34,636 research outputs found
Quantum secret sharing between m-party and n-party with six states
We propose a quantum secret sharing scheme between -party and -party
using three conjugate bases, i.e. six states. A sequence of single photons,
each of which is prepared in one of the six states, is used directly to encode
classical information in the quantum secret sharing process. In this scheme,
each of all members in group 1 choose randomly their own secret key
individually and independently, and then directly encode their respective
secret information on the states of single photons via unitary operations, then
the last one (the th member of group 1) sends of the resulting qubits
to each of group 2. By measuring their respective qubits, all members in group
2 share the secret information shared by all members in group 1. The secret
message shared by group 1 and group 2 in such a way that neither subset of each
group nor the union of a subset of group 1 and a subset of group 2 can extract
the secret message, but each whole group (all the members of each group) can.
The scheme is asymptotically 100% in efficiency. It makes the Trojan horse
attack with a multi-photon signal, the fake-signal attack with EPR pairs, the
attack with single photons, and the attack with invisible photons to be
nullification. We show that it is secure and has an advantage over the one
based on two conjugate bases. We also give the upper bounds of the average
success probabilities for dishonest agent eavesdropping encryption using the
fake-signal attack with any two-particle entangled states. This protocol is
feasible with present-day technique.Comment: 7 page
Technological innovations at the onset of the Mid-Pleistocene Climate Transition in high-latitude East Asia
The interplay between Pleistocene climatic variability and hominin adaptations to diverse terrestrial ecosystems is a key topic in human evolutionary studies. Early and Middle Pleistocene environmental change and its relation to hominin behavioural responses has been a subject of great interest in Africa and Europe, though little information is available for other key regions of the Old World, particularly from Eastern Asia. Here we examine key Early Pleistocene sites of the Nihewan Basin, in high-latitude northern China, dating between ∼1.4 to 1.0 million years ago (Ma). We compare stone tool assemblages from three Early Pleistocene sites in the Nihewan Basin, including detailed assessment of stone tool refitting sequences at the ∼1.1 Ma-old site of Cenjiawan. Increased toolmaking skills and technological innovations are evident in the Nihewan Basin at the onset of the Mid-Pleistocene Climate Transition (MPT). Examination of the lithic technology of the Nihewan sites, together with an assessment of other key Palaeolithic sites of China, indicates that toolkits show increasing diversity at the outset of the MPT and in its aftermath. The overall evidence indicates the adaptive flexibility of early hominins to ecosystem changes since the MPT, though regional abandonments are also apparent in high-latitudes, likely owing to cold and oscillating environmental conditions. The view presented here sharply contrasts with traditional arguments that stone tool technologies of China are homogeneous and continuous over the course of the Early Pleistocene.Introduction Results - Stone-tool-knapping skills recorded in the Cenjiawan assemblage - Technological comparisons of the Nihewan Basin assemblages Discussio
Probabilistic teleportation of unknown two-particle state via POVM
We propose a scheme for probabilistic teleportation of unknown two-particle
state with partly entangled four-particle state via POVM. In this scheme the
teleportation of unknown two-particle state can be realized with certain
probability by performing two Bell state measurements, a proper POVM and a
unitary transformation.Comment: 5 pages, no figur
Circular quantum secret sharing
A circular quantum secret sharing protocol is proposed, which is useful and
efficient when one of the parties of secret sharing is remote to the others who
are in adjacent, especially the parties are more than three. We describe the
process of this protocol and discuss its security when the quantum information
carrying is polarized single photons running circularly. It will be shown that
entanglement is not necessary for quantum secret sharing. Moreover, the
theoretic efficiency is improved to approach 100% as almost all the instances
can be used for generating the private key, and each photon can carry one bit
of information without quantum storage. It is straightforwardly to utilize this
topological structure to complete quantum secret sharing with multi-level
two-particle entanglement in high capacity securely.Comment: 7 pages, 2 figure
Charged coherent states related to su_{q}(2) covariance
A new kind of q-deformed charged coherent states is constructed in Fock space
of two-mode q-boson system with su_{q}(2) covariance and a resolution of unity
for these states is derived. We also present a simple way to obtain these
coherent states using state projection method.Comment: 7 pages. To appear in Modern Phyics Letter:
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