JP5032105B2 - Quantum information communication apparatus, method and program - Google Patents

Description

  The present invention relates to a quantum information communication apparatus, method, and program for performing long-distance quantum information communication using quantum information relay between multiple parties.

  In the quantum key distribution proposed as a strong cryptographic primitive, it is necessary to sufficiently reduce the strength of a signal to be transmitted in order to guarantee security. The weak signal intensity can ensure high safety, but has a problem that the quantum state is attenuated at a short communication distance. In addition, since the signal as a quantum state has a feature that it cannot be replicated if the exact observation base is not known, the signal is attenuated by reading the signal once and generating a new signal. It cannot be recovered and it is very difficult to amplify the signal as a quantum state. For this reason, a quantum information relay technique has been proposed.

  Quantum information relay is a technology that transmits a signal as a quantum state to a remote place with high fidelity, and extends the length of an EPR pair that is a photon pair entangled with each other by entanglement swapping (ES). This is a technology to ensure fidelity while gradually extending the length of the EPR pair by repeating two operations of restoring fidelity by the Entanglement Purification Protocol (EPP). . Here, the fidelity is an index indicating how close the quantum state after attenuation is to the quantum state before attenuation.

  More specifically, the quantum information relay protocol proceeds in the following procedure. First, an EPR pair is generated at each relay point, and one photon of the EPR pair is transmitted to an adjacent relay point. Thereby, an EPR pair is shared between adjacent relay points. Thereafter, the EPR pair is connected by ES. The fidelity is lowered when the EPR pair is shared between the adjacent points and the ES operation is performed. The fidelity thus lowered is improved by the EPP. Then, ES and EPP are repeatedly executed until the EPR pair is shared between the sender and the receiver. Thus, the EPR pair is shared between the sender and the receiver, and a signal as a quantum state can be transmitted to a remote place with high fidelity (for example, refer to Non-Patent Document 1).

H.J. Briegel et.al.Quantum repeaters: The role of imperfect local operations in quantum communication.Phys.Rev.Lett., Vol.81, No.26, pp.5932, 1998.

  However, the quantum communication technology using such quantum information relay has the following problems.

  In a network system in which a large number of nodes are connected, even if all nodes are connected by a classical communication network and a classical communication path is formed, a quantum communication network is not constructed between some nodes, A quantum communication path may not be formed. For this reason, the path | route by a quantum communication path | route may differ from the path | route by a classical communication path | route.

  For this reason, in a node having a quantum repeater, a classical communication route table in which a route by a classical communication route between nodes is registered and a quantum communication route table in which a route by a quantum communication route between nodes is separately maintained are maintained. ing. When quantum information is communicated from the transmission node to the reception node, both the route search using the classical communication route using the classical communication route table and the route search using the quantum communication route using the quantum communication route table are performed.

  Such two route searches increase the load on the quantum information communication device of the node.

  The present invention has been made in view of the above, and an object of the present invention is to provide a quantum information communication apparatus, method, and program capable of reducing the load of route search in quantum information communication.

In order to solve the above-described problems and achieve the object, the present invention provides a quantum information communication device connected to a quantum communication network and a classical communication network, wherein a quantum information communication between nodes connected to the quantum communication network is performed. A quantum communication path table in which a quantum communication path indicating a path by communication is registered; a classical communication path indicating a path by classical communication between nodes connected to the classical communication network; and the quantum communication path between nodes of the classical communication path Storage means for storing the correlation of the classical communication path table, and based on the network address of the transmission node and the network address of the reception node, the transmission node and the reception node from the classical communication path table, The classical communication path between the predetermined nodes existing between Route determination means for determining the quantum communication path between the predetermined nodes based on the correlation corresponding to a path, and the quantum information communication of photons according to the searched classical communication path or the determined quantum communication path And a communication means for performing the above.
The present invention also relates to a method and a program executed by the quantum information communication device.

  According to the present invention, it is possible to reduce the load of route search in quantum information communication. Further, according to the present invention, there is an effect that an optimum route search can be performed according to the state of the communication route.

  Exemplary embodiments of a quantum information communication device, method, and program according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment 1)
In the first embodiment, the quantum information communication apparatus, method and program according to the present invention are provided in a classical communication path or a quantum communication path from a transmission node to a reception node, such as quantum key distribution, from the transmission node to the reception node. In quantum information communication of photons, an EPR pair, which is an entangled photon pair, is shared with other nodes and applied to a quantum information relay apparatus that performs quantum relay to extend the distance between each photon of the EPR pair. is there.

  FIG. 1 is a block diagram of a network configuration of the quantum information communication system according to the first embodiment. As shown in FIG. 1, the quantum information communication system according to the first embodiment has a configuration in which a plurality of quantum information relay devices 100 are connected by an optical fiber 140. The network constituted by the optical fiber 140 is constituted by both a classical communication path and a quantum communication path.

  The quantum information relay device 100 is provided in a quantum communication path from a transmission node to a reception node, and relays quantum information communication of photons from the transmission node to the reception node. Here, in the present embodiment, the quantum information relay device 100 itself is configured to be a transmission node and a reception node. The quantum communication path is a path where the quantum information relay device 100 exists.

  The quantum information relay apparatus 100 includes a control classical computer 110 and a repeater 120 as shown in FIG. The control classical computer 110 has a configuration of a normal computer including a CPU, a memory, a keyboard, a mouse, a hard disk drive (HDD), and the like.

  FIG. 2 is a block diagram of a functional configuration of the control classical computer 110 and the repeater 120 according to the first embodiment.

  First, the control classical computer 110 will be described. As illustrated in FIG. 2, the control classical computer 110 mainly includes a classical path search unit 136, a quantum path determination unit 132, a communication unit 135, a classical communication path table 133, and a quantum communication path table 134. ing.

  The classical communication path table 133 is a table in which the classical communication path indicating the shortest path by classical communication between the nodes connected to the classical communication network is correlated with the correlation of the quantum communication path between the nodes of the classical communication path. is there. Here, in the present embodiment, as a correlation, a quantum communication path presence flag indicating whether or not there is a quantum communication path that is the same path as the classical communication path is held in association with the IP address of the node. When the quantum communication path presence flag is “1”, it indicates that the quantum communication path of the same path as the classical communication path exists, and when it is “0”, the quantum communication path of the same path as the classical communication path is present. Indicates that it does not exist.

  The quantum communication path table 134 is a table in which a quantum communication path indicating the shortest path by quantum communication between nodes connected to the quantum communication network is registered for each IP address of the node. The classical communication path table 133 and the quantum communication path table 134 are stored in a storage medium such as a hard disk drive (HDD) or a memory.

  Here, the data format of the IP addresses of the transmission node and the reception node will be described. FIG. 3A is a data structure diagram illustrating an example of a data format of IP addresses of a transmission node and a reception node. As shown in FIG. 3A, the IP address is composed of a plurality of segments.

  This segment indicates the set hierarchy in the network. For example, among the n segments of the IP address, the first m1 can be used for specifying the first layer, and the next m2 can be used for determining the second layer. Similarly, the determination of the i-th layer can be configured to use from the m1 +... + M (i-1) +1 segment to the m1 +.

  FIG. 3B is a schematic diagram illustrating an example in the case where the IP address includes two segments. The example in FIG. 3B is configured to be used in each hierarchy of “organization” as the first hierarchy and “party” as the second hierarchy in order from the upper segment.

  In the present embodiment, as an example, an IP address composed of two segments shown in FIG. 3-2 is used. In the present embodiment, “Alpha company” and “Beta company” networks are connected as organizational networks, and the parties' nodes are connected in each network. A case where the classical communication path and the classical communication path do not match will be described as an example.

  FIG. 4 is a schematic diagram illustrating a network configuration of “Alpha Company” and “Beta Company” and examples of quantum communication paths and classical communication paths. In FIG. 4, the solid line indicates the quantum communication path, and the dotted line indicates the classical communication path. Each quantum communication path and each classical communication path are shown with a path number for identifying the path. As shown in FIG. 4, routes between adjacent nodes have route numbers from 01 to 18, but routes 19 to 33 are provided as routes straddling a plurality of nodes. The route number of such a route is defined as follows.

