Abstract

The present invention concerns a for single photon detection comprising at least two superconducting detection means (1) as well as a bias current source (2), a filter element (3) and a readout circuit (4), wherein each superconducting detection means (1) forms a detection area adapted for absorption of incident photons and is connected in parallel, each superconducting detection means (1) being maintained at a temperature below its critical temperature (TC) and provided with an electrical bias current (IB) situated close to and below its critical current (IC) such as to normally be maintained in a non-resistive superconducting state, and being adapted to transition, at photon absorption, from said non-resistive superconducting state to a resistive state due to an increase in current density within the superconducting detection means (1) above the critical current (IC), said readout circuit (4) being adapted to sense a voltage change corresponding to said transition of the superconducting detection means (1) into its resistive state, such as to allow to create an event signal for each absorption of an incident photon by any of said superconducting detection means (1). The device distinguishes itself by the fact that it further comprises at least one current re-distribution means (5) adapted for at least partly redistributing current arising after absorption of incident photons by any of said superconducting detection means (1) into said current re-distribution means (5), such as to avoid any of the superconducting detection means (1) not having absorbed an incident photon of suffering an increase in current density above its critical current (IC). The present invention also concerns a system for single photon detection comprising at least two such devices.

IPC Classes  ?

• G01J 5/20 - Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• H10N 60/82 - Current path
• H10N 60/83 - Element shape
• H10N 69/00 - Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group
• G01J 1/42 - Photometry, e.g. photographic exposure meter using electric radiation detectors
• G01J 1/44 - Electric circuits

Abstract

A quantum key distribution (QKD) system comprising: an emitter (110) adapted to generate a QKD free-space signal, a transmitter station (220) adapted to receive the free-space signal from the emitter (110), and a remote QKD receiving station (250) supporting a QKD receiver (160) located at a different location than the transmitter station, wherein the transmitter station is adapted to receive said free space signal from the emitter and to forward said signal through a fiber link (400) to the QKD receiver (160) in said remote QKD receiving station (250).

IPC Classes  ?

• H04L 9/08 - Key distribution

Abstract

Free-Space key distribution method comprising exchanging information between an emitter (100) and a receiver (200) based on the physical layer wiretap channel model, comprising the steps of randomly preparing (710), at the emitter (100), one qubit encoded with one of two possible non-identical quantum states, sending (720) the encoded qubit to the receiver (200) through a physical layer quantum-enhanced wiretap channel (500), such that an eavesdropper (300) tapping said channel is provided with partial information about the said states only, detecting and measuring (730) the received quantum states, key sifting (740) between the emitter and the receiver through a classical channel, calculating (750, 760) an amount of information available to any eavesdropper (300) based on the detected and received quantum states.

IPC Classes  ?

• H04B 10/70 - Photonic quantum communication
• H04L 9/08 - Key distribution