Transverse Mode-Encoded Quantum Gate on a Silicon Photonic Chip.

As an important degree of freedom (d.o.f.) in photonic integrated circuits, the orthogonal transverse mode provides a promising and flexible way to increase communication capability, for both classical and quantum information processing. To construct large-scale on-chip multimode multi-d.o.f.s quantum systems, a transverse mode-encoded controlled-NOT (CNOT) gate is necessary. Here, with the help of our new transverse mode-dependent directional coupler and attenuator, we demonstrate the first multimode implementation of a 2-qubit quantum gate. The ability of the gate is demonstrated by entangling two separated transverse mode qubits with an average fidelity of 0.89±0.02 and the achievement of 10 standard deviations of violations in the quantum nonlocality verification. In addition, a fidelity of 0.82±0.01 is obtained from quantum process tomography used to completely characterize the CNOT gate. Our work paves the way for universal transverse mode-encoded quantum operations and large-scale multimode multi-d.o.f.s quantum systems.

Topologically Protected Valley-Dependent Quantum Photonic Circuits.

Topological photonics has been introduced as a powerful platform for integrated optics, since it can deal with robust light transport, and be further extended to the quantum world. Strikingly, valley-contrasting physics in topological photonic structures contributes to valley-related edge states, their unidirectional coupling, and even valley-dependent wave division in topological junctions. Here, we design and fabricate nanophotonic topological harpoon-shaped beam splitters (HSBSs) based on 120-deg-bending interfaces and demonstrate the first on-chip valley-dependent quantum information process. Two-photon quantum interference, namely, Hong-Ou-Mandel interference with a high visibility of 0.956±0.006, is realized with our 50/50 HSBS, which is constructed by two topologically distinct domain walls. Cascading this kind of HSBS together, we also demonstrate a simple quantum photonic circuit and generation of a path-entangled state. Our work shows that the photonic valley state can be used in quantum information processing, and it is possible to realize more complex quantum circuits with valley-dependent photonic topological insulators, which provides a novel method for on-chip quantum information processing.

Optimal third-harmonic generation in an optical microcavity with χ(2) and χ(3) nonlinearities.

Third-harmonic generation can be realized via both χ(3) and cascaded χ(2) nonlinear processes in a triply-resonant microcavity. It is still unknown how these processes interfere with each other and the optimization of the conversion efficiency still remains as a question. In this work, the interplay between the direct third-harmonic generation and the cascaded process combining of the second-harmonic generation and the sum-frequency generation are investigated. It is found that the interference effect between these two processes can be used to improve the conversion efficiency. By optimizing the cavity resonance and the external coupling conditions, the saturation of the nonlinear conversion is mitigated and the third-harmonic conversion efficiency is increased. A design rule is provided for achieving efficient third-harmonic generation in an optical microcavity, which can be generalized further to the high-order harmonic generations.

[Effects of light quality on growth and internal quality of Whitmania pigra].

In this study, four light color treatments (red blue, white, natural light) were tested to determine effects of light spectrum on the growth of larval Whitmania pigra (30 days old) at the same intensity. The experiment lasted for 50 days. The specific growth rate (SGR) under blue light condition was significantly higher during 30 days to 40 days. At the end of the experiment, specific growth rate (SGR) and weight gain rate under red light condition were higher (P<0.05) than those under other groups. Meanwhile, the enzymes activities of digestive enzymes (protease, amylase and lipase) were higher under red light condition. However, the enzymes activities of antioxidant enzymes (SOD, CAT, ALP) were lower under white light condition compared with the other treatments（P＜0.05）. In addition, no significant changes were observed for water content, total ash, acid insoluble ash, pH and antithrombin activity in the all treatments. After 50 days, the digestive enzymes and growth rate were higher under red light condition but antioxidant enzymes were lower under white light condition. Furthermore, light spectrum has no significant effect on the internal quality of Wh. pigra.

[Study on correlation of oxygen consumption rate and suffocation point of Whitmania pigra and Bellamya purificata and optimum way of feeding Whitmania pigra].

The oxygen consumption, oxygen consumption rate and suffocation point of different quality Whitmania pigra and Bellamya purificata were determined by hydrostatic breathing room method. The effects of feeding modes on growth of W.pigra were determined by biomass. The results showed that the oxygen consumption correlated positively with the weight of W.pigra and B. purificata（P<0.05）, suffocation point increased with the increases of the weight（P<0.05）.Oxygen consumption correlated negatively with the weight of W. pigra, the oxygen consumption rate of B.purificata first increased and then decreased with the increasing of the weight. Feeding modes had no significant effects on the finial weight, SGR, WGR, death rates of W. pigra. Feeding modes had significant effects on eating ratio. It suggested that the optimum feeding frequency of W. pigra was once every three days. Scientific and reasonable feeding amount of B. purificata should be calculated based on oxygen consumption and suffocation point of W.pigra and B.purificata at every period. Meanwhile, stocking density, water area and water exchanging frequency should be taken into consideration.

[Studies on hibernation pivotal temperature of Whitmania pigra].

