Hewlett-Packard Development Company, L.p.

Other

Hewlett Packard Enterprise Development LP

Inter-University Research Institute Corporation Research Organization of Information and Systems

William John Munro

Timothy Paul Spiller

Raymond G Beausoleil

Keith Alexander Harrison

Kae Nemoto

Sean D Barrett

Richard Stanley Williams

Philip John Kuekes

Christopher Tofts

Adrian P Kent

Pieter Kok

Marco Fiorentino

Martin Sadler

Li Zhang

Liqun Chen

Charles Santori

Michael R Tan

Yoshihisa Yamamoto

Tad H Hogg

Sean Spillane

Kay-Yut Chen

Stephen James Crane

Joanna Duligall

Radu Ionicioiu

Peter Van Loock

John Gilroy Rarity

Joanna Louise Duligall

Timothy P Spillar

Willem K Van Dam

Gerard James Milburn

Timothy Cameron Ralph

Timothy P Spiller

Sean Barrett

Nemoto Kae

A method and apparatus () are provided for routing entanglement building between a selected pairing of interface qubits (). The qubits of the selected pairing of interface qubits () are separately entangled with at least one intermediate qubit () by interacting respective light fields with the interface qubits of the selected pairing and using an optical merge arrangement () to further interact the light fields with at least one intermediate qubit (). Where there are multiple intermediate qubits () the intermediate qubits are entangled with each other. The or each entangled intermediate qubit () is then removed from entanglement.

Method and apparatus for selectively routing entanglement building

In carrying out a task that consumes data from a one-time pad, task inputs comprising at least first data and second data from the pad, are combined together to form an output from which the data used from the pad cannot be recovered without knowledge of at least one of the first and second data. The task concerned can be, for example, the encrypting of a message or the creating of an attribute verifier.

Method and device using one-time pad data

A method is provided of creating an end-to-end entanglement () between qubits in first and second end nodes () of a chain of optically-coupled nodes whose intermediate nodes () are quantum repeaters. Local entanglements () are created on an on-going basis between qubits in neighboring pairs in the chain through interaction of the qubits with light fields transmitted between the nodes. The quantum repeaters () are cyclically operated with their top-level operating cycles being synchronized. Once every top-level operating cycle, each repeater () initiates a merging of two entanglements involving respective repeater qubits that are at least expected to be entangled with qubits in nodes disposed in opposite directions along the chain from the repeater. A quantum repeater () adapted for implementing this method is also provided.

Quantum repeater and system and method for creating extended entanglements

A device is arranged to carry out security-related tasks using one-time pad data. The device has a memory for holding multiple one-time pads, each pad having a different security rating and being intended for use by the device in executing a task to that security rating. Provisioning of the pads with one-time pad data involves carrying out a process for obtaining new secret random data. This process has a security rating with the value of this rating varying according to the nature and parameters of the process concerned. The security rating of the process used to obtain the new secret random data is matched to that of the pad to be provisioned with one-time data, or the other way around, such that the security rating of the process is as least as good as that of the pad to be provisioned.

Device with multiple one-time pads and method of managing such a device

An iterative method is provided for progressively building an end-to-end entanglement between qubits in first and second end nodes () of a chain of nodes whose intermediate nodes () are quantum repeaters. At each iteration, a current operative repeater () of the chain merges an entanglement existing between qubits in the first end node () and the operative repeater, with a local entanglement formed between qubits in the operative repeater and its neighbor node towards the second end node (). For the first iteration, the operative repeater is the neighbor of the first end node (); thereafter, for each new iteration the operative repeater shifts one node further along the chain toward the second end node (). A quantum repeater adapted for implementing this method is also provided.

A QKD transmission apparatus comprises a GPS receiver module operable to receive a GPS signal, and a processor operable to use the GPS signal to derive a clock signal for transmission of a QKD signal.

Quantum key distribution method and apparatus

A photonic interconnect method avoids high capacitance electric interconnects by using optical signals to communicate data between devices. The method can provide massively parallel information output by mapping logical addresses to frequency bands, so that modulation of a selected frequency band can encode information for a specific location corresponding to the logical address. Wavelength-specific directional couplers, modulators, and detectors, which can be fabricated at defects in a photonic bandgap crystal, can be employed for the photonic interconnect method. The interconnect method can be used for both classical and quantum information processing.

