Alejandra del Río-Lima

We present an open-source homemade Stokes polarimeter for real-time determination of the state and degree of polarization of a light beam by measuring all four Stokes parameters. Our design uses standard, commercially available optical components, mounted on a 3D printed base. Our user-friendly software allows visualization of the measured polarization state on the Poincaré sphere. We model the polarimeter using realistic Mueller matrices and present a detailed methodology to characterize every optical component and calibrate the instrument. The accuracy of the polarimeter largely depends on the quality of the chosen optical components, which in turn affects its price. Depending on this choice, the instrument can be used for applications ranging from simple didactic purposes to more accurate, research-grade measurements. In our case, we estimate an accuracy better than ±2.2^∘ in the determination of the state of polarization and ±6.0% in the degree of polarization. This makes our instrument useful for the correct alignment of polarization-maintaining fibers, as it allows one to quickly and efficiently match the polarization axis of the light to the polarization axes of the fiber. The high sampling rate of 60 k samples/s opens up the possibility to analyze the polarization of rapidly fluctuating signals such as light pulses. Moreover, the flexibility of our design permits to analyze light signals in a broad range of wavelengths, from deep UV to infrared, after opportune change of the optical components, representing an alternative low cost to more expensive commercial instruments.

The dynamics of an atom of three levels in Λ configuration interacting with a quantized field of two modes in a cavity is studied within the rotating wave approximation by considering experimental values of accessible hyperfine levels of alkali atoms. The Hamiltonian model is constructed on the basis of the direct product of the atomic states with Fock states of light. This simplified basis allows us to generalize the state of light to any quantum field. The interaction term of the Hamiltonian restricts the system to a 3D Hilbert space. The system’s time evolution results show some similarities with the effective two-level system, such as the presence of collapses and revivals and the atom-field entanglement. By an analysis of the statistics of the photons, we show that when the three-level atom is interacting with a coherent field of two modes, it is possible to control experimentally the statistics of the field to be super-Poissonian or sub-Poissonian by the choice of the initial atomic state.