Protecting Quantum Information with Entanglement and Noisy Optical Modes

We incorporate active and passive quantum error-correcting techniques to protect a set of optical information modes of a continuous-variable quantum information system. Our method uses ancilla modes, entangled modes, and gauge modes (modes in a mixed state) to help correct errors on a set of information modes. A linear-optical encoding circuit consisting of offline squeezers, passive optical devices, feedforward control, conditional modulation, and homodyne measurements performs the encoding. The result is that we extend the entanglement-assisted operator stabilizer formalism for discrete variables to continuous-variable quantum information processing.Comment: 7 pages, 1 figur

Kinetics of water flow through polymer gel

The water flow through the poly(acrylamide) gel under a constant water pressure is measured by newly designed apparatus. The time evolution of the water flow in the gel, is calculated based on the collective diffusion model of the polymer network coupled with the friction between the polymer network and the water. The friction coefficient are determined from the equilibrium velocity of water flow. The Young modulus and the Poisson's ratio of the rod shape gels are measured by the uni-axial elongation experiments, which determine the longitudinal modulus independently from the water flow experiments. With the values of the longitudinal modulus and of the friction determined by the experiments, the calculated results are compared with the time evolution of the flow experiments. We find that the time evolution of the water flow is well described by a single characteristic relaxation time predicted by the collective diffusion model coupled with the water friction.Comment: 7 pages, 5 figures, 27 references, Eqs adde

MARCO POLO: near earth object sample return mission

MARCO POLO is a joint European--Japanese sample return mission to a Near-Earth Object. This Euro-Asian mission will go to a primitive Near-Earth Object (NEO), which we anticipate will contain primitive materials without any known meteorite analogue, scientifically characterize it at multiple scales, and bring samples back to Earth for detailed scientific investigation. Small bodies, as primitive leftover building blocks of the Solar System formation process, offer important clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Current exobiological scenarios for the origin of Life invoke an exogenous delivery of organic matter to the early Earth: it has been proposed that primitive bodies could have brought these complex organic molecules capable of triggering the pre-biotic synthesis of biochemical compounds. Moreover, collisions of NEOs with the Earth pose a finite hazard to life. For all these reasons, the exploration of such objects is particularly interesting and urgent. The scientific objectives of MARCO POLO will therefore contribute to a better understanding of the origin and evolution of the Solar System, the Earth, and possibly Life itself. Moreover, MARCO POLO provides important information on the volatile-rich (e.g. water) nature of primitive NEOs, which may be particularly important for future space resource utilization as well as providing critical information for the security of Earth. MARCO POLO is a proposal offering several options, leading to great flexibility in the actual implementation. The baseline mission scenario is based on a launch with a Soyuz-type launcher and consists of a Mother Spacecraft (MSC) carrying a possible Lander named SIFNOS, small hoppers, sampling devices, a re-entry capsule and scientific payloads. The MSC leaves Earth orbit, cruises toward the target with ion engines, rendezvous with the target, conducts a global characterization of the target to select a sampling site, and delivers small hoppers (MINERVA type, JAXA) and SIFNOS. The latter, if added, will perform a soft landing, anchor to the target surface, and make various in situ measurements of surface/subsurface materials near the sampling site. Two surface samples will be collected by the MSC using ``touch and go'' manoeuvres. Two complementary sample collection devices will be used in this phase: one developed by ESA and another provided by JAXA, mounted on a retractable extension arm. After the completion of the sampling and ascent of the MSC, the arm will be retracted to transfer the sample containers into the MSC. The MSC will then make its journey back to Earth and release the re-entry capsule into the Earth's atmosphere

The noble gas and nitrogen relationship between Ryugu and carbonaceous chondrites

International audienceCarbonaceous chondrites are considered to have originated from C-type asteroids and represent some ofthe most primitive material in our solar system. Furthermore, since carbonaceous chondrites can containsignificant quantities of volatile elements, they may have played a crucial role in supplying volatiles andorganic material to Earth and other inner solar system bodies. However, a major challenge of unravellingthe volatile composition of chondritic meteorites is distinguishing between which features were inher-ited from the parent body, and what may be a secondary feature attributable to terrestrial weathering.In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfullyreturned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now beenclassified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites.The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse thevolatile composition of material that originated from a CI-type asteroid without the complications arisingfrom terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventoriesof chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to ter-restrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grainscollected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into theformation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples isgreater than the average composition of previously measured CI chondrites and are primarily derivedfrom phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The largenoble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests thatthe Ryugu samples may represent some of the most primitive unprocessed material from the early solarsystem. In contrast to the noble gases, the abundance of nitrogen and d15N composition of the two Ryugupellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances andd15 N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueousalteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shownlarge variations in nitrogen concentrations and d15N indicating that alteration fluids heterogeneouslyinteracted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gasesto nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indi-cates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen,likely from soluble organic matter, without modification of the noble gas budget, which is primarilyhosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueousalteration