• <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 ?

    Hierarchical simultaneous entanglement swapping for multi-hop quantum communication based on multi-particle entangled states?

    2021-03-19 03:19:50GuangYang楊光LeiXing邢磊MinNie聶敏YuanHuaLiu劉原華andMeiLingZhang張美玲
    Chinese Physics B 2021年3期
    關(guān)鍵詞:楊光美玲

    Guang Yang(楊光), Lei Xing(邢磊), Min Nie(聶敏),Yuan-Hua Liu(劉原華), and Mei-Ling Zhang(張美玲)

    School of Communications and Information Engineering&School of Artificial Intelligence,Xi’an University of Posts and Telecommunications,Xi’an 710121,China

    Keywords: multi-hop quantum communication,entanglement swapping,teleportation,multi-particle

    1. Introduction

    Quantum entanglement plays a critical role in quantum computation and quantum communication, such as quantum teleportation,[1-3]quantum dense coding,[4-6]quantum key distribution,[7-9]and quantum secure direct communication.[10-12]In order to realize multi-user wide area quantum communication, the construction of quantum network has become the focus of attention.[13-15]However, it is difficult to distribute entangled particles between two remote users directly in a quantum network due to the inevitable losses on the quantum channel.

    Entanglement swapping(ES)is an important method that can establish the entanglement path between two quantum users who do not share entanglement initially. The ES was first presented in 1993,[16]based on which,various multi-hop quantum communication schemes have been proposed.Cheng et al. devised a routing algorithm in wireless quantum networks by using the ES to construct the quantum bridge, and thus realizing the quantum teleportation.[17]Zhou et al. proposed a routing strategy for quantum internet,where quantum routers perform ES to establish entanglement connection.[18]The establishing rate of quantum path for point-by-point ES and segmentation ES was analyzed in Ref.[19]. Yu et al. proposed a two-end approximation algorithm based on ES in a wireless quantum network.[20]The similarity among the above schemes is that each intermediate node needs to perform ES hop by hop. As a result, the end-to-end time delay of entanglement establishment grows rapidly with the increase of the length and the hop count of a quantum path. We call this type of ES the sequential ES(SEQES).

    In order to reduce the establishment delay of entanglement path in a wide area quantum network, Liu et al. proposed a three-hop simultaneous ES (SES) scheme, where all intermediate nodes simultaneously conducted Bell state measurements(BSM),and sent the measurement results to the destination node through classical channel.[21]Wang et al. proposed a teleportation scheme based on the SES in a multi-hop wireless quantum network.[22]The SES scheme was also applied to the bidirectional quantum teleportation, and the unitary operation to reconstruct the quantum state was obtained by solving the inverse matrix.[23]Gao et al. proposed a multihop W-state teleportation method based on multi-level binary tree networks with selective receiving nodes,and the nodes at all levels perform quantum measurement and result transmission simultaneously.[24]With the similar ideas, other multihop quantum information transmission schemes based on the SES were presented in Refs.[25-27].

    However, in the above SES methods, each intermediate node should send the quantum measurement results to the destination node through classical channel,which would involve the forwarding of the classical information in each classical intermediate node along the classical channel, resulting in a very high classical transmission cost, so they are not suitable for large-scale quantum networks. On the other hand,the existing SES schemes mainly focus on the entanglement swapping of two-particle entangled states. As more powerful resources, multi-particle entangled states have been used in many novel quantum information tasks, including controlled teleportation,[28-30]bidirectional teleportation,[31-33]multiparty quantum secret sharing,[34-36]and multi-party quantum key agreement.[37-39]It is of great value to explore how to realize the multi-particle communication in a multi-hop quantum network rapidly and efficiently.

    In this paper,we first put forward an SES scheme to establish the four-particle GHZ entanglement path, which is used to complete the multi-hop bidirectional teleportation of threeparticle GHZ states. Further, in order to reduce the classical information cost in SES scheme, we propose a hierarchical SES(HSES)scheme that is composed of level-1 SES and level-2 SES schemes, the former implements the inner segment entanglement swapping and the latter implements the inter segment entanglement swapping. Compared with the basic SES scheme,the HSES obtains a lower classical cost,and still shows a good time delay performance. The rest of the paper is organized as follows. In Section 2,we briefly introduce the process of bidirectional teleportation of three-particle GHZ states. In Section 3,we describe the details of SES scheme to establish the remote entanglement path for the bidirectional teleportation. In Section 4,we propose the HSES scheme. In Section 5,we analyze the performance of SES and HSES.Finally,the conclusions of our work are given in Section 6.

    2. Bidirectional teleportation of three-particle GHZ states

    In this section, we briefly introduce the scheme of the bidirectional teleportation of three-particle Greenberger-Horne-Zeilinger(GHZ)state,and the detailed process can be seen in Ref.[32]. It is supposed that Alice and Bob each have a three-particle GHZ state to be teleported to each other,which has the following form:

    Here, the parameters α0, α1, β0, β1satisfy |α0|2+|α1|2=1 and |β0|2+|β1|2=1. To accomplish the teleportation, they need to share an eight-particle complex GHZ state|ω〉as the quantum channel in advance,which is shown in Fig.1. Alice holds the particles a1,a2,a3,b4,while Bob holds the particles b1, b2, b3, a4. |ω〉 can be described as the following tensor product of two four-particle GHZ state

    Fig.1. Quantum state preparation for bidirectional teleportation of three-particle GHZ states.

    After the quantum states preparation,Alice and Bob carry out the following steps to complete the bidirectional teleportation.

