WO2019144319A1 - Puce et système de communication quantique - Google Patents

Puce et système de communication quantique Download PDF

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Publication number
WO2019144319A1
WO2019144319A1 PCT/CN2018/074019 CN2018074019W WO2019144319A1 WO 2019144319 A1 WO2019144319 A1 WO 2019144319A1 CN 2018074019 W CN2018074019 W CN 2018074019W WO 2019144319 A1 WO2019144319 A1 WO 2019144319A1
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photon
quantum communication
quantum
communication chip
chip
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PCT/CN2018/074019
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English (en)
Chinese (zh)
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张翔
熊春乐
贝尔布莱恩
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华为技术有限公司
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Priority to CN201880001173.1A priority Critical patent/CN110300725B/zh
Priority to PCT/CN2018/074019 priority patent/WO2019144319A1/fr
Publication of WO2019144319A1 publication Critical patent/WO2019144319A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics

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  • the present application relates to the field of quantum communication technologies, and in particular, to a quantum communication chip and system.
  • Quantum communication is a technique for transmitting, exchanging, and analyzing quantum information (quantum states of quantum bits) in different network nodes.
  • quantum cryptography also known as quantum key distribution (QKD).
  • QKD quantum key distribution
  • QKD Since QKD transmits a single quantum state, it is necessary to use a single photon as an information carrier for transmission.
  • a single photon is the electromagnetic wave with the smallest intensity, which is highly susceptible to loss interference, and the loss increases exponentially with the increase of the transmission distance, making it difficult to achieve ultra-long-distance QKD.
  • the first is to use a quantum repeater architecture, which uses multiple nodes to divide a long communication distance into a plurality of short communication distances, and finally realizes long-distance quantum state transmission by means of entanglement switching of adjacent nodes.
  • this architecture requires a large number of quantum memories with long coherent time.
  • the demanding technical requirements lead to excessive cost, and on the other hand, the quantum memory technology is not complete, such as multi-node relay and Limited bandwidth.
  • the second is to use a classic Trusted node to segment the quantum key and obtain the final key through calculation. That is, some trusted nodes are set between the sender and the receiver, and each intermediate node uses QKD to generate a segmentation key by itself, and the final key is the result obtained by the segmentation key through a specific algorithm.
  • the trusted node once the segmentation key is generated, it does not have unconditional security, and it is easy to acquire the segmentation key on the transmission path without being discovered, and the security is greatly reduced.
  • the embodiments of the present application provide a quantum communication chip and a quantum communication system to solve the problem that the quantum repeater architecture is difficult to implement and costly, and the security of the quantum key segmentation is lost.
  • a first aspect of an embodiment of the present application provides a quantum communication chip.
  • the chip includes a first fiber optic chip coupler for receiving photons by connecting a fiber to a chip, the fiber optic chip coupler receiving a first fiber optic chip coupler for receiving a first photon and a second photon through the quantum channel; the first photon
  • the first is a photon emitted by the sender
  • the second is a photon emitted by the first quantum communication node, and, if it is a photon emitted by the first quantum communication node, the first quantum communication node And emitting a fourth photon entangled with the first photon
  • the second photon is a photon emitted by the second quantum communication node, and the second quantum communication node further emits a third photon entangled with the second photon
  • the first photon and the second photon are subjected to Bell state measurement by the optical splitter on the quantum communication chip, so that the first photon and the second photon are collapsed to a prese
  • the first one can transmit the quantum state of the first photon emitted by the sender to the third photon emitted by the second quantum communication node, thereby
  • the second quantum communication node transmits the quantum state of the first photon as a relay, and after the second quantum communication node continues to set the quantum communication chip and the third communication node, the quantum state of the first photon can continue to be transmitted backward.
