Abstract: The present invention relates to a method of performing a fractional quantum Fourier-Kravchuk transform (QKT), characterised in that input data sequence is encoded in quantum amplitudes of a d-level (qudit) state which is processed by a quantum gate implementing an exchange interaction, and the result is read out by means of quantum detectors located behind this device,The invention relates also to a device, in particular a quantum computer, configured to implement said method.

Abstract: A method (300) for generating random numbers including: mixing (304) a bright quantum state in a first mode with a vacuum input (15), in a two mode transformation for mixing the first mode and an orthogonal second mode; after mixing, detecting (306) the intensity in the first mode, and the second mode; generating random numbers (312) based on the difference between the detected intensity of the first mode and the second mode; and simultaneously to generating random numbers, certifying the numbers as random, based on the sum of the detected intensity of the first mode and the second mode, wherein certifying confirms that the process by which the random numbers are generated is quantum in origin and so the numbers are random.

Abstract: A de-multiplexer (1) for separating two co-propagating modes of electromagnetic radiation includes a volume (2) having a path therethrough for receiving electromagnetic radiation, an input (8) for directing two co-propagating modes of electromagnetic radiation to be incident upon the volume, a control source (12) of electromagnetic radiation arranged to generate a time-dependent control field. The volume is arranged and the time-dependent control field is shaped such that, when the two co-propagating modes of electromagnetic radiation and the time-dependent control field are incident upon the volume contemporaneously, the time-dependent control field causes the volume to accept one of the two modes of electromagnetic radiation onto a mode of the volume without any parametric non-linear optical interaction taking place and to reflect or transmit the other of the two modes of electromagnetic radiation, so to spatially and/or temporally separate the two modes of electromagnetic radiation from each other.

Abstract: A universal interferometer (100) for coupling modes of electromagnetic radiation according to a transformation has N inputs and N outputs for inputting and outputting N modes of electromagnetic radiation into and from the interferometer. Waveguides (101, 102, 103, 104, 105) pass through the interferometer to connect the N inputs to the N outputs and to carry the N modes of electromagnetic radiation. The waveguides provide crossing points between pairs of waveguides and a reconfigurable beam splitter (107) implements a reconfigurable reflectivity and a reconfigurable phase shift at each crossing point. The waveguides and crossing points are arranged such that each of the N modes of electromagnetic radiation is capable of coupling with each of the other modes of electromagnetic radiation at respective reconfigurable beam splitters.

Abstract: A de-multiplexer (1) for separating two co-propagating modes of electromagnetic radiation includes a volume (2) having a path therethrough for receiving electromagnetic radiation, an input (8) for directing two co-propagating modes of electromagnetic radiation to be incident upon the volume, a control source (12) of electromagnetic radiation arranged to generate a time-dependent control field. The volume is arranged and the time-dependent control field is shaped such that, when the two co-propagating modes of electromagnetic radiation and the time-dependent control field are incident upon the volume contemporaneously, the time-dependent control field causes the volume to accept one of the two modes of electromagnetic radiation onto a mode of the volume without any parametric non-linear optical interaction taking place and to reflect or transmit the other of the two modes of electromagnetic radiation, so to spatially and/or temporally separate the two modes of electromagnetic radiation from each other.

Abstract: A universal interferometer (100) for coupling modes of electromagnetic radiation according to a transformation has N inputs and N outputs for inputting and outputting N modes of electromagnetic radiation into and from the interferometer. Waveguides (101, 102, 103, 104, 105) pass through the interferometer to connect the N inputs to the N outputs and to carry the N modes of electromagnetic radiation. The waveguides provide crossing points between pairs of waveguides and a reconfigurable beam splitter (107) implements a reconfigurable reflectivity and a reconfigurable phase shift at each crossing point. The waveguides and crossing points are arranged such that each of the N modes of electromagnetic radiation is capable of coupling with each of the other modes of electromagnetic radiation at respective reconfigurable beam splitters.

Abstract: A universal interferometer (100) for coupling modes of electromagnetic radiation according to a transformation has N inputs and N outputs for inputting and outputting N modes of electromagnetic radiation into and from the interferometer. Waveguides (101, 102, 103, 104, 105) pass through the interferometer to connect the N inputs to the N outputs and to carry the N modes of electromagnetic radiation. The waveguides provide crossing points between pairs of waveguides and a reconfigurable beam splitter (107) implements a reconfigurable reflectivity and a reconfigurable phase shift at each crossing point. The waveguides and crossing points are arranged such that each of the N modes of electromagnetic radiation is capable of coupling with each of the other modes of electromagnetic radiation at respective reconfigurable beam splitters.

