Chaos-Assisted Long-Range Tunneling for Quantum Simulation.

We present an extension of the chaos-assisted tunneling mechanism to spatially periodic lattice systems. We demonstrate that driving such lattice systems in an intermediate regime of modulation maps them onto tight-binding Hamiltonians with chaos-induced long-range hoppings t_{n}∝1/n between sites at a distance n. We provide a numerical demonstration of the robustness of the results and derive an analytical prediction for the hopping term law. Such systems can thus be used to enlarge the scope of quantum simulations to experimentally realize long-range models of condensed matter.

4s to 5s and 4p photoexcitation dynamics of K atoms from the surface of helium nanodroplets: a theoretical study.

We study the photodissociation of the potassium atom from a superfluid helium nanodroplet upon 5s 2S or 4p 2P excitation using the time-dependent helium density functional method (He-TDDFT). The importance of quantum effects is assessed by comparing the absorption spectrum obtained for a classical or a quantum description of the K atom. In the case of the 5s 2S ← 4s 2S excitation the difference is rather large, and we use a quantum description for the ensuing direct dissociation dynamics. In the case of the 4p 2P ← 4s 2S absorption spectrum, the difference is much smaller, hence a classical description of K is used to describe 4p 2P excitation dynamics. Excitation to the 4p 2Σ1/2 state leads to the direct dissociation of the K atom, while the 4p 2Π3/2 state initially leads to the formation of an exciplex and the 4p 2Π1/2 state to a bouncing atom above the droplet surface. Remarkably, electronic relaxation can be observed for the latter two states, leading to spin-orbit relaxation and the binding of the initially departing one-atom excimer as a ring excimer for the 2P3/2 state and to the formation of a bound, ring excimer for the 2Π1/2 state.

Impact of the withdrawal of macrotextured implant on reconstruction practices.

INTRODUCTION: On 22 November 2018, the French Society for Plastic, Reconstructive and Aesthetic Surgery recommended that Allergan® macrotextured breast implants be recalled, a decision endorsed by the French national health products safety agency (ANSM) on 2nd April 2019. At the Georges-François Leclerc Cancer Center (CGFL) in Dijon, we decided to stop using macrotextured implants as of November 2018 in favor of smooth implants. The purpose of this study is to evaluate the impact of the recall of macrotextured implants on breast reconstruction surgical practices and their complications. METHODS: This is a single-centre, retrospective study performed at the CGFL in Dijon, France. Reconstruction techniques and complications were compared between two periods, i.e. before the recall of macrotextured breast implants (period 1: 1st September 2017-November 22, 2018) and after the recall (period 2: 23 November 2018-31st March 2020). All patients who underwent breast reconstruction for the first time were included. RESULTS: Data were collected from 168 reconstructions in period 2, and 159 in period 2. The rate of use of breast implants during reconstructions decreased significantly in period 2 (53.6% vs. 23.9%; P<0.001). The rate of autologous reconstructions increased significantly for muscle sparing latissimus dorsi (2.4% vs. 12.6%; P<0.001) and exclusive fat grafting (9.5% vs. 21.5%; P<0.01). Clavien-Dindo Stage IIIb complications decreased in period 2 (10% vs. 18.4%; P=0.04). CONCLUSION: Since the recall of macrotextured breast implants, the reconstruction rate has decreased in our centre in favor of autologous techniques with lower complication rates.