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Quantum Internet Research Group                             AD. Dahlberg
Internet-Draft                                            MS. Skrzypczyk
Intended status: Experimental                            SW. Wehner, Ed.
Expires: April 12, 2020           QuTech, Delft University of Technology
                                                        October 10, 2019


              The Link Layer service in a Quantum Internet
                      draft-dahlberg-ll-quantum-03

Abstract

   In a classical network the link layer is responsible for transferring
   a datagram between two nodes that are connected by a single link,
   possibly including switches.  In a quantum network however, the link
   layer will need to provide a robust entanglement generation service
   between two quantum nodes which are connected by a quantum link.
   This service can be used by higher layers to produce entanglement
   between distant nodes or to perform other operations such as qubit
   transmission, without full knowledge of the underlying hardware and
   its parameters.  This draft defines what can be expected from the
   service provided by a link layer for a Quantum Network and defines an
   interface between higher layers and the link layer.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 12, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Desired service . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Interface . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Higher layers to link layer . . . . . . . . . . . . . . .   4
       4.1.1.  Header specification  . . . . . . . . . . . . . . . .   4
     4.2.  Link layer to higher layers . . . . . . . . . . . . . . .   7
       4.2.1.  Header specification  . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   7.  Informative References  . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The most important fundamental operation in a quantum network is the
   generation of entanglement between nodes.  Short-distance
   entanglement can be used to generate long-distance entanglement with
   the use of an operation called entanglement swap [1] (also formalised
   in [2]).  If nodes A and B share an entangled pair and similarly for
   B and C, B can perform a so called Bell measurement [3] and send the
   measurement outcome (2 bits) over a classical channel to A or C such
   that in the end A and C share an entangled pair.  Furthermore, long-
   distance entanglement does in turn enable long-distance qubit
   transmission by the use of quantum teleportation [3] (also formalised
   in [2]).  Node A can teleport an unknown qubit state to B by
   consuming an entangled pair between A and B and sending two classical
   bits to B.  For an overview of quantum networking and its
   applications we refer to [5].

   Long lived entanglement between distant nodes capable of storing such
   entanglement has been demonstrated over a distance of up to 1.3 km
   [4], in a proof-of-principle experiment.  This entanglement was also
   heralded, that is, there exits a so-called heralding signal that
   indicates success in entanglement production without consuming such
   entanglement.  Short lived and non-heralded entanglement has been
   observed from a satellite over a distance of 1200 km [6] in a proof
   of principle experiment.  The next step towards a quantum network is



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   to turn ad-hoc experiments that produce entanglement into a reliable
   service.  This is the role of the link layer, which turns an ad-hoc
   physical setup to a reliable entanglement generation service.
   Reliable here means that the higher layers can (unless a timeout or
   other critical failures occur) rely in deterministic entanglement
   production.  In particular, this means that since the underlying
   physical process is often probabilistic but entanglement generation
   can be confirmed using the heralding signal, one of the main tasks of
   the link layer is to manage re-tries in producing entanglement at the
   the physical layer.  Once an entangled pair has been generated, the
   nodes need to be able to agree on which qubits are involved in which
   entangled pair in order to use it, thus another main task of the link
   layer is to provide an entanglement identifier.

2.  Scope

   This draft is meant to define the service and interface of an link
   layer of a quantum network.  Further considerations that motivate
   this definition can be found in [7].  It does not present a protocol
   realising this service.  However a protocol that indeed does this
   have been proposed in [7], together with more details on use cases
   and design decisions in forming a quantum network stack.

3.  Desired service

   This section definces the service that a link layer provides in a
   quantum network.  The interface and header specification is defined
   in the next section.

   A link layer between two nodes A and B of a quantum network must
   provide the following minimal features (see [7] for an extended
   feature set):

   o  Allow both node A and B to initialize entanglement generation.

   o  Allow the initializing node to specify a desired minimum
      fidelity[3] and maximum waiting time.

   o  Notify both nodes of success or failure of entanglement generation
      before the requested maximum waiting time has passed since the
      request was initialized.

   o  If success is notified, the generated entangled pair has with high
      confidence higher (or equal) fidelity than the desired minimum
      fidelity.






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   o  For a successful request, provide an entanglement identifier to
      allow higher layers to use identify the entangled pair in the
      network without the need for further communication.

4.  Interface

   This section describes the interface between higher layers and the
   link layer in a quantum network, along with header specifications for
   the type of messages.  The interface consists of a single type of
   message from the higher layers to the link layer, which is the CREATE
   message for requesting entanglement generation.  Response messages
   from the link layer to the higher layers take either the form of an
   ACK, an OK message or one of many error messages.  The ACK is sent
   back directly upon receiving a CREATE if the link layer supports the
   request and contains a CREATE ID such that the higher layer can
   associated the subsequent OK messages to the correct request.  It is
   assumed that the nodes in the network are assigned a unique ID in the
   network, which is used in the Remote Node ID parameters of the
   messages below.

4.1.  Higher layers to link layer

   The higher layers can send a CREATE message to the link layer to
   request the generation of entanglement.  Along with other parameters,
   as specified below the higher layers can specify a minimum fidelity,
   a maximum waiting time and the number of entangled pairs to be
   produced.

4.1.1.  Header specification

   The CREATE message contains the following parameters:

   o  Remote Node ID (32 bits): Used if the node is directly connected
      to multiple nodes.  Indicates which node to generate entanglement
      with.

   o  Minimum fidelity (16 bits): The desired minimum fidelity, between
      0 and 1, of the generated entangled pair.  A binary value encoding
      the integer 'n' represents the fidelity 'n' divided by (2^16-1).

   o  Time Unit (TU) (2 bits): The time units used for specifying Max
      Time, where (00, 01, 10) each indicate (micro-seconds,
      milliseconds, seconds) respectively and 11 is unused.

   o  Max Time (14 bits): The maximum time in the time units specified
      above that the higher layer is willing to wait for the request to
      be fulfilled.  A binary value encoding the integer 'n'
      representing the time in the specified time units.



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   o  Purpose ID (16 bits): Allows the higher layer to tag the request
      for a specific purpose.  If the request is from an application
      this can be thought of as a port number.  The purpose ID can also
      be used by a network layer to specify that this entanglement
      request is part of long-distance entanglement generation over a
      specific path.

   o  Number (16 bits): The number of entangled pairs to generate.

   o  Priority (3 bits): Can be used to indicate if this request is of
      high priority and should ideally be fulfilled early.  Higher means
      faster service.

   o  Type of request (TPE) (1 bit): Either create and keep (K) or
      measure directly (M), where K stores the generated entanglement in
      memory and M measures the entanglement directly.

   o  Atomic (ATO) (1 bit): A flag that indicates that the request
      should be satisfied as a whole without interuption by other
      requests.

   o  Consecutive (CON) (1 bit): A flag indicating an OK is returned for
      each pair made for a request.  Otherwise, an OK is sent only when
      the entire request is completed (more common in application use
      cases).  For K type requests, this means all pair should be in
      memory at the same time.

   o  Random basis choice for measure directly

      *  (RL) (2 bits): Choose to measure the local qubit randomly in
         either

      *  (RR) (2 bits): Choose to measure the remote qubit randomly in
         either

      Using the following encoding:

      *  00: No random choice

      *  01: X or Z basis (BB84)

      *  10: X, Y or Z basis (six state)

      *  11: CHSH rotated bases, Z basis rotated by angles +/- pi/4
         around Y axis.

   o  Probability distributions used to sample random basis for measure
      directly:



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      *  (PL1) (8 bits): Parameter for local probability distribution
         used to sample basis if RL is not 00

      *  (PL2) (8 bits): Parameter for local probability distribution
         used to sample basis if RL is not 00

      *  (PR1) (8 bits): Parameter for remote probability distribution
         used to sample basis if RR is not 00

      *  (PR2) (8 bits): Parameter for remote probability distribution
         used to sample basis if RR is not 00

      Each value is seen as the integer representing of the binary
      value.  Probability distributions are used as follows

      *  If the specified random basis has 2 elements then the
         distribution obeys the probabilities (PL(R)1 / 255, 1 - PL(R)1
         / 255)

      *  If the specified random basis has 3 elements then the
         distribution obeys the probabilities (PL(R)1 / 255, PL(R)2 /
         255, 1 - PL(R)1 / 255 - PL(R)2 / 255)

   o  Rotation of measurement basis in the case of M types of requests
      for both the local and remote measurement.  Three rotations from
      the defaults Z basis are performed, first a rotation around the
      X-axis (ROTX1L(R)), then a rotation around the Y-axis (ROTYL(R))
      and finally a rotation again around the X-axis.  Note that
      arbitrary rotations can be composed as these three rotations, see
      <https://en.wikipedia.org/wiki/Euler_angles>.  If all three fields
      are 00000000, the qubits are measured in the Z basis.  If RL(R) is
      not 00, these three fields (ROTX1L(R), ROTYL(R) and ROTX2L(R)) are
      ignored.

