Abstract: A holographic data storage system comprises an emitter system, a holographic recording medium, and an input waveguide network formed of one or more multimode optical waveguides. The holographic recording medium has multiple recording regions, each optically coupled to a corresponding one of multiple out-coupling regions of the input waveguide network, the holographic data storage system arranged to persistently write data of an input beam, received at any one of the out-coupling regions, to the corresponding recording region. A controller is coupled to at least one of the emitter system and at least one controllable guiding element of the input waveguide network and controls at least one optical characteristic of the input beam or the at least one guiding element, so as to guide the input beam from an in-coupling region to any selected one of the multiple out-coupling regions. Similar waveguide networks are provided for carrying reference and output beams.

Abstract: A system for estimating values of a vector of variables that optimize a function comprising a weighted sum of interactions between the variables; the system comprising a plurality of parallel hardware channels, each arranged to model a contribution of a respective variable to the function, each channel comprising: a signal generator configured to generate a signal modelling a value of the respective variable; a splitter arranged to supply the signal to each of the channels; interaction logic configured to multiply the vector of signals by a vector of weights modelling an interaction between the respective variable and the vector of variables, thereby generating a feedback signal representing the contribution of the respective variable; and a feedback path to return the feedback signal to the signal generator configured to adapt the signal in dependence on the feedback signal, wherein each channel is implemented only using optical components and/or analogue electronic components.

Abstract: A holographic data storage system comprises an emitter system, a holographic recording medium, and an input waveguide network formed of one or more multimode optical waveguides. The holographic recording medium has multiple recording regions, each optically coupled to a corresponding one of multiple out-coupling regions of the input waveguide network, the holographic data storage system arranged to persistently write data of an input beam, received at any one of the out-coupling regions, to the corresponding recording region. A controller is coupled to at least one of the emitter system and at least one controllable guiding element of the input waveguide network and controls at least one optical characteristic of the input beam or the at least one guiding element, so as to guide the input beam from an in-coupling region to any selected one of the multiple out-coupling regions. Similar waveguide networks are provided for carrying reference and output beams.

Abstract: An apparatus comprising: a crystal; a wire pair formed of a first wire connected so as to receive a first alternating current, and a second wire connected so as to receive a second alternating current substantially antiparallel to the first alternating current in the first wire, and located adjacent the first wire such that a localized electromagnetic filed is created in a region local to the wire pair via constructive electromagnetic interference between the first wire and the second wire in the region local to the wire pair and destructive electromagnetic field interference between the first wire and the second wire outside of the region local to the wire pair; and a colour centre located within the crystal in the region local to the wire pair.

Abstract: An apparatus comprising: a crystal; and a colour centre located within the crystal and adapted to receive: a magnetic field, such that a projection of the magnetic field onto a colour centre axis of the colour centre causes a change in an electron spin resonance frequency of the colour centre, and an electromagnetic signal having a frequency that substantially matches the electron spin resonance frequency of the colour centre as changed by the projection of the magnetic field onto the colour centre axis.

Abstract: An apparatus comprising a crystal; at least three first wires arranged substantially parallel to each other; at least two second wires arranged substantially parallel to each other, each second wire arranged non-parallel to each first wire, such that each second wire crosses each first wire, forming at least six cross points; and at least six colour centres, each colour centre located within the crystal adjacent a different one of the at least six cross points.

Abstract: A method of reading from a storage medium to recover a group of information sectors, each comprising a respective information payload. The medium stores redundancy data comprising a plurality of separate redundancy codes for the group, each code being a linear sum of terms, each term in the sum being the information payload from a different respective one of the information sectors in the group weighted by a respective coefficient of a set of coefficients for the redundancy code. The method comprises, after the redundancy data has already been stored on the medium: identifying a set of k? information sectors to be recovered; selecting k? of the redundancy codes; determining a square matrix E of the k? information sectors by the k? sets of coefficients of the selected codes; determining a matrix D being a matrix inverse of E; and recovering the k? information payloads from the inverse matrix D.

Abstract: A holographic data storage system comprises an emitter system, a holographic recording medium, and an input waveguide network formed of one or more multimode optical waveguides. The holographic recording medium has multiple recording regions, each optically coupled to a corresponding one of multiple out-coupling regions of the input waveguide network, the holographic data storage system arranged to persistently write data of an input beam, received at any one of the out-coupling regions, to the corresponding recording region. A controller is coupled to at least one of the emitter system and at least one controllable guiding element of the input waveguide network and controls at least one optical characteristic of the input beam or the at least one guiding element, so as to guide the input beam from an in-coupling region to any selected one of the multiple out-coupling regions. Similar waveguide networks are provided for carrying reference and output beams.

Abstract: A method of performing a write operation in a holographic data storage system, in which schedule schedules at least one write operation across multiple non-contiguous write intervals, the write operation pertaining to a set of data to be stored in a region of a holographic recording medium. In each of the non-contiguous write intervals, the region of the holographic recording medium is exposed to an interference pattern caused by interference between a reference beam and an input beam carrying the set of data. The multiple non-contiguous write intervals have a total aggregate duration of sufficient length to cause a persistent state change in the exposed region, such that the set of data is recoverable from that region by the end of a final write interval of the multiple non-contiguous write intervals.

