Coherent Control of Trapped-Ion Qubits with Localized Electric Fields.

We present a new method for coherent control of trapped ion qubits in separate interaction regions of a multizone trap by simultaneously applying an electric field and a spin-dependent gradient. Both the phase and amplitude of the effective single-qubit rotation depend on the electric field, which can be localized to each zone. We demonstrate this interaction on a single ion using both laser-based and magnetic-field gradients in a surface-electrode ion trap, and measure the localization of the electric field.

Phase-Tuned Entangled State Generation between Distant Spin Qubits.

Quantum entanglement between distant qubits is an important feature of quantum networks. Distribution of entanglement over long distances can be enabled through coherently interfacing qubit pairs via photonic channels. Here, we report the realization of optically generated quantum entanglement between electron spin qubits confined in two distant semiconductor quantum dots. The protocol relies on spin-photon entanglement in the trionic Λ system and quantum erasure of the Raman-photon path information. The measurement of a single Raman photon is used to project the spin qubits into a joint quantum state with an interferometrically stabilized and tunable relative phase. We report an average Bell-state fidelity for |ψ^{(+)}⟩ and |ψ^{(-)}⟩ states of 61.6±2.3% and a record-high entanglement generation rate of 7.3 kHz between distant qubits.

Protein and amino acid bioavailability of extruded dog food with protein meals of different quality using growing mink () as a model.

The present study evaluated growing mink () as a model for dietary protein quality assessment of protein meals used in extruded dog foods. Three foods with similar CP content but of different protein quality were produced using different protein meals. The protein meals varied with respect to CP digestibility and AA composition and included lamb meal (LBM), poultry meal (PM), and fish meal (FM) with low, intermediate, and high protein quality, respectively. Nitrogen balance, BW gain, protein efficiency ratio (PER), and apparent total tract digestibility (ATTD) were used as measures of protein and AA bioavailability in growing mink. Standardized ileal digestibility (SID) was used to measure protein and AA bioavailability in adult dogs (). The mink study (3 × 3 Latin square design) included 12 kits aged 8 to 11 wk. The dog study included 12 dogs divided in 3 groups allocated to 1 of the experimental diets. The growing mink responded in accordance with the different AA supply between diets, as determined by the first limiting AA. The LBM diet deviated from the other diets with lower ( < 0.001) values for N retention, BW gain, and PER, and the diets differed ( < 0.001) in ATTD of CP and all AA, except for hydroxyproline. Retention of N was 0.66, 1.04, and 1.18 g·kg·d; BW gain was 8.2, 26.8, and 35.3 g/d; PER was 0.38, 1.39, and 1.71; and ATTD of CP was 66.8, 73.8, and 82.1% for the LBM, PM, and FM diets, respectively. In dogs, SID of CP and AA differed ( ≤ 0.017) between diets and was generally lowest for the LBM diet, intermediate for the PM diet, and greatest for the FM diet. For CP, SID was 71.5, 80.2, and 87.0% for the LBM, PM, and FM diets, respectively. The contents of digestible CP and AA (based on SID) covered the minimal requirement for adult dogs set by the NRC for all diets, except for the content of digestible Met + Cys in the LBM diet. Despite this, dietary content of Met + Cys in the LBM diet agreed with the recommended level set by the NRC and the Association of American Feed Control Officials for adult dogs but was below the level recommended by the European Pet Food Industry Federation. It was concluded that growth studies with mink kits can provide valuable information in protein quality assessment of extruded dog foods. Furthermore, the study showed that to ensure nutritional adequacy of dog food and to be able to compare protein quality of dog foods, information on AA composition and digestibility is crucial.

Quantum dot spin coherence governed by a strained nuclear environment.

The interaction between a confined electron and the nuclei of an optically active quantum dot provides a uniquely rich manifestation of the central spin problem. Coherent qubit control combines with an ultrafast spin-photon interface to make these confined spins attractive candidates for quantum optical networks. Reaching the full potential of spin coherence has been hindered by the lack of knowledge of the key irreversible environment dynamics. Through all-optical Hahn echo decoupling we now recover the intrinsic coherence time set by the interaction with the inhomogeneously strained nuclear bath. The high-frequency nuclear dynamics are directly imprinted on the electron spin coherence, resulting in a dramatic jump of coherence times from few tens of nanoseconds to the microsecond regime between 2 and 3 T magnetic field and an exponential decay of coherence at high fields. These results reveal spin coherence can be improved by applying large magnetic fields and reducing strain inhomogeneity.

Direct photonic coupling of a semiconductor quantum dot and a trapped ion.

