Abstract: According to an example aspect of the present invention, there is provided a method, comprising: receiving an input ordered set of transactions after a genesis block or a preceding compressed block in a chain of blocks, generating a compressed block on the basis of the input ordered set of transactions, wherein processing of the compressed block results to an equivalent final state as processing of the input ordered set of transactions, and providing the compressed block to a distributed network for establishing a new chain epoch and replacing a set of uncompressed blocks associated with the input ordered set of transactions.

Abstract: Apparatus, method, computer program product and computer readable medium are disclosed for trusted computing. A method comprising: at an isolated processor comprising a trusted execution environment and an isolated storage, receiving data encrypted with a first public key; decrypting the encrypted data with a first private key; performing calculation on the decrypted data by using an approved program; and providing the calculation result, wherein the approved program is authorized by a smart contract, a unique identifier of the smart contract is stored in the isolated processor, both the approved program and the isolated processor are verified by at least one participant of the smart contract, and the first public key and the first private key are generated by the isolated processor.

Abstract: Methods and apparatus for use in quantum cryptographic applications are disclosed. An optical signal having a first wavelength is encoded for quantum cryptography at a stage where the optical signal is on at least two signal paths. The wavelength of the encoded optical signal on the at least two signal paths is converted to a second wavelength before the optical signal is encoded for transmission. Encoding for transmission is applied to the optical signal on the second wavelength.

Abstract: According to an example aspect of the present invention, there is provided an apparatus comprising at least one memory configured to store positioning information, and at least one processing core configured to determine a position estimate for the apparatus based at least in part on the positioning information and on at least one direction of a steerable optical beam, the steerable optical beam being steerable by the apparatus.

Abstract: An apparatus may include an optical combiner configured to combine a first optical beam having an adjusted first polarization with a second optical beam having an adjusted second polarization into an output beam having a third polarization. The third polarization may be a linear combination of the adjusted first polarization and the adjusted second polarization. Information may be communicated by adjusting the polarization according to an information source.

Abstract: According to an example aspect of the present invention, there is provided an apparatus comprising a first and a second polarization beam splitter-rotator (140, 142), together arranged to split two incoming polarization encoded qubits into four first optical modes, the apparatus being configured to align polarizations of the four first optical modes, an interferometer stage (150) configured to obtain, from the four first optical modes, four second optical modes, and four detectors (160) arranged to receive at least one of the four second optical modes.

Abstract: For secure wireless communications the sender device uses a rail encoder that outputs dual rail-encoded states of light in a time slot. The states of light dual rail-encode information according to a phase and/or intensity difference between the dual rails, and the rail-encoded states of light may further be converted to a polarization-encoded state. This may be implemented using at least two polarizing beam-splitters with at least one quarter-wave plate disposed therebetween; and/or with integrated waveguides that convert three optical inputs to two optical outputs that are input to a polarization rotator-combiner. The encoder may randomly define the polarization-encoded state such as by randomly selecting from a finite number of at least N=3 possible polarization rotations. The recipient device may use 2N parallel channels to decode the dual rail-encoded states of light, each channel comprising a detector configured to detect one of N possible polarization states.

Abstract: A method including: generating a first comb optical signal; generating a second comb optical signal; exciting a sample using in combination the first comb optical signal and the second comb optical signal; and detecting at the sample an acoustic response of the sample.

Abstract: In respect of first virtual reality content of a scene captured by a first virtual reality content capture device and second virtual reality content of the same scene captured by a second virtual reality content capture device, the first and second virtual reality content capture devices physically arranged within a predetermined distance of one another in the same scene when the first virtual reality content and the second virtual reality content was captured; provide for display, in virtual reality, of an amalgamated virtual reality space representative of the scene, the amalgamated virtual reality space comprising an amalgamation of both the images or parts thereof of the first virtual reality content and the images or parts thereof of the second virtual reality content.

Abstract: According to an example aspect of the present invention, there is provided an apparatus (201) comprising adjustable optical equipment (290), a position sensitive photodetector (280), at least one light emitter (220), and control circuitry (104) configured to cause the light emitter (220) and the adjustable optical equipment (290) to output from the apparatus (201) a divergent beam of light, to determine a location of a light signal on the position sensitive photodetector (280) and to cause at least one of the at least one light emitter (220) and the adjustable optical equipment (290) to output from the apparatus (201) a collimated beam of light to a direction selected based at least in part on the location of the light signal on the position sensitive photodetector (280).