      *  Measurement rotation around X for local (remote) node
         (ROTX1L(R)) (8 bits): Measurement to be performed in the case
         of M types of request.  Default is Z measurement.  Specified
         measurement to be rotated around the X axis by angle of 2
         pi/256 * ROTX1

      *  Measurement rotation around Y for local (remote) node
         (ROTYL(R)) (8 bits): Measurement to be performed in the case of
         M types of request.  Default is Z measurement.  Specified
         measurement to be rotated around the Y axis by an angle of 2
         pi/256 * ROTY

      *  Measurement rotation around X for local (remote) node
         (ROTX2L(R)) (8 bits): Measurement to be performed in the case



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         of M types of request.  Default is Z measurement.  Specified
         measurement to be rotated around the X axis by an angle of 2
         pi/256 * ROTX2

   The complete header specification of the CREATE message is given in
   Figure 1.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Remote Node ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Minimum Fidelity        |TU |      Max Time             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Purpose ID          |           Number              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Prio |T|A|C|   |   |           |               |               |
   |rity |P|T|O|RL |RR | reserved  |      PL1      |      PL2      |
   |     |E|O|N|   |   |           |               |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |               |               |               |
   |      PR1      |      PR2      |     ROTX1L    |     ROTXYL    |
   |               |               |               |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |               |               |               |
   |     ROTX2L    |    ROTX1R     |     ROTYR     |     ROTX2R    |
   |               |               |               |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 1: CREATE message header format

4.2.  Link layer to higher layers

   When receiving a CREATE message from higher layers the link layer
   will directly respond and notify the higher layer whether requests
   will be scheduled for generation.  If so the link layer responds with
   an ACK containing a CREATE ID.  The higher layer may choose to use
   this CREATE ID together with the ID of the requesting node to
   associate OK messages it receives from the link layer to the correct
   request.  Note that the ID of the requesting node is needed since the
   ACK is returned directly and the CREATE ID is thus not unique for
   requests from different nodes.  If the link layer does not support
   the given request an error message is instead returned.

   When a request is satisfied an OK message is sent to the higher
   layer.  The OK message contains different fields depending on whether
   the request was of type K (keep) or M (measure directly).  For K the
   OK contains a logical qubit identifier (LQID) such that the higher



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   layer can know which logical qubit holds the generated entanglement.
   For M the OK contains the basis which the qubit was measured and the
   measurement outcome.

   Both during and after entanglement generation, the link layer can
   return error messages to the higher layers, as further described
   below.  For example if something happens to the qubit or another
   error occurs such that the entanglement is not valid anymore, the
   link layer can issue an ERR_EXPIRE message.

4.2.1.  Header specification

   To distinguish the different types of messages that the link layer
   can return to the higher layer, the first part of the header is a 4
   bit field which specifies the type of message using the following
   mapping:

   o  0001: ACK

   o  0010: Type K OK

   o  0011: Type M OK

   o  0100: ERR

   The complete header specification for these four types of messages
   are shown below in Figure 2 to Figure 5.

   The ACK message contains the following parameters:

   o  Create ID (16 bits): A Create ID that the higher layer can use to
      associate subsequent OK messages to the request.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type  |          Create ID            |         Unused        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 2: ACK message header format

   The type K OK message contains the following parameters:

   o  Create ID (16 bits): Must be the same Create ID that was given in
      the ACK of the corresponding request.

   o  Logical Qubit ID (LQID) (4 bits): A logical ID of the qubit which
      is part of the entangled pair.