  • the second method enables the fourth photon emitted by the first quantum communication node to entangle with the third photon emitted by the second quantum communication node, and the fourth photon is sent to the first quantum communication
  • the first quantum communication node of the node, and the third photon is sent to the next quantum communication node of the second quantum communication node, thereby generating two photons that are entangled at a long distance through the multi-level relay, and can pass two
  • the photon carries out the key transmission; the transfer process in the two modes does not need to set the quantum state memory, the structure is simple, and the cost is low; It does not require measurement of the quantum state at an intermediate node, thus still having unconditional security of quantum communication.
  • the beam splitter is a 50:50 splitter
  • the first state and the second photon are measured in the following manner.
  • the first photon and the second photon are input to the 50: 50 splitter two inputs
  • two photons output by the 50:50 splitter are sent to the single photon detector, and the single photon detector simultaneously detects the first of the 50:50 splitter output
  • the photon and the second photon determine that the first photon and the second photon are collapsed to a preset state. It can be seen that the 50:50 optical splitter can more easily distinguish whether the first photon and the second photon are collapsed to a preset state.
  • the single photon detector is provided on a quantum communication chip. Thereby, the first photon and the second photon emitted by the beam splitter can be directly obtained by the single photon detector on the chip, thereby increasing the integration degree of the quantum communication chip.
  • the single photon detector is not disposed on the quantum communication chip, but outside the quantum communication chip, in which case a single photon detector that generates the first photon and the second photon to the outside of the chip needs to be transmitted. Therefore, a second fiber chip coupler can also be disposed on the quantum communication chip, the second fiber chip coupler is configured to receive the first photon and the second photon output by the 50:50 splitter, And transmitting the first photon and the second photon to the single photon detector outside the quantum communication chip. It can be seen that since the single photon detector may have multiple implementation modes, and the single photon detector is not integrated on the quantum communication chip, the complexity of the chip design can be reduced on the one hand, and the quantum communication chip can be enabled on the other hand. Suitable for a variety of single photon detectors.
  • the quantum communication chip is provided with a controller or the controller is disposed outside the quantum communication chip, controls the working state of the optical splitter by communicating with the quantum communication chip, and analyzes the Bel State measurement. It can be seen that the quantum communication chip can flexibly choose to integrate or not integrate the controller according to requirements, thereby increasing the application range of the quantum communication chip.
  • a second aspect of the embodiments of the present application further provides a quantum communication chip, the chip comprising a Mach-Zehnder interferometer for receiving a pump light pulse emitted by a pump light source, and generating two pump light pulses, two pumps The arrival time of the light pulse is different.
  • the chip is also provided with a single photon generating device, which is mainly used for receiving two pump light pulses, and generates a pair of two different pump light pulses with different wavelengths and forming a time entangled quantum state.
  • the photon pair in addition, the chip is further provided with a first filter, which is mainly used for filtering the interference of the pump light pulse to the entangled state control and measurement, thereby obtaining a high quality entangled photon pair;
  • the upper splitter separates the entangled photon pairs and establishes two independent transmission paths.
  • the two entangled single photons are transmitted to the adjacent two quantum communication through the first fiber chip coupler. node. Complete the generation process of mutually entangled photon pairs.
  • a pair of mutually entangled photons can be generated from the pump light pulse emitted from the pumping source, and the pair of photons are entangled in time, that is, two generated in the same pumping light pulse.
  • the photons entangled in the time domain in addition, the wavelength of the photon in the photon pair is not the same as the wavelength of the two pumping light pulses, and the other characteristics of the two pumping light pulses are the same except for the arrival time. That is, the photons in the photon pair can satisfy the two photons required for the measurement of the Bell state in the quantum communication chip given in the first aspect or any of the implementations of the first aspect. Thereby, it is possible to realize long-distance mutual entanglement or remote transfer of quantum states by relaying, and finally increase the distance of quantum communication.
  • the Mach-Zehnder interferometer may generate some noise photons while generating two pump light pulses. These noise photons may affect the generation of mutually entangled photon pairs, and thus, in the quantum communication chip.
  • the main function of the second filter is to filter out the noise photons, so that the two pumping light pulses are input to the single photon A device is produced. It is possible to eliminate the effect of possible noise photons on the generation of mutually entangled photon pairs.
  • the quantum communication chip is provided with a controller or the controller is disposed outside the quantum communication chip, and controls the Mach-Zehnder interferometer, the first filter, and the second by communicating with the quantum communication chip.
  • the working state of the filter and the splitter It can be seen that the quantum communication chip can flexibly choose to integrate or not integrate the controller according to requirements, thereby increasing the application range of the quantum communication chip.
  • the single photon generating device can have multiple implementations, such as a waveguide having characteristics of third order nonlinearity or second order nonlinearity. That is, as long as it is a device capable of generating photon pairs different in wavelength from the two pump light pulses and forming a time-entangled quantum state.
  • the photon pair and the two pump light pulses have the property of conservation of energy and momentum.
  • the pumping source is provided on a quantum communication chip.
  • the generation of mutually entangled photon pairs can be realized only by the chip, and the integration degree of the quantum communication chip is increased.
  • the pumping source is not disposed on the quantum communication chip, but outside the quantum communication chip.
  • the generated pump light pulse needs to be transmitted to the single photon detector outside the chip.
  • a second fiber chip coupler is further disposed on the quantum communication chip, the second fiber chip coupler is configured to receive a pump light pulse emitted by a pump light source external to the chip, and send the pump light pulse to the quantum communication The Mach-Zehnder interferometer on the chip. It can be seen that since the pump light source may have multiple implementation modes, and the pump light source is not integrated on the quantum communication chip, the complexity of the chip design can be reduced on the one hand, and the quantum communication chip can be applied to the other hand on the other hand. A variety of pump sources.
  • the third aspect of the embodiment of the present application further provides a quantum communication chip, comprising the quantum communication chip provided by the first aspect or the implementation of any one of the first aspects, and the second aspect or the first aspect A quantum communication chip provided by an implementation. That is, only one type of quantum communication chip is required to simultaneously complete the generation of mutually entangled photon pairs, and to perform the Belce state measurement on the received two photons. Make the layout of the quantum communication system simpler.
  • a fourth aspect of the embodiments of the present application further provides a quantum communication system, where the system includes at least one quantum communication chip provided by the first aspect or any one of the first aspects, or the quantum provided by the third aspect.
  • the communication chip, as the first quantum communication node further includes at least one quantum communication chip provided by any one of the second aspect or the second aspect, or the quantum communication chip provided by the third aspect as the second quantum communication node;
  • the first quantum communication node and the second quantum communication node are alternately arranged to form an entire quantum communication system.
  • the first quantum communication node transmits one photon to two adjacent second quantum communication nodes, and the two photons transmitted to the adjacent two second quantum communication nodes are mutually entangled.
  • the second quantum communication node is configured to perform a Belce state measurement on the two received photons.
  • the quantum communication system can realize the long-distance transmission of the quantum state through the characteristic of the quantum teleportation or the two photons which are entangled with each other at a long distance, thereby increasing the distance of the quantum communication.
  • 1 is a schematic diagram of an implementation of a trusted node transmitting a quantum key
  • FIGS. 2a are schematic structural diagrams of a quantum communication system according to an embodiment of the present application.
  • 2b is a schematic structural diagram of a quantum communication system according to an embodiment of the present application.
  • FIG. 3 is a diagram showing an embodiment of a quantum communication chip according to an embodiment of the present application.
  • FIG. 4 is a diagram showing an embodiment of a quantum communication chip according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram showing the principle of quantum teleportation and Belce state measurement in a quantum communication chip according to an embodiment of the present application
  • FIG. 6 is a schematic structural diagram of performing a Belce state measurement by a beam splitter in a quantum communication chip according to an embodiment of the present application
  • FIG. 7 is a schematic diagram showing the principle of quantum teleportation and Belce state measurement in a quantum communication chip according to an embodiment of the present application.
  • FIG. 8 is a diagram showing an embodiment of a quantum communication chip according to an embodiment of the present application.
