Atoms in coherent and incoherent fields

Saad S. M. Hassan, R. Bullough

Miaodi Guo, Haifeng Li, Ming‐Xuan Shi

Abstract It is important to generate stable nonclassical correlation and wide‐band quantum field in quantum optical communication. In this paper, a scheme is proposed to manipulate the nonclassical intensity correlation of two output fields by a coherent coupling laser and an incoherent pumping field. The core of the scheme is that the coherent field is applied to manipulate the intracavity polaritons, and the incoherent pumping field is used to control the linear absorption and the atomic coherence. With the incoherent field, atoms are repopulated on the excited state . It induces a wide‐band zero absorption of a probe field and the negative dispersion that can be used to realize a white‐light cavity. In addition, with the increasement of the incoherent pumping rate, the wide‐band maximum stable intensity correlation and the nonclassical field with sub‐Poissonian distribution are attained, which is verified by the evolution of the second‐order correlation of two output channels.

Xue Mei Su, Hoonsoo Kang, J. Kou +2 more

We propose a scheme of electromagnetically induced left-handedness in a dense atomic vapor medium. By applying an incoherent pump field to manipulate the populations in atomic levels, and a strong coherent field to create quantum coherence, the magnetic part of the probe field can be amplified instead of strong absorption as usual materials. The system has negative permittivity and permeability simultaneously with transparent propagation of the electric part of the probe field. It is shown that the pumping rate of incoherent field, the intensity and frequency detuning of the coherent field, exert effects on the properties of the negative refractive index of left-handed material.

I. R. Senitzky

The interaction between a coherently oscillating radiation field, such as is generally encountered in micro-wave experiments, and a number of similar atomic systems coupled to the field through their electric dipole moments is analyzed for the case of resonance between atomic system and field, with both the field and molecules treated quantum-mechanically. Expressions are derived for the expectation value of field strength and the energy, and comparison between the two makes it possible to distinguish between coherent and incoherent parts of the energy, the former having its counterpart in the expectation value of the field strength, while the latter has no such counterpart. Terms corresponding to induced and spontaneous emission are identified, and it is shown that the latter includes both coherent and incoherent components. Special situations related to masers and to the coherence of spontaneous radiation are discussed. The distinction between the behavior of correlated and uncorrelated states is examined, and it is shown that both the coherent emission from uncorrelated states and the incoherent emission from correlated states may be proportional to the square of the number of molecules. The phase of the field is predictable for the coherent emission but unpredictable for the incoherent emission.

Cleanthes A. Nicolaides, Charles W. Clark, Munir Hasan Nayfeh