[QIP-Sem] QIP seminar, Mon 4/27, 4:15, 34-401B, Smith,Graeme

[Peter Shor]

MIT Quantum Information Processing seminar
Monday 4/27 at 4:15 in 34-401B
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 Smith,Graeme (IBM)

Quantum Communication With Zero-Quantum-Capacity Channels

Abstract:

Besides transmitting ordinary classical information, some quantum channels can faithfully transmit intact quantum states.  A channel's capacity for such coherent transmission, its quantum capacity, is of central importance in quantum information theory as it measures the optimum performance of quantum error-correcting codes.  I will show that two quantum channels, each of zero quantum capacity, can nevertheless achieve a positive quantum capacity when used together.   This result contrasts sharply with the classical setting, where the capacity of a channel is independent of what other channels are available.  This uniquely quantum effect unveils a rich structure in the theory of quantum communications and shows that there are several kinds of quantum information, the ability to transmit each of which is necessary but not sufficient for faithful quantum communication.

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