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Quantum Communication
Reliable transmission of information through quantum systems is a central
topic in quantum information theory. One can use quantum systems to encode
both classical and quantum information.
Quantum systems unavoidably interact with their environment, and this interaction
adds noise to the transmission. Mathematically this can described by a quantum
map, often called quantum channel, which transforms any input quantum state into
an output one, from which it is not possible to unambiguously infer the input state.
Our research deals with quantum memory channels, i.e. those channels
whose subsequent uses are correlated.
Quantum channels with memory are the natural theoretical framework for the study
of any quantum noisy communication system where correlation times are longer than the
time between consecutive uses. This scenario applies to optical fibers which may show a
birefringence fluctuating with a characteristic time longer than the separation between successive
light pulses or to solid state implementations of quantum hardware, where
several sources of decoherence exhibit a large amplitude power spectrum at low frequencies (for instance 1/f).
We study the effect of memory on the quantum information transmission, also
evaluating the impact of memory on some few-uses quantum error correcting codes (QECCs).
RECENT HIGHLIGHTS by SMT:
Enhancement of Transmission Rates in Quantum Memory Channels with Damping,
G. Benenti, A. D'Arrigo and G. Falci,
Phys. Rev. Lett. 103, 020502 (2009).
Quantum capacity of dephasing channels with memory,
A. D'Arrigo, G. Benenti, G. Falci,
New Journal of Physics 9, 310 (2007).