EP1794924A2

EP1794924A2 - Qkd system ambiguous remote control

Info

Publication number: EP1794924A2
Application number: EP05815920A
Authority: EP
Inventors: Paul Jankovich
Original assignee: MagiQ Technologies Inc
Current assignee: MagiQ Technologies Inc
Priority date: 2004-09-15
Filing date: 2005-09-14
Publication date: 2007-06-13
Also published as: JP2008514118A; CN100592679C; CN101040481A; WO2006031828A3; WO2006031828A2

Abstract

Systems, methods and architectures that allow for controlling (e.g., initializing, stabilizing and/or calibrating) a remote node (Alice/Bob) of a QKD system (10) via a local node (Bob/Alice) of the QKD system are disclosed. The system includes a graphical user interface (GUI), a family of calibration objects, and a family of card objects. The calibration objects support software that allow for the calibration and/or initialization and/or stabilization of the QKD system via the GUI at the local node. The card family of objects allows for the calibration software to interface with the physical components of each node to carry out the remote calibration, initialization and/or stabilization of the remote node from the local node.

Description

QKD SYSTEM AMBIGUOUS REMOTE CONTROL

Claim of Priority

This application claims the benefit of priority under 35 U. S. C. § 119(e) of U.S. Provisional Application Serial No. 60/610,018, filed on September 15, 2004.

Technical Field of the Invention

The present invention relates to and has industrial utility with respect to quantum cryptography, and in particular relates to and has industrial utility with respect to quantum key distribution (QKD) systems, apparatus, methods and software architectures for controlling the nodes of a QKD system for system initialization, stabilization and calibration.

Background Information

Quantum key distribution involves establishing a key between a sender ("Alice") and a receiver ("Bob") by using weak (e.g., 0.1 photon on average) optical signals transmitted over a "quantum channel." The security of the key distribution is based on the quantum mechanical principle that any measurement of a quantum system in unknown state will modify its state. As a consequence, an eavesdropper ("Eve") that attempts to intercept or otherwise measure the quantum signal will introduce errors into the transmitted signals, thereby revealing her presence.

The general principles of quantum cryptography were first set forth by Bennett and Brassard in their article "Quantum Cryptography: Public key distribution and coin tossing," Proceedings of the International Conference on Computers, Systems and Signal Processing, Bangalore, India, 1984, pp. 175- 179 (IEEE, New York, 1984). Specific QKD systems are described in publications by CH. Bennett et al entitled "Experimental Quantum Cryptography," and CH. Bennett entitled "Quantum Cryptography Using Any Two Non-Orthogonal States", Phys. Rev. Lett. 68 3121 (1992), as well as in U.S. Patent No. 5,307,410 to Bennett (the '410 patent).

The general process for performing QKD is described in the book by Bouwmeester et al., "The Physics of Quantum Information," Springer-Verlag

2001 , in Section 2.3, pages 27-33. During the QKD process, Alice uses a true i random number generator (TRNG) to generate a random bit for the basis ("basis bit") and a random bit for the key ("key bit") to create a qubit (e.g., using polarization or phase encoding) and sends this qubit to Bob.

In a typical QKD system, Alice randomly encodes the polarization or phase of single photons, and Bob randomly measures the polarization or phase of the photons. The QKD system described in the Bennett 1992 paper and in the '410 patent, which paper and patent are incorporated by reference herein, is based on a shared interferometric system. Respective parts of the interferometric system are accessible by Alice and Bob so that each can control the phase of the interferometer. The signals (pulses) sent from Alice to Bob are time-multiplexed and follow different paths.

It will be desirable to one day have multiple QKD links woven into an overall QKD network that connects its QKD endpoints via a mesh of QKD relays or routers ("nodes"). Example QKD networks are discussed in the publication by C. Elliot, New Journal of Physics 4 (2002), 46.1-46.12, and also in PCT patent application publication no. WO 02/05480.

With reference to FIG. 1 , the simplest QKD system network is defined by a single Bob node and a single Alice node optically coupled to one another, e.g., via an optical fiber link F1. Both Bob and Alice typically contain some common internal components and some specific internal components. The difference between their specific internal components is what differentiates the Bob and Alice nodes.

