• <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
    国产不卡一卡二| 日韩国内少妇激情av| av视频在线观看入口| av免费在线看不卡| 国产精品三级大全| 国产亚洲91精品色在线| 国产亚洲91精品色在线| 在线观看美女被高潮喷水网站| 国产一区二区三区在线臀色熟女| 搡老妇女老女人老熟妇| 卡戴珊不雅视频在线播放| 午夜亚洲福利在线播放| av在线观看视频网站免费| 免费观看a级毛片全部| 久久人人爽人人爽人人片va| 国产精品久久视频播放| 亚洲第一电影网av| 在线a可以看的网站| 村上凉子中文字幕在线| 国产精品爽爽va在线观看网站| 99久久精品国产国产毛片| 精品99又大又爽又粗少妇毛片| 国产精品电影一区二区三区| 日韩欧美 国产精品| 国产成人91sexporn| 最近中文字幕高清免费大全6| 在线免费观看不下载黄p国产| 国产高清三级在线| 国产亚洲精品久久久久久毛片| av国产免费在线观看| 男女边吃奶边做爰视频| 能在线免费观看的黄片| 精品久久久久久久人妻蜜臀av| 色哟哟哟哟哟哟| 美女国产视频在线观看| 一本久久中文字幕| 国产成人a区在线观看| 日日摸夜夜添夜夜添av毛片| 亚洲欧美成人精品一区二区| 欧美高清成人免费视频www| 国产精品永久免费网站| 久久久久久久久中文| 日本黄大片高清| 亚洲av男天堂| 99久久精品国产国产毛片| av黄色大香蕉| 日本黄大片高清| 日韩欧美三级三区| 亚洲国产精品成人久久小说 | 我的老师免费观看完整版| 九九热线精品视视频播放| 一级毛片电影观看 | 美女 人体艺术 gogo| 国内精品久久久久精免费| 人体艺术视频欧美日本| 国产高清视频在线观看网站| 能在线免费观看的黄片| 色5月婷婷丁香| 日韩人妻高清精品专区| 久久久久久久午夜电影| 日本欧美国产在线视频| 日韩欧美国产在线观看| 亚洲中文字幕一区二区三区有码在线看| 国产精品,欧美在线| 亚洲五月天丁香| 精品日产1卡2卡| 国产伦在线观看视频一区| 又粗又爽又猛毛片免费看| 国产一区二区在线av高清观看| 久久午夜亚洲精品久久| 国产v大片淫在线免费观看| 久久亚洲国产成人精品v| 亚洲激情五月婷婷啪啪| 激情 狠狠 欧美| 99热全是精品| 国产精品乱码一区二三区的特点| 男女下面进入的视频免费午夜| а√天堂www在线а√下载| 亚洲一区高清亚洲精品| 色综合色国产| 丰满人妻一区二区三区视频av| 国产精品久久视频播放| 国产大屁股一区二区在线视频| 大香蕉久久网| av免费观看日本| 一级毛片久久久久久久久女| 亚洲av电影不卡..在线观看| 成年版毛片免费区| 婷婷六月久久综合丁香| 亚洲av熟女| 国产精品美女特级片免费视频播放器| 欧美高清成人免费视频www| 久久久午夜欧美精品| 色哟哟·www| 午夜激情欧美在线| 麻豆成人av视频| 国产亚洲5aaaaa淫片| 久久久久久国产a免费观看| 午夜精品在线福利| 亚洲三级黄色毛片| 特级一级黄色大片| 五月伊人婷婷丁香| 久久午夜福利片| 中文字幕人妻熟人妻熟丝袜美| 国产精品1区2区在线观看.