Dual-polarization IQ modulation continuous variable quantum key distribution chip system device and method

Abstract

The invention discloses a dual-polarization IQ modulation continuous variable quantum key distribution chip system device and method, and the device achieves the intensity difference between a quantum signal and a pilot signal through the addition of an intensity modulator, can effectively reduce the requirements of a dual-polarization IQ modulation CV-QKD chip for the modulation bit width of a DAC, and improves the system performance. The problem that an existing dual-polarization IQ modulation local oscillator CV-QKD system is poor in modulation performance is effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum secure communication, and in particular relates to a dual-polarization IQ modulation continuous variable quantum key distribution chip system device and method. Background Art

[0002] Quantum secure communication technology, represented by quantum key distribution (QKD), is the core of network security in the quantum information age. It plays a significant role in ensuring the bottom line of cryptographic security and enhancing cyberspace security defense capabilities. QKD technology mainly has two technical approaches: continuous variable and discrete variable. Among them, continuous variable quantum key distribution (CV-QKD) uses the canonical component of the quantum light field as the carrier of key information. The device is compatible with classical coherent optical communication and has a high code rate under medium and short-distance transmission conditions, making it very suitable for quantum metropolitan area network and access network applications.

[0003] High-performance, highly integrated, and low-cost CV-QKD systems are essential for achieving CV-QKD networking and large-scale application. Due to the advantages of photonic chip technology in terms of energy consumption, bandwidth, speed, and size, the development of high-performance, highly integrated, and low-cost CV-QKD systems based on photonic chip technology has become a key development trend. Due to the relatively short development history of existing CV-QKD chip systems, technical specifications such as security code rate and transmission distance still require improvement. The dual-polarization IQ modulated local oscillator CV-QKD scheme, which utilizes polarization multiplexing, can theoretically double spectrum utilization, thereby doubling the security code rate. Furthermore, combined with corresponding digital deflection correction methods, it eliminates the need for additional polarization control devices, making it ideally suited for chip-based CV-QKD systems with high performance and integration requirements.

[0004] Existing dual-polarization IQ-modulated local oscillator CV-QKD schemes often use time-division multiplexing to separate the quantum signal and pilot signal. This can prevent crosstalk between the quantum and pilot signals, thereby improving system performance and stability. Because the pilot signal in a time-division multiplexed dual-polarization system is typically more than 10dB (10 times) stronger than the quantum signal, and the quantum and pilot signals are driven by the same arbitrary waveform generator (AWG), higher requirements are placed on the AWG's DAC modulation range.

[0005] For example, a local oscillator CV-QKD system based on Gaussian modulation generally requires a DAC modulation accuracy of 8 bits or more. If the pilot signal is 12dB stronger than the quantum signal (corresponding to a 4-bit modulation bit width), then the AWG's DAC total modulation bit width must be at least 12 bits to meet the system requirements. Because modulation bit width and bandwidth are mutually constrained, as the repetition frequency of the CV-QKD system increases, the required AWG signal bandwidth also increases accordingly, while the modulation bit width cannot be reduced. Since high-speed and high-modulation bit number AWGs are more expensive and more difficult to implement, or even impossible to implement, this seriously restricts the performance improvement of dual-polarization IQ modulation local oscillator CV-QKD systems.

[0006] Therefore, how to design and optimize the dual-polarization IQ modulation local oscillator CV-QKD system modulation scheme and reduce the performance requirements of the AWG driving signal has important research significance and value for improving system performance and reducing costs. Summary of the Invention

[0007] The purpose of the present invention is to address the problem of poor modulation performance of existing dual-polarization IQ modulation local oscillator CV-QKD systems, and to provide a dual-polarization IQ modulation continuous variable quantum key distribution chip system device and method. By adding an intensity modulator to achieve the intensity difference between the quantum signal and the pilot signal, the dual-polarization IQ modulation CV-QKD chip can effectively reduce the DAC modulation bit width requirements, thereby improving system performance.

[0008] On the one hand, the purpose of the present invention is achieved through the following technical solutions:

[0009] A dual-polarization IQ modulation continuous variable quantum key distribution chip system device, the dual-polarization IQ modulation continuous variable quantum key distribution chip system device comprising:

[0010] Light source generation module, outputs optical signal to chip coupling module 1;

[0011] Coupling module 1 couples the optical signal from the off-chip light source generation module to the chip and transmits it to the polarization beam splitting module;

[0012] Polarization beam splitting module, used to split the optical signal into two signals according to the polarization direction, namely the upper branch and the lower branch;

[0013] The driving module generates a driving voltage for driving the on-chip intensity modulation module and attenuation module, including generating a modulation signal and performing timing control;

[0014] Intensity modulation module 1, used for intensity modulation of the upper branch, to achieve intensity difference control of quantum signal and pilot signal;

