Abstract: A detection system for monitoring the intensity of a stream of modulated pulses, the system comprising a controller configured to provide a control signal to a component outputting modulated pulses the control signal controlling the level of modulation for each pulse exiting the component and a detector configured to measure the intensity of the pulses in the stream of pulses exiting the component outputting modulated pulses, wherein the detector comprises a gated detector, the controller being configured to send a gating signal to said detector, wherein said gating signal varies the gain of the detector with the control signal, such that pulses with a selected modulation level can be detected.

Abstract: An interference system, comprising: an interference apparatus, configured such that input light pulses interfere at an interference component; wherein the input of said interference apparatus is provided by a phase-randomised light source, said phase-randomised light source comprising: at least one slave light source; at least one master light source configured to intermittently generate master light pulses such that the phase of each master light pulse has a random relationship to the phase of each subsequently generated master light pulse, further configured to supply said master light pulses to the slave light source; and a controller, configured to apply a time varying drive signal to said at least one slave light source such that just one slave light pulse is generated during each period of time for which a master light pulse is received, such that the phase of each slave light pulse has a random relationship to the phase of each subsequently generated slave light pulse.

Abstract: A transmitter for a quantum communication system, the transmitter comprising an interferometer, the interferometer having a first path with a phase modulator and a second path configured such that light pulses entering the interferometer follow either the first path or the second path, the output of the first and second paths being combined, the transmitter further comprising an optical filter positioned such that photons exiting the interferometer pass through the optical filter, the optical filter being configured to restrict the frequency range of pulses passing through the optical filter and temporally broaden the pulses.

Abstract: A photon source comprising a semiconductor heterostructure, said semiconductor heterostructure comprising a quantum well, a barrier region adjacent said quantum well and a quantum dot provided in said quantum well, the photon source further comprising electrical contacts and a power supply coupled to first and second electrical contacts configured to apply a tuneable electric field across said quantum dot to control the emission energy of said quantum dot, said electric field being tuneable across an operating range an wherein the tunneling time of carriers from said quantum dot to said first electrical contact and the tunneling time of carriers from said quantum dot to said second electrical contact are greater than the radiative decay time of an exciton in said quantum dot over said operating range for controlling the emission energy, said photon source being configured such that emission from a single quantum dot exits said photon source.

Abstract: A random number generation system, comprising: a light source configured to generate light pulses and a driving unit configured to drive said light source such that the phase of each light pulse has a random relationship to the phase of each subsequently generated light pulse, and such that each light pulse is generated with at least two local maxima in the temporal intensity profile.

Abstract: A photon source comprising a quantum structure capable of defining one or more quantum levels such that a photon may be emitted from the quantum structure due to a transition between at least two quantum levels, a control signal configured to vary the transition energy, the transition energy being the energy separation between the at least two quantum levels; and a laser input beam configured to irradiate the quantum structure, the control signal being configured to bring the transition energy into resonance with the laser input beam and out of resonance with the laser input beam, such that the transition energy is resonant with the energy of the laser input beam for a time less than the time to output two photons from the transition.

Abstract: An apparatus for use in assessing strength of at least one knee flexor muscle of a subject, the apparatus including a support, two securing members, each securing member securing a respective lower leg of the subject in a position that in use is substantially fixed relative to the support and at least one sensor, which in use senses a force indicative of the strength of the at least one knee flexor muscle in at least one leg of the subject while the subject performs an eccentric contraction of the at least one knee flexor muscle.

Abstract: An optical device, comprising an optical component, configured to produce optical amplification; a component configured to intermittently supply coherent light to said optical component; and a controller, configured to apply a time varying signal to said optical component such that a plurality of light pulses are emitted during each period of time that said coherent light is received, wherein the plurality of light pulses emitted during each period have a fixed phase relation.

Abstract: A quantum communication system including a sending unit and a receiving unit, said sending unit comprising a photon source assembly configured to output a stream of pulses of light having at least two different intensities and a memory configured to store information for determining which pulses should be reference pulses and which pulses should be data pulses, the average intensity of reference pulses being different to the average intensity of data pulses, the receiving unit comprising a memory for storing information for identifying the position of reference pulses within the stream of pulses and a processor for determining the calibration of the quantum communication system from the reference pulses.

Abstract: A photon detection system including a photon detector configured to detect single photons, a signal divider to divide the output signal of the photon detector into a first part and a second part, wherein the first part is substantially identical to the second part, a delay mechanism to delay the second part with respect to the first part, and a combiner to combine the first and delayed second parts of the signal such that the delayed second part is used to cancel periodic variations in the first part of the output signal.

