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1.
《中国光学快报(英文版)》2015,(11)
The spectral properties of entangled photon pairs generated via quasi-phased matching in spontaneous parametric down-conversion are proposed and demonstrated experimentally. A general mathematical model for evaluating the spectral properties is developed to obtain the spectrum shape and range of down-converted photons. The model takes into account the effects of phase mismatching due to non-ideal pumping and the relationship between crystal periodic modulation function and the incidence angle of the pump beam. The spectrum curve shape is determined by the discrete Fourier transform of a Gaussian pump beam and the integration of parametric down-conversion generated by an individual plane wave. An experiment is carried out with a PPLN non-linear crystal and dispersing optics, which shows a good consistency in their spectral ranges and shapes with our model predictions within the spectrum of 600–633 nm. This therefore illustrates that both the simulation model and the experimental process are reasonable. This novel method has potential applications in high-accuracy calibration in the wide spectrum using correlated photons. 相似文献
2.
Using a basic Mach-Zehnder interferometer, we demonstrate experimentally the measurement of the photonic de Broglie wavelength of entangled photon pairs (biphotons) generated by spontaneous parametric down-conversion. The observed interference manifests the concept of the photonic de Broglie wavelength. We also discuss the phase uncertainty obtained from the experiment. 相似文献
3.
Ellipsometric measurements by use of photon pairs generated by spontaneous parametric downconversion
We present a novel interferometric technique for performing ellipsometric measurements. This technique relies on the use of a nonclassical optical source, namely, polarization-entangled twin photons generated by spontaneous parametric downconversion from a nonlinear crystal, in conjunction with a coincidence-detection scheme. Ellipsometric measurements acquired with this scheme are absolute; i.e., they do not require source and detector calibration. 相似文献
4.
Quantum state tomography (QST) is widely used to evaluate entanglement generated by spontaneous parametric down-conversion. Two-fold coincidence counts for 16 different configurations have been measured using single-photon detectors to estimate the fidelity (i.e., the probability overlap between ideal and real states) from the reconstructed density matrix. However, multi-pair emission events degrade the fidelity. Here, we numerically analyze pulse-pumped polarization-entangled photon pairs for single-photon detectors that can or cannot count the number of incident photons to estimate the fidelity given by QST. Threshold single-photon detectors are desirable for QST from a practical point of view. Our analysis suggests that using four threshold single-photon detectors for two-fold coincidence measurements offers almost the same fidelity as that given by four photon-number-resolving single-photon detectors. The fidelity estimated by QST becomes poor and loss independent when two threshold single-photon detectors are used. 相似文献
5.
In this Letter, we report the observation of the correlation between two modes of microwave radiation resulting from the amplification of quantum noise by the Josephson parametric converter. This process, seen from the pump, can be viewed as parametric down-conversion. The correlation is measured by an interference experiment displaying a contrast better than 99% with a number of photons per mode greater than 250,000. Dispersive measurements of mesoscopic systems and quantum encryption can benefit from this development. 相似文献
6.
We elucidate the dependence of purity and entanglement of two-photon states generated by spontaneous parametric down-conversion on the parameters of the source, such as crystal length, pump beam divergence, frequency bandwidth, and detectors angular aperture. The effect of crystal anisotropy is taken into account. Numerical simulations are presented for two types of commonly used source configurations. 相似文献
7.
Fedorov MV Efremov MA Volkov PA Moreva EV Straupe SS Kulik SP 《Physical review letters》2007,99(6):063901
We show both theoretically and experimentally that biphoton wave packets generated via spontaneous parametric down-conversion can be strongly anisotropic and highly entangled. The conditions under which these effects exist are found and discussed. 相似文献
8.
A new bipartite entangled state describing the parametric down-conversion process and its applications in quantum optics 下载免费PDF全文
We construct a new bipartite entangled state(NBES),which describes both the squeezing and the entanglement involved in the parametric down-conversion process and can be produced using a symmetric beam splitter.Constructing asymmetric ket-bra integrations based on the NBES leads to some new squeezing operators,which clearly exhibit the relationships between squeezing and entangled state transformations.Moreover,an entangled Wigner operator with a definite physical meaning is also presented. 相似文献
9.
Spontaneous parametric down-conversion and quantum walks in arrays of quadratic nonlinear waveguides
We analyze the process of photon-pair generation with simultaneous quantum walks in a quadratic nonlinear waveguide array. We demonstrate that the spontaneous parametric down-conversion in the array allows for creating quantum states with strongly pronounced spatial correlations, which are qualitatively different from those possible in bulk crystals or through quantum walks in linear waveguide arrays. Most importantly, the photon correlations can be controlled entirely classically by varying the spatial profile of the pump beam or the phase-matching conditions. 相似文献
10.
Improving the purity of heralded single-photon sources through spontaneous parametric down-conversion process 下载免费PDF全文
《中国物理 B》2021,30(7):70304-070304
The high-purity single-photon source plays an important role in the field of quantum information. Usually, it is generated through spontaneous parametric down-conversion process. In this paper, we investigate and summarize a few approaches on obtaining single-photon sources with a high purity using either PPKTP or PPLN nonlinear crystals. Moreover, we present improved schemes to increase the purity based on existing work, corresponding applicable conditions and procedures are discussed and analyzed. Besides, we carry out numerical simulations and show that nearly perfect purity can be reached even without using any filters. Therefore, this work might provide valuable references for the generation and application of high purity single-photon sources. 相似文献
11.
