• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Phase sensitivity with a coherent beam and twin beams via intensity difference detection

    2024-01-25 07:28:12JunLiu劉俊TaoShao邵濤ChenluLi李晨露MinyangZhang張敏洋YouyouHu胡友友DongxuChen陳東旭andDongWei衛(wèi)棟
    Chinese Physics B 2024年1期
    關(guān)鍵詞:劉俊

    Jun Liu(劉俊), Tao Shao(邵濤), Chenlu Li(李晨露), Minyang Zhang(張敏洋),Youyou Hu(胡友友), Dongxu Chen(陳東旭), and Dong Wei(衛(wèi)棟)

    1School of Science,Jiangsu University of Science and Technology,Zhenjiang 212003,China

    2Quantum Information Research Center,Shangrao Normal University,Shangrao 334001,China

    3School of Physics,Xi’an Jiaotong University,Xi’an 710049,China

    Keywords: Mach–Zehnder interferometer,phase sensitivity,quantum squeezing

    1.Introduction

    Interferometers play an important role in the field of precision measurement.[1–11]One of the most typical interferometers is the Mach–Zehnder interferometer (MZI).A general MZI is composed of two beam splitters (BS) and is used to measure phase shift variations in the two paths.The measurement sensitivity of such phase shifts can not surpasswhen the inputs are the combination of a coherent state and an vacuum state, whereNis the total photon number of the inputs, andis named as the shot noise limit (SNL) or the standard quantum limit.[12]

    In order to beat SNL, non-classical states such as the single-mode squeezed vacuum state and two-mode squeezed vacuum state are employed.[13–16]Then the phase sensitivity can reach 1/N, which is also named as the Heisenberg limit(HL).When inputs are Fock state, N00N state and entangled coherent state, the phase sensitivity can also reach sub-SNL and HL.[3,17,18]However, there are many potential problems.For the N00N state,this input state has been shown to be very sensitive to losses, and the maximum photon numberNremains very low in experiments.

    Recently, due to the good performance in phase estimation, a coherent state and a single-mode squeezed vacuum state have been investigated by many groups.[10]Caveset al.claimed that when one of the inputs is a coherent state,the optimal state of the other input is the single-mode squeezed vacuum state,[15]which has been employed in LIGO.[16]When the inputs are the combination of a single-mode squeezed vacuum state and a coherent state, several detection methods are proposed,such as intensity detection,balanced homodyne detection and parity detection.[8]Different detection methods can lead to different optimal phase sensitivities.In order to achieve the optimal phase sensitivity,all the possible measurement strategies need to be taken into account,which is impossible.Fortunately, quantum Fisher information (QFI) and its related quantum Cram′er–Rao bound (QCRB) are introduced to find the optimal theoretical phase sensitivity without considering the specific measurement strategies.

    The QFI is an effective tool in the estimation process when the inputs are the coherent state, Fock state, singlemode squeezed vacuum state, and single-mode squeezed coherent state,etc.[19–28]However,with an external phase reference beam in the detection process, the QFI can be different,which is observed by Jarzynaet al.[19]In addition,Takeokaet al.used a phase-averaging method to solve this problem.[23]Later, Youet al.claimed that the two-parameter phase estimation and the phase-averaging method is equivalent with specific inputs.[24]They also pointed out that it needs to take the reference beam into consideration when a phase reference beam is employed.Then,the detection strategy with external beams has aroused much concern.

    Recently, squeezing and entanglement-assisted input states are proposed.[17,29–33]Under the condition of the squeezing-assisted input,[17,29]the intensity difference detection with an external power reference beam is employed.In the detection process, the conjugate beam offers an external power reference and the phase sensitivity can reach sub-SNL.However, they only consider the condition that one of the inputs is the vacuum beam and the advantage of the external power reference beam is not shown.Meanwhile, the optimal phase sensitivity can only reach sub-SNL.In this paper,we focus on the phase sensitivity with one coherent beam plus one of the bright entangled twin beams(BETB).Moreover,we aim to show that when the inputs of the MZI are a coherent beam plus one of the BETB,the optimal phase sensitivity can reach sub-HL and approach QCRB.

    This paper is structured as follows.In Section 2, the scheme with intensity difference detection is introduced.The QFI and the QCRB are introduced.In Section 3, we analyze how the phase sensitivity is affected by the factors.The impacts of the detection efficiencies of the photon detectors are also studied.Then, detailed comparisons are shown in Section 4.Finally,the conclusions are drawn in Section 5.

    2.The proposed model and phase sensitivity estimation

    2.1.The scheme and operator transformation

    In the first part of Fig.1, we show the generation process of the BETB,which is named as the two-mode squeezed process.[34–37]This two-mode squeezed process can be accomplished by the FWM experiments.[38–41]The FWM transformation can be expressed as

    Fig.1.The scheme for phase sensitivity measurement based on the Mach–Zehnder interferometer (MZI).For the MZI, the inputs are one of the bright entangled twin beams and one coherent beam.The intensity difference is employed for the measurement process.M: mirror;FWM: four-wave mixing; BS: beam splitter; PD: photon detector; B:beam block;dashed line: the vacuum beam.