| 草草在线视频免费看| 亚洲五月天丁香| 国产色爽女视频免费观看| 悠悠久久av| 变态另类丝袜制服| 桃色一区二区三区在线观看| 亚洲丝袜综合中文字幕| 亚洲真实伦在线观看| 综合色丁香网| 亚洲av不卡在线观看| 国产精品乱码一区二三区的特点| 99久久精品热视频| 国产精品嫩草影院av在线观看| 精品久久久噜噜| 1000部很黄的大片| av在线天堂中文字幕| 国产精品久久久久久久久免| 国产精品99久久久久久久久| 3wmmmm亚洲av在线观看| 国内精品宾馆在线| 国产精品不卡视频一区二区| 91av网一区二区| 一区二区三区四区激情视频 | 日日撸夜夜添| 午夜激情福利司机影院| 国产黄片美女视频| 中文精品一卡2卡3卡4更新| 乱系列少妇在线播放| 人体艺术视频欧美日本| 国产极品天堂在线| 欧美成人a在线观看| 99久国产av精品| 99久久九九国产精品国产免费| 少妇丰满av| 在线观看午夜福利视频| 亚洲成av人片在线播放无| 亚洲精品日韩av片在线观看| 美女cb高潮喷水在线观看| 三级经典国产精品| 亚洲精品色激情综合| 人妻少妇偷人精品九色| 久久久久免费精品人妻一区二区| 菩萨蛮人人尽说江南好唐韦庄 | 亚洲国产精品成人综合色| 亚洲美女搞黄在线观看| 亚洲中文字幕一区二区三区有码在线看| 成人特级av手机在线观看| 中出人妻视频一区二区| 在线a可以看的网站| 欧美精品国产亚洲| 干丝袜人妻中文字幕| 一级黄色大片毛片| 18禁在线播放成人免费| 晚上一个人看的免费电影| .国产精品久久| 五月玫瑰六月丁香| 一级黄片播放器| 亚洲最大成人中文| 国产成人91sexporn| 久久久国产成人免费| 看黄色毛片网站| 国产真实伦视频高清在线观看| 日韩成人av中文字幕在线观看| 成熟少妇高潮喷水视频| 国产精品一区二区性色av| 九色成人免费人妻av| 午夜激情欧美在线| 看十八女毛片水多多多| 91久久精品国产一区二区三区| 国产一级毛片在线| 91久久精品电影网| 亚洲欧美日韩卡通动漫| av在线老鸭窝| 午夜福利在线在线| 亚洲熟妇中文字幕五十中出| 日韩av在线大香蕉| 精品国内亚洲2022精品成人| 色5月婷婷丁香| .国产精品久久| 搡女人真爽免费视频火全软件| 草草在线视频免费看| 长腿黑丝高跟| а√天堂www在线а√下载| 最近2019中文字幕mv第一页| 蜜桃久久精品国产亚洲av| 91精品一卡2卡3卡4卡| 久久欧美精品欧美久久欧美| 深夜a级毛片| 爱豆传媒免费全集在线观看| 精品久久久久久久久av| 男人和女人高潮做爰伦理| 夜夜夜夜夜久久久久| 国产69精品久久久久777片| 99热6这里只有精品| 亚洲第一电影网av| 国产成人一区二区在线| 精品一区二区三区人妻视频| 五月伊人婷婷丁香| 校园人妻丝袜中文字幕| 中文字幕精品亚洲无线码一区| 99精品在免费线老司机午夜| 久久亚洲国产成人精品v| 精品久久久久久久久av| 国产精品久久久久久精品电影小说 | 99热精品在线国产| 欧美一级a爱片免费观看看| 人妻制服诱惑在线中文字幕| 午夜福利高清视频| 久久精品久久久久久噜噜老黄 | a级毛片a级免费在线| 中出人妻视频一区二区| 日韩一本色道免费dvd| 一个人免费在线观看电影| 国产av一区在线观看免费| 亚洲精品亚洲一区二区| 久久久色成人| 国语自产精品视频在线第100页| 久久久精品94久久精品| 成人鲁丝片一二三区免费| 亚洲中文字幕日韩| 丰满的人妻完整版| 熟女人妻精品中文字幕| 亚洲第一区二区三区不卡| 偷拍熟女少妇极品色| 亚洲第一电影网av| 黄片wwwwww| 欧美色视频一区免费| 国产精品乱码一区二三区的特点| 国产一区二区激情短视频| 国产精品永久免费网站| 久久精品国产自在天天线| 国产精品嫩草影院av在线观看| 国内精品一区二区在线观看| 久久精品综合一区二区三区| 久久久a久久爽久久v久久| 久久99蜜桃精品久久| 日韩高清综合在线| 