We report an experimental demonstration of light polarization degree control during free propagation via manipulation of the coherent properties of the source. These experimental results corroborate the theory that polarization and coherence are both related to the same statistical properties of the electromagnetic field.

We introduce a simple and flexible method to generate spatially non-Markovian light with tunable coherence properties in one and two dimensions. The unusual behavior of this light is demonstrated experimentally by probing the far field and by recording its diffraction pattern after a double slit: In both cases we observe, instead of a central intensity maximum, a line-or cross-shaped dark region, whose width and profile depend on the non-Markovian coherence properties. Because these properties can be controlled and easily reproduced in experiment, the presented approach lends itself to serving as a test bed to study and gain a deeper understanding of non-Markovian processes. DOI: 10.1103/PhysRevLett.115.073901 PACS numbers: 42.25.Fx, 03.65.Yz, 42.30.Kq, 42.50.Ar In nature, non-Markovian processes are far more common than Markovian ones; however, scientists often prefer to describe the behavior of nature with Markovian models. This might be the case because Markovian models are easier to build, and it is significantly easier to combine them when constructing more complex models. Recently, however, there has been increasing interest in understanding the specific impact of non-Markovian behavior on chemical and biological processes such as electron transfer [1], the kinetics of protein folding [2], or the ion transport through membranes [3], to name but a few. In optics, the radiation dynamics in photonic crystals [4], optical gain in quantumwell lasers [5], and dephasing processes in coupled quantum-dot cavities [6] have been experimentally observed to be governed by non-Markovian behavior. Characterizing non-Markovian evolutions of quantum properties at the loss of entanglement has become the center of extensive theoretical and experimental efforts [7,8]; it is hoped that this will pave the way for better read-out mechanisms in quantum computing [9] or even controlled generation of entangled states [10]. Such quantum phenomena, or their application in logical circuits [11], are often studied using optical means [7,8]. Furthermore, the recent suggestion to initialize controlled quantum states by "optical pumping" [10] opens exciting possibilities for shaping desired quantum properties, including designed non-Markovian characteristics, in the optical regime and then transferring them to other physical systems [12,13].Non-Markovian light, which might serve as an effective tool towards these objectives, has been previously generated by overlaying a light beam with a delayed copy or echo of itself [14]. An alternative approach employs a micromechanical oscillator as a mirror in order to obtain non-Markovian properties from its Brownian movements [15]. The two methods result in light with non-Markovian properties in the time domain; they offer only a limited degree of control and practically no repeatability if the exact same conditions need to be reproduced. In this Letter we, therefore, introduce and experimentally demonstrate a technique to create spatially non-Markovian light to overcome these limitations. By u...

We report a simple and robust technique to generate a dispersive signal which serves as an error signal to electronically stabilize a monomode continuous-wave laser emitting around an atomic resonance. We explore nonlinear effects in the laser beam propagation through a resonant vapor by way of spatial filtering. The performance of this technique is validated by locking semiconductor lasers to the cesium and rubidium D 2 lines and observing long-term reduction of the emission frequency drifts, making the lasers well adapted for many atomic physics applications.

We study the interference patterns obtained from the superposition of two Bessel beams originated from a quantum two-photon state produced by a spontaneous parametric down-conversion process. Due to the nondiffracting character of the light beam, a self-imaging effect is found along the propagation direction for second-order interference patterns with periodicity proportional to / 2, characterizing a two-photon Talbot effect. Conditional interference patterns in the longitudinal plane are theoretically shown as well.