The biological characteristics, oxygen consumption, oxygen consumption rate, and activities of amylase, lipase and protease of Whitmania pigra at different temperature were studied by using direct observational method, the still water method and 3, 5-dinitrosalicylic acid colorimetry, right-nitrophenyl palmitate ester（ρ-NPP）colorimetry and folin-phenol method.The results revealed that with decreasing water temperature, the daily activity and the daily feeding ration were decreased. As the temperature was lowered to 4 ℃, the head and tail of Wh.pigra curved, showing a crescent-shape without feeding and daily activity. Oxygen consumption, oxygen consumption rate and digestive enzyme activities reduced along with temperature drops. The downward trend slowed below 10 ℃, began to stabilize below 4 ℃ and doesn't change with the decrease of temperature since then. During the 40 days treatment at 4 ℃, the changes of amylase were not significant, the lipase and protease activity decreased at the 20th day, and the lipase showed an slightly increase after the decrease and finally remained at a low level.In conclusions, the pivotal temperature of hibernation of Wh.pigra is 4 ℃ and the crescent shape can be considered as a symbol of hibernation.

[Effects of harvest and different processing methods on anti-thrombin activity of Poecilobdella manillensis].

The effects of harvest and different processing methods on the anti-thrombin activity of Poecilobdella manillensis were respectively studied. The indicators included processing methods (vacuum freeze drying, fresh homogenate, drying under sunlight, freezing, scalding, baking under different temperatures), different parts (entire body, cephalon, pygidium, exudate) and body weights (≤10, 10-20, 20-30, 30-40, ≥40 g). The anti-thrombin activities of P. manillensis with different processing methods were evaluated by direct anti-thrombin titration. The results indicated that the processing methods significantly affected the anti-thrombin activities of P. manillensis. Among the 11 groups, the anti-thrombin activity of P. manillensis processed with vacuum freeze drying (1 303.56 U•g⁻¹) was significantly highest than the other groups (P<0.05), and that processed with baking under 90 ℃ (15.44 U•g⁻¹) was the lowest. The anti-thrombin activity of the cephalon of P. manillensis (226.42 U•g⁻¹) was the highest, and that of the pygidium (102.12 U•g⁻¹) was lowest; the anti-thrombin activities for different body weights were significantly different (P<0.05); and among the five groups, the body weight of ≤10 g (328.86 U•g⁻¹) was the highest (P<0.05), and the body weight of ≥40 g (87.71 U•g⁻¹) was the lowest. In conclusion, harvest and different processing methods had a significant impact on the anti-thrombin activities of P. manillensis. In the study, for the optimal processing method for P. manillensis, the body weight between 20-30 g is recommended, and the vacuum freeze drying is preferred, which is followed by the drying under sunlight.

[Effects of stocking density and exchanging water frequency on growth and inner quality of Whitmania pigra].

The effects of stocking density and exchanging water frequency on growth, digestive enzyme activity, anti-oxidative enzyme and inner quality of Whitmania pigra Whitman were evaluated with corresponding measures. The results showed that the eventual biomass, specific growth rate, gained weight rate, activities of amylase, lipase, protease, SOD, CAT, and ALP correlated positively with stocking density and negatively with exchanging water frequency (P<0.05). Exchanging water frequency had negative correlation with ammonia nitrogen, nitrite, and hydrogen sulfide while revealed positive correlation with dissolved oxygen in the water. Stocking density and exchanging water frequency showed no significant effects on the contents of moisture, total ash, and acid-insoluble ash. It suggested that the optimum stocking density was 7.5 million per hectare and the appropriate exchanging water interval was 72 h.

Generation of multiphoton quantum states on silicon.

Multiphoton quantum states play a critical role in emerging quantum technologies and greatly improve our fundamental understanding of the quantum world. Integrated photonics is well recognized as an attractive technology offering great promise for the generation of photonic quantum states with high-brightness, tunability, stability, and scalability. Herein, we demonstrate the generation of multiphoton quantum states using a single-silicon nanophotonic waveguide. The detected four-photon rate reaches 0.34 Hz even with a low-pump power of 600 µW. This multiphoton quantum state is also qualified with multiphoton quantum interference, as well as quantum state tomography. For the generated four-photon states, the quantum interference visibilities are greater than 95%, and the fidelity is 0.78 ± 0.02. Furthermore, such a multiphoton quantum source is fully compatible with the on-chip processes of quantum manipulation, as well as quantum detection, which is helpful for the realization of large-scale quantum photonic integrated circuits (QPICs) and shows great potential for research in the area of multiphoton quantum science.

On-chip coherent conversion of photonic quantum entanglement between different degrees of freedom.

In the quantum world, a single particle can have various degrees of freedom to encode quantum information. Controlling multiple degrees of freedom simultaneously is necessary to describe a particle fully and, therefore, to use it more efficiently. Here we introduce the transverse waveguide-mode degree of freedom to quantum photonic integrated circuits, and demonstrate the coherent conversion of a photonic quantum state between path, polarization and transverse waveguide-mode degrees of freedom on a single chip. The preservation of quantum coherence in these conversion processes is proven by single-photon and two-photon quantum interference using a fibre beam splitter or on-chip beam splitters. These results provide us with the ability to control and convert multiple degrees of freedom of photons for quantum photonic integrated circuit-based quantum information process.