A fibre link is long with an attenuation of .

PHYSICS · Multi-part · Fermi University Physics · Quantum Information & Technology · Quantum information theory and communication · Quantum information theory and communication

Quantum Information and Technology, Ch Quantum key distribution and quantum networks

Problem

A fibre link is

150\,\mathrm{km}

long with an attenuation of

0.2\,\mathrm{dB\,km^{-1}}

. ((a)) Find the transmission

\eta

of the fibre. ((b)) Find the repeaterless bound on the secret-key rate in bits per pulse,

-\log_2(1-\eta)

. ((c)) A

1\,\mathrm{GHz}

pulsed source is used. Find the corresponding upper bound on the secret-key rate in bits per second.

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