99久久九九国产精品国产免费| 一级毛片电影观看 | 国产久久久一区二区三区| 国产在线男女| 91在线精品国自产拍蜜月| 亚洲av.av天堂| 人妻夜夜爽99麻豆av| 精华霜和精华液先用哪个| 中文字幕熟女人妻在线| 成人鲁丝片一二三区免费| 欧美激情国产日韩精品一区| 日本五十路高清| 国产成人福利小说| 久久99蜜桃精品久久| 日韩三级伦理在线观看| 国产精华一区二区三区| 国产精品麻豆人妻色哟哟久久 | 欧美激情在线99| 欧美成人精品欧美一级黄| 日本熟妇午夜| 寂寞人妻少妇视频99o| 日本与韩国留学比较| 国产日本99.免费观看| 亚洲丝袜综合中文字幕| 精品不卡国产一区二区三区| 美女国产视频在线观看| 一本久久精品| 韩国av在线不卡| 99久久人妻综合| 99久久九九国产精品国产免费| 少妇人妻一区二区三区视频| 乱人视频在线观看| 在线免费十八禁| 干丝袜人妻中文字幕| 啦啦啦韩国在线观看视频| 国产精品一区二区三区四区免费观看| 蜜臀久久99精品久久宅男| eeuss影院久久| 国产午夜精品久久久久久一区二区三区| 少妇被粗大猛烈的视频| 欧美一区二区国产精品久久精品| 日韩一区二区三区影片| 又黄又爽又刺激的免费视频.| 在线观看免费视频日本深夜| 欧美日韩在线观看h| 婷婷六月久久综合丁香| 成人漫画全彩无遮挡| 国产91av在线免费观看| 亚洲中文字幕日韩| 国产亚洲91精品色在线| 麻豆av噜噜一区二区三区| 人人妻人人澡人人爽人人夜夜 | 精品一区二区三区视频在线| av在线老鸭窝| 熟女电影av网| 3wmmmm亚洲av在线观看| 一区福利在线观看| 天天一区二区日本电影三级| 国产精品人妻久久久久久| 又粗又爽又猛毛片免费看| 免费观看人在逋| 又黄又爽又刺激的免费视频.| 悠悠久久av| 狠狠狠狠99中文字幕| 人妻久久中文字幕网| 亚洲中文字幕一区二区三区有码在线看| 中文字幕熟女人妻在线| 青春草国产在线视频 | 熟妇人妻久久中文字幕3abv| 少妇丰满av| 性色avwww在线观看| 中文字幕av在线有码专区| 亚洲乱码一区二区免费版| 少妇猛男粗大的猛烈进出视频 | 亚洲精品中文字幕在线视频| 久久狼人影院| 肉色欧美久久久久久久蜜桃| 日本av免费视频播放| 国产黄片视频在线免费观看| 18禁观看日本| 九九在线视频观看精品| 久久久国产一区二区| 777米奇影视久久| 久久精品久久精品一区二区三区| 又黄又爽又刺激的免费视频.| 你懂的网址亚洲精品在线观看| 午夜日本视频在线| 精品一区在线观看国产| 王馨瑶露胸无遮挡在线观看| 青春草国产在线视频| 国产精品一区二区在线观看99| 一级片'在线观看视频| 妹子高潮喷水视频| 成人亚洲精品一区在线观看| 自拍欧美九色日韩亚洲蝌蚪91| 国产视频内射| 国产一区二区三区综合在线观看 | 久久久久久久久久久免费av| 满18在线观看网站| 三级国产精品欧美在线观看| 自线自在国产av| 久久精品人人爽人人爽视色| 97超视频在线观看视频| 色婷婷久久久亚洲欧美| 久久久国产欧美日韩av| .