Photonic interconnect method

A processing arrangement of a data communication apparatus is arranged to derive an ordered plurality of modulo-2 summations of respective selections of data bits of a binary data set. The data communication apparatus may either be transmitting apparatus with the processing arrangement serving to determine a target syndrome for subsequent use in error correction, or receiving apparatus with the data processing arrangement being arranged to effect error correction of received data. The processing arrangement effects its selections of bits from the binary data set in accordance with the interconnection of nodes in a logical network of nodes and edges that together define at least a continuum of cells covering a finite toroid. The structuring provided to bit selection by this continuum can be offset by randomness provided by other structures of the network and by the random association of bits of the binary data set with the nodes of the continuum.

Data processing arrangements for use in data communication apparatus in connection with error correction

Secret random data is distributed to a plurality of devices to provision them with new one-time pad data for use in interacting with apparatus holding the same one-time pad data. This distribution is effected by provisioning a first device with a block of secret random data that is, or will become, available to the apparatus. Part of the secret random data is then distributed from the first device to one or more other devices in a hierarchical distribution pattern headed by the first device. Each device, other than those at the bottom of the distribution hierarchy, retains part of the secret random data it receives and passes on the remainder. Each device uses that part of the secret random data it has retained to provide the device with new one-time pad data. A method is also provided for tracking service usage based on the distributed one-time pad data.

Method of provisioning devices with one-time pad data, device for use in such method, and service usage tracking based on one-time pad data

To identify errored bits in a binary data set, an ordered plurality of modulo-2 summations of respective selections of the data-set bits are compared with a target syndrome. The selections of data-set bits are defined by the connection of sum nodes to variable nodes in a logical network of nodes and edges where each variable node is associated with a respective data-set bit and each sum node corresponds to a respective modulo-2 summation. Any sum node for which the corresponding summation of selected data-set bits is found to be inconsistent with the target syndrome is identified as errored. Predetermined patterns of errored sum nodes are then looked for to identify one or more associated errored data-set bits. The identified errored data-set bits can then be flipped to correct them.

Error detection method and apparatus

In order to facilitate alignment of a QKD transmitter and QKD receiver, the transmitter is provided with a retro-reflector for returning to the receiver a photon beam originating at the latter. The transmitter is arranged to polarization modulate the retro-reflected beam. The transmitter is provided both with an intensity detector for generating an indication of retro-reflected photon intensity, and an intensity-dependent controller for controlling the QKD transmitter in dependence on the detected photon intensity. In one embodiment, this control involves aborting operation of the QKD transmitter upon an unexpectedly high photon intensity being detected; in another embodiment, the intensity indication is used to control the attenuation of the retro-reflected beam so as stabilize the average retro-reflected photon count per unit time.

QKD transmitter and transmission method

A quantum repeater includes a transmitter portion including a source, a set of matter systems, and an optical system. The source produces a probe pulse in a probe state having components with different photon numbers, and each matter system has at least one state that interacts with photons in the probe pulse to introduce a change in a phase space location of the probe state. The optical system can direct the probe pulse for interaction with one of the matter systems and direct light from the matter system for transmission on a first channel.

Quantum repeater

A quantum key distribution (QKD) system is provided that makes use of a quantum signal of polarized photons and comprises a QKD device and complimentary QKD apparatus. The QKD device has a QKD subsystem comprising one of a QKD transmitter and receiver for inter-working with a complimentary QKD receiver or transmitter of said apparatus. The device also has an alignment subsystem arranged to wirelessly interact with the QKD apparatus to enable generation of user feedback and/or adjustment signals for use in aligning the QKD transmitter and receiver such that the QKD transmitter is pointing at the QKD receiver and the polarization axes of the QKD transmitter and receiver are aligned.

Quantum key distribution apparatus and method

A device stores one-time pad data for use in carrying out various tasks. In order to preserve the ability to carry out important tasks that require the use of one-time data, use of the one-time pad data held by the device is controlled such that an amount of this one-time pad data is only usable by a predetermined set of important tasks comprising at least a replenishment task for replenishing the device with one-time pad data.

Method of managing one-time pad data and device implementing this method

Structures and methods allow: transfer of quantum information represented using the states of light to a representation using the states of matter systems; transfer of quantum information represented by the states of matter systems to a representation using the states of light; and error resistant encoding of quantum information using entangled states of matter and light to minimize errors.

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Stoke Gifford Bristol, United Kingdom

William John Munro