Universitè De Genève

Id Quantique Sa

Swisscom Ag

Hugo Zbinden

Nicolas Gisin

Grégoire Ribordy

Bruno Sanguinetti

Anthony Martin

Olivier Guinnard

Beat Perny

Charles Lim

Anthony Christophe Mickaël Martin

Boris Korzh

Gianluca Boso

Antoine Muller

Bruno Huttner

Joseph Bowles

Jonatan Brask

Nicolas Brunner

Davide Rusca

The invention is directed to a Quantum Random Number Generator comprising an emitting device () triggered by a signal representing an input bit x and adapted to generate and send a physical system () characterized by one of two possible quantum states determined by said input bit x, a measurement device () adapted to detect said physical system, to identify the quantum state of said physical system through an unambiguous state discrimination measurement and to generate an output b first representing whether the quantum state has been identified or not and, if it has been identified, which quantum state among the two possible quantum states was detected by the unambiguous state discrimination measurement to a processing device (), the processing device () being adapted to estimate the entropy of the output b given the probabilities p(b|x) representing the probability of observing output b for a state preparation x, and a randomness extraction device () adapted to extract final random bit stream given the entropy estimate provided by the processing device ().

Method and device for quantum random number generation

The invention relates to a Quantum Key Distribution system comprising a transmitterand a receiverfor exchanging a quantum key via a quantum channelthrough a decoy-state three state protocol wherein the transmitter comprises a transmitter processing unitadapted to use random numbers from a quantum random generator to select a quantum state to encode from different states of intensity and basis, a Pulsed light sourceadapted to generate an optical pulse, a time-bin interferometerthrough which the generated optical pulse passes and which transforms generated optical pulse into two coherent pulses separated by the time bin duration, a single intensity modulatoradapted to change the intensity of the two pulses individually according to the choice made by the transmitter processing unit, and a variable optical attenuatoradapted to reduce the overall signal intensity to the optimum photon number per pulse.

Apparatus and method for decoy-state three-state quantum key distribution

A device for random number generation based on an optical process of quantum nature, including a light source emitting photons randomly, a light detector adapted to absorb the randomly emitted photons and to measure a number n of photons produced by the light source in a time interval T, and a randomness extractor. The detector includes a photon sensor acting as a photon-to-electron converter, an amplifier for converting the electron signal received from the photon sensor into a voltage and amplifying the voltage signal, as well as an analog-to-digital converter for processing the amplified signal received from the amplifier by encoding the amplified signal into digital values and sending these digital values to the randomness extractor for further processing such as to produce quantum random numbers (QRNs) based on the number of photons produced by the light source in a time interval T.

Method and device for optics based quantum random number generation

A data compression method wherein said data comprises noise and information, comprising a data acquisition step, a pre-compression parameter selection step, wherein said pre-compression parameters are linked to an information loss, a compression step, and a storage step, the compression step being characterized in that it comprises a lossy pre-compression for removing some noise of the data, carried out using the pre-compression parameters selected in the selection step followed by lossless compression for compressing the remaining data.

Image compression method with negligible and quantifiable information loss and high compression ratio

An apparatus and method for implementing a secure quantum cryptography system using two non-orthogonal states. For each qubit, the emitter station prepares a quantum system in one of two non-orthogonal quantum states in the time-basis to code bit values. Intra- and inter-qubit interference is then used to reveal eavesdropping attempts. Witness states are used to help reveal attacks performed across the quantum system separation.

Two non-orthogonal states quantum cryptography method and apparatus with intra- and inter-qubit interference for eavesdropper detection

An apparatus and method are disclosed for maximizing interference contrast in an interferometric quantum cryptography system to detect eavesdropping by utilizing a tunable emitter station in communications with a receiver station via a quantum communications channel and a 'public' communications channel. The tunable emitter station tracks and compensates for interferometer drifts by adjusting the interference contrast of the QC system to minimize or eliminate inherent perturbations induced into key bit transmissions. Tuning of the photo emitter's output wavelength is accomplishable using temperature and/or drive current adjustment of the emitter's tunable optical subsystem.

Apparatus and method for adjustment of interference contrast in an interferometric quantum cryptography apparatus by tuning emitter wavelength

An apparatus and method for implementing a secure quantum cryptography system using two non-orthogonal states. For each qubit, the to emitter station prepares a quantum system in one of two non-orthogonal quantum states in the time-basis to code bit values. Intra- and inter-qubit interference is then used to reveal eavesdropping attempts. Witness states are used to help reveal attacks performed across the quantum system separation.

Two non-orthogonal states quantum cryptography method and apparatus with inter-and inter-qubit interference for eavesdropper detection

In a method and apparatus for synchronizing the receiver and the emitter in an autocompensating quantum cryptography system it is allowed to one of the stations (for example the emitter) to define the timing of all its operations (for example the application of a signal onto the modulator used to encode the values of the bits) as a function of a time reference. This time reference can either be transmitted using a channel from the other station (for example the receiver). It can also consist of a time reference synchronized with that of the other station through using information transmitted along a channel and a synchronization unit. Preferably a time reference unit is provided at each station. One of these time reference units functions as a master, while the other one function as a slave. The slave is synchronized with the master using information transmitted over a communication channel by a synchronization unit.

Method and apparatus for synchronizing the emitter and the receiver in an autocompensating quantum cryptography system

A system and method for communicating a key between two stations using an interferometric system for quantum cryptography. The method includes sending at least two light pulses over a quantum channel and detecting the interference created by the light pulses. The interfering pulses traverse the same arms of an interferometer but in a different sequence such that the pulses are delayed when traversing a quantum channel. The pulses are reflected by Faraday mirrors at the ends of the quantum channel so as to cancel any polarization effects. Because the interfering pulses traverse the same arms of an interferometer, there is no need to align or balance between multiple arms of an interferometer.

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Geneva, Switzerland

Hugo Zbinden