Interatomic collisions in two-dimensional and quasi-two-dimensional confinements with spin-orbit coupling

We investigate the low-energy scattering and bound states of two two-component fermionic atoms in pure two-dimensional (2D) and quasi-2D confinements with Rashba spin-orbit coupling (SOC). We find that the SOC qualitatively changes the behavior of the 2D scattering amplitude in the low-energy limit. For quasi-2D systems we obtain the analytic expression for the effective-2D scattering amplitude and the algebraic equations for the two-atom bound state energy. Based on these results, we further derive the effective 2D interaction potential between two ultracold atoms in the quasi-2D confinement with Rashba SOC. These results are crucial for the control of the 2D effective physics in quasi-2D geometry via the confinement intensity and the atomic three-dimensional scattering length.Comment: 13pages, 5 figure

Creation of Entanglement between Two Electron Spins Induced by Many Spin Ensemble Excitations

We theoretically explore the possibility of creating spin entanglement by simultaneously coupling two electronic spins to a nuclear ensemble. By microscopically modeling the spin ensemble with a single mode boson field, we use the time-dependent Fr\"{o}hlich transformation (TDFT) method developed most recently [Yong Li, C. Bruder, and C. P. Sun, Phys. Rev. A \textbf{75}, 032302 (2007)] to calculate the effective coupling between the two spins. Our investigation shows that the total system realizes a solid state based architecture for cavity QED. Exchanging such kind effective boson in a virtual process can result in an effective interaction between two spins. It is discovered that a maximum entangled state can be obtained when the velocity of the electrons matches the initial distance between them in a suitable way. Moreover, we also study how the number of collective excitations influences the entanglement. It is shown that the larger the number of excitation is, the less the two spins entangle each other.Comment: 8 pages, 4 figure

Low Scale Unification, Newton's Law and Extra Dimensions

Motivated by recent work on low energy unification, in this short note we derive corrections on Newton's inverse square law due to the existence of extra decompactified dimensions. In the four-dimensional macroscopic limit we find that the corrections are of Yukawa type. Inside the compactified space of n-extra dimensions the sub-leading term is proportional to the (n+1)- power of the distance over the compactification radius ratio. Some physical implications of these modifications are briefly discussed.Comment: 12pages, 2 figure

Modified Bethe-Peierls boundary condition for ultracold atoms with Spin-Orbit coupling

We show that the Bethe-Peierls (BP) boundary condition should be modified for ultracold atoms with spin-orbit (SO) coupling. Moreover, we derive a general form of the modified BP boundary condition, which is applicable to a system with arbitrary kind of SO coupling. In the modified BP condition, an anisotropic term appears and the inter-atomic scattering length is normally SO-coupling dependent. For the special system in the current experiments, however, it can be proved that the scattering length is SO-coupling independent, and takes the same value as in the case without SO coupling. Our result is helpful for the study of both few-body and many-body physics in SO-coupled ultracold gases.Comment: 8 pages, significant improvement is made in the current versio

Rubisco activation limits photosynthesis in wheat

Light available for photosynthesis fluctuates continuously in the field, as clouds cross the sun and as the movement of the sun causes shadows to move across leaves. Transgenic manipulations to allow more rapid relaxation of non-photochemical quenching during sun-shade transitions increased productivity in the field by 14-20%. Rubisco activation is a key limit on photosynthesis during induction following shade-sun transitions. This suggests there may also be potential to increase photosynthesis and crop productivity by speeding up Rubisco activation

Deviations from the 1/r21/r^2 Newton law due to extra dimensions

We systematically examine corrections to the gravitational inverse square law, which are due to compactified extra dimensions. We find the induced Yukawa-type potentials for which we calculate the strength \alpha and range. In general the range of the Yukawa correction is given by the wavelength of the lightest Kaluza-Klein state and its strength, relative to the standard gravitational potential, by the corresponding degeneracy. In particular, when n extra dimensions are compactified on an n-torus, we find that the strength of the potential is \alpha=2n, whereas the compactification on an n-sphere gives \alpha= n+1. For Calabi-Yau compactifications the strength can be at most \alpha=20.Comment: 8 pages, latex, 1 figure; v2: References added and some clarifications in sec. 3 are made; v3: Physics Letters B versio

Taylor, Melba

https://egrove.olemiss.edu/pohp/1011/thumbnail.jp