Path 19 = 01-02
Path 20 = 03-04
Path 21 = 05-06
Path 22 = 07-08
Path 23 = 09-10
Path 24 = 11-12
Path 25 = 13-14
Path 26 = 15-16
Path 27 = 19-20
Path 28 = 21-22
Path 29 = 23-24
Path 30 = 25-26
Path 31 = 28-29
Path 32 = 27-28-29-30
Route 33 = 17-31-18
Here, “n−m” indicates a route including the route n and the route m.

  The network of Alpha company is assigned “001” as the address of the organization hierarchy, and as shown in FIG. 4, the quantum information relay device of the center node E that manages the network of Alpha company, and each of the nodes A and B , C, D, T, U, and other quantum information relay devices are connected. Here, the IP address of the center node E is “001.001”, the IP address of the node A is “001.002”, and the IP address of the node D is “001.003”. Further, as shown in FIG. 4, the quantum communication path and the classical communication path coincide with each other between the nodes AT, TF, FU, UE, etc., but AE, A- Only classical communication paths exist between B, BC, ED, and CD. Therefore, as the path from the node A to the node E, the classical communication path and the quantum communication path are different.

  That is, the classical communication path from the node A to the node E is the path 17, but the quantum communication path is the path 27 (= 19−20 = 01−02−03−04).

  The beta company network is assigned “002” as the organizational hierarchy address, and as shown in FIG. 4, the quantum information relay device of the center node H that manages the beta company network, and the nodes G and I. , J, K, L, V, W and other quantum information relay devices are connected. Here, the IP address of the center node H is “002.001”, the IP address of the node G is “002.002”, and the IP address of the node I is “002.003”. As shown in FIG. 4, the quantum communication path and the classical communication path coincide with each other between the nodes HW, WL, GV, and GL, but the GH and H- Only the classical communication path exists between I, IJ, JK, and KG.

  The Alpha company network and the Beta company network are connected by both the quantum communication path and the classical communication path, and the nodes M, N, O, P, Q, R, S quantum information relay devices are connected.

  The quantum information relay device 100 of the center nodes E and H holds a first layer classical communication route table 133 and a first layer quantum communication route table 134 in order to determine the route of the organization that is the first layer of the IP address. is doing.

  FIG. 5 is an explanatory diagram showing an example of a first layer (organization) classical communication path table held by the center nodes E and H, and FIG. 6 shows a first hierarchy (organization) held by the center nodes E and H. It is explanatory drawing which shows an example of the quantum communication path | route table of.

  The first layer classical communication path table 133 includes a first layer address of the IP address of the transmitting node as a sender address, a first layer address of the IP address of the receiving node as a receiver address, and between the nodes of both addresses. Are associated with the quantum communication path presence flag. The quantum communication path existence flag is a flag indicating whether or not the same path as the classical communication path between the nodes of the sender address and the receiver address, that is, the path having the same path number exists as a quantum communication path.

  The first-layer quantum communication path table 134 includes the first-layer address of the IP address of the transmitting node as the sender address, the first-layer address of the IP address of the receiving node as the receiver address, and the nodes between the two addresses. Are associated with the path numbers of the quantum communication paths.

  Here, in the quantum communication path table 134 of FIG. 6, the quantum communication path of the sender address (first layer) “001” and the receiver address (first layer) “002” is “31”. In the classical communication path table 133 of FIG. 5, the quantum communication path of the sender address (first layer) “001” and the receiver address (first layer) “002” is “31”. That is, the classical communication path and the quantum communication path between the nodes of the sender address (first layer) “001” and the receiver address (first layer) “002” are the same route. Therefore, in the classical communication path table 133, the quantum communication path presence flag corresponding to the sender address “001” and the receiver address “002” is “1”.

  When this is compared with the network configuration of FIG. 4, the node between the sender address (first layer) “001” and the receiver address (first layer) “002” is in beta from the center node E of Alpha. The company's center node H. The paths between the node E and the node H are EM, MN, NO, OP, PQ, QR, RS, and SH, and in all these paths There are a classical communication path and a quantum communication path, each of which is “05-06-07-08-09-10-11-12”. Referring to the definitions of the paths 19 to 33 described above, the following equation is obtained, and the classical communication path and the quantum communication path between the node E and the node H are “31”.

05-06-06-07-08-09-10-11-12 = 21-22-23-24
= 28-29 = 31

  Therefore, in the classical communication path table 133 of FIG. 5, “31” and the quantum communication path presence flag “1” are registered as the quantum communication path corresponding to the sender address “001” and the receiver address “002”. . In the quantum communication path table 134 of FIG. 6, “31” is registered as a quantum communication path corresponding to the sender address “001” and the receiver address “002”.

  Further, the quantum information relay apparatus 100 of each node (nodes A, B, C, D, F, T, U, and center node E) in the Alpha company network is the first under the first layer “001” of the IP address. In order to determine the path of the party that is in the second hierarchy, the classical communication path table 133 in the second hierarchy and the quantum communication path table 134 in the second hierarchy are held.

  FIG. 7 is an explanatory diagram showing an example of the second layer (party) classical communication path table held by each node in the Alpha company network, and FIG. 8 shows each node in the Alpha company network. It is explanatory drawing which shows an example of the quantum communication path | route table of a 2nd hierarchy (party).

  The second-class classical communication path table 133 includes the second-layer address of the IP address as the party address, the path number of the classical communication path between the center node E and the node of the party address, and the quantum communication path presence flag. Corresponds. The quantum communication path presence flag is a flag indicating whether or not the same path as the classical communication path between the center node E and the party address node exists as a quantum communication path.

  The second-layer quantum communication path table 134 associates the second-layer address of the IP address as the party address with the path number of the quantum communication path between the center node E and the party address node.

  Here, in the quantum communication path table 134 of FIG. 8, the quantum communication path between the party address “003” (second layer) and the node of the center node E “001” (second layer) is “63”. Further, in the classical communication path table 133 of FIG. 7, the quantum communication path between the nodes of the party address “003” (second layer) and the center node E “001” (second layer) is also “63”. The route and the quantum communication route are the same route. For this reason, in the classical communication path table 133, the quantum communication path presence flag corresponding to the party address “003” is “1”.

  On the other hand, in the quantum communication path table 134 of FIG. 8, the quantum communication path between the party address “002” (second layer) and the node of the center node E “001” (second layer) is “27”. Further, in the classical communication path table 133 of FIG. 7, the quantum communication path between the nodes of the party address “002” (second layer) and the center node E “001” (second layer) is “17”. The route and the classical communication route are different. For this reason, in the classical communication path table 133, the quantum communication path existence flag corresponding to the party address “002” is “0”.

  Compared with the network configuration of FIG. 4, a node A to a node E are between the nodes of the party address (second layer) “002” and the center node E (second layer) “001”. The shortest classical communication path between the node A and the center node E is A-E, which corresponds to the path “17”.

  On the other hand, there is no quantum communication path between A and E, and the shortest quantum communication paths between the node A and the center node E are AT, TF, FU, and UE. 01-02-03-04 ". Referring to the definitions of the paths 19 to 33 described above, the following equation is obtained, and the quantum communication path between the node A and the center node E is “27”.

01-02-03-04 = 19-20 = 27
Accordingly, in the classical communication path table 133 of FIG. 7, “17” and the quantum communication path existence flag “0” are registered as the classical communication path corresponding to the party address “002”. In the quantum communication path table 134 of FIG. 8, “27” is registered as the quantum communication path corresponding to the party address “002”.

  Further, the quantum information relay device 100 of each node (G, I, J, K, L, V, W, center node H) in the beta company network is the second under the first layer “002” of the IP address. In order to determine the path of a party that is a hierarchy, a second-layer classical communication path table 133 and a second-layer quantum communication path table 134 are held.

  FIG. 9 is an explanatory diagram showing an example of a second layer (party) classical communication path table held by each node in the beta company network, and FIG. 10 is held by each node in the beta company network. It is explanatory drawing which shows an example of the quantum communication path | route table of a 2nd hierarchy (party).

