Pulse-pumped double quantum dot with spin-orbit coupling

We consider the full driven quantum dynamics of a qubit realized as spin of electron in a one-dimensional double quantum dot with spin-orbit coupling. The driving perturbation is taken in the form of a single half-period pulse of electric field. Spin-orbit coupling leads to a nontrivial evolution in the spin and charge densities making the dynamics in both quantities irregular. As a result, the charge density distribution becomes strongly spin-dependent. The transition from the field-induced tunneling to the strong coupling regime is clearly seen in the charge and spin channels. These results can be important for the understanding of the techniques for the spin manipulation in nanostructures.Comment: 6 figure

Spin dynamics in a strongly driven system: very slow Rabi oscillations

We consider joint effects of tunneling and spin-orbit coupling on driven by electric field spin dynamics in a double quantum dot with a multi-level resonance scenario. We demonstrate that tunneling plays the crucial role in the formation of the Rabi-like spin-flip transitions. In contrast to the linear behavior for weak electric fields, the spin flip rate becomes much smaller than expected for the two-level model and shows oscillating dependence on the driving field amplitude in stronger fields. In addition, the full spin flip is very difficult to achieve in a multi-level resonant system. These two effects have a similarity with the Zeno effect of slowing down the dynamics of an observable by its measurement. As a result, spin manipulation by electric field becomes much less efficient than expected.Comment: 6 pages, 5 figure

Von Neumann spin measurements with Rashba fields

We show that dynamics in spin-orbit coupling field simulates the von Neumann measurement of a particle spin. We demonstrate how the measurement influences the spin and coordinate evolution of a particle by comparing two examples of such a procedure. First example is a simultaneous measurement of spin components, $\sigma _{x}$ and $\sigma _{y}$, corresponding to non-commuting operators, which cannot be accurately obtained together at a given time instant due to the Heisenberg uncertainty ratio. By mapping spin dynamics onto a spatial walk such a procedure determines measurement-time averages of $\sigma _{x}$ and $\sigma _{y}$, which already can be precisely evaluated in a single short-time measurement. The other, qualitatively different, example is the spin of a one-dimensional particle in a magnetic field. Here the outcome depends on the angle between the spin-orbit coupling and magnetic fields. These results can be applied to studies of spin-orbit coupled cold atoms and electrons in solids.Comment: 6 figure

Reversible strain effect on the magnetization of LaCoO3 films

The magnetization of ferromagnetic LaCoO3 films grown epitaxially on piezoelectric substrates has been found to systematically decrease with the reduction of tensile strain. The magnetization change induced by the reversible strain variation reveals an increase of the Co magnetic moment with tensile strain. The biaxial strain dependence of the Curie temperature is estimated to be below 4K/% in the as-grown tensile strain state of our films. This is in agreement with results from statically strained films on various substrates

Partners or predators? : the impact of regional trade liberalization on Indonesia

The authors empirically assess regional integration and liberalization scenarios impact on Indonesia and other Pacific Rim economies, including the complete Uruguay Round, further global liberalization and the creation of the Association of Southeast Asian Nations (ASEAN) or Asia-Pacific Economic Cooperation (APEC) free trade areas. They consider how major international exchange rate realignments affect the world trade pattern, and Indonesia in particular. The analysis uses a multi-country, computable general equilibrium (CGE) model to quantify the trade liberalization impact on countries, sectors, and factors. The extended APEC-CGE model consists of nine linked country models: Indonesia, Malaysia, and Singapore (together), the Philippines, Thailand, China (including Hong Kong), Korea and Taiwan, Japan, the United States and the European Union. Each country model is linked through explicit bilateral trade flows modeling for each traded sector. The empirical results lead to several conclusions: a) eliminating tariff and non tariff barriers in industrial countries (especially the Multifibre Agreement) gives Asian developing countries the opportunity to expand exports and achieve productivity gains; b) creation of an APEC free trade area gives participants significant benefits, with little effect on nonmembers while creation of an ASEAN free trade area gives its members little benefit, thus ASEAN countries should work toward more liberalization under GATT or hasten the APEC free trade area creation; c) all economies gain the most from further multilateral liberalization; and d) major exchange rate realignments significantly affect bilateral trade balances and world trade volume and direction. However, they have less effect than trade liberalization on the internal production and trade structure. Sectoral protection andsubsidy rates vary greatly and their elimination yields significant efficiency gains. Changes in exchange rates have less effect.Trade Policy,Environmental Economics&Policies,Payment Systems&Infrastructure,Economic Theory&Research,Transport and Trade Logistics,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Environmental Economics&Policies,Trade and Regional Integration,Trade Policy

Determination of the 5d6s 3D1 state lifetime and blackbody radiation clock shift in Yb

The Stark shift of the ytterbium optical clock transition due to room temperature blackbody radiation is dominated by a static Stark effect, which was recently measured to high accuracy [J. A. Sherman et al., Phys. Rev. Lett. 108, 153002 (2012)]. However, room temperature operation of the clock at 10^{-18} inaccuracy requires a dynamic correction to this static approximation. This dynamic correction largely depends on a single electric dipole matrix element for which theoretically and experimentally derived values disagree significantly. We determine this important matrix element by two independent methods, which yield consistent values. Along with precise radiative lifetimes of 6s6p 3P1 and 5d6s 3D1, we report the clock's blackbody radiation shift to 0.05% precision