In particular, both Bob and Alice typically contain a computer (controller) that provides an interface to discrete optical and hardware components and functions. The computer interface provides an environment by which to configure, manage, and monitor the optical and hardware components and functions under software control. The computer also provides a communications function (for instance, TCP/IP based) which is used to connect Bob and Alice over a physical communication medium such as Ethernet. Both Bob and Alice contain a timing control function and a synchronization (sync) function.

In addition to the common components and functions between Alice and Bob, Bob typically contains a quantum layer that includes a laser ("Q-Laser) for transmitting the quantum (i.e., weak) signals between the nodes. Bob also includes single-photon detectors (SPDs), discriminators, and phase modulators. In addition to the common components and functions, Alice contains, for example, a phase modulator capable of being randomly set to one of four phase settings.

When combining Bob and Alice nodes to form a QKD system network, systematic and complex calibration, turn-up, and maintenance procedures (collectively referred to herein as, "stabilization procedures") must be performed on each node to insure proper network function. Most of the procedures require some level of synchronization of activity between the nodes as well as the exchange of information. In a lab setting, both nodes are close enough to each other to allow a single user to initiate and control the calibration and turn-up procedures of both Bob and Alice by physical accessing each node. However, in the practical (e.g., commercial) implementation of QKD system networks, the physical distance between Bob and Alice will be great and therefore not allow a single user to physically access the two nodes and simultaneously control the necessary stabilization procedures. FIGS. 2 and 3 depict two other possible combinations of Bob and Alice nodes in different QKD system networks that further complicate the logistics of performing stabilization procedures between nodes.

Accordingly, there is a need for apparatus and methods that allow for control of the Bob and Alice nodes from a single node so that stabilization procedures for a QKD system network can be remotely implemented over the network.

Description of the Invention

An aspect of the invention is an architecture for object-oriented software for a QKD system having first and second QKD stations (nodes) that enables a user to remotely control a remote one of the nodes from a local one of the nodes. The architecture includes a graphical user interface (GUI) at the local node that allows the user to control the operation of both local and remote nodes via secure link connecting the nodes. The architecture also includes a calibration family of objects in each node that includes software made up of algorithms, functions, and data to support initialization, stabilization and/or calibration procedures and the GUI. The architecture further includes a card family of objects in each node that includes software constructs made up of algorithms, functions, and data adapted to interface calibration software with physical components in each node so as to effectuate QKD system initialization, stabilization and/or calibration from the local node.

Another aspect of the invention is a method controlling nodes of a QKD system after the QKD system is deployed in the field. The method includes providing each node with the above-described architecture, deploying each node, and identifying a local node and a remote node. The method also includes controlling both the local node and a remote node via the GUI on the local node to effectuate at least one of initialization, stabilization and calibration of the nodes of the QKD system.

Another aspect of the invention is a method of deploying a QKD system in the field. The method includes providing each node in the QKD system with software adapted to perform initialization, stabilization and calibration, procedures at the corresponding node and support a graphical user interface (GUI) at a local node. The method also includes operating the software at the local and remote nodes via the GUI at the local node so as to initialize and/or stabilize and/or calibrate the QKD system.

Another aspect of the invention is a QKD system that includes first and second nodes. Each node has control software adapted to control the operation of the corresponding node to perform system initialization and/or stabilization and/or calibration. The first and second nodes are operably coupled by a secure communication link. The first node is a local node and the second node is a remote node. First and second graphical user interfaces (GUI) are included that represent respective operating states of the first and second nodes. The system also includes a local client proximate to and operatively coupled to the local node and adapted to display the two GUIs and effectuate control of the local and remote nodes via said software.