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   o  Directionality flag (D) (1 bit): Specifies if the request came
      from this node (D=0) or from the remote node (D=1).

   o  Sequence number (16 bits): A sequence number for identifying the
      entangled pair.  It is assumed to be unique for entangled pairs
      between the given nodes.  Thus together with the IDs of the nodes
      between which the entanglement is produced, one can create an
      entanglement identifier which is unique in the network.

   o  Purpose ID (16 bits): The purpose ID of the request (only used by
      the node which did not initiate the request)

   o  Remote Node ID (32 bits): Used if the node is directly connected
      to multiple nodes.

   o  Goodness (16 bits): An estimate of the fidelity of the generated
      entangled pair.  Should not be seen as a guarantee.

   o  Time of Goodness (ToG) (16 bits): The time of the goodness
      estimate.  Not necessarily the time when the estimate is performed
      but rather the time for which the estimate is for.  Can be used to
      make an updated estimate based on decoherence times of the qubits.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type  |          Create ID            | LQID  |D|   Unused    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Sequence Number        |          Purpose ID           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Remote Node ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Goodness            |      Time of Goodness         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 3: Type K OK message header format

   The type M OK message contains the following parameters:

   o  Create ID (16 bits): The same Create ID that was given in the ACK
      of the corresponding request.

   o  Measurement outcome (M) (1 bit): The outcome of the measurement
      performed on the entangled pair.

   o  Basis (3 bits): Which basis the entangled pair was measured in,
      used if the basis is random, i.e. if RBC is not 00 in the CREATE.
      The following representation is used:



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      *  000: Z-basis

      *  001: X-basis

      *  010: Y-basis

      *  011: Z-basis rotated by angle pi/4 around Y-axis

      *  100: Z-basis rotated by angle -pi/4 around Y-axis

      *  101: Unused

      *  110: Unused

      *  111: Unused

   o  Directionality flag (D) (1 bit): Specifies if the request came
      from this node (D=0) or from the remote node (D=1).

   o  Sequence number (16 bits): A sequence number for identifying the
      entangled pair.  It is assumed to be unique for entangled pairs
      between the given nodes.  Thus together with the IDs of the nodes,
      one can create an entanglement identifier which is unique in the
      network.

   o  Purpose ID (16 bits): The purpose ID of the request (only used by
      the node which did not initiate the request)

   o  Remote Node ID (32 bits): Used if the node is directly connected
      to multiple nodes.

   o  Goodness (16 bits): An estimate of the fidelity of the generated
      entangled pair.  Should not be seen as a guarantee.

   Note: Time of Goodness is not needed here since there is no
   decoherence on the measurement outcomes.















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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type  |          Create ID            |M|D|Basis|   Unused    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Sequence Number        |          Purpose ID           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Remote Node ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Goodness            |            Unused             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 4: Type M OK message header format

   The ERR message contains the following parameters:

   o  Create ID (16 bits): The same Create ID that was given in the ACK
      of the corresponding request.

   o  Error code (ERR) (4 bits): Specifies what error occurred.  See
      below what the error codes mean.

   o  Expire by sequence numbers (S) (1 bit): Used by ERR_EXPIRE, to
      specify whether a range of sequence numbers should be expired
      (S=1) or all sequence numbers associated with the given Create ID
      and Origin Node (S=0).

   o  Sequence number low (16 bits): Used by error code ERR_EXPIRE to
      identify a range of sequence numbers that needs to be expired.
      Numbers above Sequence number low (inclusive) and below Sequence
      number high (exclusive) should be expired.

   o  Sequence number high (16 bits): Used by error code ERR_EXPIRE to
      identify a range of sequence numbers that needs to be expired.
      Numbers above Sequence number low (inclusive) and below Sequence
      number high (exclusive) should be expired.

   o  Origin Node (32 bits): Used if the node is directly connected to
      multiple nodes.  Needed here since Create IDs are not unique for
      request from different nodes.











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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type  |          Create ID            |  ERR  |S|   Unused    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Sequence number low        |    Sequence number high       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Origin Node                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 5: Error message header format

   The different error codes using in an error message are the
   following:

   o  Error returned directly when a CREATE message is received:

      *  ERR_UNSUPP (0001): The given request is not supported.  For
         example if the minimum fidelity is not achievable or if the
         request is of type K and the hardware cannot store
         entanglement.

      *  ERR_CREATE (0010): The create message could not be parsed.

      *  ERR_REJECTED (0011): The request was rejected by this node
         based on for example the Purpose ID.

      *  ERR_OTHER (0100): An unknown error occurred.

   o  Error returned after a CREATE message is received, before or after
      an OK is returned:

      *  ERR_EXPIRE (0101): One or more already sent OK messages have
         expired and the entangled pair is not available anymore.  Can
         either be specified as a range of sequence numbers or by a
         create ID by using the S flag.

      *  ERR_REJECTED (0011): The request was rejected by the other node
         based on for example the Purpose ID.