Coupling individual quantum systems lies at the heart of building scalable quantum networks. Here, we report the first direct photonic coupling between a semiconductor quantum dot and a trapped ion and we demonstrate that single photons generated by a quantum dot controllably change the internal state of a Yb^{+} ion. We ameliorate the effect of the 60-fold mismatch of the radiative linewidths with coherent photon generation and a high-finesse fiber-based optical cavity enhancing the coupling between the single photon and the ion. The transfer of information presented here via the classical correlations between the σ_{z} projection of the quantum-dot spin and the internal state of the ion provides a promising step towards quantum-state transfer in a hybrid photonic network.

Quantitative evaluation of correlation of dose and FDG-PET uptake value with clinical chest wall complications in patients with lung cancer treated with stereotactic body radiation therapy.

The aim of this study was to investigate quantitatively the dosimetric factors that increase the risk of clinical complications of rib fractures or chest wall pain after stereotactic body radiation therapy (SBRT) to the lung. The correlations of clinical complications with standard-uptake values (SUV) and FDG-PET activity distributions from post-treatment PET-imaging were studied. Mean and maximum doses from treatment plans, FDG-PET activity values on post-SBRT PET scans and the presence of clinical complications were determined in fifteen patients undergoing 16 SBRT treatments for lung cancer. SBRT treatments were delivered in 3 to 5 fractions using 5 to 7 fields to prescription doses in the range from 39.0 to 60.0 Gy. The dose and FDG-PET activity values were extracted from regions of interest in the chest wall that matched anatomically. Quantitative evaluation of the correlation between dose deposition and FDG-PET activity was performed by calculating the Pearson correlation coefficient using pixel-by-pixel analysis of dose and FDG-PET activity maps in selected regions of interest associated with clinical complications. Overall, three of fifteen patients developed rib fractures with chest wall pain, and two patients developed pain symptoms without fracture. The mean dose to the rib cage in patients with fractures was 37.53 Gy compared to 33.35 Gy in patients without fractures. Increased chest wall activity as determined by FDG-uptake was noted in patients who developed rib fractures. Enhanced activity from PET-images correlated strongly with high doses deposited to the chest wall which could be predicted by a linear relationship. The local enhanced activity was associated with the development of clinical complications such as chest wall inflammation and rib fracture. This study demonstrates that rib fractures and chest wall pain can occur after SBRT treatments to the lung and is associated with increased activity on subsequent PET scans. The FDG-PET activity provides a useful parameter that can be used clinically to predict chest wall complication in lung patients.

Gross tumour volume variations in primary non-small-cell lung cancer during the course of treatment with stereotactic body radiation therapy.

INTRODUCTION: We aim to quantify the variations in the gross tumour volume (GTV) during a course of stereotactic body radiotherapy (SBRT) and determine its impact on dosimetric coverage of the GTV. METHODS: The GTVs and dose coverage for 14 patients with 16 primary non-small-cell lung tumours treated with SBRT were investigated. Initial GTVs were calculated from treatment planning CT scans. The prescribed doses ranged from 48 to 60 Gy in three to five fractions. Before each treatment, patients underwent a CBCT scan. For each CBCT scan, the GTV and the dose received by the GTV were determined and followed during the course of therapy. RESULTS: There was considerable variation in the measured GTVs during the course of therapy. Increases of up to 63.3% of volume measured by initial CBCT were detected during the first few fractions, after which GTV tended to decrease. Dose coverage (V95) for any given fraction deviated no more than 5% from optimised coverage obtained in the initial treatment plan. In the long term, all patients with follow-up scans demonstrated tumour shrinkage with no radiographic evidence of tumour recurrence. CONCLUSION: GTV, as evaluated in this study, demonstrates an initial increase in volume followed by a subsequent decrease. This volume change needs to be considered in the design of treatment plans and assignment of treatment margins.

Low protein provision during the first year of life, but not during foetal life, affects metabolic traits, organ mass development and growth in male mink (Neovison vison).

Low protein provision in utero and post-partum may induce metabolic disorders in adulthood. Studies in mink have mainly focused on short-term consequences of low protein provision in utero whereas the long-term responses to low protein (LP) provision in metabolically programmed mink are unknown. We investigated whether low protein provision in utero affects the long-term response to adequate (AP) or LP provision after weaning in male mink. Eighty-six male mink were exposed to low (19% of ME from CP; crude protein) or adequate (31% of ME from CP) protein provision in utero, and to LP (~20% of ME from CP) or AP (30-42% of ME from CP) provision post-weaning. Being metabolically programmed by low protein provision in utero did not affect the response to post-weaning diets. Dietary protein content in the LP feed after weaning was below requirements; evidenced by lower nitrogen retention (p < 0.001) preventing LP mink from attaining their growth potential (p < 0.02). LP mink had a lower liver, pancreas and kidney weight (p < 0.05) as well as lower plasma IGF-1 concentrations at 8 and 25 (p < 0.05) weeks, and a higher incidence of hepatic lipidosis at 25 weeks (p < 0.05). Furthermore, LP mink had a higher body fat (p < 0.05) and lower body CP content (p < 0.05) at 50 weeks of age. It is concluded that some effects of low protein provision in utero can be alleviated by an adequate nutrient supply post-partum. However, long-term exposure to low protein provision in mink reduces their growth potential and induces transient hepatic lipidosis and modified body composition.

