Direct Wigner tomography of a superconducting anharmonic oscillator

The analysis of wave-packet dynamics may be greatly simplified when viewed in phase-space. While harmonic oscillators are often used as a convenient platform to study wave-packets, arbitrary state preparation in these systems is more challenging. Here, we demonstrate a direct measurement of the Wigner distribution of complex photon states in an anharmonic oscillator - a superconducting phase circuit, biased in the small anharmonicity regime. We test our method on both non-classical states composed of two energy eigenstates and on the dynamics of a phase-locked wavepacket. This method requires a simple calibration, and is easily applicable in our system out to the fifth level.Comment: 5 figures, 1 table and supplementary materia

Improving Compactness of 3D Metallic Microstructures Printed by Laser-Induced Forward Transfer

Laser-induced forward transfer (LIFT) has been shown to be a useful technique for the manufacturing of micron-scale metal structures. LIFT is a high-resolution, non-contact digital printing method that can support the fabrication of complex shapes and multi-material structures in a single step under ambient conditions. However, LIFT printed metal structures often suffer from inferior mechanical, electrical, and thermal properties when compared to their bulk metal counterparts, and often are prone to enhanced chemical corrosion. This is due mostly to their non-compact structures, which have voids and inter-droplet delamination. In this paper, a theoretical framework together with experimental results of achievable compactness limits is presented for a variety of metals. It is demonstrated that compactness limits depend on material properties and jetting conditions. It is also shown how a specific choice of materials can yield compact structures, for example, when special alloys are chosen along with a suitable donor construct. The example of printed amorphous ZrPd is detailed. This study contributes to a better understanding of the limits of implementing LIFT for the fabrication of metal structures, and how to possibly overcome some of these limitations

Femtosecond laser-assisted fabrication of piezoelectrically actuated crystalline quartz-based MEMS resonators

Abstract A novel technology for the precise fabrication of quartz resonators for MEMS applications is introduced. This approach is based on the laser-induced chemical etching of quartz. The main processing steps include femtosecond UV laser treatment of a Cr-Au-coated Z-cut alpha quartz wafer, followed by wet etching. The laser-patterned Cr-Au coating serves as an etch mask and is used to form electrodes for piezoelectric actuation. This fabrication approach does not alter the quartz’s crystalline structure or its piezo-electric properties. The formation of defects, which is common in laser micromachined quartz, is prevented by optimized process parameters and by controlling the temporal behavior of the laser-matter interactions. The process does not involve any lithography and allows for high geometric design flexibility. Several configurations of piezoelectrically actuated beam-type resonators were fabricated using relatively mild wet etching conditions, and their functionality was experimentally demonstrated. The devices are distinguished from prior efforts by the reduced surface roughness and improved wall profiles of the fabricated quartz structures

Individual amino acids - hungry brain and mobile gut

In every living organism amino acids are pivotally important multifunctional molecules. Single amino acids drive mayor intracellular signaling pathways controlling growth and proliferation, and enable neuronal communication in the synaptic cleft. Apart from signaling, their oxidative break down in the citric acid cycle provides energy and metabolic substrates for the cell. When several single amino acids are covalently linked and correctly folded, they form a functional protein. This certainly describes one of the most important processes in biology. All these vital functions depend on the availability of amino acids. Not surprisingly, amino acid pools are maintained within a physiological range by complex regulatory feedback mechanisms – a process termed homeostasis. A homeostatic challenge is to refill the amino acid pools without perturbing amino acid homeostasis, which might cause severe side effects. The temporal regulation of transport protein expression may solve this problem in single cell organisms, whereas eating behavior has to be balanced with the homeostatic needs and the specific available nutrient source in higher species. How this is achieved is currently under active research, but little is known in the context of individual amino acids. One reason might be that ingested proteins are broken down to twenty different individual amino acids leading to large complexity. Not only do they differ in their chemical structure, but some are also nutritionally essential. We hypothesize that, based on these structural differences; they may have distinct roles in the control of food intake and gastrointestinal function. We systematically assessed the impact of all 20 individual proteogenic amino acids on food intake and gastric function. These two functional readouts are particularly relevant in the short-term regulation of nutrient intake. Food intake determines the maximal achievable intake of nutrients, and gastric function i.e. gastric emptying and secretion dictates the concentration and the timing of nutrient release into the small intestine. Both have a direct impact on plasma nutrient concentration and the timing of nutrient appearance in plasma. Here, we show that short-term food intake was most potently reduced by oral L-arginine, L-lysine and L-glutamic acid compared to all other 17 proteogenic amino acids in the rat. As feeding behavior is controlled by neuronal circuits located in specific brain areas, we tested for neuronal activity using immunohistochemistry after L-arginine, L-lysine and L-glutamic acid application. An increased number of cFOS positive cells were detected in the blood-sensing area postrema and the nucleus of the solitary tract. To test whether circulating amino acids can directly signal to the brain to induce their anorectic effect, we administered L-arginine, L-lysine and L-glutamic acid intravenously. All three amino acids induced an anorectic response that was similar to the one induced after oral application. Surgical lesion of the area postrema abolished the anorectic responses of L-arginine and L-glutamic acid but not of L-lysine. The nucleus of the solitary tract is the main projection site of the vagus nerve which innervates the gastrointestinal tract. Surgical lesion of vagal afferents did not alter the anorectic effect of L-arginine and L-glutamic acid but of L-lysine. We presume that L-arginine and L-glutamic acid act in the area postrema to cause their anorectic response, while L-lysine stimulates hepatic vagal afferents projecting to the nucleus of the solitary tract. Interestingly, in the gastrointestinal tract all three amino acids induced gastric distension. L-arginine and L-lysine induced gastric secretion detected by changes in the alkaline tide. Gastric emptying, measured by stomach phenol red retention, was delayed after L-lysine and L-glutamic acid treatment. At the level of the small intestine, L-arginine and L-lysine accelerated phenol red dye passage into the cecum. The gastrointestinal effects of L-lysine were shown to be dose dependent in the rat and were analogously observed in healthy human subjects. The highest L-lysine dose caused self-limiting diarrhea in humans, but no other side effects were reported. The gastrointestinal effect induced by L-arginine and L-lysine was dissociated from their effect on food intake and induced conditioned taste aversion in the rat. Hence, L-arginine, L-lysine and L-glutamic acid had a remarkable specific impact on mechanism important for food processing in the gastrointestinal tract and on food intake in rats and humans. This may suggest that they act as direct sensory input to assess dietary protein content and quality in vivo. Here, we show that L-cysteine, L-lysine, L-arginine and L-tryptophan most potently delayed gastric emptying and that L-arginine and L-lysine most potently stimulated gastric secretion compared to all other proteogenic amino acids in the rat. The systematic assessment of these two key stomach functions was only feasible, because we established and validated a quantitative non-invasive high-throughput computed tomography based method. This novel method can measure simultaneously gastric emptying and secretion in rats in vivo. Future efforts aim to assess if gastric secretion and emptying induced by the candidate amino acids are conducted by a shared control mechanism, to identify its localization and potential effector molecules i.e. gastrointestinal hormones. In conclusion, we revealed remarkable amino acid specificity for two critical nutritional functions, namely food intake and gastric function. The main question arising from this work is the cellular mechanism enabling the remarkable amino acid specificity. This might give insights into how individual amino acids contribute to the control of protein intake, and how protein quality is assessed at a molecular level