Abstract: A method and system for encrypted messaging includes first and second client devices and a quantum key device having a quantum random number generator. The generator provides a first quantum random signal, and the key device provides a symmetric first master key from the first quantum random signal. The master key is transmitted to the first client device and stored. The key device uses the master key to generate an encrypted package by encrypting one of a plurality of keys. The key device generates a second encrypted package. The first pairing key is provided to the first client device by decrypting the first encrypted package using the first master key and providing the first pairing key in the second client device by decrypting the second encrypted package using the second master key to establish an encrypted connection between the first and second client devices.

Abstract: A method for driving a quantum computational network for determining an extremal value of a cost function for solutions of a quadratic unconstrained binary optimization problem includes initializing qubits, sequentially applying layers of quantum gates to the qubits, determining an output state of the quantum computational network for obtaining a solution associated with the set of variational parameters {right arrow over (?)}, and determining an output state for shifted variational parameters {right arrow over (?)}* to evaluate a partial derivative with respect to the subset of the variational parameters {right arrow over (?)} for determining a gradient of the cost function based on the output state for the shifted variational parameters {right arrow over (?)}*, and by updating the variational parameters {right arrow over (?)} based on an update function of a moving average over the gradient of the cost function and of a moving average over the squared gradient of the cost function.

Abstract: A computer-implemented method for simulating fluid flow includes solving a Lattice Boltzmann equation for a distribution function, wherein the distribution function is represented in a tensor-train format, and/or all operations carried out for computing the distribution function are carried out with the distribution function in the tensor-train format, the distribution function and/or the tensor train format comprising at least one tensor train, the tensor train having at least one tensor train core.

Abstract: A superconducting qubit circuit and a method of forming a superconducting qubit include superconducting qubit, wherein the superconducting qubit comprises a tunnel junction in a superconducting material having a critical temperature above 1.2 K. The tunnel junction is formed by a disorder-induced tunnel barrier, wherein the disorder is created by spatial crystallographic defects in the superconducting material.

Abstract: A method for quantum key distribution includes generating an encoder initial bit sequence; generating a quantum signal comprising optical pulses by modulating an intensity profile of the optical pulses according to an intensity function depending on a time and on a first encoder value of at least one first bit of the encoder initial bit sequence, and/or modulating a phase profile of the optical pulse according to a phase function which depends on a time and a second encoder value of at least one second bit of the encoder initial bit sequence; transmitting the plurality of optical pulses to a receiver device via a quantum channel; and determining a shared key shared between the transmitter device and the receiver device from the encoder initial bit sequence by classical post-processing and at least one of transmitting classical information to the receiver device and receiving further classical information from the receiver device.

Abstract: A waveguide device comprises a substrate comprising an electro-optical material; a waveguide formed in the electro-optical material; and a plurality of electrodes formed in a vicinity of the waveguide. The electro-optical material has a first refractive index. The waveguide comprises a plurality of tracks. The tracks comprise a second refractive index smaller than the first refractive index, are parallel to each other with a common direction defining a direction of the waveguide, and form an arrangement in a plane perpendicular to the direction of the waveguide. The arrangement comprises at least 40 equilateral triangles of identical side lengths, wherein all three corners of each of the equilateral triangles each coincide with a different track of the plurality of tracks in the plane perpendicular to the direction of the waveguide.

Abstract: A field effect transistor has a negative capacitance gate structure. The field effect transistor comprises a channel and a gate dielectric arranged over the channel. The negative capacitance gate structure comprises a bottom electrode structure comprising a bottom electrode, a multi-domain structure, and a top electrode structure. The multi-domain structure comprises a multi-domain element arranged over the bottom electrode, the multi-domain element comprising a plurality of topological domains and at least one topological domain wall. The top electrode structure comprises a top electrode arranged over the multi-domain element. At least a section of the bottom electrode structure of the negative capacitance gate structure is arranged over the gate dielectric and adapted to be coupled to the channel through the gate dielectric.

Abstract: A system and method for determining a secret crypto-graphic key shared between a sending unit and a receiving unit for secure communication includes obtaining, by the sending unit, a random bit sequence, and transmitting, at the sending unit, a first sequence of electromagnetic pulses to the receiving unit via a communication channel, wherein each electro-magnetic pulse of the first sequence of electromagnetic pulses corresponds to a bit of the random bit sequence according to a ciphering protocol, the signal loss is determined in the communication channel caused by an eavesdropper, and an information advantage is estimated over the eavesdropper based on the determined signal loss. Privacy amplification is performed based on the estimated information advantage in order to establish a shared secret crypto-graphic key.

Abstract: A varistor device for voltage-surge-protecting an electronic circuit at a cryogenic temperature comprises an electric lead composed of a superinsulator material, and electrical contact elements. The electrical contact elements are for connecting different positions along the electric lead to the electronic circuit. The electrical contact elements are in electric contact with the electric lead at the different positions along the electric lead. The electric lead is adapted to provide a superinsulating state or a cooper-pair insulating state at the cryogenic temperature, and to provide a non-linear resistance between the different positions at the cryogenic temperature.

Abstract: A system and method for determining a secret cryptographic key shared between a sending unit and a receiving unit by using a communication channel comprising spatially separated amplifiers for secure long-distance communication includes transmitting a sequence of electromagnetic pulses via the communication channel through the amplifiers for establishing a shared secret cryptographic key, wherein each electromagnetic pulse corresponds to a bit of a random bit sequence according to a ciphering protocol, and at least one ciphering parameter is determined by maximizing the expected key generation rate using an information theory model, wherein a measured signal loss and at least one amplification parameter are taken into account as input parameters to the information theory model.