    2.2.Phase sensitivity estimation with intensity difference detection

    According to the error propagation formula, the phase sensitivity Δφas the uncertainty in estimating the phase shiftφis

    The intensity difference detection signal can be expressed asThen the slope can be expressed as

    while the variance of intensity difference is

    The photon number of the inputs is given by

    Therefore,the SNL and HL of the scenario in Fig.1 isand 1/NB.

    2.3.The QFI and QCRB in two-parameter phase estimation

    For the parameter estimation process, the QCRB is(Δφ)2≥F(φ)?1.The inputs in Fig.1 are pure states.Under this constraint,the QFIF(φ)is

    and?φψ=?ψ/?φ,ψis the state after the phase shift.In order to avoid the potential unavailable measurement strategy,twoparameter phase estimation is necessary.As shown in Fig.1,there are two phasesφ1andφ2in the two arms of the MZI,and we define the two-parameter QFI as

    The QCRB can be better with a largerF.Then the QFIFcan be maximized withF?+=F+?=0.

    3.Analysis of the phase sensitivity

    3.1.Results

    According to Eqs.(3)and(11),figure 2 shows the phase sensitivity versus phase shift and phase difference withr=0.65,Na0=0.1, andNc=0.5.The lower value Δφrepresents the better phase sensitivity.In this scenario,with one of the BETB entering the MZI and the other one being employed for detection, the phase sensitivity can beat HL in Fig.2(a),and the optimal phase sensitivity approaches the QCRB.In the inset of Fig.2(a),it is apparent that the optimal phase sensitivity can approach QCRB.In Fig.2(b), with the variation of the phase difference, the phase sensitivity can be optimal withφd=kπ(kis an integer).Whenφd=kπ+π/2,both the QCRB and the optimal phase sensitivity with intensity difference detection become the worst.The optimal phase sensitivity with intensity difference detection can only approach the QCRB whenφd=kπ.Under this constraint,in the following part,we takeφd=0 for simplification.

    Fig.2.Phase sensitivity versus phase shift (a) and phase difference(b).Others parameters are r=0.65, Na0 =0.1, and Nc =0.5.In (a),φd =0.BETB: bright entangled twin beams; SNL: shot noise limit;HL:Heisenberg limit;QCRB:quantum Cram′er–Rao bound.The inset of(a)is the zoom of the phase sensitivity and it shows that the optimal phase sensitivity can not achieve the QCRB.

    As shown in Fig.3, the phase sensitivities vary with the squeezing parameterr, photon numberNa0, andNc.WhenNa0=0.1 andNc=0.5, the phase sensitivity and the QCRB can beat HL withr ≤0.8 in Fig.3(a).Whenrincreases, the phase sensitivity with intensity difference detection and the QCRB can only reach sub-HL.The optimal phase sensitivity always approaches QCRB with the increase ofr.In Fig.3(b),the optimal phase sensitivity and the QCRB beat HL whenNa0is less than 0.2.WhenNa0becomes larger,they can reach sub-SNL.The optimal phase sensitivity approaches SNL whenNa0≥1.Figure 3(c) shows that both the optimal phase sensitivity and QCRB can reach sub-HL whenNc ≤0.9.They become worse than HL whenNcbecomes larger.In Fig.3,only the photon numberNB≥1 is considered.

    Fig.3.Phase sensitivity versus parametric strength r(a),photon number Na0(b),photon number Nc(c),with r=0.65,Na0=0.1,and Nc=0.5.The other parameters are the same as those in Fig.2.

    Fig.4.Phase sensitivity versus parametric strength r (a) and photon number Nc (b). Na0 =0.TSVB: two-mode squeezed vacuum beam.The other parameters are the same as those in Fig.2.

    Fig.5.The device for phase sensitivity measurement with transmissivity efficiencies T1 and T2 of the photon detectors.Fictitious beam splitters are employed to represent the losses of the photon detectors.The other parameters are the same as those in Fig.2.

    In the above subsections, we show the phase sensitivity with the inputs of a coherent beam and one of the BETB.In fact,when the photon number of the coherent beamNcis zero,this scheme becomes the same as the scenario in Ref.[17].If the squeezing parameterris zero, for the MZI, the inputs are two coherent beams without the reference beam.WithNa0=0,the inputs in Fig.1 become a coherent beam and one of the two-mode squeezed vacuum beams(TSVB).The other one of the TSVB is employed as the external power reference beam.The phase sensitivities versus parametric strengthrand photon numberNcare shown in Fig.4.We immediately notice that the QCRB can beat HL and the optimal phase sensitivity with intensity difference detection is worse than SNL.In Fig.4(a),the QCRB can only reach sub-SNL whenris more than 0.95 withNc=0.5.Withr=0.65, the QCRB can beat HL whenNc ≤1.1 in Fig.4(b).Therefore, for the input of a coherent beam plus one of TSVB based on the MZI,the intensity difference detection is not preferred.

