Quantum interference manipulation and enhancement with fluctuation-correlation-induced dephasing in an atomic system

We investigate the manipulation of the quantum interference (QI) in an electromagnetically induced transparency (EIT) system via phase fluctuations and their correlation of interacting fields. We show that the field fluctuation correlation and atomic dephasing rate have a similar effect to atomic coherence, and furthermore that QI is dependent on the fluctuation and correlation. Using the theoretical model in a dressed-state representation, the contribution of QI and Autler-Townes splitting (ATS) to probe absorption can be expressed in separate terms, such that the obvious enhancement of QI is found with highly correlated fields while ATS remains unchanged. In particular, when the relative large Rabi frequency of coupling field is applied, in which case the ATS plays a more prominent role than QI, we can still modulate the QI to be higher than ATS with correlated fields. This result could allow the strict EIT condition to be relaxed and be easily realized, or it may be a method to get a narrow EIT window for applications in efficient light storage and quantum interface.

Figure 1

(a) $\mathrm{\Lambda }$-type three-level system. (b) Dressed-state representation.

Figure 2

${\mathrm{\Phi }}_0$ vs ${\kappa }_c$ and ${\kappa }_p$ for ${\kappa }_{cp}=\sqrt{{\kappa }_c{\kappa }_p}$ (first column), ${\kappa }_{cp}=0$ (second column), and ${\kappa }_{cp}=-\sqrt{{\kappa }_c{\kappa }_p}$ (third column) with ${\mathrm{\Omega }}_c=0.3\gamma$ (first row), ${\mathrm{\Omega }}_c=\gamma$ (second row), and ${\mathrm{\Omega }}_c=3\gamma$ (third row). The regions I, the regions II, and the black lines indicate ${\mathrm{\Phi }}_0<0$ (destructive QI), ${\mathrm{\Phi }}_0>0$ (constructive QI), and ${\mathrm{\Phi }}_0=0$ (no QI), respectively. The cross marks indicate the general EIT experiment condition, i.e., ${\kappa }_c={\kappa }_p=0.2\gamma$ (linewidths of $\sim 1$ MHz).

Figure 3

${\mathrm{\Phi }}_0$ vs ${\mathrm{\Omega }}_c$ (a) for different ${\kappa }_c$ with ${\kappa }_p=0.2\gamma$ and ${\kappa }_{cp}=0$; (b) for different ${\kappa }_{cp}$ with ${\kappa }_c=\gamma$ and ${\kappa }_p=0.2\gamma$. The cross marks indicate ${\mathrm{\Omega }}_c={\mathrm{\Omega }}_{\mathrm{th}}=\left|\eta \right|$.

Figure 4

${\mathrm{\Omega }}_{\mathrm{th}}$ vs ${\kappa }_c$ and ${\kappa }_p$ for (a) ${\kappa }_{cp}=\sqrt{{\kappa }_c{\kappa }_p}$, (b) ${\kappa }_{cp}=\sqrt{{\kappa }_c{\kappa }_p}/2$, (c) ${\kappa }_{cp}=0$, (d) ${\kappa }_{cp}=-\sqrt{{\kappa }_c{\kappa }_p}/2$, and (e) ${\kappa }_{cp}=-\sqrt{{\kappa }_c{\kappa }_p}$. The red lines indicate ${\mathrm{\Omega }}_{\mathrm{th}}=0$. The cross marks indicate the general EIT experiment condition, i.e., ${\kappa }_c={\kappa }_p=0.2\gamma$ (linewidths of $\sim 1$ MHz). ${\mathrm{\Omega }}_{\mathrm{th}}$ vs ${\kappa }_{cp}$ for this condition is plotted in (f).