    Step 1They perform controlled-not(CNOT)operations respectively on particles A1and b4, B1and a4, where A1and B1are the control particles.

    Step 2They perform single-qubit |Z〉-basis measurements on particles b4and a4respectively,and perform singlequbit |X〉-basis measurements on particles A2and B2respectively, then they announce the results to each other through classical channel.

    Step 3They perform single-qubit |X〉-basis measurements on particles A1and B1respectively,then they announce the measurement results thriugh classical channel.

    Step 4They perform single-qubit |X〉-basis measurements on particles A3and B3respectively,then they announce the measurement results through classical channel.

    Step 5They perform proper three-particle unitary operations on particles a1, a2, a3and b1, b2, b3according to the measurement results in Step 2, Step 3, and Step 4, then the bidirectional teleportation is finished.

    The above scheme can be extended to realizing the bidirectional teleportation of n-particle GHZ states with a 2Nparticle(N=n+1)complex GHZ channel state.

    3. SES for multi-hop bidirectional teleportation of three-particle GHZ states

    3.1. Basic scheme of SES

    In a quantum network, there is usually no direct quantum channel between two remote users. In order to realize the bidirectional teleportation in Section 2 in a multi-hop quantum network, we propose an SES scheme that can establish the remote four-particle GHZ entanglement path. At first,we consider a scenario of three-hop SES illustrated in Fig.2. The complete process consists of the following steps.

    Step 1 Entanglement state preparation and entanglement distribution

    Fig.2. Three-hop simultaneous entanglement swapping of GHZ channel state.

    In Fig.2, the particles a1, a2, a3, a4, a5, a6, a7, and a8constitute one channel for the bidirectional teleportation, and we call it channel A. The particles b1, b2, b3, b4, b5, b6, b7,and b8constitute the other channel, and we call it channel B.We take channel A for example. After the particles distribution,the total state of particles a1,a2,a3,a4,a5,a6,a7,and a8is expressed as

    Step 2Bell state measurements and unitary operations

    After the entanglement distribution, the intermediate nodes R1and R2perform Bell state measurements(BSMs)on their particles a4,a5and a6,a7simultaneously,then they obtain one of the four results |φ+〉, |φ?〉, |?+〉 and |??〉 with equal probability. Nodes R1and R2encode the four measurement results into two-bit classical codes 00,01,10 or 11,then they send the two-bit codes through classical channel to Bob simultaneously. Bob carries out an appropriate unitary operation on his particle a8according to the classical codes he has received, after which a standard four-particle GHZ state|ω1〉can be established on particles a1,a2,a3,and a8between Alice and Bob. The unitary operations can be derived from Eq.(8),which are shown in Table 1. With a similar process, another standard four-particle GHZ state can be established on particles b1,b2,b3,and b8in channel B.

    Table 1. Unitary operations of Bob in three-hop SES.

    The scheme above can be easily extended to the case of N-hop multi-particle entanglement swapping. In the N-hop scenario,there are N ?1 intermediate nodes numbered as R1,R2,...,RN?1between Alice and Bob. For the convenience of description,the particles held by Riin channel A are denoted as Ri1and Ri2respectively,and the two-bit result code of BSM on Ri1and Ri2is referred to as MRi1MRi2, then the unitary operations of Bob can be obtained from Table 2.

    Table 2. Unitary operations of Bob in N-hop SES.

    3.2. Modified unitary operations in arbitrary Bell states

    In practice,the Bell state generated by each intermediate node is not always the state |φ+〉, it may be one of the four Bell states |φ+〉, |φ?〉, |?+〉, |??〉. Therefore, in addition to sending the BSM results to Bob, the intermediate node also needs to send the type of the Bell state generated by itself. It can be proved that the final unitary operation that Bob adopts is related to the number of different types of Bell states generated by all intermediate nodes,while it is irrelevant to the order of the Bell states in the multi-hop quantum path. As a result,Bob needs to count the number of the four types of Bell states and calculate a modified unitary operation which is shown in Table 3.

    The four-bit sequence code in Table 3 denotes the mod 2 result of the count value of the four types Bell states |φ+〉,|φ?〉,|?+〉,and|??〉. Bob obtains the basic unitary operation from Table 1 or Table 2,and obtains the modified unitary operation from Table 3,then he obtains the final unitary operation by multiplying the two operations.

    Table 3. Modified unitary operations.

    4. The hierarchical simultaneous entanglement swapping

    In the SES scheme in Section 3, each intermediate node needs to send the BSM results and the type of the Bell state to Bob through the classical channel,which will lead to considerable classical information transmission costs. In order to solve this problem, we propose a hierarchical SES(HSES)scheme in this section,and the basic process of it is shown in Fig.3.

    In the HSES,the intermediate nodes on the quantum path are divided into several segments according to the scale of the network. The end node of each segment is represented in gray in Fig.3. A complete HSES process includes the following steps.

    Step 1Entanglement state preparation and entanglement distribution

    This step includes a similar process to the Step 1 of basic SES described in Subsection 3.1, except the fact that the end nodes must generate Bell state|φ+〉,while other intermediate nodes can generate arbitrary Bell states.