    3.2.Non-unit photon detection efficiency

    In this subsection,we consider the condition that the detection efficiency of the photon detectors is not ideal in Fig.5.Then the transformation of the operators in the scheme is expressed as

    where ?υ2(?υ1)and ?aoutT(?boutT)are the annihilation operators of the two input-output modes of the fictitious BS, respectively.T1andT2represent the transmissivity of the detector.Only the losses of the photon detectors are considered and we assume that there are no losses inside the interferometer.The slope is given by

    and the variance of intensity difference is Δ2?I?BT(Details can be seen in Appendix B).As displayed in Fig.6(a), withT2= 0.2 or 0.5, the phase sensitivity is always worse than SNL.WithT2=0.8,the phase sensitivity can beat SNL whenT1is larger than 0.73.When the photon detector has no loss(T2=1),the phase sensitivity is better than SNL withT1larger than 0.58.In this case, the better phase sensitivity can be achieved by the lower loss.According to Eq.(13), the transmissivityT1has no effects on the slope.The phase sensitivity is worse than SNL when the external power reference beam is absent (T1=0).The external beam can boost the phase sensitivity by reducing the variance and keeping the slope unchanged.Note that the intensity difference detection will become intensity detection withT1=0.The phase sensitivity can not beat SNL in this case.In Fig.6(b),the larger the valueT2, the better the sensitivity.The phase sensitivity can beat SNL withT2larger than 0.76 withT1=0.8.WhenT1=1,the phase sensitivity can still reach SNL withT2=0.7,which shows the good robustness of this scenario.In Fig.6, withr=1,Na0=10 andNc=102, the optimal phase sensitivity with intensity difference detection can not surpass the HL withT1=T2=1.

    Fig.6.Phase sensitivity with the increase of transmissivity T1 (a) and T2 (b),for r=1,Na0=10,and Nc=102.The other parameters are the same as those in Fig.2.

    4.Comparison

    4.1.Two coherent beams with an external coherent beam

    and the variance becomes

    Nco=.We also imposeφ1=0 andφ2=φin the error propagation formula.As displayed in Fig.8, with the employment of the external beam,the QCRB can not surpass SNL.In Figs.8(a)and 8(b),when the inputs are two coherent beams and another coherent beam is employed in the intensity difference detection, the phase sensitivity is worse than SNL.As displayed by Eqs.(14)and (15), when the external coherent beam is employed, the slope is unchanged and the variance becomes larger.BecauseNco≥0 andNb2≥0,andNco+Nb2≥Nco.Hence the external coherent beam can not boost the phase sensitivity and makes it worse.As shown in Fig.8(a), with the increase ofNa0,the photon number of the external coherent beam is larger and the phase sensitivities with the intensity difference detection can never approach SNL.Meanwhile, the QCRB can only reach SNL.In Fig.8(b),the phase sensitivity with the intensity difference detection is worse than SNL with the increase of the photon numberNc2.

    Fig.7.The device for phase sensitivity measurement based on the Mach–Zehnder interferometer with two coherent beams and another coherent beam as the external beam.The other parameters are the same as those in Fig.1.

    Fig.8.Phase sensitivity versus parameter Na0 (a)and Nc (b),for r=1,Na0 =10, and Nc =102.TCB means the phase sensitivity with two coherent beams and the intensity difference detection.The QCRB1 and QCRB2 are the quantum Cram′er–Rao bounds with bright entangled twin beams and two coherent beams.The other parameters are the same as those in Fig.2.

    4.2.One coherent beam plus one single-mode squeezed vacuum beam

    Ref.[42].In this case,the QCRB and the optimal phase sensitivity can reach HL,respectively.Considering the phase insensitive intensity squeezing degree being less than 10 dB,Gis below 5.5(r ≤1.5).

    As shown in Figs.9(a)and 9(b), withNc3=sinh2r3,the QCRB of the coherent beam plus the single-mode squeezed vacuum beam can surpass HL.Withr3=0.8, the QCRB of the coherent beam plus the BETB can beat HL.However,they are still worse than that of the coherent beam plus a singlemode squeezed vacuum beam.Note that the two scenarios have the same photon numbersNBand the BETB have been the TSVB withNc=0.In Figs.9(c) and 9(d), the practical experiments conditionsNc3?sinh2r3are considered.In this case, both the QCRBs of the Fig.1 and the coherent beam plus the single-mode squeezed vacuum state scenario can only reach sub-SNL.However, with the increase of the squeezing parameterr(r >1.86),the QCRB with BETB can beat QCRB of the coherent beam plus a single-mode squeezed vacuum beam in Fig.9(c).In Fig.9(d), the BETB have become the TSVB, and the QCRB1 can still beat the QCRB2 (r >1.8).According to Fig.9, in the HL scale, the QCRB of the scenario in Fig.1 is worse than that of the coherent beam plus a single-mode squeezed vacuum beam.However, in the sub-SNL region,with the high squeezing parameterr,the QCRB1 can beat the QCRB2.Though the squeezing parameter cannot be experimentally realized at present, it is hopeful that it can be achieved in the future.