Foetal life protein restriction in male mink (Neovison vison) kits lowers post-weaning protein oxidation and the relative abundance of hepatic fructose-1,6-bisphosphatase mRNA.

Foetal life malnutrition has been studied intensively in a number of animal models. Results show that especially foetal life protein malnutrition can lead to metabolic changes later in life. This might be of particular importance for strict carnivores, for example, cat and mink (Neovison vison) because of their higher protein requirement than in other domestic mammals. This study aimed to investigate the effects of low protein provision during foetal life to male mink kits on their protein metabolism during the early post-weaning period of rapid growth and to investigate whether foetal life protein deficiency affects the response to adequate or deficient protein provision post weaning. Further, we intended to study whether the changes in the gene expression of key enzymes in foetal hepatic tissue caused by maternal protein deficiency were manifested post-weaning. A total of 32 male mink kits born to mothers fed either a low-protein diet (LP), that is, 14% of metabolizable energy (ME) from protein (foetal low - FL), n = 16, or an adequate-protein (AP) diet, that is, 29% of ME from protein (foetal adequate - FA), n = 16) in the last 16.3 ± 1.8 days of pregnancy were used. The FL offspring had lower birth weight and lower relative abundance of fructose-1,6-bisphosphatase (Fru-1,6-P2ase) and pyruvate kinase mRNA in foetal hepatic tissue than FA kits. The mothers were fed a diet containing adequate protein until weaning. At weaning (7 weeks of age), half of the kits from each foetal treatment group were fed an AP diet (32% of ME from protein; n = 8 FA and 8 FL) and the other half were fed a LP diet (18% of ME from protein; n = 8 FA and 8 FL) until 9.5 weeks of age, yielding four treatment groups (i.e. FA-AP, FA-LP, FL-AP and FL-LP). Low protein provision in foetal life lowered the protein oxidation post-weaning compared with the controls (P = 0.006), indicating metabolic flexibility and a better ability to conserve protein. This could not, however, be supported by changes in liver mass because of foetal life experience. A lower relative abundance of Fru-1,6-P2ase mRNA was observed (P < 0.05), being lower in 9.5-week-old FL than in FA kits. It can be concluded that foetal life protein restriction leads to changes in post-weaning protein metabolism through lower protein oxidation of male mink kits.

Observation of spin-dependent quantum jumps via quantum dot resonance fluorescence.

Reliable preparation, manipulation and measurement protocols are necessary to exploit a physical system as a quantum bit. Spins in optically active quantum dots offer one potential realization and recent demonstrations have shown high-fidelity preparation and ultrafast coherent manipulation. The final challenge-that is, single-shot measurement of the electron spin-has proved to be the most difficult of the three and so far only time-averaged optical measurements have been reported. The main obstacle to optical spin readout in single quantum dots is that the same laser that probes the spin state also flips the spin being measured. Here, by using a gate-controlled quantum dot molecule, we present the ability to measure the spin state of a single electron in real time via the intermittency of quantum dot resonance fluorescence. The quantum dot molecule, unlike its single quantum dot counterpart, allows separate and independent optical transitions for state preparation, manipulation and measurement, avoiding the dilemma of relying on the same transition to address the spin state of an electron.

Gas exchange, heat production and oxidation of fat in chicken embryos from a fast or slow growing line.

The experiment comprised 48 chicken (Gallus gallus) embryos from a modern, fast growing line, Ross 308 (RO) and 48 from a slow growing line, Labresse (LA). The O(2) consumption and CO(2) production were measured in an open-air-circuit respiration unit, and heat production (HE) from embryos was calculated at an age of 10, 13, 16 and 19 days. Gas exchange was below 10 ml/h for RO and LA by an age of 10-13 days, increasing steeply to a "peak" on day 16 and then slowing down between 16 and 19 days. The pattern of curves for gas exchange was identical for RO and LA, but on a lower level for LA. HE followed the pattern of gas exchange, with a mean around 50 J/h on day 10, increasing to 528 (RO) and 402 (LA) J/h on day 19. The main source of HE was oxidized fat. In addition to respiration experiments chemical analyses were carried out on 60 eggs from RO and 60 from LA. Prior to chemical analyses the eggs were incubated for 7, 13 and 19 days. Since fat oxidation was the main energy fuel the content of fat in the eggs decreased by 2.0 (RO) and 1.6 g (LA), while protein content was fairly constant in each line. It is remarkable that the differences in heat production between chickens from fast and slow growing lines were already manifested during their embryonic development.