G. Brida M. Genovese C. Novero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):273-275
We report the measurement of the photons flux produced in parametric down-conversion, performed in photon counting regime
with actively quenched silicon avalanche photodiodes as single photon detectors. Measurements are done with the detector in
a well defined geometrical and spectral situation. By comparison of the experimental data with the theory, a value for the
second order susceptibilities of the non linear crystal can be inferred.
Received 2 July 1999 and Received in final form 2 August 1999 相似文献
12.
We study a novel scheme named the spontaneous parametric fiber loop (SPFL), configured by deliberately introducing dispersive elements into the nonlinear Sagnac loop, and show it can function as a passive switch of photon pairs. The two-photon state coming out of SPFL highly depends on the dispersion induced phase difference of photon pairs counterpropagating in the loop. By properly managing the dispersive elements, the signal and idler photons of a pair with a certain detuning and bandwidth can be directed to the desired spatial modes of SPFL. If the photon pairs are used to generate heralded single photons, the SPFL can be viewed as a switch of single photons. Moreover, our investigation about the dispersion based phase modulation is also beneficial for designing all fiber sources of entangled photon pairs. 相似文献
13.
We employ a high quantum efficiency photon number counter to determine the photon number distribution of the output field from a parametric down-converter. The raw photocount data directly demonstrates that the source is nonclassical by 40 standard deviations, and correcting for the quantum efficiency yields a direct observation of oscillations in the photon number distribution. 相似文献
14.
Entangled photon pairs from semiconductor quantum dots 总被引:1,自引:0,他引:1
Akopian N Lindner NH Poem E Berlatzky Y Avron J Gershoni D Gerardot BD Petroff PM 《Physical review letters》2006,96(13):130501
Tomographic analysis demonstrates that the polarization state of pairs of photons emitted from a biexciton decay cascade becomes entangled when spectral filtering is applied. The measured density matrix of the photon pair satisfies the Peres criterion for entanglement by more than 3 standard deviations of the experimental uncertainty and violates Bell's inequality. We show that the spectral filtering erases the "which path" information contained in the photons' color and that the remanent information in the quantum dot degrees of freedom is negligible. 相似文献
15.
Orbital and intrinsic angular momentum of single photons and entangled pairs of photons generated by parametric down-conversion 总被引:1,自引:0,他引:1
For systems that exhibit a second-order phase transition with a spontaneously broken continuous O(N) symmetry at low temperatures, we give a criterion for judging at which temperature T(K) long-range directional fluctuations of the order field destroy the order when approaching the critical temperature from below. The temperature T(K) lies always significantly below the famous Ginzburg temperature T(G) at which size fluctuations of finite range become important. 相似文献
16.
17.
采用放大传递函数理论模拟和分析了基于自发参量下转换产生参量荧光的光谱分布特性,结果表明:非简并态下随着相位匹配角的增大,参量荧光空间强度角分布呈现变大趋势,而整个荧光光谱成分的分布逐渐倾向于连续的弱分布状态.对于简并态附近出现荧光光谱具有宽带宽集中分布的特征,采用两种不同的抽运光脉冲进行了对比分析,并且对此特征关于相位匹配角变化的敏感特性,采用放大传递函数和光谱成分概率分布函数两种不同理论的模拟结果一致.
关键词:
参量下转换
参量荧光 相似文献
18.
Spontaneous parametric downconversion (SPDC) is widely used to generate entangled photon pairs; however, multi-pair emissions degrade the quality of the entanglement. We numerically evaluate polarization-entangled photon pairs created by SPDC. The effects of multi-pair emission events on the visibility of two-photon interference and on the fidelity (the probability overlap for ideal and real states) are analyzed using single-photon detectors that can count the number of incoming photons and discard multiphoton events. Compared with conventional threshold single-photon detectors, photon-number resolving single-photon detectors have higher fidelity for the same or lower visibility. 相似文献
19.
G. Kh. Kitaeva V. V. Tishkova I. I. Naumova A. N. Penin C. H. Kang S. H. Tang 《Applied physics. B, Lasers and optics》2005,81(5):645-650
A new method for characterization of periodically poled crystals is developed based on spontaneous parametric down-conversion. The method is demonstrated on crystals of Y:LiNbO3, Mg:Y:LiNbO3 with non-uniform periodically poled structures, obtained directly under the Czochralski growth procedure and designed for application of 1.064 μmpumped OPO in the mid-infrared range. Infrared dispersion of refractive index, effective working periods and wavelengths of OPO were determined by special treatment of frequency-angular spectra of spontaneous parametric down-conversion in the visible range. Two-dimensional mapping via spontaneous parametric down-conversion is proposed for characterizing spatial distribution of bulk quasi-phase matching efficiency across the input window of a periodically poled sample. 相似文献
20.
We demonstrate a narrow-band photon pair source on a rubidium (Rb) D2 line (780 nm) using a periodical poled KTiOPO4 crystal via a degenerate optical parametric oscillator far below threshold. The single longitudinal mode is selected by a spectral filtering cavity. The measured cross correlation between two photons shows that the generated photon has a linewidth of 21 MHz, which is comparable to the typical linewidth of an atomic-based quantum memory. The detected photon pair rate is about 2.7/s/MHz/mW. This system could be utilized for many applications in quantum information field, such as the storage and retrieval of a photon in Rb atomic ensemble and so on. 相似文献