Quantum communication system and a quantum communication method

Patent metadata

Field	Value
Publication number	US-2016234018-A1
Application number	US-201514816293-A
Country	US
Kind code	A1
Filing date	Aug 3, 2015
Priority date	Feb 5, 2015
Publication date	Aug 11, 2016
Grant date	—

Abstract

A quantum communication system, comprising:
a plurality of transmitter units, each transmitter unit comprising a source of quantum signals; a receiver unit, comprising:
a quantum receiver, comprising at least one detector configured to detect quantum signals; and a first classical communication device; and
a passive optical splitter, wherein the plurality of transmitter units are optically coupled to the receiver unit through the passive optical splitter, wherein the passive optical splitter is optically coupled to the quantum receiver through a first spatial channel and optically coupled to the first classical communication device through a second spatial channel, and wherein the passive optical splitter is configured to distribute an inputted optical signal irrespective of its wavelength.

First claim

1 . A quantum communication system, comprising:
a plurality of transmitter units, each transmitter unit comprising a source of quantum signals; a receiver unit, comprising:
a quantum receiver, comprising at least one detector configured to detect quantum signals; and
a first classical communication device; and
a passive optical splitter, wherein the plurality of transmitter units are optically coupled to the receiver unit through the passive optical splitter, wherein the passive optical splitter is optically coupled to the quantum receiver through a first spatial channel and optically coupled to the first classical communication device through a second spatial channel, and wherein the passive optical splitter is configured to distribute an inputted optical signal irrespective of its wavelength.

2 . A quantum communication system according to claim 1 , wherein the passive optical splitter is configured such that the first spatial channel is optically coupled through the passive optical splitter to a plurality of spatial channels and the second spatial channel is optically coupled through the passive optical splitter to the same plurality of spatial channels.

3 . The quantum communication system according to claim 1 , wherein each transmitter unit comprises a second classical communication device, which comprises a detector configured to detect classical signals, and wherein the first classical communication device comprises a source of classical signals.

4 . The quantum communication system according to claim 3 , wherein the receiver unit comprises a timing control module, configured to allow only a single transmitter unit to emit a quantum signal for each arrival time at the quantum receiver, the timing control module also allowing the transmitter unit which sent the quantum signal to be identified.

5 . The quantum communication system according to claim 4 , wherein the first classical communication device is configured to receive a signal from the timing control module and send the signal to the second classical communication device through the second spatial channel.

6 . The quantum communication system according to claim 1 , wherein the passive optical splitter comprises at least two waveguides which are evanescently coupled.

7 . The quantum communication system according to claim 1 , wherein the passive optical splitter comprises at least one multi-mode interference section.

8 . The quantum communication system according to claim 1 , wherein the first spatial channel comprises a first optical fibre and the second spatial channel comprises a second optical fibre.

9 . The quantum communication system according to claim 1 , where the first spatial channel and the second spatial channel comprise first and second spatial modes in an optical waveguide configured to transmit a plurality of spatial modes.

10 . The quantum communication system according to claim 9 , further comprising a spatial mode de-multiplexer, wherein the quantum receiver and first classical communication device are optically coupled to the passive optical splitter through the spatial mode de-multiplexer.

11 . The quantum communication system according to claim 1 , wherein the first spatial channel and the second spatial channel comprise first and second cores in a multi-core optical fibre.

12 . The quantum communication system according to claim 11 , further comprising a fibre fan-out, wherein the quantum receiver and first classical communication device are optically coupled to the passive optical splitter through the fibre fan-out.

13 . The quantum communication system according to claim 3 , wherein the classical communication system between the first classical communication device and the second classical communication device is a gigabit-capable passive optical network.

14 . The quantum communication system according to claim 3 , wherein the receiver unit comprises a decoder and the transmitter units each comprise an encoder, configured to generate an encryption key between the receiver unit and each transmitter unit.

15 . The quantum communication system of claim 14 , wherein each transmitter unit comprises a module configured to encrypt classical data using the generated encryption key, and wherein the second communication device is configured to send the encrypted classical data to the first communication device through the second spatial channel, and wherein the receiver unit comprises a module configured to decrypt the encrypted data received by the first classical communication device using the generated encryption key.

16 . The quantum communication system of claim 14 , wherein the receiver unit comprises a module configured to encrypt classical data using the generated encryption key, and wherein the first communication device is configured to send the encrypted classical data to the second communication device through the second spatial channel, and wherein the transmitter unit comprises a module configured to decrypt the encrypted data received by the second classical communication device using the generated encryption key.

17 . A quantum communication system according to claim 4 , wherein the at least one detector is a gated detector and the timing control module is configured to synchronise the gating of the detector with the arrival time of signals from the transmitter units.

18 . A quantum communication system according to claim 1 , wherein the receiver unit comprises a feedback control unit configured to generate a feedback signal for each transmitter unit, and wherein the first classical communication device is configured to transmit the feedback signal to the transmitter unit, the transmitter unit comprising a control element configured to be controlled by the feedback signal.

19 . A quantum communication system according to claim 18 , wherein the control element is the time control of the source of quantum signals.

20 . A quantum communication method for communicating over a system comprising a receiver unit, the receiver unit comprising a source of classical signals and the receiver unit further comprising a quantum receiver, the quantum receiver comprising at least one detector configured to detect quantum signals; the system further comprising a plurality of transmitter units, each transmitter unit comprising a detector configured to detect classical signals and each transmitter unit further comprising a source of quantum signals; and the system further comprising a passive optical splitter, wherein the plurality of transmitter units are optically coupled to the receiver unit through the passive optical splitter; the method comprising the steps of:
sending quantum signals from the plurality of transmitter units to the passive optical splitter; distributing the quantum signals into a first spatial channel and a second spatial channel, irrespective of the wavelength of the quantum signals; receiving the quantum signals from the first spatial channel at the quantum receiver; sending a classical signal from the receiver unit to the passive optical splitter through a second spatial channel; distributing the classical signal to the plurality of transmitter units, irrespective of the wavelength of the classical signal; wherein the passive optical splitter is optically coupled to the quantum receiver through a first spatial channel and optically coupled to the first classical communication device through a second spatial channel.

Assignees

• Toshiba Kk

Inventors

• Frohlich Bernd Matthias
• Yuan Zhiliang
• Shields Andrew James

Classifications

• H04L9/0852 Primary

  Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03) · CPC title

• H04B10/70

  Photonic quantum communication · CPC title

• H04L9/0858 Primary

  Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding · CPC title