摘要:
A system is disclosed in which a plurality of devices are arranged to use one-time pad data to interact with apparatus holding the same one-time pad data. Each of the devices and the apparatus has its own one-time pad and the pads are all provisioned with the same new one-time pad data. Upon any one of the devices wishing to effect an interaction with the apparatus using one-time pad data, an alignment operation is carried out between a set of entities comprising at least the apparatus and the device wishing to carry out the interaction. The alignment operation serves to reduce the level of the one-time pad of at least the device wishing to carry out the interaction, to the level of the lowest one-time pad of the set of entities involved in the alignment operation.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
An iterative method is provided for progressively building an end-to-end entanglement between qubits in first and second end nodes (91, 92) of a chain of nodes whose intermediate nodes (90) are quantum repeaters. At each iteration, a current operative repeater (90) of the chain merges an entanglement existing between qubits in the first end node (91) and the operative repeater, with a local entanglement formed between qubits in the operative repeater and its neighbor node towards the second end node (92). For the first iteration, the operative repeater is the neighbor of the first end node (91); thereafter, for each new iteration the operative repeater shifts one node further along the chain toward the second end node (92). A quantum repeater adapted for implementing this method is also provided.
摘要:
QKD receiving apparatus is provided with an alignment-correction system for correcting misalignment of a quantum signal received at an optical port of the apparatus relative to a quantum-signal detector of the receiving apparatus. The alignment-correction system comprises a misalignment measuring subsystem for making multiple different misalignment measures, and a misalignment compensation subsystem for adjusting the relative alignment of the quantum signal and quantum-signal detector in dependence on the misalignment measures made. The misalignment measuring subsystem comprises an alignment-beam source, an alignment-beam detector arrangement, and optical components for guiding an alignment beam from the alignment-beam source to the optical port, and for guiding the alignment beam, after external retro-reflection at a cooperating QKD transmitting apparatus from the optical port to the alignment-beam detector arrangement.
摘要:
An iterative method is provided for progressively building an end-to-end entanglement between qubits in first and second end nodes (91, 92) of a chain of nodes whose intermediate nodes (90) are quantum repeaters. At each iteration, a current operative repeater (90) of the chain merges an entanglement existing between qubits in the first end node (91) and the operative repeater, with a local entanglement formed between qubits in the operative repeater and its neighbour node towards the second end node (92). For the first iteration, the operative repeater is the neighbour of the first end node (91); thereafter, for each new iteration the operative repeater shifts one node further along the chain toward the second end node (92). A quantum repeater adapted for implementing this method is also provided.
摘要:
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.
摘要:
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.
摘要:
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.