Abstract: One exemplary embodiment can be a method of modifying an alkylation unit to increase capacity. The method may include combining a first alkylation zone with a second alkylation zone. Generally, the first alkylation zone includes a first settler having a height and a width. Typically, the width is greater than the height. In addition, the second alkylation zone may have a second settler having a height and a width. Usually, the height is greater than the width.

Abstract: An example embodiment involves a method for adjusting an operating parameter of a node in an optical network which comprises a plurality of nodes, the method comprising the steps of: measuring at the node a value of at least one characteristic associated with the operating parameter of the node; distributing the value of the characteristic to all of the other nodes in the network; receiving at the node the value of the characteristic for all of the other nodes in the network; deriving at the node optical impairment data for each link of the network based on the received values of the characteristic for all of the nodes; calculating at the node the preferred value of the operating parameter for each node based on the derived optical impairment data; and adjusting the operating parameter of the node based on the calculated preferred value for the node.

Abstract: One exemplary embodiment can be a method for altering an operation of an alkylation unit during a process upset. The method may include blocking an outlet of a settler to a separation zone, and recycling at least a portion of a hydrocarbon stream to the separation zone to prevent an uncontrolled pressure rise in one or more distillation columns during shutdown of an alkylation reactor.

Abstract: A quantum memory component including a quantum dot molecule having first and second quantum dots provided in respective first and second layers separated by a barrier layer; an exciton comprising an electron and hole bound state in said quantum dot molecule, the spin state of said exciton forming a qubit; first and second electrical contacts respectively provided below the first quantum dot and above the second quantum dot; a voltage source to apply an electric field across said quantum dot molecule; a controller to modulate the electric field across the quantum dot molecule, including an information acquiring circuit to acquire information concerning the relationship between fine structure splitting of the exciton and the applied electric field and a timing circuit to allow switching of the exciton from an indirect configuration to a direct configuration at predetermined times derived from the fine structure splitting.

Abstract: A signal manipulator, comprising: an input for multiplexed signal, a demultiplexer for separating the multiplexed signal into separate components, a retransmitter unit being configured to receive a first component from the separated components and retransmit said received first component at a higher power than it is received; a bypass channel being configured to receive a second component from the components separated by the demultiplexer; and a multiplexer for multiplexing the first and second components, wherein the retransmitter is configured to regulate the power of the first component such that the power of the multiplexed signal leaving the multiplexer is ?5 dBm or less.

Abstract: A photon detection system including a photon detector configured to detect single photons, a signal divider to divide the output signal of the photon detector into a first part and a second part, wherein the first part is substantially identical to the second part, a delay mechanism to delay the second part with respect to the first part, and a combiner to combine the first and delayed second parts of the signal such that the delayed second part is used to cancel periodic variations in the first part of the output signal.

Abstract: A photon detection system including: an avalanche photodiode; a biasing circuit configured to reverse bias the avalanche photodiode; a first measuring circuit configured to measure avalanche events occurring in the avalanche photodiode as a transient current due to photon absorption; and a second measuring circuit configured to measure the bias current flowing through the avalanche photodiode.

Abstract: A photon detection system is provided comprising a photon detector, configured to detect photons during intervals when in a receiving state and to output a signal when a photon is received, a controller, configured to generate a time varying gating signal wherein said gating signal switches said detector between the receiving state and a non-receiving state, said controller being configured to receive and process information relating to the times photons are expected to arrive at said detector, the controller being configured to generate the gating signal such that the photon detector is in the receiving state for intervals when photons are expected and also in the receiving state for additional intervals between the intervals when the photons are expected; a detection module, configured to distinguish between when the output signal from the photon detector corresponds to an interval when photons are expected and said additional intervals.

Abstract: A photon detection system comprising an avalanche photodiode and a voltage source for said avalanche photodiode, wherein said avalanche photodiode comprises Silicon or its heterostructures and wherein said voltage source is configured to bias said avalanche photodiode with a voltage component which is static with respect to time and a voltage component which varies with time.

Abstract: A photon detection system including a photon detector configured to detect single photons, the photon detector being gated such that it produces a periodic output signal and the gating signal having a frequency of at least 50 MHz. The system further includes a combiner for combining the signal from one period with signals from other periods such that periodic variations in the output signal of the detector are suppressed.