  • Embodiments of the present application provide a quantum communication chip and system, which establish a relay through quantum teleportation to realize long-distance transmission of a quantum state or generate two photons that are distantly entangled, thereby increasing quantum communication. distance.
  • the security of quantum communication is based on the basic principles of quantum mechanics, namely Heisenberg's uncertainty relationship, measurement collapse principle and quantum non-cloning principle.
  • the Heisenberg uncertainty relationship refers to the inability to accurately measure two non-complex physical quantities in a quantum system. Measuring the contraction principle means that once the quantum state is measured, the quantum state is collapsed to one of its eigenstates. The principle of non-cloning means that an unknown quantum state cannot be copied.
  • the eavesdropper measures the transmitted quantum state, the initial quantum state is changed to a certain extent, which is perceived by both communicating parties.
  • the third party cannot realize the information stealing by measuring the re-copying and sending.
  • the most commonly used information carrier for quantum communication is a single photon, and the quantum state of photons can be encoded by the properties of photon polarization and arrival time.
  • optical communication channels are inevitably depleted, so a single photon will be dissipated with a certain probability in the channel, and its probability of being dissipated is proportional to the length of the channel. For example, if the unit loss of a fiber is 0.2 dB/km, then the total loss of a 100 km long fiber channel is 20 dB, then a single photon has a 1% chance of passing through the channel without being dissipated. Therefore, if the channel of the quantum communication is too long, the two communicating parties cannot effectively transmit or receive the quantum state, resulting in an increase in the bit error rate and eventually failing to be coded.
  • the first one is to use a quantum repeater architecture, which uses multiple nodes to divide a long communication distance into multiple short communication distances, and entangles the adjacent nodes through entanglement. The method of continuously copying and purifying the quantum states stored in each node is finally sent to the receiver.
  • this architecture requires a large number of quantum memories with long coherence time.
  • quantum memory technology is not complete, such as multi-node relay and limited bandwidth.
  • the second is to use a trusted node to segment the quantum key and obtain the final key through calculation. For details, please refer to FIG. 1.
  • FIG. 1 For details, please refer to FIG. 1.
  • 1 is a schematic diagram of the implementation of the quantum key transfer by the trusted node, where Alice and There are multiple nodes between Bob, such as Node1, Node2 up to NodeN, NodeN communicates directly with Bob, Alice and node1, node1 and node2...nodeN and Bob generate keys by QKD respectively, and then pass specific operations. , get the final key.
  • the key of the trusted node once generated does not have unconditional security, the eavesdropper is likely to obtain the key here without being discovered, and the security is greatly reduced.
  • the above two methods are currently unable to fundamentally solve the above problems.
  • the present application provides a quantum communication chip and system that is different from symbol encoding using a polarization state in which a pair of mutually entangled photons are used and the entangled state is encoded using the arrival time.
  • Quantum entanglement is a phenomenon in which a plurality of particles are related to each other after interaction, and cannot be independently described.
  • the coding mode there are two optical pulses in each period with the optical pulse period as the viewing angle, and the positions of the two photons in the time domain are entangled with each other, that is, only the first light of the period appears at the same time. The pulse is either in the second light pulse.
  • the two photons are The entangled state, where
  • the relay process mainly uses the principle of quantum teleportation.
  • FIG. 2a and FIG. 2b please refer to FIG. 2a and FIG. 2b.
  • the first quantum communication node 201 and the first The second quantum communication node 202, the first quantum communication node 201 can respectively send one photon to the adjacent two second quantum communication nodes 202, and the two photons sent to the adjacent two second quantum communication nodes 202 are mutually entangled.
  • the second quantum communication node 202 is configured to perform a Belce state measurement on the received two photons, and for the sender and the receiver, the communication is realized by mutual entanglement between photons emitted by the first quantum communication node 201.
  • the photons provided to the first quantum communication node 201 may also be provided by the sender.
  • the Bel State measurement may be made adjacent to the first quantum communication node 201 by the second quantum communication node 202.