  The second-layer classical communication path table 133 includes the second-layer address of the IP address as the party address, the path number of the classical communication path between the center node H and the node of the party address, and the quantum communication path presence flag. Corresponds. The quantum communication path presence flag is a flag indicating whether or not the same path as the classical communication path between the center node H and the party address node exists as a quantum communication path.

  The second-layer quantum communication path table 134 associates the second-layer address of the IP address as the party address with the path number of the quantum communication path between the center node H and the party address node. In the example of the party addresses “002” and “003” in FIGS. 9 and 10, the quantum communication path and the classical communication path are not the same path, and therefore the quantum communication path presence flags are all “0”.

  Thus, there may be no quantum communication path that is the same as the classical communication path between the nodes in the network. For this reason, considering the case where there is no quantum communication path that is the same as the classical communication path, it is necessary to execute both the search for the classical communication path and the search for the quantum communication path.

  However, if there is a quantum communication path that is identical to the classical communication path, only the classical communication path search is performed, the quantum communication path is not searched, and the searched classical communication path is replaced with the quantum communication path. As a result, the load of the route search process can be reduced.

  Therefore, in the present embodiment, a quantum communication path presence flag indicating whether or not there is a quantum communication path of the same path is provided in the classical communication path table 133. Then, when there is a quantum communication path that is the same as the classic communication path searched by the classic path search unit 136 with reference to the flag by the quantum path determination unit 132 (quantum communication path existence flag = “1”) In this case, the classical communication route searched by the classical route search unit 136 is determined as the quantum communication route without searching for the quantum communication route, and the load of route search processing is reduced.

  Returning to FIG. 2, the communication unit 135 is a processing unit that transmits the IP address of the transmission node, the IP address of the reception node, the classical communication path, and the quantum communication path to other nodes, and receives from other nodes.

  The classical path search unit 136 uses the IP address of the transmitting node and the IP address of the receiving node specified by the user to perform classical communication between predetermined nodes existing between the transmitting node and the receiving node from the classical communication path table 133. A processing unit for searching for a route.

  Specifically, the classic route search unit 136 uses the addresses of the first to nth layers of the IP address of the designated transmission node and the IP address of the reception node as keys to search from the classic communication route table 133. A classical communication path between predetermined nodes existing between the transmitting node and the receiving node is searched, and the searched classical communication path is determined as a classical communication path between the predetermined nodes.

  Consider a case in which quantum information is transmitted from a node in the alpha company network to a node in the beta company network in the example of the network configuration shown in FIG. In this case, in the quantum information relay device 100 of each node of Alpha, when it is a transmission node, from the second layer (party) address of its own IP address to the second layer address of the center node E It is necessary to determine the classical communication path. For this reason, the classic route search unit 136 searches for the classic communication route from the classic communication route table 133 shown in FIG. 7 by using the address of the second layer of its own sender address as a key. In addition, the communication unit 135 of the quantum information relay device 100 of the transmission node transmits the sender address and the receiver address to the center node E.

  When transmission is performed from a node in the Beta company network to a node in the Alpha company network, the classical communication path table 133 shown in FIG. 9 is used in the quantum information relay device 100 serving as the transmission node of the Beta company network. The classic route search unit 136 similarly searches for the second-layer classic communication route from the self node to the center node H with reference to FIG.

  Further, when transmission is performed from a node in the Alpha company network to a node in the Beta company network, the quantum information relay device 100 of the center node E uses the first address of the receiver address from the address of the first layer of the sender address. It is necessary to determine the route to the address of the hierarchy. For this reason, in the quantum information relay device 100 of the center node E, the sender address (IP address) received from the sending node in the Alpha company network and the receiving address (IP) of the receiving node as the destination by the classical route search unit 136. The classical communication path is searched from the classical communication path table 133 shown in FIG. 5 using each address in the first layer of (address) as a key. Further, the communication unit 135 of the quantum information relay device 100 of the center node E transmits the recipient address to the center node H.

  When transmission is performed from a node in the beta company network to a node in the alpha company network, the quantum information relay device 100 serving as the center node H of the beta company network uses the classical path search unit 136 to perform the transmission. The classical communication path search from the first node to the center node E is similarly performed with reference to the classical communication path table 133 shown in FIG.

  Further, when transmission is performed from a node in the Alpha company network to a node in the Beta company network, the quantum information relay apparatus 100 of the Beta company center node H performs a second process from the center node H to the recipient address node. It is necessary to determine the route of the hierarchy (party). For this reason, in the quantum information relay apparatus 100 of the center node H of Beta company, the classical communication path shown in FIG. 9 by the classical path search unit 136 using the address of the second layer of the recipient address received from the center node E as a key. The classical communication path from the table 133 to the node of the recipient address is searched.

  When transmission is performed from a node in the Beta company network to a node in the Alpha company network, in the quantum information relay device 100 that is the center node E of the Alpha company network, the classical path search unit 136 Referring to the classical communication path table 133 shown in FIG. 7, the second-layer classical communication path from the center node E to the receiver node is similarly searched.

  The quantum path determination unit 132 is a processing unit that determines a quantum communication path between predetermined nodes based on the correlation corresponding to the classic communication path searched by the classic path search unit 136. Specifically, the quantum path determination unit 132 indicates that there is a quantum communication path whose quantum communication path existence flag corresponding to the classical communication path searched by the classical path search unit 136 is the same as the classical communication path. In the case of “1”, the searched classical communication path is determined as the quantum communication path between the predetermined nodes without searching for the quantum communication path.

  On the other hand, the quantum path determination unit 132 indicates “0” indicating that there is no quantum communication path whose quantum communication path presence flag corresponding to the classical communication path searched by the classical path search unit 136 is the same as the classical communication path. If it is, the quantum communication path between the predetermined nodes is searched from the quantum communication path table 134, and the searched quantum communication path is determined as the quantum communication path between the predetermined nodes.

  In the example of the network configuration shown in FIG. 4 where the IP address is the two-layer data structure shown in FIG. 4, when quantum information is transmitted from a node in the alpha company network to a node in the beta company network, The quantum information relay device 100 of each node determines a quantum communication path from the address of the second layer (party) of its own IP address to the address of the second layer of the center node E when it is a transmission node. There is a need. Therefore, in the quantum information relay device 100 of each node of Alpha, the quantum path determination unit 132 checks the quantum communication path existence flag corresponding to the searched classical communication path in the classical communication path table 133, and determines the value of the flag. The searched classical communication path is determined as a quantum communication path, or the quantum communication path is searched from the quantum communication path table 134 shown in FIG.

  In addition, when transmission is performed from a node in the beta company network to a node in the alpha company network, the quantum path determination unit 132 in the quantum information relay device 100 serving as the transmission node of the beta company network performs FIG. Referring to the classical communication path table 133 and the quantum communication path table 133 shown in FIG. 10, the determination of the second-layer quantum communication path from its own node to the center node H is similarly performed.

  Further, when transmission is performed from a node in the Alpha company network to a node in the Beta company network, the quantum information relay device 100 of the center node E uses the first address of the receiver address from the address of the first layer of the sender address. It is necessary to determine the route to the address of the hierarchy. For this reason, in the quantum information relay device 100 of the center node E, the quantum path determination unit 132 checks the quantum communication path existence flag corresponding to the searched classical communication path in the classical communication path table 133, and searches for the flag based on the flag value. The classical communication path is determined as the quantum communication path, or the sender address received from the sending node in the Alpha network and the address of the first layer of the receiving address of the receiving node as the destination are used as keys. The quantum communication path is searched from the quantum communication path table 134 shown in FIG.

  When transmission is performed from a node in the Beta company network to a node in the Alpha company network, the quantum path determination unit 132 in the quantum information relay device 100 serving as the center node H of the Beta company network Referring to the classical communication path table 133 shown in FIG. 5 and the quantum communication path table 133 shown in FIG. 6, the determination of the first layer quantum communication path from its own node to the center node E is similarly performed.

  Further, when transmission is performed from a node in the Alpha company network to a node in the Beta company network, the quantum information relay apparatus 100 of the Beta company center node H performs a second process from the center node H to the recipient address node. It is necessary to determine the quantum communication path of the hierarchy (party). Therefore, in the quantum information relay apparatus 100 of the center node H of Beta, the quantum path determination unit 132 checks the quantum communication path existence flag corresponding to the searched classical communication path in the classical communication path table 133, and determines the flag value. 10 is determined as the quantum communication route, or the quantum communication route is searched from the quantum communication route table 134 shown in FIG. 10 using the address of the second layer of the recipient address received from the center node E as a key. To do.