[0015] IQ modulation module 1, used for quantum signal modulation of the upper branch;

[0016] Attenuation module 1 is used to control the attenuation of the quantum signal of the upper branch, so that it is attenuated to the required quantum signal strength, while achieving the balance of the polarization signal strength of the upper branch and the lower branch;

[0017] Intensity modulation module 2, used for intensity modulation of the lower branch, to achieve intensity difference control of the quantum signal and the pilot signal;

[0018] IQ modulation module 2, used for quantum signal modulation of the lower branch;

[0019] Attenuation module 2 is used to control the quantum signal attenuation of the lower branch, so that it is attenuated to the required quantum signal strength, while achieving the balance of the polarization signal strength of the upper branch and the lower branch;

[0020] Polarization coupling module, used to achieve polarization coupling of upper branch and lower branch polarization signals;

[0021] The coupling module 2 couples the polarization-coupled optical signal to the channel optical fiber.

[0022] According to a preferred embodiment, the coupling module 1 and the coupling module 2 adopt end face coupling or grating coupling.

[0023] According to a preferred embodiment, the polarization beam splitting module is a multimode interferometer MMI, or a Mach-Zehnder interferometer MZI, or an asymmetric directional coupler ADC or a grating structure.

[0024] According to a preferred embodiment, the polarization beam splitting module is a polarization beam splitter, which makes the transmission modes of the two arm waveguides different;

[0025] Alternatively, the polarization beam splitting module is a polarization rotation beam splitter, which makes the transmission modes of the two-arm waveguides the same.

[0026] According to a preferred embodiment, the polarization coupling module is a multi-mode interferometer MMI, or a Mach-Zehnder interferometer MZI, or an asymmetric directional coupler ADC or a grating structure.

[0027] According to a preferred embodiment, the polarization coupling module is a polarization beam splitter that receives two-arm waveguides with different transmission modes;

[0028] Alternatively, the polarization coupling module is a polarization rotation coupler that receives two-arm waveguides with the same transmission mode.

[0029] According to a preferred embodiment, the intensity modulation module 1 and the intensity modulation module 2 are intensity modulators of an electro-optical MZI structure or a micro-ring structure.

[0030] According to a preferred embodiment, the signal loading mode of the intensity modulation module 1 and the intensity modulation module 2 is a periodic rectangular wave signal, and the duty cycle thereof is 10%, 50%, 90%, or other set ratios.

[0031] According to a preferred embodiment, the periodic rectangular wave signals loaded by the intensity modulation module 1 and the intensity modulation module 2 are aligned with the time-division multiplexed pilot signal and quantum signal, and the strong signal is aligned with the pilot signal sequence, and the weak signal is aligned with the quantum signal sequence.

[0032] According to a preferred embodiment, the IQ modulation module 1 and the IQ modulation module 2 are composed of an electro-optical MZI structure, or a micro-ring structure modulator and a thermo-optical phase shifter;

[0033] The attenuation module 1 and the attenuation module 2 are implemented by a thermo-optical MZI structure or a micro-ring structure modulator;

[0034] The light source generating module is outside the chip and inputs the signal into the chip through coupling, or the light source generating module is integrated inside the chip through heterogeneous and heterogeneous integration.

[0035] On the other hand, the present invention also discloses:

[0036] A dual-polarization IQ modulation continuous variable quantum key distribution method adopts the aforementioned chip system device. The dual-polarization IQ modulation continuous variable quantum key distribution method increases the intensity difference between the quantum signal and the pilot signal by adding intensity modulation module 1 and intensity modulation module 2, thereby reducing the DAC modulation bit width requirement of the dual-polarization IQ modulation continuous variable quantum key distribution chip device.

[0037] The aforementioned main solution of the present invention and its various further options can be freely combined to form multiple solutions, all of which can be adopted and protected by the present invention. After understanding the solutions of the present invention, those skilled in the art will understand that there are many combinations based on existing technology and common knowledge, all of which are technical solutions to be protected by the present invention, and these are not exhaustive here.

[0038] Beneficial effects of the present invention:

[0039] The present invention can effectively solve the problem of poor modulation performance of the existing dual-polarization IQ modulation local oscillator CV-QKD system, effectively reduce the requirements of the dual-polarization IQ modulation CV-QKD chip on the DAC modulation bit number, and thus improve the system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the dual-polarization IQ modulation continuous variable quantum key distribution chip system device of the present invention;

[0041] Figure 2It is a schematic diagram of signal loading of the intensity modulation module of the present invention. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0043] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should also be noted that, unless otherwise clearly stipulated and limited, the terms "set", "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In addition, the present invention would like to point out that, in the present invention, unless the specific structure, connection relationship, positional relationship, power source relationship, etc. are specifically written out, the structure, connection relationship, positional relationship, power source relationship, etc. involved in the present invention are all known to those skilled in the art based on the existing technology without creative work.

