Cold atom gravity measurement method and device based on entanglement enhancement

Abstract

The present invention relates to the technical field of cold atom gravity measurement, and provides a cold atom gravity measurement method and device based on entanglement enhancement. The method comprises: exciting a nonlinear crystal to obtain an entangled photon pair, the entangled photon pair comprising a first photon and a second photon in an entangled state; controlling laser parameters of a region where a cold atom group is located, and coupling the first photon into the cold atom group to obtain a plurality of cold atoms in an entangled state; and placing the plurality of cold atoms in the entangled state in a gravity field, measuring a phase difference of the cold atoms under the action of the gravity field, and determining a gravity measurement result on the basis of the phase difference. In the present invention, entangled photons are introduced to be coupled with cold atoms, so that the measurement limit is improved to the Heisenberg limit, and higher-precision gravity measurement is realized.

Description

A Cold Atom Gravity Measurement Method and Apparatus Based on Entangled State Enhancement Technical Field

[0001] This invention relates to the field of cold atom gravity measurement technology, specifically to a cold atom gravity measurement method and apparatus based on entangled state enhancement. Background Technology

[0002] Cold atom gravimeters are widely used in the field of precision gravity measurement. Their measurement principle is based on cooling atoms to near absolute zero, and then utilizing the influence of the gravitational field on their interferometric patterns to achieve measurement.

[0003] However, the measurement accuracy of cold atom gravimeters is primarily limited by the standard quantum limit (SQL), which remains insufficient for geophysical exploration, geological surveys, and fundamental physics experiments in many cases. The standard quantum limit is... Where n is the number of atoms. This means that increasing the measurement accuracy requires increasing the number of atoms, but too many atoms will increase the difficulty of cooling and the complexity of the system.

[0004] Therefore, there is an urgent need to provide a cold atom gravity measurement method and device based on entanglement state enhancement, which can improve measurement accuracy without increasing the number of atoms, so as to balance measurement accuracy and system simplicity. Summary of the Invention

[0005] In view of this, it is necessary to provide a cold atom gravity measurement method and device based on entanglement state enhancement, so as to solve the technical problem that the existing technology improves the measurement accuracy by increasing the number of atoms, which leads to high cooling difficulty and system complexity.

[0006] On the one hand, in order to solve the above-mentioned technical problems, the present invention provides a cold atom gravity measurement method based on entangled state enhancement, comprising:

[0007] A nonlinear crystal is excited to obtain a pair of entangled photons, wherein the entangled photon pair includes a first photon and a second photon in an entangled state;

[0008] By controlling the laser parameters in the region where the cold atom cluster is located, the first photon is coupled into the cold atom cluster to obtain multiple cold atoms in an entangled state;

[0009] The entangled cold atoms are placed in a gravitational field, the phase difference of the cold atoms under the action of the gravitational field is measured, and the gravity measurement result is determined based on the phase difference.

[0010] In one possible implementation, a nonlinear crystal is excited to obtain a pair of entangled photons, including:

[0011] Obtain the target parameters of the tunable laser source, and adjust the pump light based on the target parameters to obtain the target pump light;

[0012] The nonlinear crystal is excited by the target pump light to obtain the entangled photon pair.

[0013] In one possible implementation, after exciting the nonlinear crystal based on the target pump light to obtain the entangled photon pair, the method further includes:

[0014] By adjusting the phase shift between the first photon and the second photon, an enhanced entangled photon pair can be obtained;

[0015] The enhanced entangled photon pairs are processed using lock-in amplification technology to obtain stable entangled photon pairs.

[0016] In one possible implementation, before coupling the first photon to the cold atom cluster to obtain multiple cold atoms in an entangled state, the method further includes:

[0017] The wavelength and polarization state of the first photon, as well as the target wavelength and coupling characteristics of the cold atom, are obtained.

[0018] The wavelength and polarization state are adjusted based on the target wavelength and the coupling characteristics.