  When transmission is performed from a node in the Beta company network to a node in the Alpha company network, the quantum path determination unit 132 in the quantum information relay device 100 serving as the center node E of the Alpha company network Referring to the classical communication path table 133 shown in FIG. 5 and the quantum communication path table 133 shown in FIG. 6, the determination of the second-layer quantum communication path from the center node E to the receiver node is similarly performed.

  Next, returning to FIG. 2, the repeater 120 will be described. 2, the repeater 120 mainly includes an EPR pair generation unit 121, a photon input unit 122, a photon-solid EIT conversion unit, a photon-solid EIT quantum calculator 124, and a photon transmission unit 126. In preparation.

  The EPR pair generation unit 121 generates an EPR pair, and a device that generates a photon pair can be used. Here, the EPR pair is a tangled photon pair. The degree of entanglement between two photons is greatest when the two photons are in the bell state. The bell state is four states represented by the following equations (1) to (4). Note that the observation performed on two photons with the bell state as a base is called bell joint measurement.

  Here, | 0> is a state where the polarization of the photon is 0 degree, and | 1> is a state where the polarization of the photon is 90 degrees. Further, (1 / √2) (| 0> + | 1>) is a state in which the photon polarization is 45 degrees, and (1 / √2) (| 0> − | 1>) is a photon polarization of 135. It is a state of degrees.

  For details of devices that generate photon pairs, see the technical literature `` RM Stevenson, RJ Young, P. Atkinson, K. Cooper, DA Ritchie, and AJ Shields.A semiconductor wource of triggered entangled photon pairs. Nature, Vol. 439, pp. 179-182, 2006. ”.

  The photon transmission unit 126 (communication means) transmits one photon of the generated EPR pair to the quantum information relay device 100 of the adjacent node.

  The photon input unit 122 receives one photon of the EPR pair from the quantum information relay device 100 of an adjacent node.

The photon-solid EIT conversion unit 123 converts the quantum state of the received photon and the quantum state of the generated EPR pair photon into the quantum state of the nuclear spin, specifically, the oxide crystal (Y ₂ SiO ₅ ). It is replaced with the quantum state of nuclear spin of dispersed rare earth ions (Pr ³⁺ ) and output to the photon-solid EIT quantum computer 124.

  The photon-solid EIT quantum computer 124 is a computer that performs a quantum calculation using a solid EIT (Electromagnetically Indused Transparency) phenomenon for a quantum state of a photon substituted with a quantum state of a nuclear spin. is there. Here, the solid EIT phenomenon is a phenomenon induced by applying two lights to three energy levels. This is a phenomenon in which a substance that should be opaque to one or both of the light beams to be applied becomes transparent, and two of the three energy levels are in a quantum mechanical superposition state. For details of the photon-solid EIT quantum computer, see the technical literature “K. Ichimura. A simple frequency-domain quantum computer with ions in a crystal coupled to acavity mode. Optics communications, 196, pp. 119-125, 2001.” "H. Goto and K. Ichimura. Multiqubit controlled unitary gate by adiabatic passage with an optical cavity. Phys. Rev. A, Vol. 70, p. 012305, 2004."

  In the present embodiment, the photon-solid EIT quantum computer 124 performs entanglement exchange processing and entanglement purification protocol processing. As shown in FIG. 2, the photon-solid EIT quantum computer 124 includes a control unit 301, an entanglement exchange execution unit 302 (hereinafter referred to as “ES execution unit 302”), and an entanglement purification protocol execution unit 303 (hereinafter referred to as “entanglement purification protocol execution unit 302”). , “EPP execution unit 303”) and a quantum memory 125.

  The ES execution unit 302 executes an entanglement exchange process (hereinafter referred to as “ES process”) that shares an EPR pair with the quantum information relay apparatus of an adjacent node. The ES process is a process of exchanging photons (particles) of a pair partner for a plurality of EPR pairs.

  The EPP execution unit 303 performs an entanglement purification protocol process (hereinafter, “recovery of EPR pair fidelity”) with the quantum information relay device of the EPR pair sharing destination node shared by the entanglement exchange process. EPP process ") is executed. The EPP process is a protocol for generating an EPR pair with high fidelity from a plurality of EPR pairs with low fidelity. The ES process and the EPP process are executed by a quantum information relay process.

  The quantum memory 125 is composed of qubits, and is a storage medium that temporarily stores photons when one photon of an EPR pair is shared with an adjacent node.

  Here, there are various variations in the entanglement purification protocol.For details, refer to the technical document `` CH Bennett et.al.Purification of noisy entanglement and faithful teleportation via noisy entanglement.Phys.Rev.Lett., Vol.76. , No.5, pp.722, 1996. ”,“ R. Matsumoto. Conversion of a general quantum stabilizer code to an entanglement distillation protocol.uant-ph / 0209091, 2002. ”,“ PW Shor and J. Preskill. proof of security of the bb84 quantum key distribution protocol. e-print, quant-ph / 0003004, 2000.

  After the route from the sender to the receiver is determined, the control unit 301 determines the role determined by the quantum information relay device 100 of the center node according to the position of its own node in the route from the transmission node to the reception node ( The ES process and the EPP process are controlled according to the classical communication path when the ES process and the EPP process are executed, the number of times the ES process and the EPP process are executed, the execution timing of the ES process and the EPP process, and the like.

  Here, the generalized quantum relay protocol will be described. The generalized quantum relay protocol consists of a quantum state distribution step and an EPR pair length extension step. The quantum state delivery step is a step of sharing entangled photon pairs at a short distance. The step of extending the length of the EPR pair is a step of extending the length of the particle pair having a short length, and only the transmission of the classical information channel is performed without the transmission of the quantum state channel. It is.

  In the present embodiment, when the EPR pair length extension step is further divided into a plurality of stages in the quantum state distribution step and the EPR pair length extension step constituting the generalized quantum relay, Path selection is performed so that the classical communication path used in the final stage is different from any one or more of the classical communication paths used in the previous stage. Such route selection will be described in detail in EPP processing and ES processing described later.

Also, quantum information relay processing using ES processing and EPP processing will be described. Let L be the number of photon pairs that are simultaneously connected in one ES process. At this time, the N = L ^n. It is assumed that N−1 quantum information relay apparatuses C ₁ , C ₂ ,... C _N-1 are connected to the optical fiber connecting the sender A and the receiver B. It is assumed that the quantum information relay device 100 is provided with a quantum memory 125 for storing photons, a 1-qubit operation quantum circuit, and a 2-qubit operation quantum circuit.

  First, an EPR pair is shared between the quantum information relay apparatuses 100 of adjacent nodes. Specifically, each quantum information relay device 100 generates an EPR pair, and one photon of the EPR pair is in the direction of the receiver B among the two quantum information relay devices 100 of adjacent nodes. 100 is transmitted.

  Then, as the first stage ES process, L EPR pairs are connected as follows.

All quantum information relay apparatuses 100 except for the quantum information relay apparatuses C _L , C _2L ,... C _NL perform ES processing to connect the EPR pairs. As a result, N / L pairs of length L are generated and shared among A & C _L , C _L & C _2L .

  Although the fidelity of the EPR pair is reduced by this ES processing operation, if this value is larger than the lower limit of the fidelity recoverable by the EPP processing, the fidelity can be restored by executing the EPP processing. Therefore, the fidelity is restored by performing the first-stage EPP process.

  Next, as a second stage ES process, L generated EPR pairs having a length L times are further connected.

_{C kL (k = 1,2, ···} ) a quantum repeater apparatus 100 satisfying, quantum repeater apparatus C _L2, C _2L2, all quantum repeater apparatus except ··· C _N-L2 100 The EPR pair is connected by ES processing. As a result, EPR pairs in length L ² is generated ^two N / L, are shared between _{A & C L2, C L &} C 2L2 ···. Next, the second stage EPP process is executed to restore the fidelity of the EPR pair.

