Multi-dimensional quantum entangled light source

Abstract

The invention discloses a multi-dimensional quantum entangled light source, and relates to the technical field of quantum information, the multi-dimensional quantum entangled light source comprises a laser, an optical fiber amplifier, a nonlinear crystal, a first wavelength division multiplexer, a second wavelength division multiplexer and a third wavelength division multiplexer, the laser is used for preparing and outputting pump light; the optical fiber amplifier is used for amplifying the intensity of the pump light; the nonlinear crystal is used for converting the pump light after intensity amplification into an entangled photon pair comprising signal photons and idler frequency photons; the first wavelength division multiplexer is used for dividing the entangled photon pair into two paths according to wavelengths, one path is signal photons, and the other path is idler frequency photons; the second wavelength division multiplexer is used for dividing the signal photons into multiple paths according to wavelengths to obtain multiple paths of signal photons; and the third wavelength division multiplexer is used for dividing the idler frequency photons into multiple paths according to the wavelengths to obtain multiple paths of idler frequency photons, only one laser is needed, multiple independent lasers do not need to be adopted, the structure is simplified, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum information technology, and in particular to a multi-dimensional quantum entangled light source. BACKGROUND

[0002] Quantum information science is a product of the combination of quantum mechanics and information science, and quantum mechanics systems can be used to achieve quantum communication, quantum computing and quantum measurement. An entangled photon pair formed by the mutual entanglement of two photons has the following physical properties: when two photons are mutually entangled, the state of the other photon can be obtained instantaneously through the measurement of one of the two photons, no matter how far apart the two photons are. Quantum light sources include quantum entangled light sources and single photon sources, wherein quantum entangled light sources can be generated by using the parametric down-conversion process of various nonlinear crystals. Nonlinear crystal quantum light sources have the longest history and the most mature technology, and are widely used in various fields of quantum information, such as quantum key distribution, quantum teleportation, quantum simulation, etc. Common materials of nonlinear crystals include barium metaborate, potassium dihydrogen phosphate, periodically poled potassium titanyl phosphate and periodically poled lithium niobate, etc.

[0003] The existing quantum entangled light sources mostly have the following defects: (1) Only one entangled photon pair can be generated in a time period, and the generation efficiency is low; (2) The existing multi-dimensional quantum entangled light source is mainly realized by using multiple independent lasers, which has a complex structure and high cost. SUMMARY

[0004] Embodiments of the present application provide a multi-dimensional quantum entangled light source to at least partially solve the defects existing in the prior art.

[0005] Compared with the prior art, the multi-dimensional quantum entangled light source provided by the embodiments of the present application comprises: a laser for preparing and outputting pump light.

[0006] a fiber amplifier for amplifying the intensity of the pump light.

[0007] a nonlinear crystal for converting the pump light with amplified intensity into an entangled photon pair comprising signal photons and idler photons.

[0008] a first wavelength division multiplexer for dividing the entangled photon pair into two paths according to wavelength, one path being signal photons and the other path being idler photons.

[0009] a second wavelength division multiplexer for dividing the signal photons into multiple paths according to wavelength to obtain multiple paths of signal photons.

[0010] a third wavelength division multiplexer for dividing the idler photons into multiple paths according to wavelength to obtain multiple paths of idler photons, wherein: The multi-dimensional quantum entangled light source is formed by the multiple signal photons and the multiple idler photons.

[0011] In some examples, the multi-dimensional quantum entangled light source further comprises: The first detection module comprises a plurality of single-photon detectors for detecting the multiple signal photons respectively.

[0012] The second detection module comprises a plurality of single-photon detectors for detecting the multiple idler photons respectively.

[0013] In some examples, the multi-dimensional quantum entangled light source further comprises a first filter module comprising a plurality of narrow-band filters for filtering out noise signals in the multiple signal photons output by the second wavelength division multiplexer.

[0014] In some examples, the multi-dimensional quantum entangled light source further comprises a second filter module comprising a plurality of narrow-band filters for filtering out noise signals in the multiple idler photons output by the third wavelength division multiplexer respectively.

[0015] In some examples, the number of single-photon detectors in the second detection module is consistent with the number of single-photon detectors in the first detection module.

[0016] In some examples, the nonlinear crystal is a type-0 nonlinear optical crystal.

[0017] In some examples, the first wavelength division multiplexer is a coarse wavelength division multiplexer (CWDM).

[0018] In some examples, the second wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

[0019] In some examples, the third wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

[0020] Compared with the prior art, the multi-dimensional quantum entangled light source provided by the embodiments of the present application has at least the following beneficial effects: Based on the first wavelength division multiplexer, the second wavelength division multiplexer, and the third wavelength division multiplexer, only one laser is needed to form a multi-dimensional quantum entangled light source, without the need to use multiple independent lasers, thus simplifying the structure and reducing the cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of a multidimensional quantum entangled light source according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 Figure 1 As shown, the multidimensional quantum entangled light source provided in this embodiment of the invention includes a laser, an optical fiber amplifier, a nonlinear crystal, a first wavelength division multiplexer, a second wavelength division multiplexer, a third wavelength division multiplexer, a first detection module (not shown in the figure), a second detection module (not shown in the figure), a first filtering module (not shown in the figure), and a second filtering module (not shown in the figure), wherein: Lasers are used to generate and output pump light.