    Fig.9.Phase sensitivity versus parameter r.In(a)and(b),r3=0.8,and in(c)and(d)r3=1.5. Na0=0.1 in(a)and(c).In(b)and(d),Na0=0.Nc3 =sinh2r3 in (a) and (b). Nc3+sinh2r3 =NB, and they have the same SNL and HL.QCRB1 and QCRB2 are the quantum Cram′er–Rao bounds of Fig.1 and the scenario with the input of a coherent beam plus a single-mode squeezed vacuum beam.The other parameters are the same as those in Fig.2.

    5.Conclusion

    In conclusion, this paper presents the phase sensitivity with the inputs of the BETB and coherent beams based on the MZI.The optimal phase sensitivity with intensity difference detection can reach sub-HL and approach QCRB while an external power reference beam is employed.When the inputs are a coherent beam plus one of the TSVB,the QCRB can beat HL and the optimal phase sensitivity with the intensity difference detection is worse than the SNL.We have a detailed discussion about the detection efficiencies of the photon detectors.The results show that the external beam play a vital role in the measurement process and the absence of the external beam can degrade the performance of the phase sensitivity dramatically.The QCRB of the scheme can be better than that of the coherent beam plus a single-mode squeezed vacuum beam input scenario with the high squeezing parameter.Meanwhile,the external coherent beam can not boost the phase sensitivity when the inputs are two coherent beams.This method of employing the external power reference beam offers a novel measurement way for the phase precision measurement.

    Appendix A: Exact expression of the QFI elements

    The QFI matrix elements can be expressed as

    Im(·)represents the imaginary part.

    Appendix B:Slope and variance of intensity difference with non-unit photon detection efficiency

    The slope is given by

    and the variance of intensity difference Δ2?I?BTyields

    In this part,for simplification,we assume thatφd=0.

    Acknowledgments

    Project supported by the National Natural Science Foundation of China (Grant Nos.12104190, 12104189,and 12204312), the Natural Science Foundation of Jiangsu Province (Grant No.BK20210874), the Jiangsu Provincial Key Research and Development Program (Grant No.BE2022143); the Jiangxi Provincial Natural Science Foundation (Grant Nos.20224BAB211014 and 20232BAB201042), and the General Project of Natural Science Research in Colleges and Universities of Jiangsu Province(Grant No.20KJB140008).

