Simulations of prompt many-body ionization in a frozen Rydberg gas

The results of a theoretical investigation of prompt many-body ionization are reported. Our calculations address an experiment that reported ionization in Rydberg gases for densities two orders of magnitude less than expected from ionization between pairs of atoms. The authors argued that the results were due to the simultaneous interaction between many atoms. We performed classical calculations for many interacting Rydberg atoms with the ions fixed in space and have found that the many-atom interaction does allow ionization at lower densities than estimates from two-atom interactions. However, we found that the density fluctuations in a gas play a larger role. These two effects are an order of magnitude too small to account for the experimental results suggesting at least one other mechanism strongly affects ionization.

Figure 1

The probability for an atom to be ionized as a function of the atom separation for atoms in a line. The different line types correspond to different number of atoms: 2 atoms (solid line), 4 atoms (dotted line), 8 atoms (dashed line), and 16 atoms (dashed-dotted line).

Figure 2

The probability for ionization as a function of the atom separation for atoms in a square lattice. The different line types correspond to different number of atoms: $2^2$ atoms (solid line), $3^2$ atoms (dotted line), $4^2$ atoms (dashed line), and $5^2$ atoms (dashed-dotted line).

Figure 3

The probability for ionization as a function of the atom separation for atoms in a cubic array. The different line types correspond to different number of atoms: $2^3$ atoms (solid line) and $3^3$ atoms (dotted line).

Figure 4

The probability for ionization for atoms randomly placed on a line with the linear density $1/D$. The different line types correspond to different number of atoms: 2 atoms (solid line), 4 atoms (dotted line), and 8 atoms (dashed line). Note the vastly different range for $D$ compared to Fig. 1.

Figure 5

The probability for ionization for atoms randomly placed within a square with the surface density $1/D^2$. The different line types correspond to different number of atoms: $2^2$ atoms (solid line), $3^2$ atoms (dotted line), $4^2$ atoms (dashed line), and $5^2$ atoms (dashed-dotted line). Note the vastly different range for $D$ compared to Fig. 2.

Figure 6

The probability for ionization for atoms randomly placed within a cube with a density $1/D^3$. The different line types correspond to different number of atoms: $2^3$ atoms (solid line) and $3^3$ atoms (dotted line). Note the vastly different range for $D$ compared to Fig. 3.