Phosphine-Catalyzed Formation of Carbon−Sulfur Bonds: Catalytic Asymmetric Synthesis of γ-Thioesters

A method for catalytic asymmetric γ sulfenylation of carbonyl compounds has been developed. In the presence of an appropriate catalyst, thiols not only add to the γ position of allenoates, overcoming their propensity to add to the β position in the absence of a catalyst, but do so with very good enantioselectivity. Sulfur nucleophiles are now added to the three families of nucleophiles (carbon, nitrogen, and oxygen) that had earlier been shown to participate in catalyzed γ additions. The phosphine catalyst of choice, TangPhos, had previously only been employed as a chiral ligand for transition metals, not as an efficient enantioselective nucleophilic catalyst

Effective Simulation of Quantum Entanglement Based on A Single-photon Field Modulated with Pseudorandom Phase Sequences

We demonstrate that a single-photon field modulated with n different pseudorandom phase sequences (PPSs) can constitute a 2^n-dimensional Hilbert space that contains tensor product structure. By using the single photon field modulated with PPSs, we discuss effective simulation of Bell states and GHZ state, and apply both correlation analysis and von Neumann entropy to characterize the simulation. We obtain similar results with the cases in quantum mechanics and find that the conclusions can be easily generalized to n quantum particles. The research on simulation of quantum entanglement may be important, for it not only provides useful insights into fundamental features of quantum entanglement, but also yields new insights into quantum computation.Comment: 5 pages, 3 figures, a major corrected version. Added an important appendix in which we propose three theoretical prediction

Dynamically generated resonances from the vector meson-octet baryon interaction in the strangeness zero sector

The interaction potentials between vector mesons and octet baryons are calculated explicitly with a summation of t-, s-, u-channel diagrams and a contact term originating from the tensor interaction. Many resonances are generated dynamically in different channels of strangeness zero by solving the coupled-channel Lippman-Schwinger equations with the method of partial wave analysis, and their total angular momenta are determined. The spin partners N(1650)1/2^{-} and N(1700)3/2^-, N(1895)1/2^{-} and N(1875)3/2^-, and the state N(2120)3/2^- are all produced respectively in the isospin I=1/2 sector. In the isospin I=3/2 sector, the spin partners Delta(1620)1/2^- and Delta(1700)3/2^- are also associated with the pole in the complex energy plane. According to the calculation results, a J^P=1/2^- state around 2000 MeV is predicted as the spin partner of N(2120)3/2^-. Some resonances are well fitted with their counterparts listed in the newest review of Particle Data Group(PDG), while others might stimulate the experimental observation in these energy regions in the future.Comment: 28 pages, 12 figures, 8 tables. arXiv admin note: text overlap with arXiv:0905.0973 by other author

Enantioselective carbon–sulfur bond formation: γ additions of aryl thiols to allenoates catalyzed by a chiral phosphepine

An effective phosphine-catalyzed method was developed for the enantioselective addition of aryl thiols to the γ position of allenoates, thereby providing ready access to aryl alkyl sulfides in very good ee. The array of mechanistic data are consistent with the addition of the chiral phosphine to the allenoate being the turnover-limiting step of the catalytic cycle. The optimized reaction conditions, as well as the mechanistic observations, differ markedly from an earlier report on asymmetric additions of alkylthiols to allenoates, which highlights the potential for divergent behavior between alkyl and aryl thiols when acting as nucleophiles

O(α3αs)\mathcal O(\alpha^{3}\alpha_s) Study on the yields and polarizations of J/ψ(Υ)J/\psi(\Upsilon) within the framework of non-relativistic QCD via γγ→J/ψ(Υ)+γ+X\gamma\gamma \to J/\psi(\Upsilon)+\gamma+X at CEPC