    Step 2Level-one simultaneous entanglement swapping

    Level-one SES refers to the entanglement swapping in each segment, and it is carried out concurrently in all segments. With a similar process to that in Subsection 3.1, each intermediate node(except the end node)in a segment performs the BSM on the two particles in each intermediate node’s hand,then transmits the measurement result and the type of the Bell state prepared in Step 1 to the end node through the classical channel. After that, the end node calculates the unitary operation according to Tables 2 and 3, and performs the unitary operation on the particle the end node holds. When the levelone SES is finished,the standard four-particle GHZ state|ω1〉will be established between the end node and the source node in the first segment,while the standard Bell state|φ+〉will be established between the adjacent end nodes in the remaining segments(e.g.the end nodes in segment i and segment i+1),which can be seen in Fig.4. Then,level-two SES will be performed.

    Step 3Level-two simultaneous entanglement swapping

    Level-two SES refers to the entanglement swapping between segments. The end node of each segment performs the BSM on his two particles, and sends the measurement result to Bob concurrently. In this stage, since the end node of the corresponding segment has adjusted the Bell state to|φ+〉,it is not required to transmit the Bell state type information through the classical channel. After receiving all of the measurement results, Bob calculates the unitary operation according to Table 2, and performs the unitary operation on the particle he holds, so as to establish the standard four-particle GHZ state|ω1〉with Alice.

    Due to the fact that the transmission of the BSM results and the Bell state types is limited to a smaller scope in levelone swapping,and the Bell state types need not to be transmitted in level-two swapping, the classical information cost can be significantly reduced by using the HSES.

    Fig.3. Hierarchical simultaneous entanglement swapping.

    Fig.4. Level-two simultaneous entanglement swapping. Abbreviation“seg.”=segment.

    5. Analysis and discussion

    5.1. End-to-end time delay of entanglement swapping

    Suppose that there are N hops in an entanglement swapping path between Alice and Bob,which means that the total number of the intermediate nodes is N ?1.

    In the SEQES, each intermediate node needs to perform the unitary operation, BSM, and classical information transmission in sequence. The total end-to-end time delay Dseqof SEQES can be calculated from the following formula

    Here,Ddis the average entanglement distribution time in one quantum hop between two adjacent quantum nodes,Dcis the average information transmission delay in one classical hop,Hiis the number of the classical hops between the i-th intermediate node and the (i+1)-th intermediate node, Lmtis the total length of the classical packet which carries the information about the BSM result and Bell-state type,Rcis the transmission rate of classical information,Dprois the average processing time for a classical packet,Dmis the average time of a BSM,and Duis the average time of a unitary operation.

    In the SES described in Section 3,after the entanglement distribution and the BSM, each intermediate node sends the classical information to Bob simultaneously. The delay of classical information transmission depends on the maximum delay from each intermediate node to Bob. Therefore,the total end-to-end time delay Dsof SES can be calculated from

    where Hmaxrepresents the maximum classical hop count between each intermediate node and Bob.

    In the HSES described in Section 4, after the entanglement distribution, the delay of level-one SES depends on the maximum entanglement swapping delay of all segments, and the delay of level-two SES depends on the maximum delay from each end node to Bob. Therefore, the total end-to-end time delay Dhsof HSES can be calculated from

    In Eq. (11), Hmax?srepresents the maximum classical hop count between the first intermediate node and the end node in all segments, Hmax?enrepresents the maximum classical hop count between each end node and Bob,Lmrepresents the length of the classical packet which carries the BSM result.Owing to the fact that the entanglement states between the adjacent intermediate nodes have been adjusted to standard|φ+〉in level-one SES,it is not required to transmit Bell state type information.

    In the following simulation,it is assumed that the propagation rate of photon in the air is 2.996×105km,Dmis 100 ns,Duis 50 ns, Dprois 20 ns, and Rcis 100 Mbit/s. The lengths of Lmtand Lmare both taken to be 512 bits due to the fact that the classical code of BSM result and the Bell-state type must be carried in a standard data packet,then this packet should be encapsulated into MAC frame, and the length of the shortest MAC frame is 512 bits.

    The end-to-end time delay of SEQES, SES, and HSES varying with the number of the intermediate nodes are shown in Fig.5. Here,the length of one quantum hop is taken to be 10 km,and the number of the intermediate nodes of one segment of HSES is taken to be 4.We can see that the time delays of the three schemes all increase with the number of the intermediate nodes increasing, and the delay of SEQES is much higher than that of SES and HSES. This is because an intermediate node must perform the required processes one after another in SEQES,yet in SES and HSES,intermediate nodes can perform these processes simultaneously. Meanwhile, the time delay of HSES is slightly higher than that of SES.

    Suppose that the distance from Alice to Bob is given,the end-to-end delay of SEQES,SES,and HSES are given in Fig.6. when the per-hop length between two adjacent intermediate nodes is separately 5 km, 10 km, and 20 km. The number of the intermediate nodes in one segment of HSES is taken to be 4 when the per-hop length is separately 10 km and 20 km, and it is taken to be 8 when the per-hop length is 5 km. It can be seen that the delay of SEQES is still higher than that of HSES,while the delay of HSES is slightly higher than that of SES.When the per-hop length is 20 km,SEQES,SES,and HSES all obtain the lowest time delays,and they obtain the highest time delays when the per-hop length is 5 km.Obviously,a shorter per-hop length means a larger number of intermediate nodes when the distance from Alice to Bob is given. In other words, it will lead the end-to-end delay to increase when too many intermediate nodes are placed between Alice and Bob. However, when the number of the intermediate nodes decreases,the length between adjacent nodes will increase,which brings about the considerable decoherence and noise in quantum channel. As a result,it is very important to determine the per-hop length appropriately.

    Fig.5. Time delay versus number of intermediate nodes for SEQES,SES,and HSES.

