC), and construct its explicit form of the
fermionic (Gaussian) private quantum channel. First of all, we suggest a
general structure for -FPQC on the fermionic Gaussian systems with
respect to the Schatten -norm class, and then we give an explicit proof of
the statement in the trace norm. In addition, we study that the cardinality of
a set of fermionic unitary operators agrees on the -FPQC condition
in the trace norm case.Comment: 5 pages and 1 figur