  In this way, the EPR pair with high fidelity is shared between the transmitting node A and the receiving node B by alternately repeating the ES process and the EPP process in n stages. For this reason, even if the distance increases, the fidelity of the shared EPR pair can be kept constant. FIG. 11 shows the state of the EPR pair by ES processing and EPP processing when N = 4. Here, in FIG. 11 and each of FIGS. 12 to 16 shown below, it is shown that two photons connected by a solid line are entangled with each other.

  Here, the ES process will be described in detail. FIG. 12 is a schematic diagram for explaining the ES processing. As shown in FIG. 12, for example, the EPR pair consisting of photon 1 and photon 2 and the EPR pair consisting of photon 3 and photon 4 are subjected to ES processing, whereby the EPR pair consisting of photon 1 and photon 4 and photon 2 and photon Is converted to an EPR pair consisting of three. Here, considering the case where two quantum information relay apparatuses C1 and C2 exist between the sender A and the receiver B, the EPR pair shared between A-C1 and C1-B are shared. The ES process for linking a pair of EPRs is performed as follows.

  First, the bell congruent measurement is performed on the photon at C1 among the entangled photon pairs shared by A and C1 and the photon at C1 among the EPR pairs shared by C1 and B. Next, the result of the bell joint measurement is transmitted to A and B using the classical communication via the photon transmission unit 126. Then, the calculation corresponding to the measurement result is performed by A and B.

  Next, details of the EPP process will be described. For example, consider a case where EPP processing is performed on an EPR pair shared between the sender A and the receiver B. FIG. 13 is a schematic diagram for explaining the EPP process. Here, it is assumed that two pairs of EPR are shared between the sender A and the receiver B as shown in FIG.

  Both A and B perform random bilateral transformation on their two photons. Then, regarding two EPR pairs shared between A and B, control NOT (CNOT) is applied to the two particles in A, and control NOT (CNOT) is also applied to the two particles in B. Then, the qubit that is the target of the control NOT (CNOT) in A and B is observed, and the observation result in A is transmitted to B through the classical communication path. Then, B compares the observation result of A with its own observation result and performs an operation corresponding to this. As a result, the EPP process is executed, and the fidelity of the EPR pair is restored.

  In the present embodiment, the above-described ES process and EPP process are executed. 14-16 is explanatory drawing which shows the state of the photon from an EPR pair production | generation to an EPP process in the quantum information relay apparatus 100 concerning Embodiment 1. FIG. FIG. 14 shows a state of photons from generation of an EPR pair to transmission of one photon of the EPR pair to the adjacent quantum information relay device 100, and FIG. 15 shows that two EPR pairs are obtained by transmitting a photon. A state shared by two quantum information relay apparatuses 100 is shown. FIG. 16 shows a state in which the ES process is executed on the shared EPR pair. As shown in FIGS. 14 to 16, the two photons of the shared EPR pair are held in the quantum memory 125 of the photon-solid EIT quantum computer 124, and the photon-solid EIT quantum computer 124 (ES execution unit 302, EPP The execution unit 303), ES processing, and EPP processing are executed.

  In the first embodiment, the EPP execution unit 303 further selects one of the classical communication path used in the ES process executed last and the classical communication path used in the EPP process before the ES process executed last. The last EPP process is executed by selecting a classical communication path different from one or more. In addition, the ES execution unit 302 selects a classic communication path that is different from any one or more of the classic communication paths used in the ES process executed in the previous stage and used in the EPP process executed in the previous stage. ES processing is executed.

  In addition, the ES execution unit 302 selects a classical communication path that is different from any one of the classical communication path used in the ES process executed previously and the classical communication path used in the EPP process executed previously. The ES exchange process is executed.

  In the center node that manages the network, which classical communication path should be selected from the position of the node of the quantum information relay device 100 in the path to execute the ES process or the ESS process, the number of times the ES process or the EPP process is executed, the ES process And the role such as the execution timing of the EPP process are determined, and the determined role is transmitted to each quantum information relay device 100.

  Based on the received role, the control unit 301 controls the ES processing unit 302 and the EPP processing unit 303 to perform execution control of the ES processing and the EPP processing.

  Specifically, the first stage ES processing is executed for the EPR pair shared with the quantum information relay apparatus 100 on the adjacent transmitting node side, and the adjacent node and receiving node on the transmitting node side of the node that has performed the ES processing The first-stage EPP process is performed by the quantum information relay device 100 on the side. Thereafter, the second-stage ES process is performed in the quantum information relay apparatus 100 on the receiving node side that has performed the EPP process, and the second-stage EPP process is performed in the node that has performed the first-stage EPP process. EPP processing is performed between the quantum information relay device 100 in a classical communication path different from the classical communication path used in the first stage ES processing and EPP processing and the second stage ES processing.

  Next, quantum information communication processing by the plurality of quantum information relay devices 100 according to the first embodiment configured as described above will be described. Here, in the network configuration shown in FIG. 4, a case where quantum information is transmitted from the transmission node A in the alpha company network to the reception node G in the beta company network will be described as an example.

  FIG. 17 is a sequence diagram showing a flow of quantum information communication processing in the first embodiment. First, the quantum information relay device 100 of the transmission node A performs a route determination process of the second layer from the address of the second layer (party) of its own IP address (sender address) (step S1). The classical communication path and the quantum communication path of the second hierarchy to the center node E of the own network are determined. The second layer route determination process will be described later.

  Then, the sending node A sends the IP address (receiver address) of the receiving node G that is the sending destination together with its own IP address (sender address) to the center node E through the determined classical communication path or quantum communication path. Transmit (step S2).

  When the quantum information relay device 100 of the center node E receives the IP address (recipient address) of the destination receiving node G, the first layer address of the transmitting node A and the IP address of the receiving node G Based on the address of the first layer, the route determination process of the first layer (organization) is performed to determine the classical communication route and the quantum communication route to the center node H of the beta company network (step S3). The first layer route determination process will be described later.

  Then, the center node E transmits the IP address (destination) of the receiving node G to the quantum information relay device 100 of the center node H of Beta company through the determined classical communication path or quantum communication path (step S4).

  When receiving the destination (IP address) of the receiving node G, the quantum information relay device 100 of the center node H of Beta company determines the route of the second layer based on the address of the second layer (party) of the IP address of the receiving node G. Processing is performed (step S5), and a classical communication path and a quantum communication path from the center node H to the receiver node G are determined. Then, the determined classical communication path and quantum communication path are transmitted to the center node E (step S6).

  Next, in the center node H, the number of quantum information relay devices 100 (relay points) existing in the determined classical communication path and quantum communication path from the center node H to the receiving node G in the Beta company network is calculated. (Step S7b). Then, from which number, quantum communication path, classical communication path, and position of each quantum information relay device 100, which classical communication route performs ES processing and EPP processing in quantum information relay processing of each quantum information relay device 100, Roles such as the number of execution times of ES processing and EPP processing, execution timing of ES processing and EPP processing, etc. are determined (step S8b), and the determined roles are transmitted to each quantum information relay device 100 (step S9b).

  On the other hand, in the center node E that has received the classical communication path and the quantum communication path from the center node H, similarly, the determined classical communication path and quantum communication path from the transmission node A to the center node E in the alpha company network. The number of quantum information relay devices 100 (relay points) existing in the network is calculated (step S7a). Then, from the number, the quantum communication path, the classical communication path, and the position of each quantum information relay device 100, the above-described role in the quantum information relay processing of each quantum information relay device 100 is determined (step S8a). It transmits to the quantum information relay apparatus 100 (step S9a).

  Then, quantum information relay processing is performed between the networks of Alpha and Beta, and between center node E and center node H, and photons such as quantum key distribution from transmission node A to reception node G are transmitted. (Step S10). Such quantum information relay processing will be described later.

  Next, the route determination process of the first hierarchy (organization) in step S3 will be described. FIG. 18 is a flowchart showing the procedure of the route determination process of the first layer. First, in the quantum information relay device 100 (center node), the classical path search unit 136 uses the first layer address of the sender address (the IP address of the sending node) and the receiver address (the receiving node's address) received from the sending node. The classical communication path between the center nodes (between E and H) is searched from the classical communication path table 133 shown in FIG. 5 using the first layer address of (IP address) as a key (step S11).