Within the framework of the non-relativistic QCD (NRQCD), we make a systematical study of the yields and polarizations of $J/\psi$ and $\Upsilon$ via $\gamma \gamma \to J/\psi(\Upsilon)+\gamma+X$ in photon-photon collisions at the Circular Electron Positron Collider (CEPC), up to $\mathcal O(\alpha^{3}\alpha_s)$. We find that this process at CEPC is quite "clean", namely the direct photoproduction absolutely dominate over the single- and double- resolved processes, at least 2 orders of magnitude larger. It is found that the next-to-leading order (NLO) QCD corrections will significantly reduce the results due to that the virtual corrections to $^3S_1^1$ is large and negative. For $J/\psi$, as $p_t$ increases, the color octet (CO) processes will provide increasingly important contributions to the total NLO results. Moreover the inclusion of CO contributions will dramatically change the polarizations of $J/\psi$ from toally transverse to longitudinal, which can be regarded as a distinct signal for the CO mechanism. However, for the case of $\Upsilon$, the effects of the CO processes are negligible, both for yields and polarizations. For $J/\psi$, the dependence of the yields on the value of the renormalization scale $\mu_r$ is moderate, while significant for the polarization. The impact of the variation of $\mu_{\lambda}$ is found to be relatively slight. As for the case of $\Upsilon$, the uncertainties of $\mu_{r}$ and $\mu_{\lambda}$ just bring about negligible effects. The future measurements on this semi-inclusive photoproductions of $J/\psi(\Upsilon)+\gamma+X$, especially on the polarization parameters of $J/\psi$, will be a good laboratory for the study of heavy quarkonium production mechanism and helpful to clarify the problems of the $J/\psi$ polarization puzzle

Achieve Higher Efficiency at Maximum Power with Finite-time Quantum Otto Cycle

The optimization of finite-time thermodynamic heat engines was intensively explored recently, yet limited to few cycles, e.g. finite-time Carnot-like cycle. In this paper, we supplement a new type of finite-time engine with quantum Otto cycle and show the better performance. The current model can be widely utilized benefited from the general \mathcal{C}/\tau^{2} scaling of extra work for finite-time adiabatic process with long control time \tau. Such scaling allows analytical optimization of the generic finite-time quantum Otto cycle to surpass the efficiency at maximum power for the Carnot-like engine. We apply the current perturbation method to the quantum piston model and calculate the efficiency at maximum power, which is validated with exact solution.Comment: 14 pages, 10 figure

Coexistence of antiferromagnetism and topological superconductivity on honeycomb lattice Hubbard model

Motivated by the recent numerical simulations for doped $t$-$J$ model on honeycomb lattice, we study superconductivity of singlet and triplet pairing on honeycomb lattice Hubbard model. We show that a superconducting state with coexisting spin-singlet and spin-triplet pairings is induced by the antiferromagnetic order near half-filling. The superconducting state we obtain has a topological phase transition that separates a topologically trivial state and a nontrivial state with Chern number two. Possible experimental realization of such a topological superconductivity is also discussed.Comment: 20 pages, 10 figure

Direct Adaptive Controller for Uncertain MIMO Dynamic Systems with Time-varying Delay and Dead-zone Inputs

This paper presents an adaptive tracking control method for a class of nonlinearly parameterized MIMO dynamic systems with time-varying delay and unknown nonlinear dead-zone inputs. A new high dimensional integral Lyapunov-Krasovskii functional is introduced for the adaptive controller to guarantee global stability of the considered systems and also ensure convergence of the tracking errors to the origin. The proposed method provides an alternative to existing methods used for MIMO time-delay systems with dead-zone nonlinearities

Quantum Version of Gauge Invariance and Nucleon Internal Structure

The conflict between cononical commutation relation and gauge invariance, which both the momentum and angular momentum of quark and gluon should satisfy, is clarified. The quantum version of gauge invariance is studied. The gauge independence of the matrix elements of quark momentum and angular momentum operators between physical states are proved. We suggest to use the canonical quark momentum and angular momentum distributions to describe the nucleon internal structure in order to establish an internal consistent description of hadron spectroscopy and hadron structure. The same problem for the atomic spectroscopy and structure is discussed.Comment: 3 pages, in revtex4, to be published in the Proceedings of the International Conference on QCD and Hadronic Physics, Beijing, China, June 16-20, 200

Optical analogy to quantum computation based on classical fields modulated pseudorandom phase sequences

We demonstrate that a tensor product structure and optical analogy of quantum entanglement can be obtained by introducing pseudorandom phase sequences into classical fields with two orthogonal modes. Using the classical analogy, we discuss efficient simulation of several typical quantum states, including product state, Bell states, GHZ state, and W state. By performing quadrature demodulation scheme, we propose a sequence permutation mechanism to simulate certain quantum states and a generalized gate array model to simulate quantum algorithm, such as Shor's algorithm and Grover's algorithm. The research on classical simulation of quantum states is important, for it not only enables potential beyond quantum computation, but also provides useful insights into fundamental concepts of quantum mechanics.Comment: Modify the title and some errors of Eq.(1),(38) and Fig. 1; 28 pages, 13 figures, Welcome to comment! Major update version of arXiv:1003.603