Abstract: A method (300) for generating random numbers including: mixing (304) a bright quantum state in a first mode with a vacuum input (15), in a two mode transformation for mixing the first mode and an orthogonal second mode; after mixing, detecting (306) the intensity in the first mode, and the second mode; generating random numbers (312) based on the difference between the detected intensity of the first mode and the second mode; and simultaneously to generating random numbers, certifying the numbers as random, based on the sum of the detected intensity of the first mode and the second mode, wherein certifying confirms that the process by which the random numbers are generated is quantum in origin and so the numbers are random.

Abstract: A universal interferometer (100) for coupling modes of electromagnetic radiation according to a transformation has N inputs and N outputs for inputting and outputting N modes of electromagnetic radiation into and from the interferometer. Waveguides (101, 102, 103, 104, 105) pass through the interferometer to connect the N inputs to the N outputs and to carry the N modes of electromagnetic radiation. The waveguides provide crossing points between pairs of waveguides and a reconfigurable beam splitter (107) implements a reconfigurable reflectivity and a reconfigurable phase shift at each crossing point. The waveguides and crossing points are arranged such that each of the N modes of electromagnetic radiation is capable of coupling with each of the other modes of electromagnetic radiation at respective reconfigurable beam splitters.

Abstract: A spectrometer for temporally separating electromagnetic radiation (10) includes a cavity (105) having first and second reflecting mirrors (1, 2, 4, 5). The first mirror (1, 2) has an aperture (8) arranged to allow electromagnetic radiation (10) to be input into the cavity (105). The spectrometer also includes an imaging device (3) between the first and second mirrors (1, 2, 4, 5) that defines an optical axis of the cavity (105) and performs spatial Fourier transforms of the electromagnetic radiation (10). The first and/or second mirrors (1, 2, 4, 5) has a normal that is arranged at a non-parallel angle to the optical axis, such that the position and/or angle of incidence of electromagnetic radiation (10) on the second mirror is shifted after each round trip.

Abstract: The invention provides a pulse measurement apparatus and corresponding method. The apparatus comprises: a splitter for splitting a pulse to be measured into two sub-pulses propagating along different beam paths; a non-linear medium, capable of up-conversion of radiation propagating therethrough, arranged in said beam paths; at least one element for interfering the up-converted pulses resulting from propagation of the two sub-pulses in the non-linear medium; and detection apparatus for detecting the result of the interference to obtain at least one of spectral and temporal characteristics of the pulse to be measured.

Abstract: The invention provides a pulse measurement apparatus and corresponding method. The apparatus comprises: a splitter for splitting a pulse to be measured into two sub-pulses propagating along different beam paths; a non-linear medium, capable of up-conversion of radiation propagating therethrough, arranged in said beam paths; at least one element for interfering the up-converted pulses resulting from propagation of the two sub-pulses in the non-linear medium; and detection apparatus for detecting the result of the interference to obtain at least one of spectral and temporal characteristics of the pulse to be measured.

Abstract: Pulse measurement for characterization of ultra-short optical pulses using spectral phase interferometry for direct electric field reconstruction (SPIDER) is enhanced by utilizing a plurality of spectral phase differences derived from the pulse and measured and frequency sheared replicas, which are temporally and/or spatially displaced, thereby providing spatial or temporal characterization or enhancing the temporal characterization of the input pulse in amplitude and phase. Improved interferometry which is not reliant on non-linear elements can be used.

Abstract: Amplitude and phase relative to an interferometrically established phase of ultrashort replica pulses (15) utilizes spectral phase interforemetry for direct electric field reconstruction by frequency shifting chirp replica pulses (16) of an optical pulse to be measured. The replicas of the pulses, relatively delayed in time, are generated by an interferometer (12).

Abstract: Pulse measurement for characterization of ultra-short optical pulses using spectral phase interferometry for direct electric field reconstruction (SPIDER) is enhanced by utilizing a plurality of spectral phase differences derived from the pulse and measured and frequency sheared replicas, which are temporally and/or spatially displaced, thereby providing spatial or temporal characterization or enhancing the temporal characterization of the input pulse in amplitude and phase. Improved interferometry which is not reliant on non-linear elements can be used.

Abstract: Dithered-edge sampling (DES) enables ultra-wideband measurement of terahertz pulses (far infrared electromagnetic pulses) using photoconductive antennas. The terahertz pulse is sampled by first passing it through a triggered photoconductive attenuator whose fast attenuation edge (limited only by the duration of the optical gating pulse) is dithered in time. A slow photoconductive receiver then measures the component of the terahertz electric field that is modulated at the dither frequency. The current through the photoconductive element constituting the receiver passes through a locking amplifier which may be operated at dither frequency. When used alone, the receiver blurs the measured terahertz pulse width. However, the increased time resolution provided by DES enables measurement of source-limited terahertz pulse widths. In addition, DES may be used to make direct measurements of a photoconductive receiver's temporal response.