[0025] Specifically, pump light is light that can raise the energy of luminescent substances (atoms, molecules, etc.) to a higher energy level.

[0026] Fiber optic amplifiers are used to amplify the intensity of pump light.

[0027] Specifically, the fiber amplifier is an erbium-doped fiber amplifier, which increases the brightness of the pump light and ultimately increases the brightness of the entangled photon pairs.

[0028] Nonlinear crystals are used to convert amplified pump light into entangled photon pairs, including signal photons and idler photons.

[0029] In some examples, the nonlinear crystal is a type 0 nonlinear optical crystal.

[0030] Specifically, the entangled photon pairs are obtained by spontaneous parametric conversion of the pump light using a nonlinear crystal. The signal photon and idler photon in each entangled photon pair are generated simultaneously. The spontaneous parametric downconversion process involves the interaction of the high-frequency pump light with the nonlinear medium, simultaneously generating a pair of low-frequency signal and idler photons based on the pump light while satisfying energy and momentum conservation. Depending on the polarization directions between the pump light, signal photon, and idler photon, spontaneous parametric conversion can be classified into type 0, type 1, and type 2 spontaneous parametric conversion. Under Type I spontaneous parametric switching, the polarization directions of the signal photon and the idler photon are consistent and perpendicular to the polarization direction of the pump light. Under Type II spontaneous parametric switching, the polarization direction of the signal photon is perpendicular to the polarization direction of the idler photon. Under Type 0 spontaneous parametric switching, the polarization directions of the pump light, idler photon, and signal photon are consistent, and the generated entangled photon pairs have a wider spectrum and higher spectral intensity. The generation rate of entangled photon pairs is two orders of magnitude higher than that under Type I and Type II parametric switching, which improves the generation rate of entangled photon pairs and makes them more suitable for high-capacity and high-density quantum key distribution.

[0031] The first wavelength division multiplexer is used to split entangled photon pairs into two paths according to wavelength: one path is the signal photon, and the other path is the idler photon.

[0032] In some examples, the first wavelength division multiplexer is a coarse wavelength division multiplexer (CWDM).

[0033] Specifically, due to the significant difference between the wavelengths of the signal photon and the idler photon, the entangled photon pair has a broad spectrum. By employing a coarse wavelength division multiplexer (CWDM), the signal photon and the idler photon can be separated from the entangled photon pair. For example, the pump light wavelength is 769 nm, the signal light wavelength is 1530 nm, and the idler light wavelength is 1550 nm.

[0034] The second wavelength division multiplexer is used to split the signal photons into multiple paths according to wavelength, thus obtaining multiple signal photons.

[0035] In some examples, the second wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

[0036] Specifically, since there are slight differences in the wavelengths of signal photons generated at different times, by using a dense wavelength division multiplexer (DWDM), the signal photons generated at different times can be split from one path into multiple paths according to the wavelength.

[0037] The third wavelength division multiplexer is used to split the idler photons into multiple paths according to wavelength to obtain multiple idler photons.

[0038] In some examples, the third wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

[0039] Specifically, since there are slight differences in the wavelengths of idler photons generated at different times, a dense wavelength division multiplexer (DWDM) can be used to split the idler photons generated at different times from one path into multiple paths based on their wavelengths. Among these: Multiple signal photons and multiple idler photons form a multidimensional quantum entangled light source.

[0040] In some examples, the first detection module includes multiple single-photon detectors for detecting multiple signal photons separately. For example... Figure 1 As shown, the first detection module includes four single-photon detectors, one of which detects one signal photon.

[0041] Specifically, one of the multiple single-photon detectors is responsible for detecting one of the multiple signal photons.

[0042] In some examples, the second detection module includes multiple single-photon detectors for detecting multiple idler photons separately. For example... Figure 1 As shown, the second detection module includes four single-photon detectors, one of which detects one idler photon.

[0043] In some examples, the number of single-photon detectors in the second detection module is the same as the number of single-photon detectors in the first detection module.

[0044] Specifically, one of the multiple single-photon detectors corresponds to detecting one idler photon from the multiple idler photons. For example... Figure 1 As shown, the second detection module includes four single-photon detectors, one of which detects one idler photon.

[0045] Specifically, a first detection module is used to detect multiple signal photons, while a second detection module is used to detect multiple idler photons, thus realizing the entanglement test of entangled photon pairs.

[0046] Specifically, based on the first, second, and third wavelength division multiplexers, only one laser is needed to form a multidimensional quantum entangled light source, eliminating the need for multiple independent lasers, thus simplifying the structure and reducing costs. In particular, each signal photon in the multi-channel signal photon pool and each idler photon in the multi-channel idler photon pool can be used as a single-photon source.

[0047] In some examples, the first filtering module includes multiple narrowband filters for filtering out noise signals in the multiplexed signal photons of the second wavelength division multiplexing output.

