Fast compression of a cold atomic cloud using a blue detuned crossed dipole trap

We present the experimental realization of a compressible blue detuned crossed dipole trap for cold atoms allowing for fast dynamical compression (~ 5 - 10 ms) of 5x10^7 Rubidium atoms up to densities of ~ 10^13 cm^-3. The dipole trap consists of two intersecting tubes of blue-detuned laser light. These tubes are formed using a single, rapidly rotating laser beam which, for sufficiently fast rotation frequencies, can be accurately described by a quasi-static potential. The atomic cloud is compressed by dynamically reducing the trap volume leading to densities close to the Ioffe-Reggel criterion for light localization.Comment: 14 pages, 15 figures, 2 table

Observation of a phononic Mollow triplet in a hybrid spin-nanomechanical system

Reminiscent of the bound character of a qubit's dynamics confined on the Bloch sphere, the observation of a Mollow triplet in the resonantly driven qubit fluorescence spectrum represents one of the founding signatures of Quantum Electrodynamics. Here we report on its observation in a hybrid spin-nanomechanical system, where a Nitro-gen Vacancy spin qubit is magnetically coupled to the vibrations of a Silicon Carbide nanowire. A resonant microwave field turns the originally parametric hybrid interac-tion into a resonant process, where acoustic phonons are now able to induce transitions between the dressed qubit states, leading to synchronized spin-oscillator dynamics. We further explore the vectorial character of the hybrid coupling to the bidimensional de-formations of the nanowire. The demonstrated microwave assisted synchronization of the spin-oscillator dynamics opens novel perspectives for the exploration of spin-dependent forces, the key-ingredient for quantum state transfer

Deviation from the normal mode expansion in a coupled graphene-nanomechanical system

We optomechanically measure the vibrations of a nanomechanical system made of a graphene membrane suspended on a silicon nitride nanoresonator. When probing the thermal noise of the coupled nanomechanical device, we observe a significant deviation from the normal mode expansion. It originates from the heterogeneous character of mechanical dissipation over the spatial extension of coupled eigenmodes, which violates one of the fundamental prerequisite for employing this commonly used description of the nanoresonators' thermal noise. We subsequently measure the local mechanical susceptibility and demonstrate that the fluctuation-dissipation theorem still holds and permits a proper evaluation of the thermal noise of the nanomechanical system. Since it naturally becomes delicate to ensure a good spatial homogeneity at the nanoscale, this approach is fundamental to correctly describe the thermal noise of nanomechanical systems which ultimately impact their sensing capacity

Nano-optomechanical measurement in the photon counting regime

Optically measuring in the photon counting regime is a recurrent challenge in modern physics and a guarantee to develop weakly invasive probes. Here we investigate this idea on a hybrid nano-optomechanical system composed of a nanowire hybridized to a single Nitrogen-Vacancy (NV) defect. The vibrations of the nanoresonator grant a spatial degree of freedom to the quantum emitter and the photon emission event can now vary in space and time. We investigate how the nanomotion is encoded on the detected photon statistics and explore their spatio-temporal correlation properties. This allows a quantitative measurement of the vibrations of the nanomechanical oscillator at unprecedentedly low light intensities in the photon counting regime when less than one photon is detected per oscillation period, where standard detectors are dark-noise-limited. These results have implications for probing weakly interacting nanoresonators, for low temperature experiments and for investigating single moving markers

First dating results for the Middle Pleistocene industries (Acheulean – Early Middle Palaeolithic) in the Pyrenees – Garonne region: a multi methods geochronological approach (TL, OSL and TT-OSL) of the Duclos and Romentères sites

The recent development work of the A65 highway has given the opportunity to broaden the corpus of Lower and Middle Palaeolithic open-air sites known in the southern Aquitaine basin. The sites of Duclos (Auriac, Pyrénées-Orientales) and Romentères (Le Vignau, Landes), discovered in this context, have yielded an abundant lithic record which has been attributed to the Acheulean of Iberian type for the earlier and, essentially, to the Early Middle Palaeolithic for the latter. The archaeological levels are intercalated in sequences that comprise aeolian silts and colluvial units separated by interglacial luvisols. The pedostratigraphic context of the two sites has provided a rare opportunity to propose a reliable chronostratigraphic framework in this area. To achieve this objective, a study combining several methods of luminescence dating was conducted to complete the geomorphological data. Optically Stimulated Luminescence (OSL) and Thermically Transferred OSL (TT-OSL) dating methods were applied in order to determine the ages of sedimentary quartz grains and thus, of the sampled deposits. In parallel, heated flint and quartzite samples were dated by thermoluminescence (TL). The Pyrenees-Garonne Acheulean industry of Duclos has been attributed to the boundary between Marine Isotopic Stages (MIS) 7 and 6 while the human occupations of Romentères date from MIS 6 for the most recent series (Early Middle Palaeolithic) and from MIS 9 and 8 for the older

Quantum-mechanics free subsystem with mechanical oscillators

Quantum mechanics sets a limit for the precision of measurement of the position of an oscillator. The quantum noise associated with the measurement of a quadrature of the motion imprints a backaction on the orthogonal quadrature, which feeds back to the measured observable in the case of a continuous measurement. In a quantum backaction evading measurement, the added noise can be confined in the orthogonal quadrature. Here we show how it is possible to evade this limitation and measure an oscillator without backaction by constructing one effective oscillator from two physical oscillators. This facilitates detection of weak forces and the creation and measurement of nonclassical motional states of the oscillators. We realize the proposal using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum backaction by $8$ decibels on both of them, obtaining a total noise within a factor two from the full quantum limit. Moreover, by modifying the measurement we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity $1.3$ decibels below the separability bound

Ground-state cooling of a mechanical oscillator by heating

Dissipation and the accompanying fluctuations are often seen as detrimental for quantum systems, since they are associated with fast relaxation and loss of phase coherence. However, it has been proposed that a pure state can be prepared if external noise induces suitable downwards transitions, while exciting transitions are blocked. We demonstrate such a refrigeration mechanism in a cavity optomechanical system, where we prepare a mechanical oscillator in its ground state by injecting strong electromagnetic noise at frequencies around the red mechanical sideband of the cavity. The optimum cooling is reached with a noise bandwidth smaller than, but on the order of the cavity decay rate. At higher bandwidths, cooling is less efficient. In the opposite regime where the noise bandwidth becomes comparable to the mechanical damping rate, damping follows the noise amplitude adiabatically, and the cooling is also suppressed

The Life Cycle of Toxoplasma gondii in the Natural Environment

Chapitre 1International audienc