[0019] In one possible implementation, laser parameters in the region where the cold atom cluster is located are controlled to couple the first photon into the cold atom cluster, thereby obtaining multiple cold atoms in an entangled state, including:

[0020] By controlling the laser parameters in the region where the cold atom cluster is located, the entanglement response between each cold atom in the cold atom cluster and the first photon is constructed.

[0021] Based on the interaction between the plurality of cold atoms and the entanglement response, the plurality of cold atoms in an entangled state are obtained.

[0022] In one possible implementation, the method further includes:

[0023] Simultaneously acquire the first phase data of the cold atom and the second phase data of the first photon;

[0024] The coupling strength of the entanglement response is determined based on the first phase data and the second phase data;

[0025] When the coupling strength does not meet the requirements, the laser parameters are adjusted so that the coupling strength of the entanglement response meets the requirements.

[0026] In one possible implementation, the laser parameters include the laser field frequency and the laser field phase.

[0027] In one possible implementation, the method further includes: before determining the gravity measurement result based on the phase difference, the method further includes:

[0028] The phase difference is subjected to noise filtering.

[0029] In one possible implementation, after noise filtering of the phase difference, the method further includes:

[0030] Noise compensation is performed on the phase difference after noise filtering based on a quantum noise compensation algorithm.

[0031] On the other hand, the present invention also provides a cold atom gravity measurement device based on entanglement-enhanced states, comprising:

[0032] An entangled photon pair generation module is used to excite a nonlinear crystal to obtain an entangled photon pair, wherein the entangled photon pair includes a first photon and a second photon in an entangled state;

[0033] A photon-cold atom coupling module is used to control the laser parameters in the region where the cold atom cluster is located, and to couple the first photon into the cold atom cluster to obtain multiple cold atoms in an entangled state;

[0034] The gravity measurement module is used to place the plurality of cold atoms in an entangled state in a gravitational field, measure the phase difference of the cold atoms under the action of the gravitational field, and determine the gravity measurement result based on the phase difference.

[0035] The beneficial effects of this invention are as follows: The cold atom gravity measurement method based on entanglement enhancement provided by this invention obtains entangled photon pairs by exciting a nonlinear crystal, and then couples the first photon of the entangled photon pair into a cold atom cluster to obtain multiple cold atoms in an entangled state. This provides additional quantum resources for cold atom gravity measurement, and utilizes the quantum entanglement effect to reduce phase uncertainty, thereby improving measurement accuracy from the standard quantum limit. This is improved to the Heisenberg limit (1 / n), which means that the measurement accuracy of cold atom gravity measurement is improved. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 is a schematic flowchart of an embodiment of the cold atom gravity measurement method based on entanglement state enhancement provided by the present invention;

[0038] Figure 2 is a schematic flowchart of an embodiment of S101 in Figure 1 of the present invention;

[0039] Figure 3 is a schematic flowchart of an embodiment of the present invention for adjusting the wavelength and polarization state of the first photon;

[0040] Figure 4 is a schematic flowchart of an embodiment of S102 in Figure 1 of the present invention;

[0041] Figure 5 is a schematic flowchart of an embodiment of the present invention for adjusting the entanglement response;

[0042] Figure 6 is a schematic diagram of an embodiment of the cold atom gravity measurement device based on entanglement state enhancement provided by the present invention. Detailed Implementation

[0043] 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 a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0045] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0046] This invention provides a cold atom gravity measurement method and apparatus based on entangled state enhancement, which will be described below.

[0047] Figure 1 is a schematic flowchart of an embodiment of the entanglement-enhanced cold atom gravity measurement method provided by the present invention. As shown in Figure 1, the entanglement-enhanced cold atom gravity measurement method includes:

[0048] S101. Excite the nonlinear crystal to obtain a pair of entangled photons, the pair of entangled photons including a first photon and a second photon in an entangled state;

[0049] S102. Control the laser parameters in the region where the cold atom cluster is located, couple the first photon into the cold atom cluster, and obtain multiple cold atoms in an entangled state;

[0050] S103. Place multiple cold atoms in an entangled state in a gravitational field, measure the phase difference of the cold atoms under the action of the gravitational field, and determine the gravity measurement result based on the phase difference.