    Fig.6. Time delay versus length of nulti-hop path for SEQES and HSES in the case of different per-hop lengths.

    5.2. Classical information cost of entanglement swapping

    In the SEQES,each intermediate node needs to send the classical information about the BSM results and the type of the Bell state to the next intermediate node. The overall classical information cost of SEQES is

    In the SES described in Section 3,each intermediate node needs to send classical information to Bob,so the overall classical information cost can be calculated from

    In the HSES described in Section 4, the overall classical information cost is

    In the following simulation,we use the packet as the unit of the classical cost due to the fact that the classical information should be carried in a data packet which is encapsulated in Mac frame.

    The classical costs of SEQES, SES, and HSES varying with the increase of the number of intermediate nodes are shown in Fig.7. Here,we assume that the classical hop count between two adjacent intermediate nodes is 1, and we take 4 intermediate nodes in one segment in HSES.It can be seen that the classical cost of SES is the highest in the three schemes,while the classical cost of HSES is much lower than that of SES,and the classical cost of SEQES is the lowest.

    Fig.7. Classical costs versus number of intermediate nodes for SEQES,SES,and HSES.

    Suppose that the total number of the intermediate nodes between Alice and Bob is given, figure 8 shows the classical costs of HSES when the numbers of intermediate nodes are 1,4,8,and 16 in one segment. It can be seen that when there is 1 node in a segment,which is equal to the scenario of SES,the classical cost is the highest; and the cost is the lowest when there are 8 nodes in a segment,while the cost in the case of 4 nodes and 16 nodes are a bit higher. Therefore,a larger node number in a segment does not always bring lower cost because it leads to a higher cost of level-one SES. Consequently, it is very important to give an appropriate segmentation method,thereby obtaining an optimal classical cost.

    Fig.8. Classical costs versus number of intermediate nodes for HSES with different numbers of nodes in one segment.

    Assume that the total number of the intermediate nodes is given in HSES,figure 9 shows the comparison among the classical costs when the classical hop counts between two adjacent intermediate nodes are different.The number of the intermediate nodes in one segment is taken to be 4. From Fig.9. we can see that the classical cost is the highest when the classical hop count is 3,while it is the lowest when the classical hop count is 1. Due to the fact that each classical node in one classical hop must store and forward the classical packets,the classical cost rises with the increase of the classical hop count.

    Fig.9. Classical costs versus number of intermediate nodes for HSES with different classical hops between adjacent quantum intermediate nodes.

    5.3. Discussion on challenge of Bell-state measurement

    A significant challenge in multi-hop quantum entanglement swapping is the need of performing complete BSM,which also plays a critical role in other quantum information tasks,such as quantum teleportation and quantum dense coding. However,traditional BSM schemes with linear optics can only distinguish two of the four Bell states unambiguously,thus the success probability is no more than 50%.[40-42]

    Although the complete BSM schemes with nonlinear optical elements have been presented, such as the cross-Kerr nonlinearity and the quantum-dot system,[43-45]they are still hard to put into practical application. In the past few years,researchers have been working on achieving a complete BSM with linear optics, and several improved schemes have been proposed, such as the use of auxiliary particles,[46,47]compression operation,[48]and ancillary degree of freedom(DOF).[49-52]Grice proposed a complete BSM by using the linear optical elements with the addition of ancillary entangled photons,[46]showing that the addition of 2N?2 ancillary photons yields a success rate of 1 ?1/2N. Zaidi and van Loock presented a dual-rail unambiguous BSM scheme by using single-mode squeezers and beam splitters with a success probability of 64.3%.[47]Kwait and Weinfurter first proposed a scheme to perform the complete BSM with linear optics by using entanglement in polarization DOF and ancillary DOF.[48]After that,a series of complete BSM schemes was put forward by using the hyperentangled states,such as hyperentanglement in polarization-momentum,[49]polarization-frequency,[50]and polarization-time mode.[51,52]In these schemes,the quantum message is usually carried by the polarization DOF,while the ancillary DOFs are used to expand the measurement space.

    Owing to the above progresses, the practical BSM technology has been greatly developed, while how to distinguish Bell states unambiguously and efficiently in quantum information fields is still a very crucial research topic,and this will also be an important aspect of our future work.

    6. Conclusions

    In this work, we present a multi-particle HSES scheme for the bidirectional teleportation of three-particle GHZ states,in which the intermediate nodes on the quantum path are divided into several segments, and the whole entanglement swapping includes level-one SES and level-two SES. Owing to the fact that the classical information transmission is limited to a smaller scope in level-one SES, and only the intermediate nodes need to transmit classical information to Bob in level-two SES, the classical information cost can be significantly reduced. Compared with the existing SEQES and SES schemes, the HSES has the advantages to obtain the optimal performance tradeoff between the end-to-end delay and the classical information cost.

    The HSES scheme in this paper can be easily extended for other quantum communication tasks. Generally, a large scale quantum network is divided into quantum access network(QAN)and quantum core network(QCN).In the QAN,different types of entanglements can be distributed between the user node and the network edge node according to the requirements of quantum communication tasks,such as W state,GHZ state, cluster state, etc. In the QCN, the intermediate nodes only need to prepare and distribute Bell states. Using the HSES scheme, the multi-hop entanglement between remote users can be established with low delay and low classical information cost. Such a scheme is of positive value for improving the quality of large scale quantum networks and promoting the development of practical quantum communication,which will have a potential application prospect in constructing the future quantum land networks and quantum satellite networks.