Abstract: One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

Abstract: In an optical data transfer system, a beam modulator is configured to embed a set of data in an input beam. A multimode optical waveguide network has an in-coupling region for receiving the input beam. The multimode optical waveguide network is configured to guide the input beam to an out-coupling region of the multimode optical waveguide network. A spatial coherent detector is configured to measure a phase and an amplitude of an output optical field at multiple locations. The output optical field is at least partially defined by the input beam and thus exhibiting distortion effects caused by the passage of the beam through the multimode waveguide network. Signal processing is applied to an output of the spatial coherent detector, in order to compensate for the distortion effects, and thereby recover, from the output of the spatial coherent detector, the set of data embedded in the input beam.

Abstract: A method of reading from a storage medium to recover a group of information sectors, each comprising a respective information payload. The medium stores redundancy data comprising a plurality of separate redundancy codes for the group, each code being a linear sum of terms, each term in the sum being the information payload from a different respective one of the information sectors in the group weighted by a respective coefficient of a set of coefficients for the redundancy code. The method comprises, after the redundancy data has already been stored on the medium: identifying a set of k? information sectors to be recovered; selecting k? of the redundancy codes; determining a square matrix E of the k? information sectors by the k? sets of coefficients of the selected codes; determining a matrix D being a matrix inverse of E; and recovering the k? information payloads from the inverse matrix D.

Abstract: A multimode optical waveguide network comprises a parent waveguide and a plurality of child waveguides. Each waveguide is a multimode optical waveguide having a first surface region, multiple second surface regions, and at least one guiding element attached to a surface of the waveguide or embedded within the waveguide, each second surface region of the parent waveguide optically coupled to the first surface region of a corresponding child waveguide. The guiding element(s) of the parent waveguide is arranged to guide a beam, from or to its first surface region, to or from any selected second surface region of its multiple second surface regions. The guiding element(s) of each of the waveguides is configurable for selecting the second surface region of that waveguide and/or responsive to at least one beam characteristic for selecting the second surface region of that waveguide via modulation of the at least one beam characteristic.

Abstract: One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

Abstract: One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

Abstract: A server system comprising storage devices, processing devices and a storage fabric all operating according to a storage fabric protocol. The storage fabric comprises a plurality of individual switches having a modular design from which an overall switch is built, and the individual switches have individual respective configuration settings which determine which processing devices are allocated to use which of the storage devices. The system comprises an API enabling a software control function to configure the overall switch. The API is operable to receive from the control function an overall mapping of the storage devices to the processing devices instead of requiring the individual configuration settings of each of the individual switches to be specified by the control function, the API being configured to convert the overall mapping into the individual configuration settings of the individual switches to produce the overall mapping.

Abstract: One example provides a system for reading birefringent data. The system comprises one or more light sources, a first polarization state generator positioned to generate first polarized light from light of a first wavelength band output by the one or more light sources, a second polarization state generator positioned to generate second polarized light from light of a second wavelength band output by the one or light sources, an image sensor configured to acquire an image of the sample region via the first polarized light and the second polarized light, a polarization state analyzer disposed between the sample region and the image sensor, a first bandpass filter configured to pass light of the first wavelength band onto the image sensor, and a second bandpass filter configured to pass light of the second wavelength band onto the image sensor.

Abstract: Examples are disclosed that relate to encoding data on a data-storage medium. The method comprises obtaining a representation of a measurement performed on the data-storage medium, the representation being based on a previously recorded pattern of data encoded in the data-storage medium in a layout that defines a plurality of data locations. The method further comprises inputting the representation into a data decoder comprising a trained machine-learning function, and obtaining from the data decoder, for each data location of the layout, a plurality of probability values, wherein each probability value is associated with a corresponding data value and represents the probability that the corresponding data value matches the actual data value in the previously recorded pattern of data at a same location in the layout.

Abstract: Examples are disclosed that relate to reading stored data. The method comprises obtaining a representation of a measurement performed on a data-storage medium, the representation being based on a previously recorded pattern of data encoded in the data-storage medium in a layout that defines a plurality of data locations. The method further comprises inputting the representation into a data decoder comprising a trained machine-learning function, and obtaining from the data decoder, for each data location of the layout, a plurality of probability values, wherein each probability value is associated with a corresponding data value and represents the probability that the corresponding data value matches the actual data value in the previously recorded pattern of data at a same location in the layout.

Abstract: A server system comprising storage devices, processing devices and a storage fabric all operating according to a storage fabric protocol. The storage fabric comprises a plurality of individual switches having a modular design from which an overall switch is built, and the individual switches have individual respective configuration settings which determine which processing devices are allocated to use which of the storage devices. The system comprises an API enabling a software control function to configure the overall switch. The API is operable to receive from the control function an overall mapping of the storage devices to the processing devices instead of requiring the individual configuration settings of each of the individual switches to be specified by the control function, the API being configured to convert the overall mapping into the individual configuration settings of the individual switches to produce the overall mapping.