[0048] Specifically, such as Figure 1As shown, the first filtering module includes four narrowband filters, each of which filters out noise signals from one signal photon.

[0049] In some examples, the second filtering module includes multiple narrowband filters for filtering out noise signals in the multiple idler photons of the third wavelength division multiplexing output.

[0050] Specifically, such as Figure 1 As shown, the second filtering module includes four narrowband filters, each of which filters out noise signals from one idler photon.

[0051] Specifically, multiple narrowband filters can selectively transmit light of a specific wavelength to filter out noise signals doped in multiple signal photons or multiple idler photons.

[0052] Example 2 The working principle of the multidimensional quantum entanglement light source provided in this embodiment of the invention is as follows: Pump light is generated and output using a laser; The intensity of the pump light is amplified using an optical fiber amplifier; A nonlinear crystal is used to convert the amplified pump light into entangled photon pairs, which include signal photons and idler photons. Using a first wavelength division multiplexer, the entangled photon pair is split into two paths according to wavelength: one path is the signal photon, and the other path is the idler photon. The signal photons are divided into multiple paths according to wavelength using the second wavelength division multiplexer to obtain multiple signal photons. Then, the noise signals in each signal photon are filtered out by the narrowband filter modules in the first filter module. Finally, the signal photons after the noise signals are filtered out are detected by the single photon detectors in the first detection module. Using a third wavelength division multiplexer, the idler photons are split into multiple paths according to wavelength, resulting in multiple idler photons. Then, using narrowband filter modules in the second filter module, noise signals in each idler photon are filtered out. Finally, using single-photon detectors in the second detection module, each idler photon after the noise signal has been filtered out is detected. The multiple signal photons and the multiple idler photons form a multidimensional quantum entangled source, that is, one signal photon from the multiple signal photons and one idler photon from the multiple idler photons form a one-dimensional quantum entangled source.

[0053] The basic principles of this invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this invention are merely examples and not limitations, and should not be considered as essential features of the various embodiments disclosed in this invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this invention to the necessity of employing the specific details described above.

[0054] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0055] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0056] The methods and apparatus disclosed in this invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods disclosed in this invention are not limited to the order specifically described above, unless otherwise specifically stated. Furthermore, in some embodiments, this invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods disclosed in this invention. Thus, this invention also covers recording media storing programs for performing the methods disclosed in this invention.

[0057] It should also be noted that in the apparatus, devices, and methods disclosed in this invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalent solutions disclosed in this invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention disclosed herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention disclosure. Therefore, this invention disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0058] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention disclosed herein to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0059] It is understood that the relevant features in the above methods and apparatus can be referenced interchangeably. Furthermore, the terms "first," "second," etc., in the above embodiments are used to distinguish between embodiments and do not represent the superiority or inferiority of any particular embodiment.

[0060] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0061] It should be noted that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A multidimensional quantum entangled light source, characterized in that, include: Lasers are used to generate and output pump light; An optical fiber amplifier is used to amplify the intensity of the pump light; Nonlinear crystals are used to convert amplified pump light into entangled photon pairs, including signal photons and idler photons. The first wavelength division multiplexer is used to split the entangled photon pair into two paths according to wavelength, one path being the signal photon and the other path being the idler photon; The second wavelength division multiplexer is used to split the signal photons into multiple paths according to wavelength to obtain multiple signal photons; The third wavelength division multiplexer is used to split the idler photons into multiple paths according to wavelength, resulting in multiple idler photons, wherein: The multiple signal photons and the multiple idler photons form a multidimensional quantum entangled light source.

2. The multidimensional quantum entangled light source according to claim 1, characterized in that, Also includes: The first detection module includes multiple single-photon detectors, which are used to detect each signal photon in the multiple signal photons respectively; The second detection module includes multiple single-photon detectors, which are used to detect each idler photon in the multiple idler photons.

3. The multidimensional quantum entangled light source according to claim 1, characterized in that, It also includes a first filtering module, which includes multiple narrowband filters, for filtering out noise signals in the multiple signal photons output by the second wavelength division multiplexer.

4. The multidimensional quantum entangled light source according to claim 1, characterized in that, It also includes a second filtering module, which includes multiple narrowband filters, for filtering out noise signals in the multiple idler photons output by the third wavelength division multiplexer.

5. The multidimensional quantum entangled light source according to claim 2, characterized in that, The number of single-photon detectors in the second detection module is the same as the number of single-photon detectors in the first detection module.

6. The multidimensional quantum entangled light source according to claim 1, characterized in that, The nonlinear crystal is a type 0 nonlinear optical crystal.

7. The multidimensional quantum entangled light source according to claim 1, characterized in that, The first wavelength division multiplexer is a coarse wavelength division multiplexer (CWDM).

8. The multidimensional quantum entangled light source according to claim 1, characterized in that, The second wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

9. The multidimensional quantum entangled light source according to claim 1, characterized in that, The third wavelength division multiplexer is a dense wavelength division multiplexer (DWDM).

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