[0051] Specifically, the nonlinear crystal in step S101 is a lithium niobate crystal.

[0052] In this entangled state, the first and second photons have the same or similar frequencies, are spatially separated but maintain a quantum entanglement relationship, allowing the state of one of the photons to be transmitted to the cold atom cluster.

[0053] It should be understood that a cold atom group refers to a collection of multiple cold atoms.

[0054] Cold atoms refer to rubidium or cesium atoms placed in optical clamps and cooled to an ultra-low temperature state close to absolute zero (a few nanokelvin). Then, mutually perpendicular laser cooling axes are configured to capture and cool the atoms by laser, gradually reducing their velocity to near a stationary state. At this point, the atoms reach a superfluid state or a Bose-Einstein condensate.

[0055] Superfluid states or Bose-Einstein condensates can ensure that cold atoms have high coherence and long coherence time. Cold atom clusters in ultra-low temperature states can achieve collective coherent motion in quantum states, thereby stably maintaining quantum interference modes in a gravitational field, which greatly improves the accuracy of gravity measurement and reduces the interference of thermal noise on the measurement.

[0056] It should be noted that the purpose of coupling the first photon to the cold atom cluster in step S102 is to enable the atom to capture and retain the phase information provided by the first photon.

[0057] It should also be noted that the measurement of the phase difference of cold atoms under the action of gravity in step S103 is as follows: the wave function of the cold atom group is divided into two parts by a beam splitter to obtain two beams of light. The two beams of light evolve freely under the action of gravity, and a small phase difference occurs during this process. The direction of the beams after beam splitting is controlled by a reflector. When the two beams re-merge, the interference fringes after the interference of the two beams are recorded by a detector, and the phase difference is obtained based on the interference fringes.

[0058] Since gravity measurement results depend on phase difference, in order to improve the measurement accuracy of phase difference and thus improve the measurement accuracy of gravity measurement results, in some embodiments of the present invention, phase difference can be detected in real time based on a highly sensitive quantum state detection system to ensure that the measurement accuracy of quantum state reaches the single-photon level.

[0059] Additionally, it can be equipped with fast-response photodetectors and time-resolved detectors to accurately detect and feedback the phase difference of cold atoms in a short time, thereby improving the real-time response capability of gravity measurement.

[0060] Compared with existing technologies, the entanglement-enhanced cold atom gravity measurement method provided in this invention obtains entangled photon pairs by exciting a nonlinear crystal, and then couples the first photon of the entangled photon pair into a cold atom cluster to obtain multiple cold atoms in an entangled state. This provides additional quantum resources for cold atom gravity measurement, reduces phase uncertainty by utilizing the quantum entanglement effect, and improves measurement accuracy from the standard quantum limit. This is improved to the Heisenberg limit (1 / n), which means that the measurement accuracy of cold atom gravity measurement is improved.

[0061] In some embodiments of the present invention, as shown in FIG2, step S101 includes:

[0062] S201. Obtain the target parameters of the tunable laser source, and adjust the pump light based on the target parameters to obtain the target pump light;

[0063] S202. Excite the nonlinear crystal based on the target pump light to obtain entangled photon pairs.

[0064] The purpose of the target parameters is to ensure that the generated entangled photon pairs have strong quantum entanglement properties, so as to ensure the accuracy of subsequent gravity measurements.

[0065] Specifically, the target parameter can be the wavelength of the tunable laser source.

[0066] Furthermore, the target parameters of a tunable laser source can also be parameters related to the generation rate of entangled photon pairs and the purity of the entangled state, which will not be elaborated here.

[0067] It should be noted that in some embodiments of the present invention, the quantum entanglement properties of the generated entangled photon pairs can also be ensured by adjusting the nonlinear coefficient of the nonlinear crystal and by utilizing the Spontaneous Parametric Down-Conversion (SPDC) effect of the nonlinear crystal.