    猜你喜歡
    劉俊
    Dynamic modeling of total ionizing dose-induced threshold voltage shifts in MOS devices
    Raman lasing and other nonlinear effects based on ultrahigh-Q CaF2 optical resonator
    Synthetical optimization of the structure dimension for the thermoacoustic regenerator
    劉俊
    In fluence of Ni/Mn ratio on magnetostructural transformation and magnetocaloric effect in Ni48?x Co2Mn38+x Sn12(x=0,1.0,1.5,2.0, and 2.5)ferromagnetic shape memory alloys?
    我和你打個賭
    小飯店,大飯店
    三月三(2014年11期)2014-11-05 03:24:03
    漫漫看
    只送你更貴的
    意林(2011年17期)2011-04-09 05:47:31
    方向盤被盜
    遼河(2009年3期)2009-05-04 10:15:20
    每晚都被弄得嗷嗷叫到高潮| 国产免费av片在线观看野外av| 日韩欧美国产一区二区入口| 亚洲成人免费av在线播放| 韩国精品一区二区三区| 天堂动漫精品| 久久香蕉激情| 免费观看精品视频网站| 亚洲欧美精品综合一区二区三区| 新久久久久国产一级毛片| 十八禁网站免费在线| 久久中文字幕人妻熟女| 亚洲av熟女| 亚洲五月婷婷丁香| 久久久久久亚洲精品国产蜜桃av| 男女高潮啪啪啪动态图| xxxhd国产人妻xxx| 欧美 亚洲 国产 日韩一| 久久香蕉精品热| 免费观看a级毛片全部| 麻豆国产av国片精品| 亚洲一区高清亚洲精品| 制服人妻中文乱码| 在线观看舔阴道视频| 欧美日韩精品网址| 久久人人97超碰香蕉20202| av视频免费观看在线观看| 欧美日本中文国产一区发布| 亚洲九九香蕉| 大型av网站在线播放| 桃红色精品国产亚洲av| 视频区图区小说| 99香蕉大伊视频| 18禁黄网站禁片午夜丰满| 操美女的视频在线观看| 无人区码免费观看不卡| 欧美另类亚洲清纯唯美| 久久久久久久久免费视频了| 真人做人爱边吃奶动态| 精品久久久精品久久久| av免费在线观看网站| 国产无遮挡羞羞视频在线观看| av天堂在线播放| 久久久精品免费免费高清| 19禁男女啪啪无遮挡网站| 捣出白浆h1v1| 亚洲视频免费观看视频| 欧美最黄视频在线播放免费 | 老汉色∧v一级毛片| 欧美+亚洲+日韩+国产| 午夜福利视频在线观看免费| 精品国产一区二区三区四区第35| 亚洲男人天堂网一区| 亚洲性夜色夜夜综合| 夜夜爽天天搞| 69精品国产乱码久久久| 久久久久视频综合| 91老司机精品| 国产成+人综合+亚洲专区| 亚洲三区欧美一区| 久久久国产欧美日韩av| 国产高清激情床上av| 久久中文字幕一级| 成人三级做爰电影| 黄色成人免费大全| 99精品欧美一区二区三区四区| 国产成人影院久久av| 国产高清videossex| 水蜜桃什么品种好| 男女床上黄色一级片免费看| 麻豆国产av国片精品| 久久青草综合色| 免费在线观看影片大全网站| 91成年电影在线观看| 18禁黄网站禁片午夜丰满| 久久午夜综合久久蜜桃| 制服人妻中文乱码| 天天添夜夜摸| 亚洲av第一区精品v没综合| 大香蕉久久成人网| 国产亚洲欧美98| 熟女少妇亚洲综合色aaa.| xxxhd国产人妻xxx| 成年人午夜在线观看视频| 999精品在线视频| 啦啦啦免费观看视频1| 亚洲熟妇中文字幕五十中出 | 久久久国产精品麻豆| 一级,二级,三级黄色视频| 99久久国产精品久久久| 多毛熟女@视频| 久久国产亚洲av麻豆专区| 少妇 在线观看| 精品亚洲成国产av| 国产亚洲欧美在线一区二区| 男人操女人黄网站| 欧美乱码精品一区二区三区| 国产淫语在线视频| 久久九九热精品免费| 淫妇啪啪啪对白视频| 国产无遮挡羞羞视频在线观看| 亚洲精品美女久久av网站| 99精品久久久久人妻精品| 一级毛片精品| 91字幕亚洲| 午夜福利免费观看在线| 自拍欧美九色日韩亚洲蝌蚪91| 精品久久久久久久久久免费视频 | av网站在线播放免费| 黄色丝袜av网址大全| 免费在线观看日本一区| 亚洲一区中文字幕在线| 老熟女久久久| 在线天堂中文资源库| 午夜福利免费观看在线| 久久中文看片网| 午夜福利视频在线观看免费| 国产在线一区二区三区精| 12—13女人毛片做爰片一| 