A quantum key distribution system

Abstract

This invention provides an optical quantum key distribution system, including a receiver. The receiver comprises a focusing secondary mirror, a deflector, a beam splitter, a single-receiver quantum key distribution device, and a Hartmann wavefront sensor. The focusing secondary mirror receives a single-photon beam carrying key information. The beam then passes sequentially through the deflector and beam splitter. The deflector adjusts the beam direction, and the beam splitter divides the beam into two paths: one path enters the single-receiver quantum key distribution device, and the other path enters the Hartmann wavefront sensor. The Hartmann wavefront sensor provides feedback on the beam spot information, which is used to adjust the focal length of the focusing secondary mirror and the position of the deflector to correct for the effects of atmospheric turbulence. The single-receiver quantum key distribution device randomly selects a pair of basis vectors to interact with the transmitter, completing the optical quantum key distribution. This system effectively receives single photons from the transmitter, improving the success rate of signal optical quantum key distribution and enhancing communication quality.

Description

Technical Field

[0001] This invention relates to the field of quantum communication technology, and in particular to an optical quantum key distribution system. Background Technology

[0002] With the continuous development and progress of society, people's demand for information encryption is also constantly increasing. Most encryption schemes in classical cryptography are based on computational complexity, but these complex calculations will be easier to implement with the advent of quantum computers. With the further development of quantum mechanics research, quantum secure communication based on quantum key distribution (QKD) has been widely applied in the field of information encryption. QKD can satisfy the two conditions of "generating truly random keys" and "securely distributing keys," thus guaranteeing the unconditional security of quantum secure communication. Therefore, quantum key distribution has become a research hotspot both domestically and internationally, and is currently the most mature technology in the field of quantum technology.

[0003] Currently, traditional fiber optic channels are commonly used for quantum key distribution. The transmitter randomly generates a bit (qubit) and randomly selects a pair of orthogonal states (basis vectors) to prepare a random quantum state. This single photon is then transmitted to the receiver through the fiber optic channel. The receiver interacts with the transmitter by randomly selecting a pair of basis vectors, thereby completing the key distribution.

[0004] Currently, traditional fiber optic channels are often used for quantum key distribution in special environments. This key distribution method mainly transmits single photons to the receiving end through optical fibers or network cables. However, this type of key distribution system is limited by the limited optical fiber resources and high costs. In particular, when carrying out key distribution across rivers and lakes, the scarcity of optical fiber resources and the high cost of independently building optical fibers will seriously restrict the development of quantum secure communication.

[0005] For scenarios where fiber optic channels cannot be used for key distribution, experiments have shown that successful key distribution using laser transmission capabilities via free channels has been achieved. However, in practical applications, photons emitted by this key distribution method are easily affected by near-surface atmospheric turbulence during transmission, causing laser deflection and jitter. This results in fewer photons reaching the receiver, while noise from the near-surface environment accumulates, ultimately leading to a higher bit error rate. When the bit error rate exceeds a certain threshold, the system can no longer generate secure keys. In other words, due to complex geographical environments (such as wide rivers and lakes, high mountains and deep valleys), photons are easily affected by near-surface atmospheric turbulence during transmission. Therefore, ensuring successful quantum key distribution over a range of several kilometers or even tens of kilometers and improving communication quality has become a key issue in the development of quantum secure communication. Summary of the Invention

[0006] The optical quantum key distribution system provided by this invention mainly solves the technical problem of low success rate and poor communication quality of optical quantum key distribution due to the influence of atmospheric turbulence.

