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Parametric generation and phase locking of multiple sidebands in the regime of full-back-conversion

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High Power Laser Science and Engineering 2023年第2期11卷 44-51页

作者： Wenhao Wang Yudong Tao Jingui Ma Jing Wang Peng Yuan Dongfang Zhang Liejia Qian School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina

Parametric interaction allows both forward and backward energy transfers among the three interacting waves.The back-conversion effect is usually detrimental when unidirectional energy transfer is desired.In this theoretical work,we manifest that the back-conversion effect underpins the direct generation of the picosecond pulse train without the need for a laser resonator.The research scenario is an optical parametric amplification(OPA)that consists of a second-order nonlinear medium,a quasi-continuous pump laser and a sinusoidal amplitude-modulated seed signal.The back-conversion of OPA can transfer the modulation peaks(valleys)of the incident signal into output valleys(peaks),which inherently induces spectral sidebands.The generation of each sideband is naturally accompanied with a phase shift of±π.In the regime of full-back-conversion,the amount and amplitude of the sidebands reach the maximum simultaneously,and their phase constitutes an arithmetic sequence,leading to the production of a picosecond pulse train.The generated picosecond pulse train can have an ultrahigh repetition rate of 40 GHz or higher,which may facilitate ultrafast applications with ultrahigh speed.

关键词： picosecond pulse train quadratic parametric process sideband generation

Controllable Modulation to Quantum Well States on β-Sn Islands

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Chinese Physics Letters 2020年第9期37卷 42-45页

作者：王泽睿赵晨晓王观勇秦晋夏冰杨波管丹丹王世勇郑浩李耀义刘灿华贾金锋 Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai 200240China

We investigate the surface structure and electronic properties ofβ-Sn islands deposited on a graphitized 6 H-SiC(0001)substrate via low temperature scanning tunneling microscopy and spectroscopy.Owing to the confinement of the island geometry,quantum well states(QWSs)are formed,manifesting as equidistant peaks in the tunneling spectra.Furthermore,a distinct strip feature appears on the surfaces of odd-layer Sn islands,ranging from 15-19 layers,which is not present on the surfaces of even-layer Sn islands.The spatial distribution of strips can be modified by applying a bias pulse,using an STM tip.Furthermore,the strip-like structure shows significant impacts on the QWS.An energy splitting of the lowest unoccupied QWSs is observed in strip regions;this may be ascribed to caused the phase shift of the wave functions of the QWSs on the top surface,due to surface distortions created by the aforementioned strips.

关键词： strip tunneling surface

Numerical study of spatial chirp distortion in quasi-parametric chirped-pulse amplification

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High Power Laser Science and Engineering 2022年第3期10卷 19-24页

作者： Yirui Wang Jing Wang Jingui Ma Peng Yuan Liejia Qian School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

Optical parametric chirped-pulse amplification is inevitably subject to high-order spatial chirp,particularly under the condition of saturated amplification and a Gaussian pump;this corresponds to an irreversible spatiotemporal distortion and consequently degrades the maximum attainable focused intensity.In this paper,we reveal that such spatial chirp distortion can be significantly mitigated in quasi-parametric chirped-pulse amplification(QPCPA)with idler absorption.Simulation results show that the quality of focused intensity in saturated QPCPA is nearly ideal,with a spatiotemporal Strehl ratio higher than 0.98.As the seed bandwidth increases,the idler absorption spectrum may not be uniform,but the Strehl ratio in QPCPA can be still high enough due to stronger idler absorption.

关键词： gain saturation quasi-parametric chirped-pulse amplification spatiotemporal distortions

Neutrinos,supernovae,and the origin of the heavy elements

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Science China(Physics,Mechanics & Astronomy) 2018年第4期61卷 1-6页

作者： YongZhong Qian School of Physics and Astronomy University of MinnesotaMinneapolis 55455USA Tsung-Dao Lee Institute Shanghai 200240China

Stars of～8-100 M_⊙end their lives as core-collapse supernovae(SNe). In the process they emit a powerful burst of neutrinos,produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for SN progenitors results in diverse neutrino signals, explosion energies, and nucleosynthesis products. A major mechanism to produce nuclei heavier than iron is rapid neutron capture, or the r process. This process may be connected to SNe in several ways. A brief review is presented on current understanding of neutrino emission, explosion, and nucleosynthesis of SNe.

关键词：中微子重元素起源中子俘获爆炸多元素原子核生产

Generation of a curved plasma channel from a discharged capillary for intense laser guiding

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High Power Laser Science and Engineering 2023年第5期11卷 85-92页

作者： Jian-Long Li Bo-Yuan Li Xin-Zhe Zhu Ze-Wu Bi Xin-Hui Wen Lin Lu Xiao-Hui Yuan Feng Liu Min Chen Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghaiChina

Straight plasma channels are widely used to guide relativistic intense laser pulses over several Rayleigh lengths for laser wakefield acceleration.Recently,a curved plasma channel with gradually varied curvature was suggested to guide a fresh intense laser pulse and merge it into a straight channel for staged wakefield acceleration[Phys.Rev.Lett.120,154801(2018)].In this work,we report the generation of such a curved plasma channel from a discharged capillary.Both longitudinal and transverse density distributions of the plasma inside the channel were diagnosed by analyzing the discharging spectroscopy.Effects of the gas-filling mode,back pressure and discharging voltage on the plasma density distribution inside the specially designed capillary are studied.Experiments show that a longitudinally uniform and transversely parabolic plasma channel with a maximum channel depth of 47.5µm and length of 3 cm can be produced,which is temporally stable enough for laser guiding.Using such a plasma channel,a laser pulse with duration of 30 fs has been successfully guided along the channel with the propagation direction bent by 10.4◦.