一进一出抽搐gif免费好疼 | 精品久久久久久久久久免费视频 | 99国产精品免费福利视频| 90打野战视频偷拍视频| 欧美精品一区二区免费开放| 国产单亲对白刺激| 日日摸夜夜添夜夜添小说| 黑人巨大精品欧美一区二区mp4| 亚洲 国产 在线| 国产91精品成人一区二区三区| 亚洲精品中文字幕一二三四区| 日韩一卡2卡3卡4卡2021年| 搡老乐熟女国产| 欧美 亚洲 国产 日韩一| videos熟女内射| 国产三级黄色录像| 青草久久国产| 黑人猛操日本美女一级片| 久久精品亚洲精品国产色婷小说| 免费在线观看影片大全网站| 国产一卡二卡三卡精品| 亚洲国产欧美一区二区综合| 日本一区二区免费在线视频| av免费在线观看网站| 国产av一区二区精品久久| 亚洲一区二区三区欧美精品| 视频区图区小说| 精品国产国语对白av| 丝瓜视频免费看黄片| 1024香蕉在线观看| 亚洲五月天丁香| 高清在线国产一区| 一级黄色大片毛片| 天堂动漫精品| 国产av又大| 午夜成年电影在线免费观看| 欧美国产精品va在线观看不卡| 在线观看免费视频日本深夜| 王馨瑶露胸无遮挡在线观看| 飞空精品影院首页| 欧美精品高潮呻吟av久久| 亚洲人成77777在线视频| 亚洲熟女精品中文字幕| 成人影院久久| 色婷婷久久久亚洲欧美| 人人妻,人人澡人人爽秒播| 五月开心婷婷网| 久9热在线精品视频| 久久国产精品人妻蜜桃| 午夜激情av网站| 久久狼人影院| 黄频高清免费视频| 两人在一起打扑克的视频| 丝袜美足系列| av天堂在线播放| 亚洲国产精品一区二区三区在线| 国产激情久久老熟女| 757午夜福利合集在线观看| 午夜福利乱码中文字幕| 欧美日韩福利视频一区二区| 国产精品98久久久久久宅男小说| 国产精品一区二区在线观看99| 美女扒开内裤让男人捅视频| 日韩制服丝袜自拍偷拍| 在线观看免费日韩欧美大片| av不卡在线播放| 18禁国产床啪视频网站| 十分钟在线观看高清视频www| 亚洲五月色婷婷综合| 精品人妻熟女毛片av久久网站| 日本wwww免费看| 午夜日韩欧美国产| 精品国产国语对白av| 狂野欧美激情性xxxx| 日日夜夜操网爽| 国产精品综合久久久久久久免费 | 中文字幕人妻熟女乱码| 高潮久久久久久久久久久不卡| 一区二区三区激情视频| 亚洲视频免费观看视频| 中亚洲国语对白在线视频| 亚洲综合色网址| 久久精品亚洲熟妇少妇任你| 村上凉子中文字幕在线| 99精国产麻豆久久婷婷| 免费在线观看亚洲国产| 好看av亚洲va欧美ⅴa在| 午夜影院日韩av| 亚洲中文av在线| 欧美成人免费av一区二区三区 | 午夜福利在线观看吧| 丝袜美足系列| 国产欧美日韩精品亚洲av| 久久久久国产一级毛片高清牌| 黄网站色视频无遮挡免费观看| 丝袜美腿诱惑在线| 亚洲情色 制服丝袜| 色在线成人网| 99热国产这里只有精品6| 老熟妇乱子伦视频在线观看| 极品教师在线免费播放| 亚洲色图综合在线观看| 欧美午夜高清在线| 老司机午夜福利在线观看视频| 国产亚洲一区二区精品| 日韩欧美免费精品| 一级毛片高清免费大全| 中文字幕人妻丝袜一区二区| 色综合欧美亚洲国产小说| 免费在线观看影片大全网站| 18禁裸乳无遮挡免费网站照片 | 亚洲精品美女久久av网站| 色综合欧美亚洲国产小说| 中文字幕制服av| 久久亚洲真实| 两性午夜刺激爽爽歪歪视频在线观看 | 国产乱人伦免费视频| 国产精品.久久久| 久久久国产一区二区| 欧美亚洲日本最大视频资源| 午夜福利免费观看在线| 亚洲欧洲精品一区二区精品久久久| videos熟女内射| 男人操女人黄网站| 中文亚洲av片在线观看爽 | 成人特级黄色片久久久久久久| 中文字幕人妻丝袜制服| 国产99久久九九免费精品| 一a级毛片在线观看| 18禁黄网站禁片午夜丰满| 精品少妇一区二区三区视频日本电影| 天堂中文最新版在线下载| 欧美最黄视频在线播放免费 | 视频区欧美日本亚洲| 黑人猛操日本美女一级片| 国产野战对白在线观看| 免费在线观看黄色视频的| 少妇 在线观看| 中文字幕另类日韩欧美亚洲嫩草| 热re99久久国产66热| 亚洲第一青青草原| 精品午夜福利视频在线观看一区| 国产亚洲精品第一综合不卡| 99久久国产精品久久久| 一进一出抽搐gif免费好疼 | 亚洲国产精品sss在线观看 | 久久ye,这里只有精品| 国产野战对白在线观看| aaaaa片日本免费| 美女视频免费永久观看网站| 亚洲五月婷婷丁香| 久热爱精品视频在线9| 午夜亚洲福利在线播放| 亚洲国产欧美网| 亚洲,欧美精品.