    猜你喜歡
    楊光美玲
    長大以后做什么
    吃糖的好處你了解多少?
    Polysaccharides Based Random and Unidirectional Aerogels for Thermal and Mechanical Stability
    瓜蛋
    小小說月刊(2020年3期)2020-04-15 07:18:59
    雞飛蛋打一場空
    Higgs and Single Top Associated Production at the LHC in the Left-Right Twin Higgs Model?
    美玲:我的幸福是與萌貨親密接觸
    金色年華(2017年10期)2017-06-21 09:46:49
    趙美玲
    劉亮、楊光設(shè)計作品
    春天的早晨
    蜜臀久久99精品久久宅男| 我要搜黄色片| 久久久久久九九精品二区国产| 又爽又黄a免费视频| 成人av在线播放网站| 久久久久九九精品影院| 亚洲aⅴ乱码一区二区在线播放| 美女国产视频在线观看| 永久免费av网站大全| 国产黄片美女视频| 国产亚洲精品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| 国产欧美另类精品又又久久亚洲欧美| 婷婷六月久久综合丁香| 26uuu在线亚洲综合色| 日韩大片免费观看网站 | 亚洲中文字幕一区二区三区有码在线看| 国产精品.久久久| 日本黄色视频三级网站网址| 国产精品美女特级片免费视频播放器| 两性午夜刺激爽爽歪歪视频在线观看| 婷婷六月久久综合丁香| av播播在线观看一区| av在线蜜桃| 少妇熟女aⅴ在线视频| 建设人人有责人人尽责人人享有的 | 国产一区二区在线av高清观看| 亚洲18禁久久av| 五月玫瑰六月丁香| 久久亚洲精品不卡| 七月丁香在线播放| 三级国产精品欧美在线观看| 亚洲va在线va天堂va国产| 少妇裸体淫交视频免费看高清| 我要看日韩黄色一级片| 免费看美女性在线毛片视频| 成人午夜高清在线视频| 午夜免费激情av| 一本一本综合久久| 色播亚洲综合网| 九色成人免费人妻av| 国产单亲对白刺激| 亚洲欧美一区二区三区国产| 亚洲国产精品成人久久小说| 三级毛片av免费| 欧美成人免费av一区二区三区| 亚洲天堂国产精品一区在线| 午夜精品国产一区二区电影 | 久久久久久久国产电影| 国产一区有黄有色的免费视频 | 亚洲人成网站在线播| 国产探花在线观看一区二区| 亚洲欧美日韩高清专用| 久久久久久久久久黄片| 日本猛色少妇xxxxx猛交久久| 国产视频首页在线观看| 国产精品久久视频播放| 久久99热这里只频精品6学生 | 成人午夜精彩视频在线观看| 亚洲欧美日韩卡通动漫| 搡老妇女老女人老熟妇| 深爱激情五月婷婷| 18禁在线播放成人免费| 水蜜桃什么品种好| 国产成人a区在线观看| 成人高潮视频无遮挡免费网站| 国产视频首页在线观看| 97在线视频观看| 综合色丁香网| 99久久无色码亚洲精品果冻| 麻豆精品久久久久久蜜桃| 中文字幕亚洲精品专区| 日韩欧美国产在线观看| 色尼玛亚洲综合影院| 亚洲不卡免费看| 欧美高清性xxxxhd video| 成人综合一区亚洲| 欧美+日韩+精品| 最近中文字幕2019免费版| 日本-黄色视频高清免费观看| 亚洲av免费在线观看| 欧美成人a在线观看| 亚洲精品一区蜜桃| 一区二区三区高清视频在线| 最近视频中文字幕2019在线8| 久久久久性生活片| 成年版毛片免费区| 亚洲熟妇中文字幕五十中出| 国产真实乱freesex| 国产精品野战在线观看| 91av网一区二区| av在线播放精品| 国产91av在线免费观看| 夜夜看夜夜爽夜夜摸| 欧美精品国产亚洲| 国产成人aa在线观看| 少妇的逼水好多| 国产av在哪里看| 精品免费久久久久久久清纯| 精品人妻一区二区三区麻豆| 欧美精品一区二区大全| 色综合站精品国产| 中文字幕制服av| 看十八女毛片水多多多| 美女国产视频在线观看| 午夜激情福利司机影院| 国产成人freesex在线| 中文字幕av成人在线电影| 精品国产三级普通话版| 免费电影在线观看免费观看| 国产精品乱码一区二三区的特点| 最近的中文字幕免费完整| 三级国产精品片| 久久久国产成人精品二区| videos熟女内射| 内射极品少妇av片p| 你懂的网址亚洲精品在线观看 | 色综合站精品国产| 国国产精品蜜臀av免费| 美女内射精品一级片tv| 人妻少妇偷人精品九色| 久热久热在线精品观看| 一级毛片aaaaaa免费看小| 三级经典国产精品| 免费不卡的大黄色大毛片视频在线观看 | 亚洲欧美日韩高清专用| 在线播放无遮挡| 成人三级黄色视频| 