关键词： curved plasma channel discharging spectroscopy laser guiding

e^(+)e^(-)对撞机物理中超子衰变CP破缺探索

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Science Bulletin 2022年第18期67卷 1840-1843页

作者：何小刚 Jusak Tandean German Valencia Tsung-Dao Lee Institute KLPAC and SKLPPC laboratoriesSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Gayungsari III/20 Surabaya 60235Indonesia School of Physics and Astronomy Monash UniversityMelbourne VIC-3800Australia

The phenomenon of CP violation——the breaking of the combination of charge-conjugation symmetry(C) and parity symmetry(P)——is one of the least understood aspects of high-energy physics.The frst evidence for CP viol... 详细信息

关键词： symmetry 超子衰变 neutral

Phenomenological advantages of the normal neutrino mass ordering

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Chinese Physics C 2020年第8期44卷 33-39页

作者：葛韶锋朱景宇 Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityChina School of Physics and Astronomy Shanghai Jiao Tong UniversityChina

The preference of the normal neutrino mass ordering from the recent cosmological constraint and the global fit of neutrino oscillation experiments does not seem like a wise choice at first glance since it obscures the neutrinoless double beta decay and hence the Majorana nature of neutrinos.Contrary to this naive expectation,we point out that the actual situation is the opposite.The normal neutrino mass ordering opens the possibility of excluding the higher solar octant and simultaneously measuring the two Majorana CP phases in future 0ν2βexperiments.Especially,the funnel region will completely disappear if the solar mixing angle takes the higher octant.The combined precision measurement by the JUNO and Daya Bay experiments can significantly reduce the uncertainty in excluding the higher octant.With a typical O(meV)sensitivity on the effective mass|mee|,the neutrinoless double beta decay experiment can tell if the funnel region really exists and hence exclude the higher solar octant.With the sensitivity further improved to sub-meV,the two Majorana CP phases can be simultaneously determined.Thus,the normal neutrino mass ordering clearly shows phenomenological advantages over the inverted one.

关键词： neutrino mass ordering higher solar octant neutrinoless double beta decay Majorana CP phases

Optimizing Raman quantum memory with dynamic phase

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Science China(Information Sciences) 2023年第8期66卷 61-71页

作者： Sheng MING Jinxian GUO Yuan WU Guzhi BAO Shuhe WU Minwei SHI Liqing CHEN Weiping ZHANG School of Physics and Astronomy and Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai Research Center for Quantum Sciences State Key Laboratory of Precision Spectroscopy Quantum Institute of Atom and Light Department of PhysicsEast China Normal University Collaborative Innovation Center of Extreme Optics Shanxi University Shanghai Branch Hefei National Laboratory

Optical quantum memory is a key component of emerging quantum technologies and applications. One of the most promising protocols, far-off-resonant Raman memory, is still beset by its efficiency.Until now, the only effective method for enhancing its efficiency in experiments has been the intensity modulation method on the control field, while the experimental demonstrations still fail to meet the theoretical expectation. In this study, we experimentally demonstrate how to optimize the Raman quantum memory process using a new method called phase modulation; 52.7% total memory efficiency is realized by applying a phase modulation on the control field with a near-square intensity waveform of the control field, thereby resulting in an increase in efficiency of 13.3% compared to the best case of no phase modulation. Additionally, a hybrid method, combining the phase and intensity modulations, is demonstrated with 87.3% memory efficiency. Such high-efficiency results in 99.0% unconditional fidelity even at near single photon level. The unconditional fidelity is always higher than that of the intensity method as the input photon number of the signal increases and can still beat the nonclone limit, even at 128.1 photons/pulse. Our phase modulation method has great potential applications in quantum information processing due to the advantages of low experimental requirements but an additional degree of freedom and high performance, especially for the high speed and high photon number state manipulation.

关键词： quantum information quantum optics quantum communication quantum memory Raman scattering

Gravitational Equivalence Theorem and Double-Copy for Kaluza-Klein Graviton Scattering Amplitudes

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Research 2022年第4期2022卷 411-420页

作者： Yan-Feng Hang Hong-Jian He Tsung-Dao Lee Institute and School of Physics and Astronomy Key Laboratory for Particle Astrophysics and Cosmology(MOE)Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghaiChina institute of Modern Physics and Department of Physics Tsinghua UniversityBeijingChina Center for High Energy Physics Peking UniversityBeijingChina

We analyze the structure of scattering amplitudes of the Kaluza-Klein (KK) gravitons and of the KK gravitational Goldstone bosons in the compactified 5d general relativity (GR). Using a general Rξ gauge fixing, we study the geometric Higgs mechanism for the massive spin-2 KK gravitons. We newly propose and prove a gravitational equivalence theorem (GRET) to connect the scattering amplitudes of longitudinal KK gravitons to that of the KK gravitational Goldstone bosons, which formulates the geometric gravitational Higgs mechanism at the scatteringS-matrix level. We demonstrate that the GRET provides a general energy cancellation mechanism guaranteeing the N-point longitudinal KK graviton scattering amplitudes to have their leading energy dependence cancelled down by a large power factor of E^(2N)(N≥4) up to any loop level. We propose an improved double-copy approach to construct the massive KK graviton (Goldstone) amplitudes from the KK gauge boson (Goldstone) amplitudes. With these, we establish a new correspondence between the two types of energy cancellations in the four-point longitudinal KK amplitudes at tree level: E^(4)→E0 in the KK gauge theory and E^(10)→E^(2) in the KK GR theory.

关键词： theory gauge guarantee