  • the quantum state of the photon sent to the adjacent other first quantum communication node 201 is the same as the quantum state of the photon of the transmitting side, completing the transfer of the quantum state, thereby increasing the quantum communication distance.
  • the quantum communication chip as the first quantum communication node and the second quantum communication node in the system of the embodiment of the present application will be described below.
  • FIG. 3 is a diagram showing an embodiment of a quantum communication chip according to an embodiment of the present application.
  • the device shown by the dotted line frame is an optional device in the quantum communication chip 3, wherein the quantum communication chip 3 includes a Mach-Zehnder interferometer 301, a single photon generating device 302, a first filter 303, a beam splitter 304, and a first fiber chip coupler 305 forming a light path: wherein
  • the Mach-Zehnder interferometer 301 is configured to generate two pump light pulses after receiving the pump light pulse emitted by the pump light source 300;
  • the single photon generating device 302 After receiving the two pump light pulses, the single photon generating device 302 generates a pair of photon pairs different in wavelength from the two pumping light pulses and forming a time-entangled quantum state;
  • the two pump light pulses are filtered out by the first filter 303 to obtain a high quality entangled photon pair;
  • Two single photons are input to the beam splitter 304, which establishes two independent propagation paths, and two entangled single photons are sent to the phase through the first fiber chip coupler 305 according to the propagation path.
  • Two adjacent quantum communication node fiber chips Two adjacent quantum communication node fiber chips.
  • the first fiber chip coupler 305 serves as an optical interface of the quantum communication chip, and the photon generated by the quantum communication chip is sent to the optical fiber connected to the first fiber chip coupler 305.
  • the Mach-Zehnder interferometer 301 is an unequal-arm Mach-Zehnder interferometer. After receiving the pumping light pulse, the interferometer first divides into two pumping lights through a spectroscope inside the Mach-Zehnder interferometer 301. Pulse, then, the two pump light pulses respectively reach the output through the signal arm and the reference arm. Since the signal arm and the reference arm are not asymmetric, the two pump light pulses are transmitted in different times to reach the output. The time of the end is also different, so that two pump light pulses are generated one after the other in time.
  • the two pump light pulses are The optical characteristics are identical except for the different arrival times, and the optical characteristics of the pump light pulse emitted by the pump source are the same.
  • the unequal-arm Mach-Zehnder interferometer is a special form of the Mach-Zehnder interferometer, and the difference between the lengths of the two interference arms is the propagation speed of the light in the interference arm multiplied by the two pump lights. The interval of the pulse in the time domain.
  • the single photon generating device 302 is a waveguide made of a material having a third order nonlinearity or a second order nonlinearity.
  • a pair of photons having different wavelengths from the pump light pulse are generated by a nonlinear effect with a certain probability.
  • the nonlinear effect may be a second-order nonlinear effect, that is, a pump photon is converted into a pair of single photons different from the pumping pulse frequency, and the pair of photons and the converted pump photons ensure energy and momentum conservation.
  • the above nonlinear effect may be a third-order nonlinear effect, that is, two pump photons are converted into a pair of single photons different from the pumping pulse frequency, and the pair of photons and the two pump photons being converted ensure energy. conserveed with momentum.
  • the probability of photon pair generation is small, the events of generating a pair of photons simultaneously by the two pump light pulses are negligible, and the generated photon pairs form a time-entangled quantum state:
  • the pump light pulse is filtered out by the first filter 303 to obtain two single photons.
  • the two single photons are separated by the beam splitter 304, and the two photons are passed through the quantum channel through the first fiber chip coupler 305. Transmitted to two adjacent quantum communication nodes, since the quantum communication node in this embodiment is the first quantum communication node, the generated photon pair can be sent to two second adjacent to the first quantum communication node. A quantum communication node to cause the second quantum communication node to perform a Bel State measurement.
  • the quantum communication chip 3 further includes a second filter 306 between the Mach-Zehnder interferometer 301 and the single-photon generating device 302, the second filter. The 306 is used to filter out the above noise photons.