69av精品久久久久久| 高清在线视频一区二区三区 | 欧美一区二区亚洲| 国产精品一区www在线观看| 青春草视频在线免费观看| 亚洲激情五月婷婷啪啪| 在线观看美女被高潮喷水网站| 日韩高清综合在线| 中文字幕久久专区| 国产精品久久久久久久电影| 色吧在线观看| 啦啦啦啦在线视频资源| 国产极品精品免费视频能看的| 国产成人福利小说| 亚洲国产成人一精品久久久| 精品一区二区三区人妻视频| 校园人妻丝袜中文字幕| 亚洲三级黄色毛片| 亚洲精品,欧美精品| 两个人视频免费观看高清| 天堂影院成人在线观看| 日日啪夜夜撸| 日韩欧美精品免费久久| 亚洲欧美成人精品一区二区| 99热网站在线观看| 非洲黑人性xxxx精品又粗又长| 国产免费男女视频| 欧美精品国产亚洲| 久热久热在线精品观看| 国产精品综合久久久久久久免费| 深爱激情五月婷婷| 观看免费一级毛片| 亚洲欧美精品专区久久| 1024手机看黄色片| 人妻制服诱惑在线中文字幕| 国产一区二区亚洲精品在线观看| 午夜福利成人在线免费观看| 久久久久久久久久成人| av黄色大香蕉| 久久久国产成人精品二区| 日本一本二区三区精品| 国产精品乱码一区二三区的特点| 日本免费一区二区三区高清不卡| 精品国产三级普通话版| 久久6这里有精品| 亚洲精品乱码久久久v下载方式| 精品熟女少妇av免费看| 国产视频首页在线观看| 国产 一区 欧美 日韩| 日本免费一区二区三区高清不卡| 国产精品久久视频播放| 高清视频免费观看一区二区 | 有码 亚洲区| 免费看av在线观看网站| 身体一侧抽搐| 嫩草影院入口| 国产精品野战在线观看| 国产私拍福利视频在线观看| 免费在线观看成人毛片| 你懂的网址亚洲精品在线观看 | .国产精品久久| 长腿黑丝高跟| 特大巨黑吊av在线直播| 日本免费一区二区三区高清不卡| 一级毛片我不卡| 中文在线观看免费www的网站| 成年女人看的毛片在线观看| 听说在线观看完整版免费高清| 国产精品永久免费网站| 国产极品天堂在线| 男人和女人高潮做爰伦理| 国产伦一二天堂av在线观看| 亚洲一级一片aⅴ在线观看| 国产精品熟女久久久久浪| 91精品一卡2卡3卡4卡| 亚洲欧洲国产日韩| 秋霞在线观看毛片| 全区人妻精品视频| 69人妻影院| 亚洲三级黄色毛片| 久久久久久伊人网av| 能在线免费观看的黄片| 99视频精品全部免费 在线| 激情 狠狠 欧美| 99久久成人亚洲精品观看| 亚洲av中文av极速乱| 欧美zozozo另类| 夜夜爽夜夜爽视频| 精品一区二区免费观看| 亚洲精品456在线播放app| 国产成人精品久久久久久| 国产黄色小视频在线观看| 国产日韩欧美在线精品| 国产午夜精品久久久久久一区二区三区| 最后的刺客免费高清国语| 久久久久久久久中文| 99久久精品热视频| 极品教师在线视频| 日产精品乱码卡一卡2卡三| 一区二区三区乱码不卡18| 久久久久免费精品人妻一区二区| 亚洲av福利一区| 99久国产av精品| 国产一级毛片七仙女欲春2| 少妇裸体淫交视频免费看高清| 成人美女网站在线观看视频| 精品一区二区免费观看| 午夜福利成人在线免费观看| 亚洲欧美精品专区久久| 亚洲精品国产av成人精品| 欧美高清性xxxxhd video| 久久6这里有精品| 午夜激情福利司机影院| 天堂网av新在线| 老司机影院毛片| 草草在线视频免费看| 美女内射精品一级片tv| videos熟女内射| 国产午夜福利久久久久久| 在线免费观看的www视频| 成年免费大片在线观看| 纵有疾风起免费观看全集完整版 | 青青草视频在线视频观看| 久久久精品大字幕| 亚洲综合色惰| 欧美成人午夜免费资源| 中文欧美无线码| 国内精品宾馆在线| 最近中文字幕2019免费版| 观看美女的网站| 啦啦啦韩国在线观看视频| 99久久精品热视频| 男人狂女人下面高潮的视频| 久久久久久九九精品二区国产| 久久午夜福利片| 日韩成人伦理影院| 有码 亚洲区| 级片在线观看| 男女下面进入的视频免费午夜| 久久人人爽人人片av| 99视频精品全部免费 在线| 久久99热这里只频精品6学生 | 日韩欧美三级三区| 又爽又黄a免费视频| 国产 一区精品| 老司机影院成人| 女人久久www免费人成看片 | 国产精品乱码一区二三区的特点| 美女黄网站色视频| 老司机福利观看| 亚洲精品久久久久久婷婷小说 | 一级黄色大片毛片| av卡一久久| 亚洲性久久影院| 麻豆国产97在线/欧美| 久久精品国产亚洲av天美| 亚洲国产精品sss在线观看| 国产美女午夜福利| 午夜福利网站1000一区二区三区| 日本欧美国产在线视频| 最近中文字幕2019免费版| 日日干狠狠操夜夜爽| 国产亚洲精品av在线| 亚洲内射少妇av| 久久久a久久爽久久v久久| 日本午夜av视频| 