| 成熟少妇高潮喷水视频| 免费黄频网站在线观看国产| 免费观看a级毛片全部| 久久国产精品影院| 亚洲九九香蕉| 国产精品免费大片| 曰老女人黄片| 亚洲午夜精品一区,二区,三区| 久久人人97超碰香蕉20202| 久久久国产精品麻豆| 免费在线观看黄色视频的| 在线十欧美十亚洲十日本专区| 欧美午夜高清在线| 在线观看免费午夜福利视频| 两个人看的免费小视频| 亚洲欧美激情在线| 精品久久久久久久毛片微露脸| 无人区码免费观看不卡| 国产在视频线精品| 村上凉子中文字幕在线| 亚洲国产欧美一区二区综合| 亚洲欧美日韩高清在线视频| 嫩草影视91久久| 狠狠狠狠99中文字幕| 国产精品一区二区在线不卡| 午夜视频精品福利| 丝袜美腿诱惑在线| 亚洲精品国产色婷婷电影| 婷婷成人精品国产| 极品教师在线免费播放| 高清在线国产一区| 国产欧美日韩一区二区三区在线| 51午夜福利影视在线观看| 国产高清videossex| 午夜视频精品福利| 欧美日韩乱码在线| 黑人欧美特级aaaaaa片| 亚洲欧美色中文字幕在线| 国产成人影院久久av| 亚洲精品久久午夜乱码| 欧美老熟妇乱子伦牲交| www.熟女人妻精品国产| 热99久久久久精品小说推荐| www.熟女人妻精品国产| 欧美午夜高清在线| 成人18禁高潮啪啪吃奶动态图| 午夜福利一区二区在线看| 久久草成人影院| 日本五十路高清| 一进一出抽搐动态| 日韩欧美国产一区二区入口| 性少妇av在线| 免费黄频网站在线观看国产| 亚洲第一欧美日韩一区二区三区| 免费黄频网站在线观看国产| 久久精品国产99精品国产亚洲性色 | 免费人成视频x8x8入口观看| 下体分泌物呈黄色| 国产精品 国内视频| 老司机亚洲免费影院| 久久人妻福利社区极品人妻图片| 国产在视频线精品| 久久精品国产亚洲av高清一级| 一区二区三区国产精品乱码| 另类亚洲欧美激情| 一边摸一边抽搐一进一小说 | 首页视频小说图片口味搜索| 亚洲自偷自拍图片 自拍| 日韩欧美一区二区三区在线观看 | 精品国产国语对白av| 久久久精品免费免费高清| 99精品久久久久人妻精品| 女人爽到高潮嗷嗷叫在线视频| 99热只有精品国产| 亚洲一区高清亚洲精品| 亚洲精品中文字幕在线视频| 亚洲欧美一区二区三区黑人| 精品一区二区三区av网在线观看| 91成人精品电影| 两性夫妻黄色片| 在线十欧美十亚洲十日本专区| 十八禁网站免费在线| 久久久国产一区二区| 国产欧美日韩一区二区三区在线| 亚洲av欧美aⅴ国产| 欧美日韩国产mv在线观看视频| 十八禁网站免费在线| 欧美国产精品一级二级三级| 大型黄色视频在线免费观看| 女警被强在线播放| 极品少妇高潮喷水抽搐| 十分钟在线观看高清视频www| 午夜影院日韩av| 欧美黄色淫秽网站| 美女午夜性视频免费| av网站在线播放免费| 国产淫语在线视频| 久久ye,这里只有精品| 午夜免费观看网址| 淫妇啪啪啪对白视频| 99精品欧美一区二区三区四区| 精品一区二区三区av网在线观看| 国产精品九九99| 啦啦啦视频在线资源免费观看| 大香蕉久久网| 9191精品国产免费久久| 男女之事视频高清在线观看| 午夜激情av网站| 色精品久久人妻99蜜桃| 精品一区二区三区视频在线观看免费 | 欧美激情高清一区二区三区| 国产精品国产高清国产av | 亚洲国产欧美日韩在线播放| 操出白浆在线播放| 精品人妻1区二区| 国产97色在线日韩免费| 久久狼人影院| 国产aⅴ精品一区二区三区波| 国产精品免费一区二区三区在线 | 80岁老熟妇乱子伦牲交| av天堂久久9| 亚洲av美国av| 少妇猛男粗大的猛烈进出视频| 国产亚洲欧美在线一区二区| 好看av亚洲va欧美ⅴa在| 性色av乱码一区二区三区2| 欧美精品啪啪一区二区三区| 久久久久国内视频| 老司机靠b影院| 中文字幕人妻熟女乱码| 精品亚洲成a人片在线观看| 国产97色在线日韩免费| 亚洲片人在线观看| 91大片在线观看| 十八禁网站免费在线| 免费一级毛片在线播放高清视频 | 老汉色av国产亚洲站长工具| 9191精品国产免费久久| 国产成人精品久久二区二区91| 欧美不卡视频在线免费观看 | 国产在线精品亚洲第一网站| 欧美激情极品国产一区二区三区| 美国免费a级毛片| 男女免费视频国产| 国产亚洲av高清不卡| 如日韩欧美国产精品一区二区三区| ponron亚洲| 免费不卡黄色视频| 亚洲精品久久成人aⅴ小说| 男女高潮啪啪啪动态图| 国产一区二区三区综合在线观看| 亚洲中文日韩欧美视频| 欧美性长视频在线观看| av超薄肉色丝袜交足视频| 亚洲欧美日韩另类电影网站| 久久香蕉激情| 色在线成人网| av一本久久久久| 91精品三级在线观看| 亚洲中文日韩欧美视频| 高清黄色对白视频在线免费看| 一级a爱视频在线免费观看| 成人手机av| 久久久久久久国产电影| 可以免费在线观看a视频的电影网站| 亚洲精品久久成人aⅴ小说| av天堂久久9| 在线天堂中文资源库| netflix在线观看网站| 亚洲av第一区精品v没综合| av免费在线观看网站| 欧美精品一区二区免费开放| 婷婷精品国产亚洲av在线 | 