[0045] Example 1

[0046] refer to Figure 1 and Figure 2 As shown, the figure shows a dual-polarization IQ modulation CV-QKD system method and device for a photonic integrated chip, which is applied to the CV-QKD transmitter and includes the following functional modules.

[0047] The light source generating module outputs the optical signal to the chip coupling module 1.

[0048] The coupling module 1 couples the optical signal of the off-chip light source generation module to the chip and transmits it to the polarization beam splitting module.

[0049] The polarization beam splitting module is used to split the optical signal into two signals according to the polarization direction, namely the upper branch and the lower branch.

[0050] The driving module generates a driving voltage for driving the on-chip modulation module and attenuation module, including functions such as modulation signal generation and timing control.

[0051] The intensity modulation module 1 is used for intensity modulation of the upper branch to realize intensity difference control of the quantum signal and the pilot signal.

[0052] IQ modulation module 1 is used for quantum signal modulation of the upper branch.

[0053] Attenuation module 1 is used to control the attenuation of the quantum signal of the upper branch, so that it is attenuated to the required quantum signal strength, and at the same time achieve the balance of the polarization signal strength of the upper branch and the lower branch.

[0054] The intensity modulation module 2 is used for intensity modulation of the lower branch to realize intensity difference control of the quantum signal and the pilot signal.

[0055] IQ modulation module 2 is used for quantum signal modulation of the lower branch.

[0056] Attenuation module 2 is used to control the attenuation of the quantum signal of the lower branch, so that it is attenuated to the required quantum signal strength, while achieving the balance of the polarization signal strength of the upper branch and the lower branch.

[0057] The polarization coupling module is used to realize polarization coupling of the upper branch and the lower branch polarization signals.

[0058] The coupling module 2 couples the polarization-coupled optical signal to the channel optical fiber.

[0059] Furthermore, the coupling module 1 and the coupling module 2 may be end-face coupled or grating coupled.

[0060] Furthermore, the polarization beam splitting module can be a structure such as a multimode interferometer (MMI), a Mach-Zehnder interferometer (MZI), an asymmetric directional coupler (ADC), and a grating.

[0061] Furthermore, the polarization beam splitting module can be a polarization beam splitter to make the transmission modes of the two-arm waveguides different, or can be a polarization rotation beam splitter to make the transmission modes of the two-arm waveguides the same.

[0062] Furthermore, the polarization coupling module can be a structure such as a multimode interferometer (MMI), a Mach-Zehnder interferometer (MZI), an asymmetric directional coupler (ADC), and a grating.

[0063] Furthermore, the polarization coupling module may be a polarization coupler for receiving two-arm waveguides with different transmission modes, or a polarization rotation coupler for receiving two-arm waveguides with the same transmission mode.

[0064] Furthermore, the intensity modulation module 1 and the intensity modulation module 2 may be intensity modulators such as an electro-optical MZI structure and a micro-ring structure.

[0065] Furthermore, the positions of the intensity modulation module 1 and the intensity modulation module 2 are irrelevant to the positions of the IQ modulation module 1 and the IQ modulation module 2 .

[0066] Furthermore, the functions of the intensity modulation module 1 and the intensity modulation module 2 can be replaced by one intensity modulation module, which is located before the polarization splitting or after the polarization coupling.

[0067] Furthermore, the signal loading mode of the intensity modulation module 1 and the intensity modulation module 2 is a periodic rectangular wave signal, and the duty cycle thereof can be 10%, 50%, 90% or other ratios.

[0068] Furthermore, the periodic rectangular wave signals loaded by the intensity modulation module 1 and the intensity modulation module 2 are required to be aligned with the time-division multiplexed pilot signal and quantum signal, and ensure that the strong signal is aligned with the pilot signal sequence and the weak signal is aligned with the quantum signal sequence.

[0069] Furthermore, the IQ modulation module 1 and the IQ modulation module 2 may be composed of a high-speed intensity modulator such as an electro-optical MZI structure, a micro-ring structure, and a thermo-optical phase shifter.

[0070] Furthermore, the light source generating module can be external to the chip through coupling input into the chip, or can be integrated inside the chip through heterogeneity or heterogeneity.

[0071] Furthermore, the attenuation module 1 and the attenuation module 2 can be implemented by intensity modulators such as thermo-optical MZI structures and micro-ring structures.

[0072] The present invention realizes the intensity difference between the quantum signal and the pilot signal by adding an intensity modulator, which can effectively reduce the requirements of the dual-polarization IQ modulation CV-QKD chip on the DAC modulation bit width, thereby improving the system performance and effectively solving the problem of poor modulation performance of the existing dual-polarization IQ modulation local oscillator CV-QKD system.