国产精品国产三级国产专区5o | 亚洲国产成人一精品久久久| 亚洲四区av| 国产久久久一区二区三区| 自拍偷自拍亚洲精品老妇| 精品一区二区三区视频在线| 亚洲第一区二区三区不卡| 亚洲aⅴ乱码一区二区在线播放| 国产伦理片在线播放av一区| 欧美性猛交╳xxx乱大交人| 国产精品野战在线观看| 国产一区二区在线av高清观看| 男女那种视频在线观看| 亚洲精品乱久久久久久| 亚洲人成网站高清观看| 国产欧美另类精品又又久久亚洲欧美| 真实男女啪啪啪动态图| 国产成人免费观看mmmm| 精品99又大又爽又粗少妇毛片| 欧美日韩在线观看h| 国产麻豆成人av免费视频| 1000部很黄的大片| 好男人视频免费观看在线| 夜夜爽夜夜爽视频| 伦精品一区二区三区| 欧美97在线视频| 精品熟女少妇av免费看| 国产亚洲最大av| 中文字幕亚洲精品专区| 在线天堂最新版资源| 久久久久久久午夜电影| 亚洲欧美精品综合久久99| 最近中文字幕2019免费版| 国产视频首页在线观看| 亚洲精品456在线播放app| 最近中文字幕2019免费版| 国产男人的电影天堂91| 超碰97精品在线观看| 熟女电影av网| 九九热线精品视视频播放| 欧美成人免费av一区二区三区| 熟女电影av网| 狂野欧美激情性xxxx在线观看| 欧美另类亚洲清纯唯美| 国产乱人视频| 三级毛片av免费| 国产精品综合久久久久久久免费| 国产精品美女特级片免费视频播放器| 91午夜精品亚洲一区二区三区| 在线免费十八禁| 日本黄色视频三级网站网址| 一本久久精品| 在线天堂最新版资源| 国产免费男女视频| 最近中文字幕高清免费大全6| 欧美+日韩+精品| 一级二级三级毛片免费看| 国产伦精品一区二区三区四那| 少妇的逼好多水| 夜夜爽夜夜爽视频| 变态另类丝袜制服| 小蜜桃在线观看免费完整版高清| 乱人视频在线观看| 国产精品99久久久久久久久| 亚洲av熟女| 伊人久久精品亚洲午夜| 日日摸夜夜添夜夜爱| 九草在线视频观看| 18禁在线无遮挡免费观看视频| www.av在线官网国产| 欧美zozozo另类| 色综合色国产| 亚洲五月天丁香| 亚洲色图av天堂| 91精品伊人久久大香线蕉| 人妻制服诱惑在线中文字幕| 亚洲五月天丁香| 国产高清不卡午夜福利| 大香蕉97超碰在线| 麻豆久久精品国产亚洲av| 日本一二三区视频观看| 人妻夜夜爽99麻豆av| 麻豆成人午夜福利视频| 天天躁夜夜躁狠狠久久av| 狂野欧美白嫩少妇大欣赏| 日韩精品青青久久久久久| 久久人人爽人人片av| 蜜臀久久99精品久久宅男| 国产精品一二三区在线看| 日本五十路高清| 人妻系列 视频| 久久99蜜桃精品久久| 国产单亲对白刺激| 免费播放大片免费观看视频在线观看 | 极品教师在线视频| 婷婷六月久久综合丁香| 久久久a久久爽久久v久久| 亚洲精品色激情综合| 欧美97在线视频| 亚洲欧洲日产国产| 中文字幕av在线有码专区| or卡值多少钱| 国产精品乱码一区二三区的特点| 18禁在线无遮挡免费观看视频| 亚洲成人av在线免费| 插阴视频在线观看视频| 身体一侧抽搐| 久久人人爽人人片av| 黄片无遮挡物在线观看| 欧美高清性xxxxhd video| 国产精品久久久久久精品电影| 观看免费一级毛片| 色哟哟·www| 日韩在线高清观看一区二区三区| 观看美女的网站| 国产毛片a区久久久久| 精品久久久久久久末码| 欧美最新免费一区二区三区| 一本一本综合久久| 久久久午夜欧美精品| 婷婷色av中文字幕| 99久久精品热视频| 成人综合一区亚洲| 中国国产av一级| 国产精品乱码一区二三区的特点| 欧美成人一区二区免费高清观看| 我的老师免费观看完整版| 国产麻豆成人av免费视频| 2021天堂中文幕一二区在线观| 免费看日本二区| 久久亚洲精品不卡| 亚洲在线自拍视频| 97在线视频观看| 色5月婷婷丁香| 欧美激情在线99| 亚洲av二区三区四区| 午夜福利视频1000在线观看| 国内少妇人妻偷人精品xxx网站| 久久精品国产亚洲网站| 色噜噜av男人的天堂激情| av线在线观看网站| 国产高清视频在线观看网站| 国产精品不卡视频一区二区| 最近中文字幕高清免费大全6| 国语自产精品视频在线第100页| 最近手机中文字幕大全| 亚洲精品乱码久久久久久按摩| 日韩一区二区三区影片| 成人国产麻豆网| 中文字幕人妻熟人妻熟丝袜美| 亚洲国产欧美在线一区| 日韩在线高清观看一区二区三区| 丝袜美腿在线中文| 国产成人精品久久久久久| 在线免费观看不下载黄p国产| 只有这里有精品99| 日本三级黄在线观看| 精品久久久久久电影网 | 99热这里只有是精品50| 国产av不卡久久| 亚洲精华国产精华液的使用体验| 欧美激情在线99| 你懂的网址亚洲精品在线观看 | 日韩中字成人| 