  Next, the quantum path determination unit 132 acquires the content of the quantum communication path presence flag corresponding to the searched classic communication path in the classic communication path table 133 (step S12), and the value of the acquired quantum communication path presence flag Is “1”, that is, whether there is a quantum communication path identical to the searched classical communication path (step S13).

  As a result, when the value of the quantum communication path presence flag is “1”, that is, when the same quantum communication path as the searched classical communication path exists (step S13: Yes), the quantum communication path table 134 The classical communication path determined by the classical path search unit 136 is determined as a quantum communication path without searching for (step S14). For example, in FIG. 5, when the classical communication route is determined as “31” by the classical route search unit 136, the quantum communication route is determined as “31” of the same route.

  On the other hand, when the value of the quantum communication path presence flag is not “1” (in the case of “0”) in step S13, that is, when the same quantum communication path as the searched classical communication path does not exist (step S13). : No), by the quantum path determination unit 132, the address of the first layer of the sender address (IP address of the transmission node) and the address of the first layer of the receiver address (IP address of the reception node) received from the transmission node Using these as keys, a quantum communication path between center nodes (between E and H) is searched from the quantum communication path table 134 shown in FIG. 6 (step S15). Then, the searched quantum communication path is determined as a quantum communication path between center nodes (between E and H) (step S16). In this way, the route determination process of the first hierarchy is performed.

  Next, the route determination process of the second hierarchy (party) in steps S2 and S5 will be described. FIG. 19 is a flowchart showing the procedure of the route determination process of the second hierarchy. First, in the quantum information relay apparatus 100 of the nodes in the networks of Alpha and Beta, the classical communication path table shown in FIG. 7 or 8 is used by the classical path search unit 136 using the second layer address of the IP address as a key. A classical communication path between nodes is searched from 133 (step S21).

  The second-layer address used as a key is selected as follows. In other words, when the second-level route is determined by the transmission node (in the case of step S2), the second-layer address of the IP address of the transmission node is used as a key. As a result, the second-layer classical communication path from the transmitting node to the center node of the network to which the transmitting node belongs is searched. For example, in the example of FIG. 4, when transmitting from the transmitting node A to the receiving node G, the transmitting node A searches the classical communication path table 133 using the address of the second layer of its own IP address as a key.

  Further, when the route of the second layer is determined at the center node of the network to which the receiving node belongs (in the case of step S5), the second layer address of the IP address of the receiving node is used as a key. Thereby, the classical communication path of the second hierarchy from the center node to the receiving node is searched. For example, in the example of FIG. 4, when transmitting from the transmission node A to the reception node G, the center node H of Beta company uses the second-layer address of the IP address of the reception node G as a key and uses the classical communication path table 133 as a key. Search for.

  Next, the quantum path determination unit 132 acquires the content of the quantum communication path presence flag corresponding to the searched classical communication path in the classical communication path table 133 (step S22), and the value of the acquired quantum communication path presence flag Is “1”, that is, whether there is a quantum communication path identical to the searched classical communication path (step S23).

  As a result, when the value of the quantum communication path presence flag is “1”, that is, when the same quantum communication path as the searched classical communication path exists (step S23: Yes), the quantum communication path table 134 The classical communication path determined by the classical path search unit 136 is determined as a quantum communication path without searching for (step S24).

  On the other hand, if the value of the quantum communication path presence flag is not “1” (in the case of “0”) in step S23, that is, if the same quantum communication path as the searched classical communication path does not exist (step S23). : No), the quantum path determination unit 132 searches for a quantum communication path between nodes from the quantum communication path table 134 shown in FIG. 8 or 10 by using the address of the second layer of the IP address as a key (step S25). Then, the searched quantum communication path is determined as a quantum communication path between center nodes (between E and H) (step S16). In this way, the route determination process of the second hierarchy is performed.

  Here, the second-layer address as a key is selected in the same manner as in the case of determining the route of the classical communication route described above.

  In this way, in the route determination processing of the first layer and the second layer, when there is a quantum communication route that is the same route as the classical communication route, the classical communication route is not subjected to the quantum communication search without performing the quantum communication route search. Since the route is determined, the load of the route search process can be reduced.

  Next, the quantum information relay process in step S10 will be described. Here, the quantum information relay processing from the transmission node A to the center node E in the Alpha company network will be described as an example. The quantum information relay process from the center node E to the center node H and from the center node H to the receiving node G is performed in the same manner.

  As shown in FIG. 4, the quantum communication paths from the transmission node A to the center node E are AT, TF, FU, and UE, and the classical communication path is AE. .

  FIG. 20 is a flowchart illustrating a procedure of quantum information communication processing in each quantum information relay device 100 of the first embodiment.

  First, an EPR pair is generated in the quantum information relay devices A, T, F, U, and E (steps S31 to S35). Next, one photon of the EPR pair generated by the quantum information relay device A, T, F, U is transmitted to the adjacent quantum information relay device (steps S36 to S39). As a result, the EPR pairs are shared between AT, TF, FU, and UE.

  Then, the first stage ES process is executed in the quantum information relay apparatuses T and U (steps S40 and S41). As a result, the EPR pair is shared between A-F and FE.

  Next, in the quantum information relay apparatuses A and F, the first-stage EPP process is executed between A and F, and in the quantum information relay apparatuses F and E, the first-stage EPP process is executed between FE. (Steps S42 to S44). This restores the fidelity of the EPR pair between A-F and FE.

  Next, in the quantum information relay apparatus F, the second-stage ES process is executed (step S45). As a result, the EPR pair is shared between the quantum information relay devices AE.

  Here, the classical communication path used is as follows. As shown in FIG. 4, in the first-stage ES processing, the path AT-F and the path F-U-E are used as classical communication paths. In the first-stage EPP processing, the route A-T-F and the route F-E-E are used. Further, in the second stage ES processing, the path AT-F and the path F-U-E are used.

  Next, in the quantum information relay devices A and E, the second-stage EPP process is executed between A and E (steps S46 and S47). This restores the fidelity of the EPR pair between A and E. That is, in the second-stage EPP process, the classical communication path A-E different from the classical communication path used in the first-stage ES process and the EPP process and the classical communication path used in the second-stage ES process are different. I use it. Thereby, when communicating from A to E, it is possible to communicate directly through the short-range A-E classical communication path without going through the quantum information relay device F, and the fidelity of the EPR pair. Attenuation is also prevented.

As described above, in the quantum information communication system according to the first embodiment, in the route determination process, when there is a quantum communication route that is the same as the classical communication route, the classical communication route is not searched without performing the quantum communication route search. Is determined as the quantum communication path, the load of the path search process can be reduced.
In the quantum information communication system according to the first embodiment, in the route determination process, when a quantum communication route that is the same route as the classical communication route does not exist, the quantum communication route is searched. The optimum route search can be performed according to the situation.

(Embodiment 2)
In the quantum information relay device 100 according to the first embodiment, the route determination is performed by the quantum information relay device 100 serving as the transmission node and the center node in the network. In the second embodiment, the route determination is performed by the network management. Run on the device.

  FIG. 21 is a block diagram of a network configuration of the quantum information communication system according to the second embodiment. As illustrated in FIG. 21, the quantum information communication system according to the second embodiment has a configuration in which a plurality of quantum information relay apparatuses 2100 and a network management apparatus 2130 are connected by an optical fiber 140.

  FIG. 22 is a block diagram illustrating a functional configuration of the network management device 2130. As shown in FIG. 22, the network management apparatus 2130 according to the present embodiment includes a communication unit 2131, a classical path search unit 2133, a quantum path determination unit 2132, a classical communication path table 133, and a quantum communication path table 134. And mainly.

  Here, the classical communication path table 133 and the quantum communication path table 134 are the same as the tables of the first embodiment, and are stored in a storage medium such as an HDD or a memory.

  The communication unit 2131 receives a route determination request message including the IP address (sender address) of the transmission node and the IP address (recipient address) of the reception node from the quantum information relay device 100 serving as the transmission node, and the classical route search unit A path message including the classical communication path determined by 2133 and the quantum communication path determined by the quantum path determination unit 2132 is generated, and the generated path message exists in the determined classical communication path and quantum communication path. This is a processing unit that transmits to the quantum information relay device 2100 of all nodes.

