Spin-exchange collisions in hot vapors creating and sustaining bipartite entanglement

Bipartite entanglement and entropic boundary law in lattice spin systems

We investigate bipartite entanglement in spin-1/2 systems on a generic lattice. For states that are an equal superposition of elements of a group G of spin flips acting on the fully polarized state |0〉 , we find that the von Neumann entropy depends only on the boundary between the two subsystems A and B. These states are stabilized by the group G. A physical realization of such states is given ...

Spin-Exchange in Hydrogen-Antihydrogen Collisions

We consider the spin-exchange in ultracold collisions of hydrogen (H) and antihydrogen (H̄) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange in H̄ − H collisions is basically driven by the strong force between proton and antiproton, that spin-exchange cross-sections are proportional to the difference of singlet an...

Spin exchange in elastic e-O2 collisions.

Spin exchange rates in electron-hydrogen collisions

The spin temperature of neutral hydrogen, which determines the 21 cm optical depth and brightness temperature, is set by the competition between radiative and collisional processes. In the high-redshift intergalactic medium, the dominant collisions are typically those between hydrogen atoms. However, collisions with electrons couple much more efficiently to the spin state of hydrogen than do co...

Spin exchange rates in proton-hydrogen collisions

The spin temperature of neutral hydrogen, which determines the optical depth and brightness of the 21 cm line, is determined by the competition between radiative and collisional processes. Here we examine the role of proton-hydrogen collisions in setting the spin temperature. We use recent fully quantum-mechanical calculations of the relevant cross sections, which allow us to present accurate r...