Abstract: A technique, comprising: receiving at a node of a distributed ledger network one or more vehicle route requests shared among nodes of the distributed ledger network; computing one or more route solutions for said one or more vehicle route requests; and sharing said one or more route solutions with other nodes of said distributed ledger network, for establishing a consensus route solution for one or more of said one or more vehicle route requests.

Abstract: According to an example aspect of the present invention, there is provided an apparatus comprising a phase modulator configured to modify a phase of light incoming into the phase modulator, to generate phase-encoded light, a dual rail encoder configured to modify the phase-encoded light in dependence of a control signal, to thereby impart a polarization rotation compensation into the phase-encoded light, and a polarization rotator combiner coupled to the dual rail encoder, configured to convert dual rail light from the dual rail encoder into polarization encoded light, wherein the apparatus is arranged to transmit the polarization encoded light.

Abstract: An apparatus including a display; a single pixel detector; and a beam splitter. The beam splitter is located relative to the display and the single pixel detector to allow a projected image from the display to pass through the beam splitter and direct a reflected image from an eye to the single pixel detector, where the reflected image is based at least partially upon the projected image.

Abstract: In accordance with an example embodiment of the present invention, there is provided an apparatus comprising a dual-rail encoder (120) configured to receive light from a light source and to output dual-rail encoded light, a combiner (130) configured to convert the dual-rail encoded light into polarization encoded light, and at least one processing core configured to obtain compensation adjustment information concerning a fiber (145) and to control the dual-rail encoder (120) based at least in part on the compensation adjustment information.

Abstract: According to an example aspect of the present invention, there is provided an apparatus comprising at least one memory configured to store positioning information, and at least one processing core configured to determine a position estimate for the apparatus based at least in part on the positioning information and on at least one direction of a steerable optical beam, the steerable optical beam being steerable by the apparatus.

Abstract: According to an example aspect, there is provided an apparatus comprising a fibre interface coupled, via a first waveguide, with at least one encoder, a controller configured to cause the at least one encoder to encode light received in the apparatus via the fibre interface with information, and to cause a frequency shift in the light, and wherein the apparatus is configured to cause the light to propagate back to the fibre interface.

Abstract: Methods and apparatuses, including computer program code are disclosed. The apparatus may include at least one processor and at least one memory including computer program code. The at least one processor, the at least one memory, and the computer program code may be configured to cause the apparatus to generate a divergent beam for an optical source that is coincident with a divergent beam for an optical detector. The apparatus may determine an adjustment to a mirror to cause an optical alignment of an incoming beam with the optical detector based on at least an optical intensity across the optical detector, wherein the alignment is with respect to at least another apparatus. The apparatus may adjust a position of the mirror according to the determined adjustment, and change the divergent beam to a collimated beam to enable optical communications with the other apparatus via the collimated beam.

Abstract: A light input is divided into a plurality of light outputs by a structure comprising a first beam splitter configured to divide the light input into a first part and a second part, a first polarization beam splitter configured to provide from the first part a first polarized part and a second polarized part, wherein the first polarized part is for providing a first output and the second polarized part for providing a second output, at least one polarization altering device configured to alter the polarization of light in the second part, and at least one second polarization beam splitter configured to receive light altered by respective at least one polarization altering device and provide therefrom at least one third polarized part for providing at least one third output. A light output can be generated based on similar principles in reverse.

Abstract: According to an example aspect, there is provided an apparatus comprising a first optical converter coupled to a fibre interface and to two waveguides, a dual rail encoder configured to encode dual rail form light from the two waveguides with payload information, and wherein the dual rail encoder is coupled to the first optical converter or to a second optical converter disposed between the dual rail encoder and the fibre interface, and wherein the first optical converter or the second optical converter is coupled so as to provide polarization encoded light into the fibre interface.

Abstract: Adjustment of an optical component of a device includes determining of at least one derivative of coupling efficiency of the optical component as a function of parameters used for control of a steering function of the optical component. At least one oscillating component is induced into the parameters for the determining. The adjustment of the optical component is based on the determined at least one derivative.