[0068] As described above, the entangled states of multiple cold atoms are crucial to the gravity measurement results. Therefore, in some embodiments of the present invention, after step S202, the cold atom gravity measurement method based on entangled state enhancement further includes:

[0069] By adjusting the phase shift between the first and second photons, enhanced entangled photon pairs can be obtained;

[0070] Stable entangled photon pairs are obtained by processing enhanced entangled photon pairs using lock-in amplification technology.

[0071] Then the first photon and the second photon in step S101 are two photons in a stable entangled photon pair.

[0072] This invention enhances the coherence of the cold atom entanglement formation process by adjusting the phase offset of the first and second photons. By processing the enhanced entangled photon pairs based on lock-in amplification technology, it ensures that the generated stable entangled photon pairs have a stable phase relationship, thus guaranteeing the phase control accuracy during subsequent gravity measurements.

[0073] To maximize the transmission efficiency of the phase information of the first photon in the cold atom cluster, in some embodiments of the present invention, as shown in FIG3, before step S102, the following steps are further included:

[0074] S301. Obtain the wavelength and polarization state of the first photon, as well as the target wavelength and coupling characteristics of the cold atom;

[0075] S302. Adjust the wavelength and polarization state based on the target wavelength and coupling characteristics.

[0076] The wavelength and polarization state can be adjusted using waveplates and polarization beam splitters.

[0077] This invention adjusts the wavelength and polarization state of the first photon based on the target wavelength and coupling characteristics of the cold atom, so that the first photon adapts to the wavelength and coupling characteristics of the cold atom, thereby matching the transition frequency of the first photon with that of the cold atom, and thus maximizing the transmission efficiency of the phase information of the first photon in the cold atom cluster.

[0078] In some embodiments of the present invention, as shown in FIG4, step S102 includes:

[0079] S401. Control the laser parameters in the region where the cold atom cluster is located, and construct the entanglement response between each cold atom in the cold atom cluster and the first photon;

[0080] S402. Based on the interaction and entanglement response between multiple cold atoms, multiple cold atoms in an entangled state are obtained.

[0081] It should be noted that the entanglement response between each cold atom in the cold atom cluster and the first photon is independent. Therefore, the laser parameters controlling the region where the cold atom cluster is located in step S401 should be the laser parameters controlling the position of each cold atom to ensure that an entanglement response is constructed for each cold atom and the first photon.

[0082] The principle of obtaining multiple cold atoms in an entangled state in step S402 is as follows: the first photon transmits phase information to multiple cold atoms through its coherence, and the multiple cold atoms influence each other through the group effect to obtain multiple cold atoms in an entangled state.

[0083] In a specific embodiment of the present invention, the laser parameters include the laser field frequency and the laser field phase.

[0084] Since the entanglement response between the first photon and the cold atom may collapse or decay under the influence of the external environment or other perturbations, making it impossible to accurately measure gravity, to avoid this problem, in some embodiments of the present invention, as shown in FIG5, the cold atom gravity measurement method based on entanglement enhancement further includes:

[0085] S501, Simultaneously acquire the first phase data of the cold atom and the second phase data of the first photon;

[0086] S502. Determine the coupling strength of the entanglement response based on the first phase data and the second phase data;

[0087] S503. When the coupling strength does not meet the requirements, adjust the laser parameters to make the coupling strength of the entanglement response meet the requirements.

[0088] This invention ensures the coupling strength of the entanglement response under any circumstances by synchronously detecting the first phase data of the cold atom and the second phase data of the first photon, and adjusting the laser parameters based on the detected coupling strength. This means that the entanglement response can be quickly adjusted when it is unstable under the influence of external environment or disturbance, ensuring the reliability and stability of the entanglement response, thereby ensuring that coherent information can be effectively transmitted to the cold atom and improving the accuracy of subsequent gravity measurements.

[0089] Furthermore, the embodiments of the present invention simultaneously acquire the first phase data and the second phase data, avoiding the adverse effects of different acquisition times on the determination of coupling strength, thereby ensuring the accuracy of gravity measurement.

