Probing the dynamics and coherence of a semiconductor hole spin via acoustic phonon-assisted excitation

Spins in semiconductor quantum dots are promising local quantum memories to generate polarization-encoded photonic cluster states, as proposed in the pioneering Rudolph-Lindner scheme [1]. However, harnessing the polarization degree of freedom of the optical transitions is hindered by resonant excitation schemes that are widely used to obtain high photon indistinguishability. Here we show that acoustic phonon-assisted excitation, a scheme that preserves high indistinguishability, also allows to fully exploit the polarization selective optical transitions to initialise and measure single spin states. We access the coherence of hole spin systems in a low transverse magnetic field and directly monitor the spin Larmor precession both during the radiative emission process of an excited state or in the quantum dot ground state. We report a spin state detection fidelity of $94.7 \pm 0.2 \%$ granted by the optical selection rules and a $20\pm5$~ns hole spin coherence time, demonstrating the potential of this scheme and system to generate linear cluster states with a dozen of photonsComment: 3 figure

Dental implants placed on bone subjected to vertical alveolar distraction show the same performance as those placed on primitive bone

INTRODUCTION: Vertical osteogenic alveolar distraction (VOAD) allows for the augmentation of the alveolar ridge for the placement of dental implants in atrophic alveolar ridges. The goal of this paper is to assess long-term peri-implant bone resorption in implants placed on bones subjected to VOAD, comparing it with a group of patients who had implants placed directly on the alveolar bone without previous bone regeneration. MATERIAL AND METHODS: We conducted a follow-up study on 32 patients who were divided into two groups: The Distraction Group (14 patients), and the Distraction-Free Group (18 patients), who received a total of 100 implants. Peri-implant bone loss was measured by means of panoramic X-rays, at the time of loading and one year later, and in 35 implants of each group after 3 years of functional loading. RESULTS: The peri-implant bone resorption (PBR) average observed in the Distraction Group at the time of prosthetic placement is higher (0.50 +/- 0.09 mm) than in the Distraction-Free Group (0.25 +/- 0.06 mm), showing statistically significant results (p=0.047). PBR levels 1 year after loading were the same for both groups (0.66 mm). At 3 years, they were higher in the Distraction Group (1.03 +/- 0.22 mm vs. 0.68 +/- 0.08 mm)

High-rate entanglement between a semiconductor spin and indistinguishable photons

International audiencePhotonic graph states—quantum light states where multiple photons are mutually entangled—are key resources for optical quantum technologies. They are notably at the core of error-corrected measurement-based optical quantum computing and all-optical quantum networks. In the discrete variable framework, these applications require the high-efficiency generation of cluster states whose nodes are indistinguishable photons. Such photonic cluster states can be generated with heralded single-photon sources and probabilistic quantum gates, yet with challenging efficiency and scalability. Spin–photon entanglement has been proposed to deterministically generate linear cluster states. First demonstrations have been obtained with semiconductor spins, achieving high photon indistinguishability, and most recently with atomic systems with a high collection efficiency and record length. Here we report on the efficient generation of three-partite cluster states made of one semiconductor spin and two indistinguishable photons. We harness a semiconductor quantum dot inserted in an optical cavity for efficient photon collection and electrically controlled for high indistinguishability. We demonstrate two- and three-particle entanglement with fidelities of 80 ± 4% and 63 ± 5%, respectively, with photon indistinguishability of 88 ± 0.5%. Owing to the high operation rate allowed by the quantum-dot platform, the spin–photon and spin–photon–photon entanglement rates exceed, by three and two orders of magnitude, respectively, those of the previous state of the art. Our system and experimental scheme, a monolithic solid-state device controlled with a resource-efficient simple experimental configuration, are very promising for future scalable applications

Laser and Light-Based Therapies in the Treatment of Hair Loss

Laser and light-based therapies including low-level laser and light therapy, fractional, excimer, and other lasers are increasingly well-regarded treatment options for patients with hair loss. Lasers emit wavelengths of light specific to a chromophore in the tissue, causing a targeted thermal response with minimal damage to surrounding tissue. The cascade of events downstream of the initial injury is responsible for the clinical effects seen. Low-level laser or light therapy (LLLT) was accidentally discovered in the 1960s when Hungarian scientist Endre Mester attempted to repeat an experiment performed by American Paul McGuff, who had cured malignant tumors in rats using a ruby laser. Mester’s laser was much less powerful than McGuff’s, and while he did not successfully cure any tumors, he observed for the first time that a low-level laser induced hair growth and improved wound healing. The mechanism by which this occurs is described as photobiomodulation or the stimulation of biological processes in the target tissue. This accidental discovery is the basis for the huge variety of LLLT products available on the market today. In the last 2 years alone, the number of approved items classified as laser, comb, or hair products intended for the purpose of the growth of scalp hairs on the FDA’s 510(k) premarket notification list, meaning the device is demonstrated to be at least safe and effective, has nearly doubled to a total of 50. This chapter will summarize current knowledge regarding all laser and light devices for patients with various forms of alopecia and will outline treatment strategy, device parameters, and appropriate limitations of use to guide providers toward optimal patient management