      *  ERR_TIMEOUT (0110): The request was not satisfied within the
         requested max waiting time.

5.  IANA Considerations

   This memo includes no request to IANA.





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6.  Acknowledgements

   The authors would like to acknowledge funding received from the EU
   Flagship on Quantum Technologies, Quantum Internet Alliance.

   The authors would further like to acknowledge Tim Coopmans, Leon
   Wubben, Filip Rozpedek, Matteo Pompili, Arian Stolk, Przemyslaw
   Pawelczak, Robert Knegjens, Julio de Oliveria Filho, Sidney Cadot,
   Joris van Rantwijk and Ronald Hanson for inputs and discusssion and
   Wojciech Kozlowski for useful feedback on this draft.

7.  Informative References

   [1]        Briegel, H., Dur, W., Cirac, J., and P. Zoller, "Quantum
              repeates: The Role of Imperfect Local Operations in
              Quantum Communication", Physical Review Letters 81, 26,
              1998, <https://journals.aps.org/prl/abstract/10.1103/
              PhysRevLett.81.5932>.

   [2]        Kompella, K., Aelmans, M., Wehner, S., Sirbu, C., and A.
              Dahlberg, "Advertising Entanglement Capabilities in
              Quantum Networks", QIRG Internet-Draft, 2018,
              <https://datatracker.ietf.org/doc/draft-kaws-qirg-
              advent/>.

   [3]        Nielsen, M. and I. Chuang, "Quantum Computation and
              Quantum Information", Book Cambridge University Press,
              2010, <https://doi.org/10.1017/CBO9780511976667>.

   [4]        Hensen, B., Bernien, H., Dreau, A., Reiserer, A., Kalb,
              N., Blok, M., Ruitenberg, J., Vermeulen, R., Schouten, R.,
              Abellan, C., Amaya, W., Pruneri, V., Mitchell, M.,
              Markham, M., Twitchen, D., Elkouss, D., Wehner, S.,
              Taminiau, T., and R. Hanson, "Loophole-free Bell
              inequality violation using electron spins separated by 1.3
              kilometres", Nature 526, 682-686, 2015,
              <https://arxiv.org/abs/1508.05949>.

   [5]        Wehner, S., Elkouss, D., and R. Hanson, "Quantum internet:
              A vision for the road ahead", Science 362, 6412, 2018,
              <http://science.sciencemag.org/content/362/6412/
              eaam9288?intcmp=trendmd-sci>.









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   [6]        Yin, J., Cao, Y., Li, Y., Liao, S., Zhang, L., Ren, J.,
              Cai, W., Liu, W., Li, B., Dai, H., Li, G., Lu, Q., Gong,
              Y., Xu, Y., Li, S., Li, F., Yin, Y., Jiang, Z., Li, M.,
              Jia, J., Ren, G., He, D., Zhou, Y., Zhang, X., Wang, N.,
              Chang, X., Zhu, Z., Liu, N., Chen, Y., Lu, C., Shu, R.,
              Peng, C., Wang, J., and J. Pan, "Satellite-based
              entanglement distribution over 1200 kilometers",
              Science 356, 6343, 2017,
              <https://arxiv.org/abs/1707.01339>.

   [7]        Dahlberg, A., Skrzypczyk, M., Coopmans, T., Wubben, L.,
              Rozpedek, F., Pompili, M., Stolk, A., Pawelczak, P.,
              Knegjens, R., de Oliveira Filho, J., Hanson, R., and S.
              Wehner, "A Link Layer Protocol for Quantum Networks",
              arXiv pre-print arXiv:1903.09778, 2019,
              <https://arxiv.org/abs/1903.09778>.

Authors' Addresses

   Axel Dahlberg
   QuTech, Delft University of Technology
   Lorentzweg 1
   Delft  2628 CJ
   Netherlands

   Phone: +31 (0)65 8966821
   Email: e.a.dahlberg@tudelft.nl


   Matthew Skrzypczyk
   QuTech, Delft University of Technology
   Lorentzweg 1
   Delft  2628 CJ
   Netherlands

   Email: m.d.skrzypczyk@student.tudelft.nl


   Stephanie Wehner (editor)
   QuTech, Delft University of Technology
   Lorentzweg 1
   Delft  2628 CJ
   Netherlands

   Email: s.d.c.wehner@tudelft.nl






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