[0090] The laser parameters can be adjusted in real time using a phase modulator and a frequency modulator to ensure that the entanglement response between the first photon and the cold atom remains stable throughout the measurement process.

[0091] Because quantum systems are easily affected by their surrounding environment (light, temperature, etc.), any interaction with the environment can lead to information leakage, causing the entangled state to gradually decay—a process called "decoherence." Decoherence is one of the major obstacles to be overcome in quantum computing and quantum communication. To avoid this technical problem, in some embodiments of the present invention, before determining the gravity measurement result based on the phase difference in step S103, the following step is also included:

[0092] Noise filtering is applied to the phase difference.

[0093] The specific method for noise filtering of phase difference is as follows: measure the phase difference noise using a spectrum analyzer, and set the filtering parameters of the noise filter based on the phase difference noise, thereby achieving noise filtering.

[0094] This invention minimizes the error in gravity measurement results by filtering out noise from the surrounding environment, such as ambient light and temperature changes, through phase difference noise filtering.

[0095] To further improve the accuracy of gravity measurement results, in some embodiments of the present invention, after noise filtering of the phase difference, the method further includes:

[0096] Noise compensation is performed on the phase difference after noise filtering based on a quantum noise compensation algorithm.

[0097] The embodiments of the present invention can dynamically compensate for measurement errors caused by quantum noise by setting a quantum noise compensation algorithm, thereby further improving the accuracy of gravity measurement.

[0098] The quantum noise compensation algorithm can be any existing noise compensation algorithm adapted to the embodiments of the present invention, and will not be described in detail here.

[0099] In summary, the entanglement-enhanced cold atom gravity measurement method proposed in this invention couples the first photon of an entangled photon pair into a cluster of cold atoms, obtaining multiple cold atoms in an entangled state. This provides additional quantum resources for cold atom gravity measurement. By utilizing the quantum entanglement effect to reduce phase uncertainty, the phase noise of cold atom gravity measurement is significantly reduced, improving measurement accuracy from the standard quantum limit. The accuracy was increased to the Heisenberg limit (1 / n), which means that the measurement accuracy of cold atom gravity measurement was improved, breaking through the standard quantum limit and realizing high-precision measurement of gravity signals.

[0100] To better implement the entanglement-enhanced cold atom gravity measurement method in this embodiment of the invention, based on the entanglement-enhanced cold atom gravity measurement method, this embodiment of the invention also provides an entanglement-enhanced cold atom gravity measurement device, as shown in FIG6. The entanglement-enhanced cold atom gravity measurement device 600 includes:

[0101] Entangled photon pair generation module 601 is used to excite a nonlinear crystal to obtain a pair of entangled photons, the entangled photon pair including a first photon and a second photon in an entangled state;

[0102] The photon-cold atom coupling module 602 is used to control the laser parameters in the region where the cold atom cluster is located, and to couple the first photon into the cold atom cluster to obtain multiple cold atoms in an entangled state;

[0103] The gravity measurement module 603 is used to place multiple cold atoms in an entangled state in a gravitational field, measure the phase difference of the cold atoms under the action of the gravitational field, and determine the gravity measurement result based on the phase difference.

[0104] The entangled-state-enhanced cold atom gravity measurement device 600 provided in the above embodiments can realize the technical solutions described in the embodiments of the entangled-state-enhanced cold atom gravity measurement method. The specific implementation principles of each module or unit can be found in the corresponding content in the embodiments of the entangled-state-enhanced cold atom gravity measurement method, which will not be repeated here.