Brief Description of the Drawings

FIG. 1 is a schematic diagram of a simple QKD system network having two nodes Bob and Alice coupled to one another via an optical fiber link, and illustrating an example embodiment of components common to Alice and Bob and components specific to Alice and Bob; FIG. 2 is a schematic diagram of a QKD system network formed from cascaded Bob and Alice pairs;

FIG. 3 is a schematic diagram of a QKD system network having a single Bob node and multiple Alice nodes stemming therefrom;

FIG. 4 is a schematic diagram of a QKD system network that includes QKD ambiguous node remote control (ANRC), wherein a local client manager is connected to a local node (e.g., Bob) via a secure connection SC1 , wherein Bob and Alice are connected via a secure connection SC2, and wherein the local client manager includes graphical user interfaces (GUIs) that display information about the operational status of the local and remote nodes;

FIG. 5 is a schematic diagram of the calibration object inherited relationships;

FIG. 6 is a schematic diagram of the card object inherited relationships;

FIG. 7A is a schematic diagram of Bob's local calibration;

FIG. 7B is a schematic diagram of Bob's card objects in connection with the calibration flow of FIG. 7A;

FIG. 8A is a schematic diagram of Alice's remote calibration;

FIG. 8B is a schematic diagram of Alice's card objects in connection with the calibration flow of FIG. 8A;

FIG. 9A is a schematic diagram of Alice's local calibration; and

FIG. 9B is a schematic diagram of Alice's card objects in connection with the calibration flow of FIG. 9A.

The various elements depicted in the drawings are merely representational and are not necessarily drawn to scale. Certain sections thereof may be exaggerated, while others may be minimized. The drawings are intended to illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.

Detailed Description of the Best Mode of the Invention

The deployment of a QKD system network comprised of, for example, a single point-to-point Bob node and Alice node pair (FIG.1), cascaded Bob node and Alice node pairs (FIG. 2) or a single Bob node connected to multi-point Alice nodes (FIG. 3) that involve long distances of fiber requires the ability to coordinate and control system stabilization procedures between any of the nodes in the system. The present invention allows a single user to initiate and control the stabilization procedures between Bob and Alice nodes in a conventional QKD system network through apparatus and methods that allow for remote implementation of stabilization procedures via a single node in the network.

Example QKD systems are illustrated in the '410 patent, and also in PCT patent application no. PCT/US2004/03394, which PCT patent application is incorporated by reference herein.

Stabilization procedures

In an example embodiment, a list of the common stabilization procedures performed on both the Bob and Alice nodes includes the following: 1. Setup sync laser and ensure synchronization lock.

In an example embodiment, the stabilization procedures specific to Bob include:

1. Set Q-laser bias.

2. Set Q-laser pulse width and timing.

3. Set the SPD temperature.

4. Set each SPD bias and discriminator sensitivity level.

5. Determine SPD timing.

6. Determine modulator timing.

7. Set modulator's voltage.

In an example embodiment, the stabilization specific to Alice include:

1. Determine the modulator timing.

2. Set modulator voltages.

QKD ANRC

The present invention, referred to herein as "QKD system network ambiguous node remote control" or "QKD ANRC," allows a single user physically located at either a Bob or Alice node to carry out (e.g., initiate, control, and monitor) the complex stabilization procedures required for the QKD system network to function on an ongoing basis. In an example embodiment, the QKD ANRC presents the user with Graphical User Interfaces (GUI) for both Bob and Alice at the node of control. Depending on which node the user is physical located (called the "local node"), the far-end node relative to the local node is defined as the "remote node" and is so indicated by the GUI.

FIG. 4 is a schematic diagram of an example embodiment of the QKD ANRC as part of a QKD system network 10. With reference to FIG. 4, a secure connection SC2 is established between the local node and any remote node for the purpose of supporting QKD ANRC messaging.

The definition of local node is applied to the node(s) of the QKD system network where the stabilization procedures affect the optical and hardware components directly at the node.

The definition of remote node is applied to the node(s) of a QKD system network where the stabilization procedures affect the optical and hardware components of the node through messaging over the Secure Connection. All remote nodes are inherently local nodes to some degree because all actions received remotely cause some local activity.

The definition of control node is applied to a single node of a QKD system network where all stabilization procedures are initiated.

Each node of the QKD system network is responsible for managing and maintaining its own data related to the stabilization procedures. All of the data presented to a user on a remote control GUI at a local client connected to the local node via a secure connection SC1 is collected from the remote node by the local node using messaging over the secure connection SC2. Any data modified in the remote control GUI of a remote node on the local node is pushed to the remote node by the local node using messaging over the secure connection.

FIG. 5 is a schematic diagram illustrating the inherited relationships between calibration objects. FIG. 6 is a schematic diagram illustrating the inherited relationships of card objects.

