Terahertz detection of angular momentum states in Rydberg atoms

In alkali Rydberg atoms, states with higher angular momentum $\ell \geq 3$ are degenerate in energy, and cannot be distinguished by standard methods such as field-ionization. In this poster, we propose a method of selective re-distribution of angular momentum states by terahertz frequency half-cycle pulses. The redistributed population can then be read-out easily, giving a signature of the original angular momentum. These results are expected to be an important advance in quantum information processing. \newline C. Rangan and R. J. A. Murray, Phys. Rev. A {\bf 72}, 053409 (2005).