We investigate ultrafast generation of spin-motion entanglement of a trapped and Gaussian-pulse-kicked two-level ion in the Lamb-Dicke limit and high field regime. A set of exact motional states and the probabilities occupying different pseudospin states are derived and the visible differences between the results with those of the delta-kick case are shown during a kick moment, which analytically evidence the ultrafast generation of an exact spin-motion entangled state regardless of initial state. Our results can be justified with the current experimental capability and provide an analytical method for further study of the ultrafast entanglement in atomic qubits.

We wish to point out and to correct a misprint in formula (3) of this paper where a factor 1 2 was missed. The correct expression for Eq. (3) should be, which governs the time evolution of the probability amplitudes. The factor 1/2 should also appear just before G(t) in Eq. (1) of this paper.This misprint does not affect the results and conclusions of the paper.

Exact solutions for spin-orbit (SO) coupled cold atomic systems are very important and rare in physics. In this paper, we propose a simple method of combined modulations to generate the exactly analytic solutions for a single SO-coupled ultracold atom held in a driven double well. For the cases of synchronous combined modulations and the spin-conserving tunneling, we obtain the generally accurate solutions of this system respectively. For the case of spin-flipping tunneling under asynchronous combined modulations, we get the specially exact solutions in simple form when the driving parameters are appropriately chosen. Based on these obtained exact solutions, we reveal some intriguing quantum spin dynamical phenomena, for instance, the arbitrary coherent population transfer (ACPT) with and/or without spin-flipping, the controlled coherent population conservation (CPC), and the controlled coherent population inversion (CPI). The results may provide a possibility for generating the accurate quantum entangled states and the exact control of spin dynamics for a SO-coupled ultracold atomic system.

We investigate the coherent control of spin tunneling for a spin-orbit (SO) coupled boson trapped in a driven triple well. In the high-frequency limit, the quasienergies of the system are obtained analytically and the fine energy band structures are shown. By regulating the driving parameters, we reveal that the directed spin-flipping or spin-conserving tunneling of an SO-coupled boson occurs along different pathways and in different directions. The analytical results are demonstrated by numerical simulations and good agreements are found. Further, an interesting scheme of quantum spin tunneling switch with or without spin-flipping is presented. The results may have potential applications in the design of spintronic devices.

We introduce a three-dimensional chaotic system and reveal the relation between signal amplitude and the system parameters which can enrich the key for a cryptosystem. To study application of the relation to multi-media security, we propose an image encryption scheme based on the permutation-diffusion architecture. Security of immunity to known-plaintext attack and chosen-plaintext attack is ensured by adopting plaintext sequence and amplitude parameter to generate key stream with the ideology of one-time pad. Numerical experiments are implemented and prominent advantage of the theoretical scheme is confirmed.