  • the pump light source 300 may be a device disposed on the quantum communication chip 3 or a device not disposed on the quantum communication chip 3.
  • a second fiber chip coupler 307 may be disposed on the quantum communication chip 3, and the second fiber chip coupler 307 is configured to receive the quantum communication chip. 3 pumping light pulse from the external pumping light source 300, and sending the pumping light pulse to the Mach-Zehnder interferometer 301; wherein the light emitted by the pumping light source 300 can be transmitted to the quantum communication chip through the transmission medium 3, for example, through an optical fiber.
  • the pump light source 300 may have multiple implementation modes, and the pump light source is not integrated on the quantum communication chip, the complexity of the chip design can be reduced on the one hand, and the quantum communication chip can be applied on the other hand. For a variety of pumping sources. Further, if the pump light source 300 is integrated on the quantum communication chip 3, the degree of integration of the quantum communication chip can be increased. The choice of integration or not can be determined according to actual needs, without limitation.
  • the quantum communication chip 3 is provided with a controller 308 or the controller 308 is disposed outside the quantum communication chip, and the controller 308 is mainly used for the Mach-Zehnder interferometer 301, the first filter 303, Control of the normal operation of the second filter 306 and the beam splitter 304.
  • the quantum communication chip 3 can flexibly select an integrated or non-integrated controller as needed, thereby increasing the range of application of the quantum communication chip 3.
  • a pair of mutually entangled photons can be generated from the pump light pulse emitted from the pumping source, and the pair of photons are temporally entangled in time, that is, in the same pumping light pulse.
  • the two photons generated in the photon in addition, the wavelength of the photon in the photon pair is not the same as the wavelength of the pumping light pulse, and the photon pair and the two pumping light pulses have the property of conservation of energy and momentum. That is, the photons in the photon pair can satisfy the two photons required for the measurement of the Bell state in the quantum communication chip given in the first aspect or any of the implementations of the first aspect. Thereby, it is possible to realize long-distance mutual entanglement or remote transfer of quantum states by relaying, and finally increase the distance of quantum communication.
  • FIG. 4 is a diagram of an embodiment of a quantum communication chip according to an embodiment of the present application.
  • the device shown by the dotted line in FIG. 4 is an optional device in the quantum communication chip 4.
  • the quantum communication chip 4 includes:
  • first fiber optic chip coupler 401 receiving a first photon and a second photon through a quantum channel, wherein the first photon has two situations, the first is a photon emitted by the sender,
  • the second type is a photon emitted by the first quantum communication node, and if it is a photon emitted by the first quantum communication node, the first quantum communication node further emits a fourth photon entangled with the first photon;
  • the second The photon is a photon emitted by the second quantum communication node, and the second quantum communication node further emits a third photon entangled with the second photon;
  • a beam splitter 402 configured to perform a Belce state measurement on the first photon and the second photon, such that the first photon and the second photon are collapsed to a preset state;
  • the third photon is made to have a quantum state of the first photon; or, when the first photon is a photon emitted by the first quantum communication node
  • the fourth photon and the third photon are entangled with each other.
  • the optical splitter 402 can be a 50:50 optical splitter, and the Belce state measurement can be that the first photon and the second photon are input to two input ends of the optical splitter 402, and the optical splitter 402 outputs Two photons are sent to the single photon detector. If the single photon detector simultaneously detects the two photons output by the beam splitter 402, it is determined that the first photon and the second photon are collapsed to a preset state. It can be seen that the splitter 402 can more easily distinguish whether the first photon and the second photon are collapsed to a preset state, thereby improving the analysis efficiency of the Bel State measurement.
  • the single photon detector 403 is disposed on the quantum communication chip 4.
  • the first photon and the second photon emitted by the beam splitter 402 can be directly obtained by the single photon detection 403 on the chip, increasing the integration degree of the quantum communication chip 4.
