Spinor Bose-Einstein condensates of positronium
Abstract
Bose-Einstein condensates (BECs) of positronium (Ps) have been of experimental and theoretical interest due to their potential application as the gain medium of a γ-ray laser. Ps BECs are intrinsically spinor due to the presence of ortho-positronium (o-Ps) and para-positronium (p-Ps), whose annihilation lifetimes differ by three orders of magnitude. In this paper, we study the spinor dynamics and annihilation processes in the p-Ps/o-Ps system using both solutions of the time-dependent Gross-Pitaevskii equations and a semiclassical rate-equation approach. The spinor interactions have an O(4) symmetry which is broken to SO(3) by an internal energy difference between o-Ps and p-Ps. For an initially unpolarized condensate, there is a threshold density of ≈1019 cm-3 at which spin mixing between o-Ps and p-Ps occurs. Beyond this threshold, there are unstable spatial modes accompanied by spin mixing. To ensure a high production yield above the critical density, a careful choice of external field must be made to avoid the spin mixing instability.
- Publication:
-
Physical Review A
- Pub Date:
- April 2014
- DOI:
- 10.1103/PhysRevA.89.043624
- arXiv:
- arXiv:1402.5159
- Bibcode:
- 2014PhRvA..89d3624W
- Keywords:
-
- 03.75.Mn;
- 36.10.Dr;
- 42.55.Vc;
- Multicomponent condensates;
- spinor condensates;
- Positronium muonium muonic atoms and molecules;
- X- and gamma-ray lasers;
- Condensed Matter - Quantum Gases;
- Physics - Atomic Physics
- E-Print:
- 14 pages, 9 figures