[0007] To address the aforementioned technical problems, this invention provides an optical quantum key distribution system, comprising a receiver, which includes a focusing secondary mirror, a deflector, a beam splitter, a single-receiver quantum key distribution device, and a Hartmann wavefront sensor. The focusing secondary mirror receives a single-photon beam carrying key information. The beam then passes sequentially through the deflector and the beam splitter. The deflector adjusts the beam direction, and the beam splitter divides the beam into two paths: one path enters the single-receiver quantum key distribution device, and the other path enters the Hartmann wavefront sensor. The Hartmann wavefront sensor provides feedback on the beam spot information, which is used to adjust the focal length of the focusing secondary mirror and the position of the deflector to correct for the effects of atmospheric turbulence. The single-receiver quantum key distribution device randomly selects a pair of basis vectors to interact with the transmitter, completing the optical quantum key distribution.

[0008] Furthermore, the focusing secondary lens is a large-size focusing secondary lens, with a size range of Φ150mm to Φ500mm.

[0009] Furthermore, the single-receiver quantum key distribution device completes the distribution of optical quantum keys by discarding bits with different basis vectors from the transmitter and restoring the remaining bits to their shared key.

[0010] Furthermore, the optical quantum key distribution system also includes a transmitter, which includes a single-photon quantum key distribution device, a lens, a reflector, and an attenuator. The single-photon quantum key distribution device is used to generate and emit polarized light based on the key information to be distributed, which passes through the lens, reflector, and attenuator in sequence to become a single-photon beam and then emits it.

[0011] Furthermore, the single-send quantum key distribution device transmits via polarization encoding or phase encoding.

[0012] The beneficial effects of this invention are:

[0013] According to the present invention, an optical quantum key distribution system includes a receiver, which comprises a focusing secondary mirror, a deflector, a beam splitter, a single-receiver quantum key distribution device, and a Hartmann wavefront sensor. The focusing secondary mirror receives a single-photon beam carrying key information. The beam then passes sequentially through the deflector and beam splitter. The beam direction is adjusted by the deflector, and the beam is split into two paths by the beam splitter. One path enters the single-receiver quantum key distribution device, and the other path enters the Hartmann wavefront sensor. The Hartmann wavefront sensor provides feedback on the beam spot information, which is used to adjust the focal length of the focusing secondary mirror and the position of the deflector to correct for the effects of atmospheric turbulence. The single-receiver quantum key distribution device randomly selects a pair of basis vectors to interact with the transmitter to complete the optical quantum key distribution. The system can effectively receive single photons from the transmitter, improve the success rate of signal optical quantum key distribution, and improve communication quality. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an optical quantum key distribution system according to Embodiment 1 of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0016] Example 1:

[0017] This embodiment provides an optical quantum key distribution system. By utilizing the spot information fed back in real time by a Hartmann wavefront sensor at the receiving end, the position of the deflector and the focal length of the focusing secondary mirror are controlled to receive more optical signals, thereby improving the success rate of signal optical quantum key distribution and enhancing communication quality. Please refer to [link to relevant documentation]. Figure 1 A quantum key distribution system mainly consists of a transmitter and a receiver, wherein:

[0018] The transmitter includes a single-shot quantum key distribution device, a lens, a reflector, and an attenuator. The single-shot quantum key distribution device generates and emits polarized light based on the key information to be distributed. The light passes through the lens, reflector, and attenuator in sequence to become a single-photon beam before being emitted. The single-shot quantum key distribution device can emit light using either polarization encoding or phase encoding.

[0019] The receiving end includes a focusing secondary mirror, a deflector, a beam splitter, a single-receiver quantum key distribution device, and a Hartmann wavefront sensor. The focusing secondary mirror receives a single-photon beam carrying key information. The beam then passes sequentially through the deflector and beam splitter. The deflector adjusts the beam direction, and the beam splitter divides the beam into two paths: one path enters the single-receiver quantum key distribution device, and the other enters the Hartmann wavefront sensor. The Hartmann wavefront sensor provides feedback on the beam spot information, which is used to adjust the focal length of the focusing secondary mirror and the position of the deflector to correct for atmospheric turbulence. The single-receiver quantum key distribution device randomly selects a pair of basis vectors to interact with the transmitting end, completing the optical quantum key distribution. It should be understood that the single-receiver quantum key distribution device discards bits with different basis vectors from the transmitting end, restoring the remaining bits to their shared key, thereby completing the optical quantum key distribution.

