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Efficient Quantum Cryptography Network without Entanglement and Quantum Memory 总被引:1,自引:0,他引:1 下载免费PDF全文
An efficient quantum cryptography network protocol is proposed with d-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are |0〉. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse. 相似文献
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A multiparty quantum secret report scheme is proposed with quantum encryption. The boss Alice and her M agents first share a sequence of (M + 1)-particle Greenberger-Horne-Zeilinger (GHZ) states that only Alice knows which state each (M + 1)-particle quantum system is in. Each agent exploits a controlled-not (CNot) gate to encrypt the travelling particle by using the particle in the GHZ state as the control qubit. The boss Alice decrypts the travelling particle with a CNot gate after performing a aσ∞ operation on her particle in the GHZ state or not. After the GHZ states (the quantum key) are used up, the parties check whether there is a vicious eavesdropper, say Eve, monitoring the quantum line, by picking out some samples from the GHZ states shared and measuring them with two measuring bases. After confirming the security of the quantum key, they use the remaining GHZ states repeatedly for the next round of quantum communication. This scheme has the advantage of high intrinsic efficiency for the qubits and total efficiency. 相似文献
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This paper presents a scheme for faithfully distributing a pure
entanglement between two parties over an arbitrary collective-noise
channel with linear optics. The transmission is assisted by an
additional qubit against collective noise. The receiver can take
advantage of the time discrimination and the measurement results of
the assistant qubit to reconstruct a pure entanglement with the
sender. Although the scheme succeeds probabilistically, the resource
used to get a pure entanglement state is finite, and so is easier to
establish entanglement in practice than quantum entanglement
purification. 相似文献
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We have extracted the nuclear asymptotic normalization coefficients (ANC) for the virtual transitions B→A+N via some transfer reactions and the radioactive nuclear beam experiments. With these coefficients, root-mean-square (rms) radii for the valence particle in some possible halo nuclei have been calculated. The values of rms radii extracted with ANC approach are nearly model-independent, hence are a good quantity for the investigation of nuclear halo. In addition, we have also calculated the rms radii for the two valence neutrons in some three-body systems in terms of the relationship between the radii of valence particle, core nucleus and nuclear matter. With two conditions for nuclear halo formation, we have examined these extracted rms radii. The results show that 11Be(1/2+, g.s), 12B(1-, 2.621 MeV), 13C(1/2+, 3.089 MeV), 14C(0-, 6.903 MeV), 14C(1-, 6.094 MeV), 15C(1/2+, g.s) and 19C(1/2+, g.s) with the valence particle in the 2s ground or excited state are the neutron halo nuclei, whereas 17F(1/2+, 0.495 MeV) and 21Na(1/2+, 2.423 MeV) are the proton halo nuclei in the excited state. For three-body systems, except the well-established two-neutron halo nuclei 6He and 11Li, 14Be and 17B might be the two-neutron halo nuclei as well. 相似文献
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