  The classical route search unit 2133 uses the IP address of the sending node and the IP address of the receiving node included in the route determination request message, from the classical communication route table 133, to the classical node between the predetermined nodes existing between the sending node and the receiving node. It is a processing unit that searches for a communication path.

  Specifically, the classical route search unit 2133 uses the IP address of the sending node and the IP address of the receiving node as a part of addresses from the first layer to the n-th layer as keys, and from the classical communication route table 133 to the sending node. A classical communication path between predetermined nodes existing between the receiving nodes is searched, and the searched classical communication path is determined as a classical communication path between the predetermined nodes.

The classical route search unit 2133 of the network management device 2130 according to the present embodiment determines the classical communication route for all layers of the IP address.
The quantum path determination unit 2132 is a processing unit that determines a quantum communication path between predetermined nodes based on the correlation corresponding to the classic communication path searched by the classic path search unit 2133. Specifically, the quantum path determination unit 2132 indicates that there is a quantum communication path whose quantum communication path existence flag corresponding to the classical communication path searched by the classical path search unit 136 is the same as the classical communication path. In the case of “1”, the searched classical communication path is determined as the quantum communication path between the predetermined nodes without searching for the quantum communication path.

  On the other hand, the quantum path determination unit 2132 indicates that there is no quantum communication path whose quantum communication path existence flag corresponding to the classic communication path searched by the classic path search unit 2133 is the same as the classic communication path. If it is, the quantum communication path between the predetermined nodes is searched from the quantum communication path table 134, and the searched quantum communication path is determined as the quantum communication path between the predetermined nodes.

  The quantum path determination unit 2132 of the network management apparatus 2130 according to the present embodiment determines the classical communication path for all layers of the IP address.

  The network management apparatus 2130 selects which classical communication path should be selected from the node position of the quantum information relay apparatus 100 in the path to execute the ES process or the ESS process, the number of times the ES process or the EPP process is executed, the ES process or the EPP Roles such as processing execution timing are determined, and the determined role is transmitted to each quantum information relay device 100 by the communication unit 2131.

  The network management device 2130 of this embodiment includes a control device such as a CPU, a storage device such as a ROM (Read Only Memory) and a RAM, an external storage device such as an HDD and a CD drive device, and a display device such as a display device. And an input device such as a keyboard and a mouse, and a communication device such as a network board, and has a hardware configuration using a normal computer.

  Next, the quantum information relay device 2100 according to the second embodiment will be described. FIG. 23 is a block diagram of a functional configuration of the quantum information relay apparatus 2100 according to the second embodiment. The quantum information relay apparatus 2100 according to the second embodiment includes a control classical computer 2110 and a repeater 120 as shown in FIG. The control classical computer 2110 has a configuration of a normal computer including a CPU and a memory. The functional configuration of repeater 120 is the same as that in the first embodiment.

  The control classical computer 2110 mainly includes a communication unit 135. In the present embodiment, since the classical communication path and the quantum communication path are determined by the network management device 2130, the classical route search unit and the quantum route determination unit as in the quantum information relay device 100 of the first embodiment. Is not provided.

  As in the first embodiment, the communication unit 135 is a processing unit that transmits the IP address of the transmission node, the IP address of the reception node, the classical communication path and the quantum communication path to other nodes, and receives from other nodes. is there.

  In addition, when the quantum information relay device 100 is a transmission node, the communication unit 135 includes a route determination request message to the network management device 2130 including the IP address of the transmission node and the IP address of the reception node. As a response to the request, a route message including the classical communication route and the quantum communication route determined from the network management device 2130 is received.

  Next, quantum information communication processing by the plurality of quantum information relay devices 100 according to the second embodiment configured as described above will be described. Here, in the network configuration shown in FIG. 4, a case where quantum information is transmitted from the transmission node A in the alpha company network to the reception node G in the beta company network will be described as an example.

  FIG. 24 is a sequence diagram showing a flow of quantum information communication processing in the second embodiment. First, the quantum information relay apparatus 2100 of the transmission node A sends the IP address (recipient address) of the reception node G as a transmission destination together with its own IP address (sender address) to its own network (alpha company network). The data is transmitted to the network management device 2130 (step S51).

  The network management device 2130 that has received the IP address of the receiving node G uses the first layer path from the first layer (organization) address of the IP address of the transmitting node A and the first layer address of the IP address of the receiving node G. A determination process is performed (step S52), and the first-layer classical communication path and quantum communication path from the center node E to the center node H of the destination network (Beta company network) are determined.

  Then, the network management apparatus 2130 of Alpha company transmits the IP address (recipient address) of the receiving node G that is the transmission destination to the network management apparatus 2130 of the network of the transmission destination (Beta company network) (step S53). .

  Then, the alpha network management device 2130 performs route determination processing of the second hierarchy from the address of the second hierarchy (party) of the IP address (sender address) of the transmission node A (step S54). The classical communication path and the quantum communication path of the second hierarchy to the center node E of the own network are determined.

  On the other hand, when receiving the IP address of the receiving node G, the network management device 2130 of the destination network (Beta company network), based on the address of the second layer (party) of the IP address of the receiving node G, A route determination process is performed (step S55), and a classical communication route and a quantum communication route from the center node H to the receiver node G are determined. Then, the determined classical communication path and quantum communication path are transmitted to the network management apparatus 2130 of Alpha (step S56).

  Note that the first layer route determination process in step S52 and the second layer route determination process in steps S54 and S55 are performed in the same manner as each route determination process in the first embodiment.

  Alpha network management apparatus 2130 transmits the received classical communication path and quantum communication path, and the classical communication path and quantum communication path determined in steps S52 and S54 to transmitting node A (step S57).

  Then, the alpha network management device 2130 includes the quantum information relay device 2100 (relay point) existing in the determined classical communication path and quantum communication path from the transmission node A to the center node E in the alpha company network. The number is calculated (step S58a). Then, from which number, quantum communication path, classical communication path, and position of each quantum information relay device 2100, which classical communication route performs ES processing and EPP processing in quantum information relay processing of each quantum information relay device 2100, Roles such as the number of executions of ES processing and EPP processing, execution timing of ES processing and EPP processing, etc. are determined (step S59a), and the determined roles are transmitted to each quantum information relay device 2100 in its own network (step S60a). .

  On the other hand, in the network management apparatus 2130 of Beta, similarly, the number of quantum information relay apparatuses 2100 (relay points) existing in the determined classical communication path and quantum communication path from the center node H to the receiving node G is calculated ( Step S58b), determination of the above-mentioned role in the quantum information relay processing of each quantum information relay device 2100 (Step S59b), and processing of transmission to each quantum information relay device 2100 in the network of the determined role (Step S60b) Is executed.

  Then, quantum information relay processing is performed between the networks of Alpha and Beta, and between center node E and center node H, and photons such as quantum key distribution from transmission node A to reception node G are transmitted. (Step S61). Such quantum information relay processing is performed in the same manner as in the first embodiment.

  As described above, in the quantum information communication system according to the second embodiment, the network management device 2130 searches for the classical communication route and determines the quantum communication route, so that the route search burden in the quantum information relay device 2100 of each node is determined. Thus, the processing efficiency of quantum information communication can be improved.

  In the second embodiment, the network management apparatus 2310 is described as a normal computer and is configured differently from the quantum information relay apparatus 2100 of each node. However, the present invention is not limited to this. For example, the quantum information of the center node The relay apparatus 2100 may be configured to have a function as a network management apparatus.

  Further, in the first and second embodiments, the description has been given using the IP address of the data structure of the two layers, but the IP address of the data structure of the three layers or more can also be used. The route determination is performed in the same manner as the route determination processing of the first layer and the second layer.

  In the present embodiment, the quantum information communication system having the network configuration shown in FIG. 4 has been described as an example. However, the present invention is not limited to this, and a network in which both a classical communication path and a quantum communication path exist. Any of them can be applied.