Abstract: An electronics device comprises a substrate, a first layer of a first layered material arranged over the substrate, a second layer of a second layered material arranged over the substrate, an overlap region, and a contact layer. In the overlap region, the second layer is arranged over the first layer, and a section of a bottom surface of the second layer is parallel to a section of a top surface of the first layer. The contact layer comprises a plurality of electrically conductive lines and an electrical insulation element. The plurality of electrically conductive lines comprises a first electrically conductive line and a second electrically conductive line. The first electrically conductive line and/or the second electrically conductive line comprises a superconductor material.

Abstract: A method for determining a preimage element of a cryptographic hash function includes providing an output value of a cryptographic hash function and hash function operations of the cryptographic hash function; for each of the hash function operations, determining at least one hash function relation, comprising an equation and/or an inequality; determining an optimization problem comprising: the output value, at least one constraint assigned to an iteration of the cryptographic hash function, and optimization variables comprising internal state variables of the cryptographic hash function and at least one preimage variable, wherein the at least one constraint is determined from the at least one hash function relation and comprises preceding internal state variables assigned to a preceding iteration; and solving the optimization problem and determining a preimage element of the cryptographic hash function from an optimizing value of the at least one preimage variable.

Abstract: A method for determining a cryptographic key is carried out in a data processing system, and comprises: providing a plaintext and a ciphertext determined from the plaintext using a cryptographic key and a cryptographic procedure which comprises cryptographic operations; for each cryptographic operation of the cryptographic procedure, providing at least one intermediate relation which comprises an intermediate equation and/or an intermediate inequality; determining an optimization problem comprising: the plaintext and the ciphertext; at least one optimization expression assigned to a round of the cryptographic procedure; and optimization variables comprising state variables of the cryptographic procedure and a cryptographic key variable; wherein the at least one optimization expression is determined from the at least one intermediate relation and comprises at least one preceding state variable assigned to a preceding round.

Abstract: A system and method for encoding a dataset in a quantum circuit for quantum machine learning in a system includes providing a dataset comprising a plurality of input features; for each input feature of the plurality of input features, applying the plurality of encoding quantum gates on one quantum bit (qubit) or a plurality of qubits, wherein each of the plurality of encoding quantum gates rotates the one qubit or the plurality of qubits by a rotation angle which is proportional to the input feature and one of a plurality of scaling factors, each of the plurality of encoding quantum gates is assigned a different one of the plurality of scaling factors, and the plurality of scaling factors comprises powers of two; applying the plurality of variational quantum gates; determining a plurality of measurement values for the qubit; adjusting the quantum circuit; and determining output data.

Abstract: A method for training a hybrid quantum-classical computation system for approximating a labeling function for an input feature vector, the system comprising a variational quantum circuit, a machine learning model, and a labeling module configured to receive a first output generated by the variational quantum circuit and a second output generated by the machine learning model and to generate an output label, wherein the method comprises an iterative process comprising providing an input feature vector of the sample dataset, providing the first output and the second output to the labeling module, and determining a parameter update of the variational parameters, the machine-learning parameters, and the trainable combination parameters based on a value of a cost function for the output label for the input feature vector.

Abstract: A method for quantum key distribution includes determining a ratio between a target maximum gain and a target operating gain of an optical amplifier; determining an active fiber section length such that the optical signals with a target maximum signal power are amplified with at most the target maximum gain; determining an operating pumping power of a pumping device below the maximum pumping power such that the optical signals are amplified with a target operating gain according to the determined ratio between the target maximum gain and the target operating gain; and determining a shared key between a first data processing device and a second data processing device by quantum key distribution comprising amplifying the optical signals via the optical amplifier by operating the pumping device at the operating pumping power.

Abstract: A system or a method for optical signal amplification includes determining a target operating gain of an optical amplifier; determining a target maximum gain of the optical amplifier; determining an active fiber section length such that the optical signals are amplified with at most the target maximum gain; determining a core cross-sectional area size of the active fiber section based on a maximum allowable pulse shape distortion and a target maximum energy per pulse such that high-energy pulses with the target maximum energy per pulse are distorted by at most the maximum allowable pulse shape distortion; and determining an operating pumping power of the pumping device below the maximum pumping power such that the optical signals are amplified with the target operating gain.

Abstract: A laser system suitable for modification of a calcified blood vessel includes a laser source; a feedback controller configured to regulate a dosimetry of the laser source to produce spatially and/or temporally modulated laser light; a catheter comprising a first optical delivery element, the first optical delivery element configured to guide the modulated laser light to an in-vivo object in the blood vessel; and a detecting element, configured to detect one or more physical, chemical, mechanical and/or dimensional characteristics of an area of the in-vivo object in real-time, wherein the feedback controller is configured to process the real-time detected information pertaining to the one or more physical, chemical, mechanical and/or dimensional characteristics of the area in real-time, wherein the feedback controller is further configured to regulate the dosimetry of the laser source for a controlled formation of a porous structure and/or a zone of denaturized tissue in the in-vivo object.

Abstract: A ferroelectric nanoparticle capacitor-device comprises a pair of conductive elements electrically insulated from each other, and ferroelectric nanoparticles arranged between the conductive elements of the pair. The ferroelectric nanoparticles are adapted to provide at least three polarization states with different total ferroelectric polarizations.

Abstract: A ferroelectric nanoparticle capacitor-device comprises a pair of conductive elements electrically insulated from each other, and ferroelectric nanoparticles arranged between the conductive elements of the pair. The ferroelectric nanoparticles are adapted to provide at least three polarization states with different total ferroelectric polarizations.