依托于学科优势的物理实验教学改革研究

通过改革和实践,提高了学生的学习主动性和创新能力,促进了教学科研的良性互动,实现了教学科研协同育人。     

噪声引入对EPR导引的影响

EPR(Einstein-Podolsky-Rosen)导引展现出一种不同于量子纠缠态与Bell非局域性的量子非局域性,其中单向EPR导引在量子秘密共享中尤为重要。提出了一种通过在EPR纠缠态的一方增加噪声来改变EPR导引特性的方案,在引入噪声之后,分析了导引参数与可变分束器的反射率之间的关系,并研究了EPR导引的方向由双向到单向的改变过程。该研究对非对称的量子非局域性操控以及量子信息传递过程中的量子控制具有重要意义。     

Parallel generation of 31 tripartite entangled states based on optical frequency combs

Quantum entangled states, especially those having particular properties, are key resources for quantum information and quantum computation. In this paper, we put forward a new scheme to produce 31 continuous–variable(CV) tripartite entanglement fields based on three optical frequency combs via cascade nonlinear processes in an optical parametric cavity,and investigate the spectral characteristics of three frequency combs. The center wavelengths of the three combs are designed as 852 nm, 780 nm(atomic transition lines), and 1550 nm(fiber communication wavelength). The positivity under partial transposition(PPT) criterion, which is sufficient and necessary, is used to evaluate the entanglement in each group of comb lines. This scheme is experimentally feasible and valuable for constructing quantum information networks in future.     

Generation of entangled TEM_(01) modes with periodically poled KTiOPO_4 crystal

Spatial quantum optics based on the high-order transverse mode is important for the super-resolution measurement and quantum image beyond the shot noise level. Quantum entanglement of the transverse plane Hermite–Gauss TEM_(01) mode has been demonstrated experimentally in this paper. Two squeezed TEM_(01) modes, which are generated by a pair of degenerate optical parametric amplifiers(DOPA) with the nonlinear crystals of periodically poled KTi OPO_4, have been combined to produce TEM_(01) mode entanglement using a beam splitter. The 1.5 dB for the sum of amplitude and 1.2 dB for the difference of phase below shot-noise level is achieved with the measurement system of a Bell state detection.     

高阶TEM_(01)模压缩态Wigner准概率分布函数的量子重构

将Nd:YVO4-KTP固体激光器输出的532nm和1064nm激光分别作为抽运光和种子光注入一个内置周期极化磷酸氧钛晶体的简并光学参量放大器,通过非线性光学参量过程产生明亮的高阶横模TEM01正交振幅压缩态光场,利用平衡零拍探测系统测得其压缩度为2.2dB,利用数字存储示波器记录经信号处理系统变换的数据,再通过自编的软件利用量子层析测量技术得到了该压缩态光场在相空间的Wigner准概率分布函数,并将其与理论结果作了对比,两者基本一致。     

Experimental Demonstration of a Displacement Measurement of an Optical Beam beyond the Quantum Noise Limit

We experimentally generate a spatially squeezed light beam and realize a small-displacement measurement beyond the quantum noise limit with this squeezed light. Moreover, we measure about -2.2±0.2dB spatial squeezing and reduce the minimum measurable displacement from 1.17A to 0.99A with the signal-to-noise ratio normalized to 1.     

非经典态的wigner函数重构实验

实验上经过对相干态进行频率调制，模拟了相干态光场的正交振幅信息，从而实现了包含振幅和噪声信息的量子态重构。在此基础上，采用波长为1080nm／540BE的内腔倍频激光器，通过泵浦光学参量放大器（OPA）实现对非经典态的制备。并利用平衡零拍探测系统结合高速率数据采集技术和Labview程序对实验数据进行采集，最后实现对非经典态的wigner函数重构。     

Generation of squeezed TEMM01 modes with periodically poled KTiOPO4 crystal

Spatial quantum optics and quantum information based on the high order transverse mode are of importance for the super-resolution measurement beyond the quantum noise level. We demonstrated experimentally the transverse plane TEM₀₁ Hermite-Gauss quantum squeezing. The squeezed TEM₀₁ mode is generated in a degenerate optical parametric amplifier with the nonlinear crystal of periodically poled KTiOPO₄. The level of 2.2-dB squeezing is measured using a spatial balance homodyne detection system.     

单频光纤激光器的噪声抑制

对单频光纤激光系统的输出噪声进行了测量和研究,利用前置光电负反馈方法对光纤激光器的强度噪声进行了抑制,调节反馈增益和延迟时间,可以在不同的边频处接近散离噪声极限,在分析频率6.0 MHz处抑制程度达到22 dB.     

孪生光束时域内的关联特性

本文在实验上测量了运转于阈值以上的双共振光学参量振荡器所产生的孪生光束在时域内的关联特性.在分析腔带宽对孪生光束强度量子关联影响的基础上,通过时域内的数据采集,运用改变孪生光束其中一臂的时间延时的方法来考察时域内孪生光束关联度的变化.在实验上给出了孪生光束关联度大小随时间变化的结果.