  The quantum information communication programs executed by the quantum information relay apparatuses 100 and 2100 and the network management apparatus 2130 according to the first and second embodiments are provided by being incorporated in advance in a ROM or the like.

  The quantum information communication program executed by the quantum information relay apparatuses 100 and 2100 and the network management apparatus 2130 according to the first and second embodiments is an installable format or executable file, and is a CD-ROM or flexible disk (FD). , A CD-R, a DVD (Digital Versatile Disk), or the like may be provided by being recorded on a computer-readable recording medium.

  Further, the quantum information communication program executed by the quantum information relay apparatuses 100 and 2100 and the network management apparatus 2130 according to the first and second embodiments is stored on a computer connected to a network such as the Internet and downloaded via the network. You may comprise so that it may provide. Further, the quantum information communication program executed by the quantum information relay apparatuses 100 and 2100 and the network management apparatus 2130 of the first and second embodiments may be provided or distributed via a network such as the Internet.

  The quantum information communication program executed by the quantum information relay apparatuses 100 and 2100 and the network management apparatus 2130 according to the first and second embodiments includes the above-described units (classical path search unit, quantum path determination unit, communication unit, ES execution unit, The module configuration includes an EPP execution unit and a control unit. As actual hardware, the CPU (processor) reads the quantum information relay program from the ROM and executes it, and the units are loaded onto the main memory. A classical path search unit, a quantum path determination unit, a communication unit, an ES execution unit, an EPP execution unit, and a control unit are generated on the main storage device.

  It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a block diagram showing a network configuration of a quantum information communication system according to a first exemplary embodiment. FIG. 3 is a block diagram illustrating a functional configuration of a control classical computer and a repeater according to the first embodiment; It is a data structure figure which shows an example of the data format of an IP address. It is a data structure figure of the IP address comprised from two segments. 3 is a schematic diagram illustrating an example of a network configuration, a quantum communication path, and a classical communication path according to Embodiment 1. FIG. It is explanatory drawing which shows an example of the classical communication path | route table of a 1st hierarchy. It is explanatory drawing which shows an example of the quantum communication path table of a 1st hierarchy. It is explanatory drawing which shows an example of the classical communication path | route table of a 2nd hierarchy. It is explanatory drawing which shows an example of the quantum communication path table of a 2nd hierarchy. It is explanatory drawing which shows the other example of the classical communication path table of a 2nd hierarchy. It is explanatory drawing which shows the other example of the quantum communication path table of a 2nd hierarchy. It is a schematic diagram which shows the example of the state of the EPR pair by ES process and EPP process. It is a schematic diagram for demonstrating ES process. It is a schematic diagram for demonstrating an EPP process. It is explanatory drawing which shows the state of the photon from an EPR pair production | generation to an EPP process. It is explanatory drawing which shows the state of the photon from an EPR pair production | generation to an EPP process. It is explanatory drawing which shows the state of the photon from an EPR pair production | generation to an EPP process. 6 is a sequence diagram showing a flow of quantum information communication processing in Embodiment 1. FIG. It is a flowchart which shows the procedure of the route determination process of a 1st hierarchy. It is a flowchart which shows the procedure of the route determination process of a 2nd hierarchy. 3 is a flowchart illustrating a procedure of quantum information communication processing according to the first embodiment. It is a block diagram which shows the network structure of the quantum information communication system concerning Embodiment 2. FIG. It is a block diagram which shows the functional structure of a network management apparatus. It is a block diagram which shows the functional structure of the quantum information relay apparatus concerning Embodiment 2. FIG. FIG. 11 is a sequence diagram showing a flow of quantum information communication processing in the second embodiment.

Explanation of symbols

100, 2100 Quantum information repeater 110, 2110 Control classical computer 121 EPR pair generation unit 122 Photon input unit 123 Photon-solid EIT conversion unit 124 Photon-solid EIT quantum computer 125 Memory 126 Photon transmission unit 132, 2132 Quantum path determination Unit 133 classical communication route table 134 quantum communication route table 135, 2131 communication unit 136, 2133 classical route search unit 140 optical fiber 301 control unit 302 ES execution unit 303 EPP execution unit

Claims (6)

A quantum information communication device connected to a quantum communication network and a classical communication network,
A quantum communication path table in which quantum communication paths indicating paths by quantum communication between nodes connected to the quantum communication network are registered; and a classical communication path indicating paths by classical communication between nodes connected to the classical communication network; Storage means for storing a classical communication path table that associates the correlation of the quantum communication paths between the nodes of the classical communication path;
Based on the network address of the sending node and the network address of the receiving node, the classical route search for retrieving the classical communication route between predetermined nodes existing between the sending node and the receiving node from the classical communication route table. Means,
Quantum path determining means for determining the quantum communication path between the predetermined nodes based on the correlation corresponding to the searched classical communication path;
Communication means for performing quantum information communication of photons according to the searched classical communication path or the determined quantum communication path;
A quantum information communication device comprising: The classical communication path table includes presence information indicating presence / absence of the quantum communication path that is the same path as the classical communication path as the correlation,
The quantum path determining means, when the presence information corresponding to the searched classical communication path indicates that the quantum communication path of the same path as the classical communication path exists, the searched classical communication The quantum information communication device according to claim 1, wherein a route is determined as the quantum communication route between the predetermined nodes.   The quantum path determining means further includes the quantum communication path when the presence information corresponding to the searched classical communication path indicates that the quantum communication path that is the same path as the classical communication path does not exist. The quantum information communication apparatus according to claim 2, wherein the quantum communication path between the predetermined nodes is searched from a table. EPR pair generating means for generating an EPR pair that is an entangled photon pair in quantum information communication of photons from the transmitting node to the receiving node;
Photon transmission means for transmitting one photon of the generated EPR pair to the quantum information communication device of an adjacent node;
Entanglement exchange execution means for executing an entanglement exchange process for sharing the EPR pair with the quantum information communication device of an adjacent node;
An entanglement purification protocol process, which is a process for recovering the fidelity of the EPR pair, is executed with the quantum information communication apparatus of the node to which the EPR pair is shared by the entanglement exchange process. An entanglement purification protocol execution means,
The communication means further performs quantum relay for sharing the EPR pair with other nodes and extending the distance between the photons of the EPR pair,
The entanglement purification protocol execution means executes the entanglement purification process executed last and the entanglement exchange process executed when the last entanglement purification protocol process is executed. Classical communication that is different from any one or more of the classical communication path used in the previously executed entanglement exchange process and the classical communication path used in the previously executed entanglement purification protocol process The quantum information communication apparatus according to claim 1, wherein a route is selected. A quantum information communication method executed by a quantum information communication device connected to a quantum communication network and a classical communication network,
The quantum information communication device includes a quantum communication path table in which a quantum communication path indicating a path by quantum communication between nodes connected to the quantum communication network is registered, and classical communication between nodes connected to the classical communication network. A storage means for storing a classical communication path indicating a path and a classical communication path table in which a correlation between the quantum communication paths between nodes of the classical communication path is associated;
Based on the network address of the sending node and the network address of the receiving node, the classical route search for retrieving the classical communication route between predetermined nodes existing between the sending node and the receiving node from the classical communication route table. Steps,
A quantum path determination step of determining the quantum communication path between the predetermined nodes based on the correlation corresponding to the searched classical communication path;
A communication step of performing quantum information communication of photons according to the searched classical communication path or the determined quantum communication path;
A quantum information communication method comprising: A quantum information communication program executed by a computer connected to a quantum communication network and a classical communication network,
The computer shows a quantum communication route table in which a quantum communication route indicating a route by quantum communication between nodes connected to the quantum communication network is registered, and a route by classical communication between nodes connected to the classical communication network. A storage means for storing a classical communication path and a classical communication path table in which the correlation of the quantum communication path between nodes of the classical communication path is associated,
Based on the network address of the sending node and the network address of the receiving node, the classical route search for retrieving the classical communication route between predetermined nodes existing between the sending node and the receiving node from the classical communication route table. Steps,
A quantum path determination step of determining the quantum communication path between the predetermined nodes based on the correlation corresponding to the searched classical communication path;
A communication step of performing quantum information communication of photons according to the searched classical communication path or the determined quantum communication path;
A quantum information communication program for causing the computer to execute.

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