Abstract: A system and method for determining a nuclear magnetic resonance relaxation time of a probe includes polarizing first nuclei and second nuclei by applying a longitudinal static magnetic field to the probe, exchanging the polarizations of the first nuclei and the second nuclei by irradiating a swap sequence of transverse magnetic field pulses, transversely magnetizing the second nuclei by irradiating at least one excitation pulse and measuring the resulting magnetization signal of the second nuclei, and determining the nuclear magnetic resonance relaxation time of the second nuclei based on the measured magnetization signal of the second nuclei.

Abstract: A system and method incudes generating a first target cryptocurrency key pair and a corresponding first target cryptocurrency address. A first cryptocurrency asset is transferred from to the first target cryptocurrency address employing a first cryptocurrency protocol, while providing a first password in a first user device and first user data assigned to a first user with a first vault asset corresponding to the at least one first cryptocurrency asset. The first password is transmitted from the first device to the server employing a first quantum key distribution protocol. Upon verification of the first key, a second vault asset is removed from the first user data, and a second target cryptocurrency key pair and a corresponding second target cryptocurrency address of a second cryptocurrency asset corresponding to the second vault asset are transmitted from the server to the first user device employing the first quantum key distribution protocol.

Abstract: A method for determining a quantum communication setup includes providing a component set indicative of a quantum communication setup comprising quantum communication components; selecting an action of a set of actions each indicative of a further quantum communication component; including the selected further quantum communication component in the component set; determining, from the component set, a quantum model; determining, from the component set and the quantum model, a maximum key rate by optimizing over an optimization parameter set comprising quantum communication component parameters; adjusting the reward value depending on the size of the maximum key rate in relation to a previous maximum key rate; and iteratively repeating the above steps until a termination criterion is satisfied, yielding an optimal component set and an optimal setup parameter set.

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 high-temperature superconducting qubit implements a quantum mechanical two-level system. The high-temperature superconducting qubit comprises a first superconductor, a second superconductor, and an overlap region. The first superconductor comprises a first high-temperature superconductor material. The second superconductor comprises a second high-temperature superconductor material. In the overlap region, at least a first section of the first surface and at least a second section of the second surface overlap, the first section and the second section are arranged in parallel at a distance corresponding to a predefined distance, and the first orientation and the second orientation are arranged with an angle corresponding to a predefined angle. The high-temperature superconducting qubit comprises a Josephson junction between the first high-temperature superconductor material and the second high-temperature superconductor material.

Abstract: A method for converting physiological signals includes: obtaining a first signal as a function of a time parameter, wherein the first signal represents electrocardiogram data; obtaining a second signal as a function of the time parameter, wherein the second signal represents physiological data different from the electrocardiogram data; mixing the first signal and the second signal to obtain a mixed signal; and generating a frequency spectrum pertaining to the mixed signal.

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: The invention relates to a method for determining the component of a magnetic field in a predetermined direction. The method comprises preparing a quantum system in a coherent superposition state (S1), letting the quantum system evolve for a delay time period (S2) and performing a readout operation and a projective measurement on the quantum system (S3). The steps (S1, S2, S3) are iteratively repeated in an iteration loop, wherein the delay time period increases linearly by the same time increment after each iteration. The method further comprises determining the component of the magnetic field in the predetermined direction according to the outcome of the projective measurements (S4).

Abstract: A method employs a device with a heterostructure as a resonator for electrons of an electrical circuit or for a terahertz electromagnetic wave. The heterostructure comprises at least one dielectric layer and at least one ferroelectric layer. The at least one ferroelectric layer comprises a plurality of ferroelectric polarization domains. The plurality of ferroelectric polarization domains forms a polarization pattern. The polarization pattern is adapted to perform an oscillation with a resonance frequency in a terahertz frequency range. The method comprises functionally coupling the oscillation of the polarization pattern and an oscillation of the electrons of the electrical circuit or of the terahertz electromagnetic wave by the device.

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: A system and method for quantum key distribution includes determining an intrinsic loss along a quantum channel; generating a pulse sequence; transmitting the pulse sequence via the quantum channel; receiving the pulse sequence; determining invalid signal positions and providing the invalid signal positions; determining a first reconciled signal from the first signal and the invalid signal positions, and determining a second reconciled signal from the second signal and the invalid signal positions; determining a total loss along the quantum channel from the at least one test pulse received, determining a signal loss from the total loss and the intrinsic loss, and providing the signal loss; determining a shared by error correcting the first reconciled signal and the second reconciled signal; and determining an amplified key from the shared key by shortening the shared key by a shortening amount that is determined from the signal loss.

Abstract: A method of driving a quantum computational network for finding a solution to a computational problem comprising a system of linear binary relations includes initializing computation qubits, applying a set of quantum gates and measuring an outcome state. A solution is determined based on a plurality of solution candidates, wherein a state of the register qubits is associated with a select one of the binary relations and a state of the ancilla qubits is associated with a solution candidate for the select one of the binary relations. The solution is then iteratively improved.

Abstract: A system method for quantum key includes providing an initial key in a first data processing device and a second data processing device; providing, in the second data processing device, a quantum signal comprising a plurality of quantum states; determining, in the second data processing device, a plurality of quantum measurement parameters, a raw signal by quantum measuring the plurality of quantum states employing the plurality of quantum measurement parameters; generating with the initial key, in the second data processing device, an encrypted signal; determining, in at least one of the first data processing device and the second data processing device, a reconciled signal from the encrypted signal; determining, in at least one of the first data processing device and the second data processing device, a shared key from the reconciled signal by correcting the first reconciled signal.

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 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 system and method for determining a nuclear magnetic resonance relaxation time of a probe includes polarizing first nuclei and second nuclei by applying a longitudinal static magnetic field to the probe, exchanging the polarizations of the first nuclei and the second nuclei by irradiating a swap sequence of transverse magnetic field pulses, transversely magnetizing the second nuclei by irradiating at least one excitation pulse and measuring the resulting magnetization signal of the second nuclei, and determining the nuclear magnetic resonance relaxation time of the second nuclei based on the measured magnetization signal of the second nuclei.

Abstract: The disclosure relates to a method of driving a quantum computational network for determining an extremal value of a cost function for solutions of a quadratic unconstrained binary optimization problem, the method comprising: initializing qubits, sequentially applying layers of quantum gates to the qubits, wherein each layer comprises multi-qubit quantum gates acting on a plurality of qubits and a plurality of variational quantum gates with two eigenvalues and variable actions onto the qubits, wherein the variable actions of the variational quantum gates of the layers of quantum gates form a set of variational parameters {right arrow over (?)}, and determining an output state of the quantum computational network for obtaining a solution associated with the set of variational parameters {right arrow over (?)}, wherein each binary variable of the quadratic unconstrained binary optimization problem is associated with a computational basis state of the register qubits, and the solution is obtained by evaluating t

Abstract: The invention relates to a method for determining the component of a magnetic field in a predetermined direction. The method comprises preparing a quantum system in a coherent superposition state (S1), letting the quantum system evolve for a delay time period (S2) and performing a readout operation and a projective measurement on the quantum system (S3). The steps (S1, S2, S3) are iteratively repeated in an iteration loop, wherein the delay time period increases linearly by the same time increment after each iteration. The method further comprises determining the component of the magnetic field in the predetermined direction according to the outcome of the projective measurements (S4).