[0105] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.), and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0106] The present invention provides a detailed description of a cold atom gravity measurement method and apparatus based on entanglement state enhancement. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, those skilled in the art will know that there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A cold atom gravity measurement method based on entangled state enhancement, characterized in that, include: A nonlinear crystal is excited to obtain a pair of entangled photons, wherein the entangled photon pair includes a first photon and a second photon in an entangled state; By controlling the laser parameters in the region where the cold atom cluster is located, the first photon is coupled into the cold atom cluster to obtain multiple cold atoms in an entangled state; The entangled cold atoms are placed in a gravitational field, the phase difference of the cold atoms under the action of the gravitational field is measured, and the gravity measurement result is determined based on the phase difference. By controlling the laser parameters in the region where the cold atom cluster is located, the first photon is coupled into the cold atom cluster to obtain multiple cold atoms in an entangled state, including: By controlling the laser parameters in the region where the cold atom cluster is located, the entanglement response between each cold atom in the cold atom cluster and the first photon is constructed. Based on the interaction between the plurality of cold atoms and the entanglement response, the plurality of cold atoms in an entangled state are obtained.

2. The cold atom gravity measurement method based on entangled state enhancement according to claim 1, characterized in that, Excitation of a nonlinear crystal yields a pair of entangled photons, including: Obtain the target parameters of the tunable laser source, and adjust the pump light based on the target parameters to obtain the target pump light; The nonlinear crystal is excited by the target pump light to obtain the entangled photon pair.

3. The cold atom gravity measurement method based on entangled state enhancement according to claim 2, characterized in that, After exciting the nonlinear crystal based on the target pump light to obtain the entangled photon pair, the process further includes: By adjusting the phase shift between the first photon and the second photon, an enhanced entangled photon pair can be obtained; The enhanced entangled photon pairs are processed using lock-in amplification technology to obtain stable entangled photon pairs.

4. The cold atom gravity measurement method based on entangled state enhancement according to claim 1, characterized in that, Before coupling the first photon into the cold atom cluster to obtain multiple cold atoms in an entangled state, the process further includes: The wavelength and polarization state of the first photon, as well as the target wavelength and coupling characteristics of the cold atom, are obtained. The wavelength and polarization state are adjusted based on the target wavelength and the coupling characteristics.

5. The cold atom gravity measurement method based on entangled state enhancement according to claim 1, characterized in that, The method further includes: Simultaneously acquire the first phase data of the cold atom and the second phase data of the first photon; The coupling strength of the entanglement response is determined based on the first phase data and the second phase data; When the coupling strength does not meet the requirements, the laser parameters are adjusted so that the coupling strength of the entanglement response meets the requirements.

6. The cold atom gravity measurement method based on entanglement-enhanced states according to any one of claims 1-5, characterized in that, The laser parameters include the laser field frequency and the laser field phase.

7. The cold atom gravity measurement method based on entangled state enhancement according to claim 1, characterized in that, The method further includes: before determining the gravity measurement result based on the phase difference, it further includes: The phase difference is subjected to noise filtering.

8. The cold atom gravity measurement method based on entangled state enhancement according to claim 1, characterized in that, After noise filtering of the phase difference, the method further includes: Noise compensation is performed on the phase difference after noise filtering based on a quantum noise compensation algorithm.

9. A cold atom gravity measurement device based on entangled state enhancement, characterized in that, include: An entangled photon pair generation module is used to excite a nonlinear crystal to obtain an entangled photon pair, wherein the entangled photon pair includes a first photon and a second photon in an entangled state; A photon-cold atom coupling module is used to control the laser parameters in the region where the cold atom cluster is located, and to couple the first photon into the cold atom cluster to obtain multiple cold atoms in an entangled state; The gravity measurement module is used to place the plurality of cold atoms in an entangled state in a gravitational field, measure the phase difference of the cold atoms under the action of the gravitational field, and determine the gravity measurement result based on the phase difference; By controlling the laser parameters in the region where the cold atom cluster is located, the first photon is coupled into the cold atom cluster to obtain multiple cold atoms in an entangled state, including: By controlling the laser parameters in the region where the cold atom cluster is located, the entanglement response between each cold atom in the cold atom cluster and the first photon is constructed. Based on the interaction between the plurality of cold atoms and the entanglement response, the plurality of cold atoms in an entangled state are obtained.

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