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A fast and highly enantioselective chlorination of 4-pyrazolones catalyzed by bis(oxazoline)–Cu(ClO4)2·6H2O complexes has been developed. Under the optimized conditions, a series of pyrazolones bearing stereogenic chlorine-attached carbon centers were obtained in moderate to high yields (up to 98%) and with enantioselectivities of up to 98% ee.

A chiral amine squaramide catalyzed the conjugated addition of pyrazolin-5-ones to in situ generated ortho-quinomethanes (o-QMs) was developed to construct 4-tetrasubstituted pyrazolin-5-ones featuring adjacent quaternary and tertiary stereocenters in oil–water phases. High yields, excellent stereoselectivities, mild conditions and accessible scale-up demonstrated the fascination of this reaction protocol.

A highly regioselective and enantioselective N-alkylation of isoxazol-5-ones with para-quinone methides promoted by bi-functional squaramide catalysts was developed. This unexpected asymmetric N-addition of isoxazolinones afforded a series of enantioenriched N-diarylmethane substituted isoxazolinones with high yields and enantioselectivities (up to 97 : 3 er). This reaction not only provides a useful approach for intermolecular chiral C–N bond formation but also demonstrates the immense potential of isoxazol-5-ones as N-nucleophiles in catalytic asymmetric reactions.

Continuous variable (CV) quantum entanglement is an essential resource for quantum computation and communication protocols. The use of CV quantum entanglement at a telecommunication wavelength of 1.5m in combination with existing fiber telecommunication networks offers the possibility to implement long-distance quantum communication protocols like quantum key distribution (QKD) and applications such as quantum repeaters, quantum teleportation in the future. In spite of the fact that the optical power attenuation of light in a standard telecommunication fiber is lowest at a wavelength of 1.5m, the entangled states will interact with fiber channels and the disentanglement will occur. It is one of the important factors restricting the development of long distance quantum information. In this paper, CV entangled state at 1.5m telecommunication band is obtained by using a type-II periodically poled KTP (PPKTP) crystal inside a nondegenerate optical parametric amplifier (NOPA). A wedged PPKTP is used for implementing frequency-down-conversion of the pump field to generate the optically entangled state and achieving the dispersion compensation between the pump and the subharmonic waves. By controlling the temperature and the length of the PPKTP crystal, a triply resonant optical parametric oscillator with a threshold of 80 mW is realized. Einstein-PodolskyRosen (EPR)-entangled beams with quantum correlation of 8.3 dB for both the amplitude and phase quadratures are experimentally generated by using a single NOPA at a pump power of 40 mW and an injected signal power of 10 mW when the relative phase between the pump and injected signal is locked to . The generated entangled state is coupled into a single-mode optical fiber, and the transmission characteristics of the generated EPR entangled beams through standard single-mode fibers are investigated experimentally and theoretically. A fiber polarization controller is used to compensate for the polarization state variation induced by random fluctuations of birefringence of the single mode fiber when the light propagates along the fiber, and to keep the polarization of light linear at the fiber output. A 0.21 dB quantum entanglement could still be observed for the EPR-entangled beams transmitted through a 50-km-long single-mode fiber. The theoretical prediction considering the excess noise in fiber channel is in good agreement with the experimental result. The generated CV quantum entanglement is highly suitable for the required experiments, such as CV measurement-device-independence QKD based on standard fibers, owing to the fact that the tolerance of the excess noise in the quantum channel can be enhanced significantly with respect to a coherent state if EPR-entangled beams are used.

Continuous variable quantum entanglement at a telecommunication wavelength of 1550 nm is experimentally generated using a single nondegenerate optical parametric amplifier based on a type-II periodically poled KTiOPO4 crystal. The triply resonant of the nondegenerate optical parametric amplifier is adjusted by tuning the crystal temperature and tilting the orientation of the crystal in the optical cavity. Einstein–Podolsky–Rosen-entangled beams with quantum correlations of 8.3 dB for both the amplitude and phase quadratures are experimentally generated. This system can be used for continuous variable fibre-based quantum communication.

The squeezed light at 1.5 m telecommunication band has been considered as an important resource of continuous variable (CV) practical fiber-based quantum information research because it is the lowest loss in fiber. A bright phase quadrature squeezed light for continuous variable at 1.5 m is demonstrated from a semi-monolithic degenerate optical parametric amplifier (DOPA) based on a periodically poled KTiOPO4 (PPKTP) crystal. The laser source is a continuous wave (CW) single-frequency fiber laser at 1.5 m, which is sent through a ring mode cleaner (MC) as a preliminary spatial and noise filter. And then the main portion of the output from the MC is used for external-enhanced second harmonic generation to obtain a CW single-frequency low noise laser at 780 nm that acts as the pump of the DOPA. The residual light of the output from the MC at 1.5 m is used as the injected signal light of the DOPA and the local oscillator (LO) of a balanced homodyne detector (BHD) system. The DOPA is built by using a type-I PPKTP crystal and a piezo-actuated output coupler and works in double-resonance case with a threshold power of 230 mW. When the DOPA is operating in the state of amplification, the output down-conversion field should be a bright phase quadrature squeezed light, where the relative phase between the pump and the injected signal is locked to 0. A 4.7 dB bright phase quadrature squeezed light is measured by the BHD system with the pump light of 110 mW and the injected signal of 3 mW, where the relative phase between the down-conversion field and the LO is locked to 0. Our measurement is limited by the optical losses and the detection efficiency. We have taken into account the detection efficiency of 86.6%, and the actual squeezing of the squeezed light being 6.3 dB. Moreover, because it is so crucial a process for CV quantum information system that the transmission and evolution of the CV squeezed states in the fiber may reappear in all information of the quantum states in the phase space, then the bright squeezed light is detected by a BHD system in the time domain, and its Wigner quasi-probability distribution function can be reconstructed by using a quantum tomographic technique. Furthermore, the bright squeezed state at 1.5 m is an ideal source for fiber-based long-distance quantum information because of its stability and bright mean field.