Each node of the QKD network system includes the software objects illustrated in FIG. 5 and 6. The relationships between the objects are defined by class hierarchy. The determination of which objects are created is defined by the local node type and remote node type for each physical node. The calibration object family includes software constructs that comprise all of the algorithms, functions, and data that support the initialization, stabilization and calibration procedures and GUI(s) for the QKD ANRC. The calibration object hierarchy is composed of the following objects:

• Calibration: The base object, responsible for GUI, calibration algorithms and functions, and GUI input validation.

• Local Calibration: Handles access to underlying hardware and services messages from remote calibration.

• Remote calibration: Initiates messaging for remote calibration on local node and services message replies from the remote node.

• Bob Local Calibration: Bob specific local calibration functionality.

• Alice Local Calibration: Alice specific local calibration functionality.

• Bob Remote Calibration: Bob specific remote calibration functionality on the local node

• Alice Remote Calibration: Alice specific remote calibration functionality on the local node.

The card family of objects includes software constructs that comprise all of the algorithms, functions, and data that support the interface of the calibration object family with the different physical optical and hardware components of QKD network system nodes. The card object hierarchy is composed of the following objects (see FIG. 6).

• Card: Supports all of the common and generic algorithms, functions, and data to access, control, and manage common optical and hardware components of a QS system node.

• Bob Card: Supports the Bob Node specific algorithms, functions, and data to access, control, and manage Bob specific optical and hardware component.

• Alice Card: Supports the Alice Node specific algorithms, functions, and data to access, control, and manage Alice specific optical and hardware component.

A relationship between the calibration objects and card objects is established by the base calibration object to allow the calibration objects to access and control optical and hardware components of the local nodes. On the local node, the calibration objects and card objects highlighted in FIGS. 7 A and 7B are created and utilized for Bob local calibration.

On the local node, the calibration objects and card objects highlighted in FIGS. 8A and 8B are created and utilized for Alice remote calibration.

FIGS. 9A and 9B are schematic diagrams illustrating the local calibration path (FIG. 9A) and card objects (FIG. 9B) at Alice.

QKD ANRC advantages

The QKD ANRC system of the present invention has a number of key advantages, such as:

1. Eliminate the requirement of calibrating QKD system nodes with deployment specifications prior to shipment and delivery.

2. Reduces the number of field technicians to one (1) at a designated control node in the system.

3. Enables a single node in the system to assume the characteristics of either Bob or Alice. Therefore, more complex configuration of the QKD system network can be achieved beyond single point to point nodes.

Claims

What is claimed is:

1. An architecture for object-oriented software for a QKD system having first and second QKD stations (nodes) that enables a user to remotely control a remote one of the nodes from a local one of the nodes, comprising: a graphical user interface (GUI) at the local node that allows the user to control the operation of both local and remote QKD stations via secure link connecting the nodes; a calibration family of objects in each node that includes software made up of algorithms, functions, and data to support initialization, stabilization and/or calibration procedures and the GUI; and a card family of objects in each node that includes software constructs made up of algorithms, functions, and data adapted to interface calibration software with physical components in each node so as to effectuate QKD system initialization, stabilization and/or calibration from the local node.

2. A method controlling nodes of a QKD system after the QKD system is deployed, comprising: providing each node with the architecture of claim 1; deploying each node; identifying a local node and a remote node; and controlling both the local node and a remote node via the GUI on the local node to effectuate at least one of initialization, stabilization and calibration of the nodes of the QKD system.

3. A method of deploying a QKD system, comprising: providing each node in the QKD system with software adapted to perform initialization, stabilization and calibration, procedures at the corresponding node and support a graphical user interface (GUI) at a local node; operating the software at the local and remote nodes via the GUI at the local node so as to initialize and/or stabilize and/or calibrate the QKD system.

4. A QKD system comprising: first and second nodes each having control software adapted to control the operation of the corresponding node to perform system initialization and/or stabilization and/or calibration, the first and second nodes operably coupled by a secure communication link, wherein the first node is a local node and the second node is a remote node; a graphical user interface (GUI) that represents respective operating states of the first and second nodes; and a local client proximate to and operatively coupled to the local node and adapted to display the GUI and effectuate control of the local and remote nodes via said software.