国产精品久久| 一区二区三区精品91| 九色成人免费人妻av| 狂野欧美白嫩少妇大欣赏| 免费日韩欧美在线观看| 亚洲熟女精品中文字幕| 在线观看一区二区三区激情| 涩涩av久久男人的天堂| 80岁老熟妇乱子伦牲交| 国产一区二区在线观看日韩| 五月天丁香电影| 五月天丁香电影| 最近2019中文字幕mv第一页| 成人午夜精彩视频在线观看| 日本免费在线观看一区| 欧美日韩成人在线一区二区| av播播在线观看一区| 美女xxoo啪啪120秒动态图| 欧美亚洲日本最大视频资源| 日本黄色日本黄色录像| 欧美人与性动交α欧美精品济南到 | 国产白丝娇喘喷水9色精品| 精品国产一区二区久久| 一本大道久久a久久精品| tube8黄色片| 久久久久久久久久久免费av| 777米奇影视久久| 欧美xxxx性猛交bbbb| 国产探花极品一区二区| 日本色播在线视频| 黄色毛片三级朝国网站| 婷婷成人精品国产| 午夜福利,免费看| 国产精品国产av在线观看| 久久99热这里只频精品6学生| 高清av免费在线| 亚洲精品第二区| 日韩熟女老妇一区二区性免费视频| 久久99精品国语久久久| 日韩成人av中文字幕在线观看| 久久精品国产亚洲av天美| 精品一品国产午夜福利视频| 黄片无遮挡物在线观看| 男女高潮啪啪啪动态图| 99久久人妻综合| 亚洲天堂av无毛| 美女cb高潮喷水在线观看| 午夜免费男女啪啪视频观看| 午夜av观看不卡| 久久99热这里只频精品6学生| 日本欧美国产在线视频| 国产黄片视频在线免费观看| 国产精品蜜桃在线观看| 亚洲人成77777在线视频| 国产一区二区在线观看日韩| 简卡轻食公司| 熟女电影av网| 国产综合精华液| 妹子高潮喷水视频| 免费高清在线观看日韩| 制服人妻中文乱码| 自线自在国产av| 国产熟女午夜一区二区三区 | 国语对白做爰xxxⅹ性视频网站| 国产成人午夜福利电影在线观看| 亚洲欧洲国产日韩| 97精品久久久久久久久久精品| 男女无遮挡免费网站观看| 又大又黄又爽视频免费| 一级黄片播放器| 成人亚洲欧美一区二区av| 一级毛片电影观看| 亚洲国产毛片av蜜桃av| 久久热精品热| av国产久精品久网站免费入址| 国产精品人妻久久久久久| 亚洲av福利一区| av不卡在线播放| 一个人看视频在线观看www免费| av又黄又爽大尺度在线免费看| 插阴视频在线观看视频| 最后的刺客免费高清国语| 老司机影院成人| 久久久久久久久久成人| 午夜激情久久久久久久| 新久久久久国产一级毛片| 九九久久精品国产亚洲av麻豆| 晚上一个人看的免费电影| 如日韩欧美国产精品一区二区三区 | 国产男女内射视频| 特大巨黑吊av在线直播| 亚洲一区二区三区欧美精品| 嫩草影院入口| 99久久精品一区二区三区| 26uuu在线亚洲综合色| 熟女人妻精品中文字幕| 国产伦理片在线播放av一区| 色吧在线观看| 最近手机中文字幕大全| 国产不卡av网站在线观看| 久久久久久久久大av| 蜜桃国产av成人99| 天天操日日干夜夜撸| 亚洲成人手机| 日韩欧美精品免费久久| 我的女老师完整版在线观看| 青春草国产在线视频| 满18在线观看网站| 人人澡人人妻人| 国产成人精品一,二区| 久久精品久久久久久噜噜老黄| 国产黄色视频一区二区在线观看| 国产精品99久久久久久久久| 亚洲怡红院男人天堂| 精品久久久久久电影网| 国产精品99久久99久久久不卡 | 亚洲成人av在线免费| 国产黄片视频在线免费观看| 免费看不卡的av| 一区二区av电影网| 国产精品久久久久久精品古装| 国产黄色免费在线视频| 日本欧美国产在线视频| av.