An apparatus and method for detecting the number of atoms in a cold atom interferometric gravimeter

Abstract

The present invention provides an atomic number detection device for a cold atom interferometer gravimeter, comprising a laser, a polarization-maintaining fiber, a laser collimator, a first half-wave plate, a first polarization cube beam splitter, a second half-wave plate, a second polarization cube beam splitter, a third half-wave plate, and a prism, arranged in sequence along the same axis. Atom detection laser light emitted by the laser passes through the polarization-maintaining fiber, the laser collimator, the first half-wave plate, the first polarization cube beam splitter, the second half-wave plate, and the second polarization cube beam splitter to form a first detection light and a second output light. The second output light passes through the prism to form a second detection light. The first detection light and the second detection light form a detection area below the vacuum chamber of the cold atom interferometer gravimeter. The present invention also provides a detection method for the atomic number detection device of the cold atom interferometer gravimeter. The present invention utilizes a symmetrical structural design to suppress common-mode noise, effectively solving the problems of low atomic number detection efficiency and susceptibility to background jitter in cold atom interferometer gravimeters.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and in particular to an atomic number detection device and method for a cold atom interferometer gravimeter. Background Art

[0002] Cold atom interferometry (CAI) is an emerging gravity measurement technology that has emerged over the past decade. Its high resolution and repeatability have made it a crucial measurement technology in fields such as national defense and mineral resource exploration. Atom number detection, one of the core technologies of CAI, has been a hot topic of research, and the precise and effective detection of the number of atoms participating in the interferometry has played a crucial role in improving CAI performance. Summary of the Invention

[0003] In order to overcome the technical problems of low common-mode accuracy, high detection noise, complex structure and high cost of atomic number detection in existing cold atom interferometer gravimeter atomic number detection devices, the present invention provides an atomic number detection device and method for cold atom interferometer gravimeter.

[0004] A first aspect of the present invention provides an atomic number detection device for a cold atom interferometer gravimeter, comprising a laser, a polarization-maintaining fiber, a laser collimator, a first half-wave plate, a first polarization cube beam splitter, a second half-wave plate, a second polarization cube beam splitter, a third half-wave plate, and a prism, which are arranged in sequence from top to bottom along the same axis.

[0005] The atom detection laser emitted by the laser is connected to a laser collimator through a polarization-maintaining optical fiber, and the laser collimator collimates the atom detection laser into a first outgoing light directed vertically downward; the first outgoing light passes through a first 1 / 2 wave plate and is incident on a beam splitting surface of a first polarization cube beam splitter, the beam splitting surface of the first polarization cube beam splitter is set at 45 degrees to the outgoing light, and the beam splitting surface of the first polarization cube beam splitter completely transmits the first outgoing light, and the first outgoing light passes through the first polarization cube beam splitter and then reaches the second polarization cube beam splitter after being emitted from the first polarization cube beam splitter; the beam splitting surface of the second polarization cube beam splitter is set at 45 degrees to the outgoing light, and the first outgoing light is divided into a first detection light directed horizontally to the right and a second outgoing light directed vertically downward under the action of the beam splitting surface of the polarization cube beam splitter; the second outgoing light passes through a third 1 / 2 wave plate and is incident on a prism, and is reflected by the reflecting oblique surface of the prism to form a second detection light directed horizontally to the right;

[0006] The first detection light and the second detection light are directed horizontally to the right and pass through the vacuum chamber of the atomic interferometer gravimeter, and a first reflector and a second reflector are provided at positions on the right side of the vacuum chamber corresponding to the first detection light and the second detection light;

[0007] After passing through the vacuum chamber of the atomic interferometer gravimeter, the first probe light is incident on the first reflector, which returns the first probe light along its original path to form a third probe light directed horizontally to the left. The third probe light directed horizontally to the left passes through the first quarter-wave plate and is reflected by the beam splitting surface of the second polarization cube beam splitter to form a third probe light directed vertically upward. The third probe light directed vertically upward enters the first polarization cube beam splitter and is reflected by the reflective surface of the first polarization cube beam splitter to form a first reflected light directed horizontally to the left. The first reflected light is converged onto the first photoelectric probe through the first focusing lens, which is used to detect changes in the intensities of the first and third probe lights.