观看免费一级毛片| 国产精品爽爽va在线观看网站| 国产精品乱码一区二三区的特点| 国产在视频线精品| 日韩精品青青久久久久久| 国产精品久久久久久久久免| 亚洲国产精品专区欧美| 青春草视频在线免费观看| 中国国产av一级| 亚洲欧美日韩东京热| 免费观看人在逋| 国产伦理片在线播放av一区| 日韩制服骚丝袜av| 免费电影在线观看免费观看| 女人被狂操c到高潮| 中文字幕av成人在线电影| 亚洲婷婷狠狠爱综合网| 伊人久久精品亚洲午夜| 日韩成人av中文字幕在线观看| 欧美不卡视频在线免费观看| 国产老妇伦熟女老妇高清| 2021天堂中文幕一二区在线观| 国产精品久久电影中文字幕| АⅤ资源中文在线天堂| 麻豆成人av视频| 欧美xxxx黑人xx丫x性爽| 国内精品美女久久久久久| 青春草国产在线视频| 亚洲美女视频黄频| 秋霞伦理黄片| 女人十人毛片免费观看3o分钟| 欧美三级亚洲精品| 非洲黑人性xxxx精品又粗又长| 在线观看一区二区三区| 国产精品电影一区二区三区| 日韩成人av中文字幕在线观看| 欧美区成人在线视频| 狂野欧美白嫩少妇大欣赏| 久久精品国产自在天天线| 精品久久久噜噜| 床上黄色一级片| 国产欧美日韩精品一区二区| 国产三级中文精品| 少妇被粗大猛烈的视频| 久久久久网色| 亚洲中文字幕一区二区三区有码在线看| 久久午夜福利片| 国产高清不卡午夜福利| 美女内射精品一级片tv| 人人妻人人澡人人爽人人夜夜 | 国产av在哪里看| 免费在线观看成人毛片| 汤姆久久久久久久影院中文字幕 | 欧美xxxx黑人xx丫x性爽| 老司机影院毛片| 97热精品久久久久久| 九九在线视频观看精品| 一区二区三区乱码不卡18| 国产老妇女一区| 午夜福利视频1000在线观看| 亚洲中文字幕一区二区三区有码在线看| 在现免费观看毛片| 纵有疾风起免费观看全集完整版 | 亚洲欧美中文字幕日韩二区| 国产精品久久久久久久电影| 精品人妻熟女av久视频| 久久精品夜夜夜夜夜久久蜜豆| 国产免费又黄又爽又色| 午夜亚洲福利在线播放| av.在线天堂| 成人鲁丝片一二三区免费| 国产精品国产三级国产av玫瑰| 久久久久免费精品人妻一区二区| 男人舔奶头视频| 亚洲精品乱码久久久v下载方式| 成年女人永久免费观看视频| 大香蕉久久网| 最近2019中文字幕mv第一页| 久久婷婷人人爽人人干人人爱| 亚洲丝袜综合中文字幕| 一个人观看的视频www高清免费观看| 国产免费一级a男人的天堂| 久久久国产成人精品二区| 黑人高潮一二区| 精品少妇黑人巨大在线播放 | 国产三级在线视频| 久久人妻av系列| 免费观看人在逋| 午夜福利在线观看免费完整高清在| 三级国产精品片| 一本—道久久a久久精品蜜桃钙片 精品乱码久久久久久99久播 | 最近2019中文字幕mv第一页| 久久婷婷人人爽人人干人人爱| 欧美高清成人免费视频www| 最后的刺客免费高清国语| 久久热精品热| 久久精品国产鲁丝片午夜精品| 激情 狠狠 欧美| 全区人妻精品视频| 一级av片app| 国产国拍精品亚洲av在线观看| 国产精品一区二区三区四区免费观看| 国产老妇伦熟女老妇高清| 少妇丰满av| 免费一级毛片在线播放高清视频| 亚洲aⅴ乱码一区二区在线播放| 久久久亚洲精品成人影院| 亚洲久久久久久中文字幕| 91久久精品国产一区二区三区| 美女脱内裤让男人舔精品视频| 免费看av在线观看网站| 长腿黑丝高跟| 亚洲av二区三区四区| 精品一区二区三区视频在线| 汤姆久久久久久久影院中文字幕 | 两性午夜刺激爽爽歪歪视频在线观看| 变态另类丝袜制服| 久久久久久久久中文| 超碰av人人做人人爽久久| 国产亚洲精品av在线| 超碰av人人做人人爽久久| 一级毛片aaaaaa免费看小| 亚洲国产欧洲综合997久久,| 99久久精品一区二区三区| 日韩强制内射视频| 国产精品不卡视频一区二区| 少妇裸体淫交视频免费看高清| 日韩,欧美,国产一区二区三区 | 国产成人一区二区在线| 国产精品女同一区二区软件| 久久这里有精品视频免费| 亚洲精品国产成人久久av| 久久精品熟女亚洲av麻豆精品 | 日韩精品有码人妻一区| 国产成人a区在线观看| av在线天堂中文字幕| 国产精品国产高清国产av| 亚洲综合精品二区| 日韩欧美 国产精品| 麻豆精品久久久久久蜜桃| 看非洲黑人一级黄片| 亚洲人成网站高清观看| 一二三四中文在线观看免费高清| 2022亚洲国产成人精品| 丝袜喷水一区| 日韩av在线大香蕉| 午夜日本视频在线| 亚洲av成人精品一区久久| 女人十人毛片免费观看3o分钟| 波多野结衣高清无吗| 久久久久久久亚洲中文字幕| 91久久精品国产一区二区成人| 久久99精品国语久久久| 亚洲三级黄色毛片| 欧美成人一区二区免费高清观看| 美女大奶头视频|