[0073] Example 2

[0074] Based on Example 1, this embodiment further discloses a dual-polarization IQ modulation continuous variable quantum key distribution method, which uses the chip system device described in Example 1. The dual-polarization IQ modulation continuous variable quantum key distribution method increases the intensity difference between the quantum signal and the pilot signal by adding intensity modulation module 1 and intensity modulation module 2, thereby reducing the dual-polarization IQ modulation continuous variable quantum key distribution chip device's requirements for the DAC modulation bit width.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-polarization IQ modulation continuous variable quantum key distribution chip system device, characterized in that: The dual-polarization IQ modulation continuous variable quantum key distribution chip system device comprises: A light source generating module outputs light signals to a coupling module 1 of the chip; Coupling module 1 couples the optical signal of the off-chip light source generation module to the chip and transmits it to the polarization beam splitting module; A polarization beam splitter module is used to split the optical signal into two signals according to the polarization direction, namely an upper branch and a lower branch; A driving module generates a driving voltage for driving the on-chip intensity modulation module and the attenuation module, including generating a modulation signal and performing timing control; Intensity modulation module 1, used for intensity modulation of the upper branch, to achieve intensity difference control of the quantum signal and the pilot signal; IQ modulation module 1, used for quantum signal modulation of the upper branch; Attenuation module 1 is used for controlling the attenuation of the quantum signal of the upper branch, so that it is attenuated to a quantum signal strength that meets the requirements, and at the same time, the polarization signal strength of the upper branch and the lower branch is balanced; Intensity modulation module 2, used for intensity modulation of the lower branch, to achieve intensity difference control of the quantum signal and the pilot signal; IQ modulation module 2, used for quantum signal modulation of the lower branch; Attenuation module 2 is used for controlling the attenuation of the quantum signal of the lower branch, so that it is attenuated to a quantum signal strength that meets the requirements, and at the same time, the polarization signal strength of the upper branch and the lower branch is balanced; A polarization coupling module is used to realize polarization coupling of polarization signals of the upper branch and the lower branch; The coupling module 2 couples the polarization-coupled optical signal to the channel optical fiber.

2. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The coupling module 1 and the coupling module 2 adopt end face coupling or grating coupling.

3. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The polarization beam splitting module is a multi-mode interferometer MMI, or a Mach-Zehnder interferometer MZI, or an asymmetric directional coupler ADC or a grating structure.

4. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1 or 3, characterized in that: The polarization beam splitting module is a polarization beam splitter, which makes the transmission modes of the two arm waveguides different; Alternatively, the polarization beam splitting module is a polarization rotation beam splitter, which makes the transmission modes of the two-arm waveguides the same.

5. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The polarization coupling module is a multi-mode interferometer MMI, or a Mach-Zehnder interferometer MZI, or an asymmetric directional coupler ADC or a grating structure; The polarization coupling module is a polarization beam splitter, which receives two-arm waveguides with different transmission modes; or the polarization coupling module is a polarization rotation coupler, which receives two-arm waveguides with the same transmission mode.

6. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The intensity modulation module 1 and the intensity modulation module 2 are used to realize the function of generating high-speed modulated rectangular waves, and are intensity modulators of electro-optical MZI structure or micro-ring structure.

7. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The signal loading mode of the intensity modulation module 1 and the intensity modulation module 2 is a periodic rectangular wave signal, and the duty cycle thereof is 10%, 50%, 90%, or other set ratios.

8. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The periodic rectangular wave signals loaded by the intensity modulation module 1 and the intensity modulation module 2 are aligned with the time-division multiplexed pilot signal and quantum signal, and the strong signal is aligned with the pilot signal sequence, and the weak signal is aligned with the quantum signal sequence.

9. The dual-polarization IQ modulation continuous variable quantum key distribution chip system device according to claim 1, characterized in that: The IQ modulation module 1 and the IQ modulation module 2 are composed of an electro-optical MZI structure, or a micro-ring structure modulator and a thermo-optical phase shifter; The attenuation module 1 and the attenuation module 2 are implemented by a thermo-optical MZI structure or a micro-ring structure modulator; The light source generating module is outside the chip and inputs the signal into the chip through coupling, or the light source generating module is integrated inside the chip through heterogeneity or heterogeneity.

10. A dual-polarization IQ modulation continuous variable quantum key distribution method, characterized in that: Using the chip system device as described in any one of claims 1 to 9, the dual-polarization IQ modulation continuous variable quantum key distribution method increases the intensity difference between the quantum signal and the pilot signal by adding intensity modulation module 1 and intensity modulation module 2, thereby reducing the requirements of the dual-polarization IQ modulation continuous variable quantum key distribution chip device for the DAC modulation bit width.

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