Nonlinear Optical Response of a Four Level Atomic System.

Ka-Di Zhu, W.-S. Li

С. А. Бахрамов

S. Rebić, David Vitali, Carlo Ottaviani +4 more

We analyze the nonlinear optical response of a four-level atomic system driven into a tripod configuration. The large cross-Kerr nonlinearities that occur in such a system are shown to produce nonlinear phase shifts of order $\ensuremath{\pi}$. Such a substantial shift may be observed in a cold atomic gas in a magneto-optical trap where it could be feasibly exploited towards the realization of a polarization quantum phase gate. The experimental feasibility of such a gate is here examined in detail.

Kh. V. Nerkararyan

Mostafa Sahrai, Hamid Reza Hamedi, Meisam Memarzadeh

The nonlinear response to applied fields of a four-level Y-type atomic system is investigated. The effect of laser intensity and quantum interference induced by spontaneous emission on optical bistability, optical multi-stability and Kerr nonlinearity is then discussed. It is found that the threshold of the optical bistability can substantially be reduced by the quantum interference. So, an enhanced Kerr nonlinearity with reduced absorption can be achieved.

Ya-Wei Guo, Si-Liu Xu, Jun-Rong He +3 more

We investigate the linear and nonlinear optical response to an optical pumping of a four-level atomic system with electromagnetically induced transparency (EIT) in a cold Rydberg atomic gas. It is found that the transient behavior (especially, the third- and fifth-order susceptibilities) of the probe field, and the steady-state EIT spectrum of the gas, depend crucially on the Rydberg atoms' interaction. Furthermore, we find that the response speed of the Rydberg interaction with EIT can be as much as six times faster than the EIT without the Rydberg interaction, and that the nonlinear response time of the fifth-order optical susceptibility is longer than that of the third-order susceptibility. It is established that the Rydberg blockade effect plays a significant role in increasing the response speed of the Rydberg with EIT.