中文字幕人妻丝袜一区二区| 亚洲午夜理论影院| 高清黄色对白视频在线免费看| 黑人巨大精品欧美一区二区mp4| 免费高清在线观看日韩| av国产精品久久久久影院| 美女高潮喷水抽搐中文字幕| 色综合婷婷激情| 久久国产精品大桥未久av| www日本在线高清视频| 日韩大码丰满熟妇| 日韩制服丝袜自拍偷拍| 老司机福利观看| 亚洲第一青青草原| 精品卡一卡二卡四卡免费| 久久99一区二区三区| 又紧又爽又黄一区二区| 精品熟女少妇八av免费久了| 国产精品久久久av美女十八| 久久热在线av| 国产成人精品在线电影| 亚洲色图av天堂| 亚洲色图 男人天堂 中文字幕| 久久精品国产a三级三级三级| 中出人妻视频一区二区| 人妻一区二区av| 丝袜美足系列| 电影成人av| 飞空精品影院首页| 久久草成人影院| 久久中文看片网| 中文字幕高清在线视频| 天天操日日干夜夜撸| 欧美日韩黄片免| 色婷婷av一区二区三区视频| 国产免费av片在线观看野外av| 亚洲 欧美一区二区三区| 日韩欧美免费精品| 亚洲成人免费电影在线观看| 日本vs欧美在线观看视频| avwww免费| 人妻丰满熟妇av一区二区三区 | 99精品在免费线老司机午夜| 免费女性裸体啪啪无遮挡网站| 少妇 在线观看| 国产欧美日韩综合在线一区二区| 国产一区在线观看成人免费| 人妻丰满熟妇av一区二区三区 | 美女福利国产在线| 欧美精品人与动牲交sv欧美| 中文字幕制服av| 99久久综合精品五月天人人| 99国产精品免费福利视频| 香蕉久久夜色| 桃红色精品国产亚洲av| 国产精品影院久久| 男女高潮啪啪啪动态图| 国产成人精品在线电影| 一级黄色大片毛片| 免费在线观看亚洲国产| 久久天堂一区二区三区四区| 亚洲成人手机| 一级,二级,三级黄色视频| 午夜精品国产一区二区电影| 国产亚洲欧美精品永久| 捣出白浆h1v1| 色老头精品视频在线观看| 制服诱惑二区| 欧美精品高潮呻吟av久久| 久久人人爽av亚洲精品天堂| 午夜亚洲福利在线播放| 久久久久久免费高清国产稀缺| 亚洲成a人片在线一区二区| 亚洲视频免费观看视频| 咕卡用的链子| 欧美亚洲 丝袜 人妻 在线| 女人高潮潮喷娇喘18禁视频| 黄色丝袜av网址大全| 午夜福利免费观看在线| 亚洲欧美日韩另类电影网站| aaaaa片日本免费| 91麻豆精品激情在线观看国产 | 久久国产乱子伦精品免费另类| 久久影院123| 国内毛片毛片毛片毛片毛片| 久久久精品区二区三区| 中文字幕色久视频| 亚洲精品美女久久av网站| 岛国在线观看网站| 精品熟女少妇八av免费久了| 精品一品国产午夜福利视频| 一级毛片精品| 色精品久久人妻99蜜桃| 亚洲伊人色综图| 亚洲欧洲精品一区二区精品久久久| 天天添夜夜摸| 精品国产亚洲在线| 久久草成人影院| 亚洲精品美女久久av网站| 亚洲一区中文字幕在线| 人人妻人人澡人人看| 日韩欧美一区二区三区在线观看 | 天堂√8在线中文| 老司机亚洲免费影院| 中文字幕人妻熟女乱码| 久久精品国产亚洲av香蕉五月 | 日韩人妻精品一区2区三区| 日韩欧美国产一区二区入口| 国产亚洲欧美98| 久久国产精品男人的天堂亚洲| 免费av中文字幕在线| 久久狼人影院| 成人18禁在线播放| 精品国产美女av久久久久小说| 成人影院久久| 精品人妻熟女毛片av久久网站| 在线观看免费高清a一片| 日韩欧美免费精品| 9热在线视频观看99| 久久精品成人免费网站| 亚洲精品在线美女| x7x7x7水蜜桃| 欧美在线黄色| 成人影院久久| 亚洲熟妇熟女久久| 在线观看舔阴道视频| 一级,二级,三级黄色视频| 老熟妇仑乱视频hdxx| 性少妇av在线| 久久精品国产亚洲av香蕉五月 | 十八禁网站免费在线| 亚洲午夜理论影院| 国产精品久久久久久人妻精品电影| 动漫黄色视频在线观看| 精品久久久久久电影网| 国产亚洲精品第一综合不卡| 校园春色视频在线观看| 天堂动漫精品| 香蕉久久夜色| 色精品久久人妻99蜜桃| 日韩免费av在线播放| 777米奇影视久久| 欧美精品高潮呻吟av久久| 熟女少妇亚洲综合色aaa.| 男女午夜视频在线观看| 午夜成年电影在线免费观看| 国产欧美日韩精品亚洲av| 黑人操中国人逼视频| cao死你这个sao货| 国产亚洲一区二区精品| 日韩一卡2卡3卡4卡2021年| 成年动漫av网址| 人妻丰满熟妇av一区二区三区 | 青草久久国产| 韩国精品一区二区三区| 亚洲第一欧美日韩一区二区三区| 另类亚洲欧美激情| av国产精品久久久久影院| 国产有黄有色有爽视频| 777久久人妻少妇嫩草av网站| 欧美乱妇无乱码| 大型黄色视频在线免费观看| 久久精品国产99精品国产亚洲性色 | 久久久水蜜桃国产精品网| 精品高清国产在线一区| 狠狠狠狠99中文字幕| 国产无遮挡羞羞视频在线观看| 99久久精品国产亚洲精品|