We analyse the capacity of a simultaneous quantum secure direct communication scheme between the central party and other M parties via M＋1-particle GHZ states and swapping quantum entanglement. It is shown that the e...We analyse the capacity of a simultaneous quantum secure direct communication scheme between the central party and other M parties via M＋1-particle GHZ states and swapping quantum entanglement. It is shown that the encoding scheme should be secret if other M parties wants to transmit M ＋ 1 bit classical messages to the centre party secretly. However, when the encoding scheme is announced publicly, we prove that the capacity of the scheme in transmitting the secret messages is 2 bits, no matter how large M is.展开更多
基金Supported by the Natural Science Foundation of Hebei Province under Grant Nos A2004000141 and A2005000140, and the Natural Science Foundation of Hebei Normal University.
文摘We analyse the capacity of a simultaneous quantum secure direct communication scheme between the central party and other M parties via M＋1-particle GHZ states and swapping quantum entanglement. It is shown that the encoding scheme should be secret if other M parties wants to transmit M ＋ 1 bit classical messages to the centre party secretly. However, when the encoding scheme is announced publicly, we prove that the capacity of the scheme in transmitting the secret messages is 2 bits, no matter how large M is.
