分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Self-reference interferometry of optical vortices using a Michelson interferometer is investigated in this paper. It is found that the detection of topological charge (TC) for the optical vortices is constrained by some physical conditions. We present these conditions through the theoretical analyses, numerical simulation and experimental results. For different parameters, the maximal detectable TCs are different, which is helpful for the measurement of TC in the practical application. Within the range allowed by the constrained conditions, we also study the detection of TC using the interference pattern of two-way optical vortex by changing the inclined angle of one mirror of the Michelson interferometer.
分类: 生物学 >> 生态学 提交时间: 2017-11-17
摘要: It is urgent to discover new anti-influenza drugs considering the threat of so called swine flu and Spanish flu. Though Adamantane derivatives are the only M2 inhibitors as anti-influenza virus A drugs, they are limited to use in the US due to drug resistant. Herein we reported that multiple lead compounds as M2 inhibitors were rapidly generated through the screening of focused library designed with scaffold-hopping strategy based on Amantadine.
分类: 生物学 >> 生态学 提交时间: 2017-11-17
摘要: The discovery of new anti-influenza drugs is urgent, particularly considering the recent threat of swine flu. Although amantadine derivatives are the only M2 drugs for influenza virus A, their use is limited in the US due to drug resistance. Here we report the discovery of multiple M2 inhibitor lead compounds that were rapidly generated through focused screening of a small primary amine library which was designed using a scaffold-hopping strategy based on amantadine.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: The pursuit of compact lasers with low-thresholds has imposed strict requirements on tight light confinements with minimized radiation losses. Bound states in the continuum (BICs) have been recently demonstrated as an effective mechanism to trap light along the out-of-plane direction, paving the way to low-threshold lasers. To date, most reported BIC lasers are still bulky due to the absence of in-plane light confinement. In this work, we combine BICs and photonic band gaps to realize three-dimensional (3D) light confinements, as referred to miniaturized (mini-) BICs. Together with 3D carrier confinements provided by quantum dots (QDs) as optical gain materials, we have realized highly-compact active BIC resonators with a record-high quality ($Q$) factor up to 32500, which enables single-mode continuous wave (CW) lasing with the lowest threshold of 80 W/cm$^{2}$ among the reported BIC lasers. In addidtion, our photon statistics measurements under both CW and pulsed excitations confirm the occurence of the phase transition from spontaneous emission to stimulated emission, further suggesting that conventional criteria of input-output and linewidth are not sufficient for claiming nanoscale lasing. Our work reveal a via path towards compact BIC lasers with ultra-low power consumption and potentially boost the applications in cavity quantum electrodynamics (QEDs), nonlinear optics and integrated photonics.
分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30
摘要: Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment pro#2;cess. However, severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiationtherapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Netwas proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with con#2;volutional block attention modules. The datasets contained 20 groups of head and neck images. The CT imageswere registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, wastrained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and theoriginal sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT,CBCT, and SCT images were compared using four metrics: mean absolute error (MAE), root mean square error(RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM). The mean values ofthe MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919,respectively, which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the rangeaccuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scannedfield and simple plan were calculated to compare the effects of the noise reduction capabilities of the originalU-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively thansCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reductionin proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed modelprovided relatively explicit information regarding patient tissues. Moreover, it can be used in dose calculationand adaptive treatment planning in the future.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Chaotic semiconductor lasers have been widely investigated for high-speed random bit generation, which is applied for the generation of cryptographic keys for classical and quantum cryptography systems. Here, we propose and demonstrate a self-chaotic microlaser with enhanced chaotic bandwidth for high-speed random bit generation. By designing tri-mode interaction in a deformed square microcavity laser, we realize a self-chaotic laser caused by two-mode internal interaction, and achieve an enhanced chaotic standard bandwidth due to the photon-photon resonance effect by introducing the third mode. Moreover, 500 Gb/s random bit generation is realized and the randomness is verified by the NIST SP 800-22 statistics test. Our demonstration promises the applications of microlasers in secure communication, chaos radar, and optical reservoir computing, and also provides a platform for the investigations of multimode nonlinear laser dynamics.
分类: 材料科学 >> 材料科学(综合) 分类: 材料科学 >> 金属与冶金 提交时间: 2020-01-07
摘要: Nano-crystalline metals (NCs) exhibit radiation-tolerance due to the sink of grain boundaries (GBs) for radiation-induced defects such as self-interstitial atoms (SIAs) and vacancies (Vs). However, the relevant mechanisms for the radiation damage accumulation and GB structural relaxation under high radiation field in NCs are still not well understood due to the lack of self-consistent across-scale techniques for simulating radiation-induced microstructures evolution. In this article, by combining coarse-grained and atomistic simulations, we proposed a coupling method to investigate the evolution of the microstructure and SIA/V-GB interaction under cumulative irradiation in NC iron. The SIA overloaded effect was revealed in iron GBs at a high radiation dose rate and/or low temperature. Two types of GB structural response were observed to cumulative irradiation. With the SIA accumulated at the GB, the new GB phase formed and then a critical concentration of the SIA at the GB transited to the small quantity of the V during the GB structural recovery, accompanied by the local GB motion. Consequently, the GB’s role for Vs nearby alternated between the trapping and annihilation center with radiation dose. Alternatively, GB developed to a disordered structure after trapping abundant SIAs. The GB response pattern to cumulative irradiation that is related to the SIA formation energy at the GB or the GB thermal stability is well manifested in the cumulative distribution function of the defects formation energy and its energy level density. The present work reveals the dynamic healing picture for radiation damage near the GB under cumulative irradiation.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Contextuality, a hallmark feature of the quantum theory, captures the incompatibility between quantum correlations and any noncontextual hidden-variable model. The Greenberger--Horne--Zeilinger (GHZ)-type paradoxes are proofs of contextuality which reveal this incompatibility with deterministic logical arguments. However, the simplest GHZ-type paradox with the fewest number of complete contexts and the largest degree of nonclassicality remains elusive. Here, we derive a GHZ-type paradox utilising only three complete contexts and show this number cannot be further reduced. We forward to demonstrating the paradox with an experiment which recovered all essential ingredients in a 37-dimensional contextuality test based on high-speed modulation, optical convolution and homodyne detection of time-multiplexed modes of coherent light that can be interpreted as a classical entity. By proposing and observing a strong form of contextuality in an extremely high-dimensional system, our results pave the way for the exploration of exotic quantum correlations with optical systems.