  • the single photon detector 403 is not disposed on the quantum communication chip 4, but outside the quantum communication chip 4. At this time, it is necessary to transmit the first photon and the second photon to the single photon detector 403 outside the chip. Therefore, a second fiber chip coupler 404 can also be disposed on the quantum communication chip 4, and the second fiber chip coupler 404 is configured to receive the first photon and the second photon output by the beam splitter 402.
  • the communication chip 4 can be applied to a variety of single photon detectors 403.
  • the single photon detector 403 can be flexibly selected according to actual needs, which is not limited herein.
  • the quantum communication chip 4 is provided with a controller 405 or the controller 405 is disposed outside the quantum communication chip 4, and controls the working state of the optical splitter 402 by communicating with the quantum communication chip 4, and performs measurement on the Bell state. analysis. It can be seen that the quantum communication chip 4 can flexibly select the integrated or non-integrated controller 405 according to requirements, thereby increasing the application range of the quantum communication chip.
  • the first scenario corresponds to the scenario corresponding to the system of FIG. 2a
  • the second scenario corresponds to the scenario corresponding to the system of FIG. 2b.
  • the first quantum communication node also emits a fourth photon
  • the two photons and the first photon are entangled with two photons, when the first photon and the second photon are collapsed to a preset In the state
  • the fourth photon and the third photon are also two photons entangled with each other;
  • the third photon has a quantum state of the first photon.
  • FIG. 5 is a schematic diagram of the principle of quantum teleportation and Bell state measurement in the quantum communication chip of the present application
  • FIG. 6 is a schematic diagram of the present application.
  • a fourth photon photon 1 in FIG. 5
  • a first photon photon 2 in FIG. 5
  • first quantum communication nodes Fig. 5
  • 5 is a pair of mutually entangled photon pairs generated by the chip 1), wherein the photon 2 is sent to the quantum communication chip 4 (the chip 2 in FIG.
  • the photon 1 is sent to the previous quantum communication chip or the sender;
  • the second photon (photon 3 in Fig. 5) and third photon (photon 4 in Fig. 5) are a pair of mutually entangled photon pairs generated by a quantum communication node (chip 3 in Fig. 5), wherein photons 3 are sent to chip 2.
  • the photon 4 is sent to the next quantum communication chip or receiver.
  • Photon 2 and photon 3 are measured on the chip 2, and the photon 1 and photon 4 are entangled based on the measurement results.
  • the quantum mechanics of this process are expressed as follows:
  • photon 2 and photon 3 enter the 50:50 Beam Splitter (BS), respectively, and at the output, the same single photon detector 403 is used for detection, such as detector d1 and detector d2, if two The detector detects photons at the same time, proving that the first photon and the second photon collapse to State, otherwise, if two photons exit from the same port, they cannot distinguish their entangled states.
  • BS Beam Splitter
  • quantum communication is performed between Alice and Bob mainly through quantum entanglement effect and quantum teleportation, as shown in the architecture of Fig. 2a, through the second quantum communication node 2, the second quantum communication Node 4, until the second quantum communication node n-1 performs a Bel State measurement to realize entanglement between the photons emitted by the first quantum communication node 1, the first quantum communication node, and the first quantum communication node n, and finally the first quantum The photons transmitted by the communication node 1 to Alice and the photons sent by the first quantum communication node n to Bob are entangled.
  • FIG. 7 is a schematic diagram of the principle of quantum teleportation and Bell state measurement in the quantum communication chip of the present application.
  • the first quantum communication node Transmitter Alice in Fig. 7
  • the vector sub-communication chip 4 (chip 1 in Fig. 7) transmits a first photon (photon 1 in Fig. 7) having the quantum state
  • the second quantum communication node (chip 2 in Fig. 7) generates a second photon (photon 2 in Fig. 7) and a third photon (photon 3 in Fig. 7), and photon 2 and photon 3 are entangled with each other. a photon.
  • photon 2 is sent to chip 1, and photon 3 is sent to the next quantum communication chip or receiver.
  • Photon 1 and photon 2 are measured on the chip 1 and the quantum state of photon 1 is transferred to photon 3.
