K-quantum nonlinear coherent states: formulation, realization and nonclassical effects

We introduce a generalized class of states called K-quantum nonlinear coherent states. Each K-state has K j-components corresponding to one and the same eigenvalue. Each Kj-component can be composed of K K=1-states in a correlated manner. The introduced states are shown to be realized in the long-term behavior of the vibrational motion of an ion properly trapped and laser-driven. Nonclassical properties of the states are studied in detail.Comment: 6 pages, 9 figure

Quantum dialogue

We propose an entanglement-based protocol for two people to simultaneously exchange their messages. We show that the protocol is asymptotically secure against the disturbance attack, the intercept-and-resend attack and the entangle-and-measure attack. Our protocol is experimentally feasible within current technologies.Comment: 4 pages, Revtex

Multi-directional higher-order amplitude squeezing

Fan-even K-quantum nonlinear coherent states are introduced and higher-order amplitude squeezing is investigated in such states. It is shown that for a given K the lowest order in which an amplitude component can be squeezed is 2K and the squeezing appears simultaneously in K directions separated successively in phase by \pi/K.Comment: 7 pages, 4 figures, text improved, references added, accepted in Phys. Lett.

Reply to Yang et al.'s comment

This is to reply to a recent comment by Yang, Yuan and Zhang on ``Teleportation of two-quNit entanglement: Exploiting local resorces''.Comment: 1 page, No figures, RevTe

Quantum exam

Absolutely and asymptotically secure protocols for organizing an exam in a quantum way are proposed basing judiciously on multipartite entanglement. The protocols are shown to stand against common types of eavesdropping attack.Comment: RevTex4, no fig

Cavity-catalyzed deterministic generation of maximal entanglement between nonidentical atoms

By exactly solving the underlying Sch\"{o}dinger equation we show that one and the same resonant cavity can be used as a catalyst to maximally entangle atoms of two nonidentical groups. The generation scheme is realistic and advantageous in the sense that it is deterministic, efficient, scalable and immune from decoherence effects.Comment: RevTex4, 1 fi

The average detection probability of the quantum dialogue protocol under the disturbance attack is 3/4

We prove explicitly that the detection probability of the disturbance attack in the recently proposed quantum dialogue protocol is 3/4 in average. The purpose is not only to reply a comment but also to provide a deeper understanding of a kind of tampering in an unauthorized communication.Comment: 3 pages, Revtex

Multimode cat-state entanglement and network teleportation

Schemes for generation and protocols for network teleportation of multimode entangled cat-states are proposed. Explicit expressions for probability of successful teleportation are derived for both symmetric and asymmetric networks.Comment: 14 pages, 5 figures, RevTe

Generation of fan-states of radiation field in a cavity

A scheme of generating recently introduced fan-states | \alpha, 2k>_F (\alpha is complex, k=1,2,3,...) is proposed basing on a \Lambda-type atom-cavity field interaction. We show that with suitable atomic preparations and measurements a passage of a sequence of N atoms through a cavity may transform an initial field coherent state | \alpha> to a fan-state | \alpha, 2k>_F with k=2^{N-2}.Comment: 9 pages, 5 figures, RevTe

Hillery-type squeezing in fan-states

We study the Hillery-type, i.e. $N$-th power, amplitude squeezing in the fan-state $| \xi ;2k,f>_{F}$ characterized by $\xi \in \mathcal{C}$, $k=1,2,3,...$ and $f$ a nonlinear operator-valued function. We show that for a given $k$ there exists a critical $\xi_c$ such that for $0<|\xi|\leq|\xi_c|$ squeezing occurs simultaneously in $2k$ directions for the powers $N$ which are a multiple of $2k$. This result does not depend on the concrete form of $f$, i.e. it holds true for both $f\equiv 1$ and $f\neq 1$. However, for $f\neq 1$, which is realized here in the ion trap context, the squeezing directions as well as the magnitude of $\xi$ can be controlled by adjusting the system driving parameters.Comment: 8 pages, 5 figure