[0020] In other embodiments of the present invention, the focusing secondary mirror is a large-size focusing secondary mirror, with a size ranging from Φ150mm to Φ500mm. Designing a larger focusing secondary mirror at the receiving end facilitates the reception of more optical signals, thereby improving the success rate of optical quantum key distribution.

[0021] This invention proposes an optical quantum key distribution system. By designing a larger focusing secondary mirror at the receiving end and leveraging the ability of a Hartmann wavefront detector to correct for the effects of atmospheric turbulence, the system adjusts the focal length of the focusing secondary mirror and the position of the deflector based on the real-time feedback of the light spot information from the Hartmann wavefront detector. This corrects for the effects of atmospheric turbulence, ensuring the integrity of the received single-photon signal, and enabling quantum key distribution in an atmospheric environment. This improves the success rate of signal optical quantum key distribution and expands the application scenarios of quantum key distribution.

[0022] Existing quantum key distribution systems based on fiber optic channels are difficult to apply to quantum secure communication across rivers and mountains due to the scarcity of fiber optic resources in special environments, the difficulty and high cost of laying fiber optic cables. This invention adopts an atmospheric environment space optical channel, which can greatly reduce the cost and difficulty of laying fiber optic cables.

[0023] Existing quantum key distribution systems based on free channels do not consider the influence of near-surface atmospheric turbulence. Atmospheric turbulence can easily cause light spot deflection and jitter, which can lead to the inability to receive complete optical signals at the receiving end. This invention uses a large-size focusing secondary mirror and utilizes a Hartmann wavefront sensor to adjust the focal length of the secondary mirror and the position of the deflector in real time to ensure that the received light spot information is as complete as possible and to greatly reduce the influence of atmospheric turbulence.

[0024] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a computer storage medium (ROM / RAM, magnetic disk, optical disk) for execution by the computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Therefore, the present invention is not limited to any particular hardware and software combination.

[0025] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A photonic quantum key distribution system comprising a receiving end, characterized in that, The receiving end comprises a focusing secondary mirror, a deflection mirror, a beam splitter, a single-receiving quantum key distribution device, and a Hartmann wavefront sensor; the focusing secondary mirror is used to receive a single-photon light beam carrying key information; then the light beam sequentially passes through the deflection mirror and the beam splitter, is split into two paths by the beam splitter after the direction of the light beam is adjusted by the deflection mirror; one path enters the single-receiving quantum key distribution device, and the other path enters the Hartmann wavefront sensor; the Hartmann wavefront sensor is used to feed back spot information, so that the focal length of the focusing secondary mirror and the position of the deflection mirror are adjusted based on the spot information to correct the influence of atmospheric turbulence; the single-receiving quantum key distribution device is used to randomly select a pair of base vectors to interact with the transmitting end to complete optical quantum key distribution; the single-receiving quantum key distribution device restores the remaining bits to a common key by discarding bits of different base vectors between the transmitting end, thereby completing optical quantum key distribution.

2. The optical quantum key distribution system of claim 1, wherein, The focusing secondary mirror is a large-size focusing secondary mirror, and the size range is Φ150mm-Φ500mm.

3. The optical quantum key distribution system of claim 1, wherein, The optical quantum key distribution system further comprises a transmitting end, and the transmitting end comprises a single-transmitting quantum key distribution device, a lens, a mirror, and an attenuator; the single-transmitting quantum key distribution device is used to generate and transmit polarized light based on key information to be distributed, and sequentially passes through the lens, the mirror, and the attenuator to become a single-photon light beam and is transmitted.

4. The optical quantum key distribution system of claim 3, wherein, The single-transmitting quantum key distribution device is transmitted by a polarization encoding or phase encoding mode.

Images