  • the quantum mechanics of this process are expressed as follows:
  • a and b are normalization coefficients of the quantum state
  • the method of measuring the Bell state is that photon 1 and photon 2 respectively enter the 50:50 splitter 402, and at the output end, the same single photon detector is used for detection, if two detectors simultaneously detect photons, proof The photon 3 collapses to -a
  • quantum communication is performed between Alice and Bob mainly through quantum entanglement effect and quantum teleportation.
  • the quantum state of photons emitted by Alice passes through the second quantum communication.
  • the Bell state measurement on node 1 is passed to the photon sent by the first quantum communication node 2 to the second quantum communication node 3, and then the quantum state of the photon sent by the first quantum communication node 2 to the second quantum communication node 3 is again
  • the photons that are passed to the first quantum communication node 4 and sent to the next chip are transmitted in a sequential manner, and finally the quantum state of the photons emitted by Alice is finally transmitted to the photons sent by the first quantum communication node n to Bob, so that Bob receives the measurement by measurement.
  • the quantum state of the photon can be used to know the quantum state of the photon emitted by Alice.
  • FIG. 8 is a diagram of an embodiment of a quantum communication chip according to an embodiment of the present application, which is used for generating photon and user Bell state analysis. Control only needs to use the same controller.
  • the arrow indicates the optical path direction, and the non-arrow line is the signal line.
  • the portion of the quantum communication chip 8 that generates the photon pair includes the second fiber chip coupler 801, the Mach-Zehnder interferometer 802, and the second filter. 803, a single photon generating device 804, a first filter 805, a beam splitter 806, and a first fiber optic chip coupler 807; a pumping light pulse from the pumping source 9 is sent to the second fiber optic chip coupler 801, and the generated photon pair It is emitted by the first fiber chip coupler 807.
  • the portion of the quantum communication chip 8 that performs the Bel State measurement includes a fourth fiber chip coupler 808, a beam splitter 809, and a third fiber chip coupler 810, wherein the two photons being measured enter through the third fiber chip coupler 810.
  • the two photons output by the beam splitter are sent to the single photon detector 10 through the fourth fiber chip coupler 808.
  • the controller 11 is connected with a classic channel on the one hand for communicating with other devices, and on the other hand, sequentially connects and controls the Mach-Zehnder interferometer 802, the second filter 803, the first filter 805, and the optical splitter 806. And beam splitter 809.
  • the disclosed system, apparatus, and method may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in the embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biophysics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Optical Communication System (AREA)

Abstract

La présente invention concerne le domaine technique de la communication quantique, et concerne en particulier une puce et un système de communication quantique. La puce comprend un interféromètre de Mach-Zehnder qui est utilisé pour recevoir des impulsions de lumière de pompe et générer deux impulsions de lumière de pompe, les temps d'arrivée des deux impulsions de lumière de pompe étant différents ; un dispositif de génération de photon unique qui est utilisé pour recevoir des impulsions de lumière de pompe, et pour générer une paire parmi les paires de photons qui ont des longueurs d'onde différentes des impulsions de lumière de pompe et former un état quantique d'enchevêtrement temporel ; un premier filtre qui est utilisé pour filtrer les deux impulsions de lumière de pompage afin d'obtenir deux photons uniques ; et un diviseur qui est utilisé pour recevoir les deux photons uniques, établir des trajets de propagation de chacun des deux photons uniques respectivement, et envoyer les deux photons uniques à deux nœuds de communication quantique adjacents selon le trajet de propagation au moyen d'un premier coupleur de puce de fibre optique. La paire de photons uniques à enchevêtrement temporel mutuel générée par la puce peut être utilisée pour une téléportation quantique et pour générer un enchevêtrement mutuel à longue distance ou une transmission à distance d'un état quantique au moyen d'un relais, ce qui permet finalement d'augmenter la distance de la communication quantique.
PCT/CN2018/074019 2018-01-24 2018-01-24 Puce et système de communication quantique WO2019144319A1 (fr)

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