Quantum state transfer via the ferromagnetic chain in a spatially modulated field

We show that a perfect quantum state transmission can be realized through a spin chain possessing a commensurate structure of energy spectrum, which is matched with the corresponding parity. As an exposition of the mirror inversion symmetry discovered by Albanese et. al (quant-ph/0405029), the parity matched the commensurability of energy spectra help us to present the novel pre-engineered spin systems for quantum information transmission. Based on the these theoretical analysis, we propose a protocol of near-perfect quantum state transfer by using a ferromagnetic Heisenberg chain with uniform coupling constant, but an external parabolic magnetic field. The numerical results shows that the initial Gaussian wave packet in this system with optimal field distribution can be reshaped near-perfectly over a longer distance.Comment: 5 pages, 2 figure

Quantum information storage and state transfer based on spin systems

The idea of quantum state storage is generalized to describe the coherent transfer of quantum information through a coherent data bus. In this universal framework, we comprehensively review our recent systematical investigations to explore the possibility of implementing the physical processes of quantum information storage and state transfer by using quantum spin systems, which may be an isotropic antiferromagnetic spin ladder system or a ferromagnetic Heisenberg spin chain. Our studies emphasize the physical mechanisms and the fundamental problems behind the various protocols for the storage and transfer of quantum information in solid state systems.Comment: 11 pages, 9 figures, Review article on the quantum spin based quantum information processing, to appear the special issue of Low Temperature Physics dedicated to the 70-th anniversary of creation of concept "antiferromagnetism" in physics of magnetis

Perfect transference of a d-level quantum state over pseudo-distance-regular networks

Following the prescription of Ref. \cite{PST} in which perfect state transference (PST) of a qubit over distance regular spin networks was discussed, in this paper PST of an arbitrary $d$-level quantum state (qudit) over antipodes of more general networks called pseudo distance-regular networks, is investigated. In fact, the spectral analysis techniques used in the previous work \cite{PST}, and algebraic structures of pseudo distance-regular graphs are employed to give an explicit formula for suitable coupling constants in the Hamiltonians so that the state of a particular qudit initially encoded on one site will evolve freely to the opposite site without any dynamical control, i.e., we show that how to derive the parameters of the system so that PST can be achieved. Keywords:Perfect state transfer, $d$-level quantum state, Stratification, Pseudo-distance-regular network PACs Index: 01.55.+b, 02.10.YnComment: 28 pages, 5 figure

Observation of a near-threshold enhancement in th p pbar mass spectrum from radiative J/psi-->gamma p pbar decays

We observe a narrow enhancement near 2mp in the invariant mass spectrum of ppbar pairs from radiative J/psi-->gamma ppbar decays. The enhancement can be fit with either an S- or P-wave Breit Wigner fuction. In the case of the S-wave fit, the peak mass is below the 2mp threshold and the full width is less than 30 MeV. These mass and width values are not consistent with the properties of any known meson resonance.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Let

Observation of J/ψJ/\psi decays to e+e−e+e−e^{+}e^{-}e^{+}e^{-} and e+e−μ+μ−e^{+}e^{-}\mu^{+}\mu^{-}

Using a data sample of $4.481\times 10^8$ $\psi(3686)$ events collected with the BESIII detector, we report the first observation of the four-lepton-decays $J/\psi\to e^+e^-e^+e^-$ and $J/\psi\to e^+e^-\mu^+\mu^-$ utilizing the process $\psi(3686)\to \pi^+\pi^- J/\psi$. The branching fractions are determined to be $[4.32\pm0.26~(\rm stat)\pm0.19~(\rm syst)]\times 10^{-5}$ and $[2.45~\pm0.21~(\rm stat)\pm0.10~(\rm syst)]\times 10^{-5}$, respectively. The results deviate from theoretical predictions, by 2.8 and 5.2 $\sigma$, respectively. No significant signal is observed for $J/\psi\to \mu^+\mu^-\mu^+\mu^-$, and an upper limit on the branching fraction is set at $1.6\times 10^{-6}$ at the 90$\%$ confidence level. A CP asymmetry observable is constructed for the first two channels, which is measured to be $(-0.019\pm0.067\pm0.025)$ and $(-0.016\pm0.081\pm0.003)$, respectively. No evidence for CP violation is observed in this process.Comment: 9 pages, 1 figur

Partial Wave Analyses of J/ψ→γK+K−J/\psi\to\gamma K^+K^- and γKS0KS0\gamma K^0_SK^0_S

Results are presented on $J/\psi$ radiative decays to $K^+K^-$ and $K^0_SK^0_S$ based on a sample of 58M $J/\psi$ events taken with the BES II detector. A partial wave analysis is carried out using the relativistic covariant tensor amplitude method in the 1-2 GeV mass range. There is conspicuous production due to the $f'_2(1525)$ and $f_0(1710)$. The latter peaks at a mass of $1740\pm 4^{+10}_{-25}$ MeV with a width of $166{^{+5}_{-8}}{^{+15}_{-10}}$ MeV. Spin 0 is strongly preferred over spin 2. For the $f'_2(1525)$, the helicity amplitude ratios are determined to be $x^2 = 1.00\pm0.28^{+1.06}_{-0.36}$ and $y^2 = 0.44\pm{0.08}^{+0.10}_{-0.56}$.Comment: 16 pages, 5 figure

Study of ψ(3686)→ΛΛˉω\psi(3686)\rightarrow\Lambda\bar{\Lambda}\omega

Based on a data sample of $(448.1\pm2.9)\times10^6$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII collider, the branching fraction of $\psi(3686)\rightarrow\Lambda\bar{\Lambda}\omega$ is measured to be $\rm (3.30\pm0.34(stat.)\pm0.29(syst.))\times10^{-5}$ for the first time. In addition, the $\Lambda\omega$ (or $\bar{\Lambda}\omega$) invariant mass spectra is studied and the potential presence of excited $\Lambda$ states has been investigated