在线天堂| 啦啦啦中文免费视频观看日本| 久久毛片免费看一区二区三区| 欧美精品国产亚洲| 伊人久久国产一区二区| 97在线视频观看| 伊人久久国产一区二区| 国产精品秋霞免费鲁丝片| 熟妇人妻不卡中文字幕| 少妇被粗大猛烈的视频| 亚洲国产成人一精品久久久| 26uuu在线亚洲综合色| 国产亚洲一区二区精品| 亚洲成人av在线免费| 亚洲精品久久午夜乱码| 亚洲人成网站在线观看播放| 亚洲精品乱久久久久久| 欧美成人午夜免费资源| 亚洲天堂av无毛| 一边摸一边做爽爽视频免费| 亚洲少妇的诱惑av| 国产精品 国内视频| 最近2019中文字幕mv第一页| 久久99一区二区三区| 一本久久精品| 久久久久久久久久人人人人人人| 国产成人a∨麻豆精品| 亚洲性久久影院| 在线观看国产h片| 久久毛片免费看一区二区三区| 91久久精品电影网| 日本vs欧美在线观看视频| 久久久久久人妻| 最黄视频免费看| 免费黄网站久久成人精品| 最黄视频免费看| 成年av动漫网址| 久久精品国产自在天天线| 九九爱精品视频在线观看| 一区二区av电影网| 乱人伦中国视频| 极品人妻少妇av视频| 国产亚洲精品第一综合不卡 | 免费观看a级毛片全部| 午夜激情福利司机影院| 免费高清在线观看视频在线观看| 国产无遮挡羞羞视频在线观看| 大香蕉久久成人网| 飞空精品影院首页| 亚洲美女视频黄频| 精品人妻一区二区三区麻豆| 亚洲av.av天堂| 高清毛片免费看| 日韩中字成人| 欧美3d第一页| 美女主播在线视频| 性色av一级| 91国产中文字幕| 国产精品嫩草影院av在线观看| 亚洲成人av在线免费| 午夜91福利影院| 黑丝袜美女国产一区| 亚洲婷婷狠狠爱综合网| 亚洲在久久综合| 黄色怎么调成土黄色| 日韩在线高清观看一区二区三区| 欧美另类一区| 成人午夜精彩视频在线观看| 日韩中文字幕视频在线看片| 中文字幕制服av| 美女主播在线视频| 欧美成人午夜免费资源| 一本—道久久a久久精品蜜桃钙片| 国产一区有黄有色的免费视频| 亚洲国产av新网站| 精品人妻一区二区三区麻豆| 日韩中文字幕视频在线看片| 亚洲少妇的诱惑av| 最近最新中文字幕免费大全7| 国产亚洲av片在线观看秒播厂| 国产精品人妻久久久影院| 91成人精品电影| 成人国产av品久久久| 成人二区视频| 黑丝袜美女国产一区| 日日摸夜夜添夜夜爱| 我要看黄色一级片免费的| 男人添女人高潮全过程视频| 午夜福利网站1000一区二区三区| 插阴视频在线观看视频| 人妻一区二区av| 男人操女人黄网站| 大香蕉97超碰在线| 亚洲国产精品999| 欧美国产精品一级二级三级| 熟妇人妻不卡中文字幕| 欧美bdsm另类| 能在线免费看毛片的网站| 久久久精品免费免费高清| 美女国产视频在线观看| 三级国产精品片| 交换朋友夫妻互换小说| 在线观看免费高清a一片| 亚洲三级黄色毛片| 少妇的逼好多水| 狠狠精品人妻久久久久久综合| 国产精品一国产av| 热re99久久国产66热| 99re6热这里在线精品视频| 午夜福利视频精品| 国产午夜精品一二区理论片| 七月丁香在线播放| 美女视频免费永久观看网站| 18+在线观看网站| 午夜免费鲁丝| 国产午夜精品一二区理论片| 大片电影免费在线观看免费| 日日啪夜夜爽| 九九久久精品国产亚洲av麻豆| 国产乱来视频区| 中文天堂在线官网| 久久久精品区二区三区| 欧美亚洲 丝袜 人妻 在线| 欧美3d第一页| 国产精品偷伦视频观看了| 三上悠亚av全集在线观看| 成人毛片a级毛片在线播放| 在线观看免费高清a一片| 99精国产麻豆久久婷婷| 亚洲色图综合在线观看| 性高湖久久久久久久久免费观看| 夫妻午夜视频| 自线自在国产av| 国产成人免费观看mmmm| 久久精品久久久久久久性| 免费播放大片免费观看视频在线观看| 久久久久精品性色| av不卡在线播放| 婷婷色av中文字幕| 日韩av不卡免费在线播放| 美女cb高潮喷水在线观看| 全区人妻精品视频| 亚洲国产最新在线播放| 男女免费视频国产| 嫩草影院入口|