A Delayed Choice Quantum Eraser

This paper reports a "delayed choice quantum eraser" experiment proposed by Scully and Dr\"{u}hl in 1982. The experimental results demonstrated the possibility of simultaneously observing both particle-like and wave-like behavior of a quantum via quantum entanglement. The which-path or both-path information of a quantum can be erased or marked by its entangled twin even after the registration of the quantum.Comment: twocolumn, 4pages, submitted to PR

Testing foundations of quantum mechanics with photons

The foundational ideas of quantum mechanics continue to give rise to counterintuitive theories and physical effects that are in conflict with a classical description of Nature. Experiments with light at the single photon level have historically been at the forefront of tests of fundamental quantum theory and new developments in photonics engineering continue to enable new experiments. Here we review recent photonic experiments to test two foundational themes in quantum mechanics: wave-particle duality, central to recent complementarity and delayed-choice experiments; and Bell nonlocality where recent theoretical and technological advances have allowed all controversial loopholes to be separately addressed in different photonics experiments.Comment: 10 pages, 5 figures, published as a Nature Physics Insight review articl

Single and double interaction zone with comoving fields in Stern-Gerlach atom interferometry

We present two applications of the use, in Stern-Gerlach interferometry with metastable hydrogen atoms, of comoving magnetic fields, i.e.  fields travelling at atomic velocites, which could allow us to reach the slow-atom domain. In the first application, atoms interact with a single extended zone of comoving B-field. A velocity coherent filtering effect is demonstrated and characterized. In the second one, atoms interact with a double zone of comoving B-field. This Ramsey's type configuration takes advantage of the fact that the sensitivity of the apparatus with respect to velocity changes is significantly enhanced

Aircraft Wake Vortex Study and Characterization with 1.5 µm Fiber Doppler Lidar

International audienceFor ten years now, Onera has been developing lidar tools for wake vortex detection and studies. Since 2003, new developments based on 1.5 µM fibered laser sources have been achieved in parallel with extensive research work on the laser sources themselves.Three innovative lidars have been developed and are presented in this paper:1) A mini-lidar, based on a CW (continuous-wave) 2 W / 1.5 µM laser source, for aircraft model wake vortex characterization in a catapult facility. A self-triangulation technique allows the vortex core position to be found with 10 cm error, and the circulation error is 10 %.2) A pulsed 1.5 µM lidar, based on a 50 µJ / 15 kHz MOPA (Master Oscillator Power Amplifier) source, for lateral wake vortex monitoring at airports. The range is 400 m, the core position error is about ± 2 m and the circulation error is about 10 %.3) A pulsed 1.5 µM lidar, based on a 120 µJ / 12 kHz MOPA source, for onboard axial wake vortex detection. Ground based lidar tests at Orly airport have demonstrated wake vortex detection up to 1.2 km

Dynamic Jahn–Teller Effect in the Metastable High-Spin State of Solvated [Fe(terpy)₂]²⁺

Characterizing structural distortions in the metastable spin states of d4–d7 transition metal ion complexes is crucial to understand the nature of their bistability and eventually control their switching dynamics. In particular, the impact of the Jahn–Teller effect needs to be assessed for any electronic configuration that could be effectively degenerate, as in e.g. the high-spin (HS) manifold of highly symmetric homoleptic FeII complexes. However, capturing its manifestations remains challenging since crystallization generally alters the molecular conformations and their interconversion. With the rapid progress of ultrafast X-ray absorption spectroscopy, it is now possible to collect data with unprecedented signal-to-noise ratio, opening up for detailed structural characterization of transient species in the homogeneous solution phase. By combining the analysis of picosecond X-ray absorption spectra with DFT simulations, the structure of the photoinduced HS state is elucidated for solvated [Fe(terpy)2]2+ (terpy = 2,2′:6′,2″-terpyridine). This species can be viewed as the average 5B structure in D2 symmetry that originates from a dynamic Jahn–Teller effect in the HS manifold. These results evidence the active role played by this particular instance of vibronic coupling in the formation of the HS state for this benchmark molecule. Ultimately, correlating the interplay between intramolecular and intermolecular degrees of freedom to conformational strain and distortions in real time should contribute to the development of advanced functionalities in transition metal ion complexes