[0008] After passing through the vacuum chamber of the atomic interferometer gravimeter, the second detection light is incident on the second reflector, which returns the second detection light along its original path to form a fourth detection light directed horizontally to the left. The fourth detection light directed horizontally to the left passes through the second quarter-wave plate and is reflected by the prism to form a fourth detection light directed vertically upward. The fourth detection light directed vertically upward enters the second polarization cube beam splitter and is reflected by the reflective surface of the second polarization cube beam splitter to form a second reflected light directed horizontally to the left. The second reflected light is converged onto the second photoelectric probe through the second focusing lens, and the second photoelectric probe is used to detect changes in the intensity of the second detection light and the fourth detection light.

[0009] Furthermore, the first photoelectric probe is connected to the positive input terminal of the operational amplifier, and the second photoelectric probe is connected to the negative input terminal of the operational amplifier.

[0010] A second aspect of the present invention provides a detection method for a cold atom interferometer gravimeter atomic number detection device, comprising the following steps:

[0011] Step 1: Turn on the laser. The first probe light X1, the third probe light X3, the second probe light X2, and the fourth probe light X4 form a detection area at the bottom of the vacuum chamber of the cold atom interferometer gravimeter. After participating in the interference, the cold atom clusters are distributed in two ground state energy levels, that is, the cold atom clusters are in a superposition state.

[0012] Step 2: The cold atom cluster in the superposition state continues to fall under the action of gravity. When the cold atom cluster falls to the first detection light X1, due to the photoelectric effect between the first detection light X1 and the cold atom cluster, one of the ground-state atoms in the cold atom cluster absorbs the photons in the first detection light X1, causing the intensity of the first reflected light X5 to decrease. The first photoelectric probe PD1 is used to detect the changes in the first detection light X1 and the third detection light X3.

[0013] In step 3, when the cold atomic cluster in the superposition state falls to the second detection light X2, the atoms in the other ground state in the cold atomic cluster absorb the photons in the second detection light X2, causing the intensity of the second reflected light X6 to weaken. The changes in the second detection light X2 and the fourth detection light X4 can be detected by the second photoelectric probe PD2.

[0014] Furthermore, in step 2, when the cold atomic cluster passes through the first detection light X1 and the third detection light X3, the second detection light X2 and the fourth detection light X4 will not be affected by the cold atomic cluster. At this moment, the change detected by the second photoelectric probe PD2 is the background jitter of the detection light; the signals between the first photoelectric probe PD1 and the second photoelectric probe PD2 are differentially suppressed by the operational amplifier circuit to suppress the common-mode noise in the detection light path.

[0015] Furthermore, in step 3, when the cold atomic cluster passes through the second detection light X2 and the fourth detection light X4, the first detection light X1 and the third detection light X3 will not be affected by the cold atomic cluster. At this moment, the change detected by the first photoelectric probe PD1 is the background jitter of the detection light; the signals between the first photoelectric probe PD1 and the second photoelectric probe PD2 are differentially suppressed by the operational amplifier circuit to suppress the common-mode noise in the detection light path.

[0016] The beneficial effects of the present invention are: utilizing symmetrical structural design to suppress common mode noise, solving the problems of low atomic number detection efficiency and susceptibility to background jitter in cold atom interferometric gravimeters, and effectively improving the detection accuracy of atomic numbers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 It is a schematic diagram of the cold atomic cluster of the present invention falling onto the first detection light X1.

[0019] Figure 3 It is a schematic diagram of the cold atomic cluster of the present invention falling onto the second detection light X2.

[0020] Explanation of the accompanying symbols: 1. Polarization-maintaining optical fiber; 2. Laser collimator; 3. Vacuum cavity of atomic interferometer gravimeter; 4. Cold atomic cluster; 5. Prism; 6. Fixed frame; 7. Operational amplifier; 8. Light shield. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific contexts.

[0024] With reference to the accompanying drawings, a first embodiment of the present invention provides an atomic number detection device for a cold atom interferometer gravimeter, comprising a laser, a polarization-maintaining fiber, a laser collimator, a first half-wave plate B1, a first polarization cube beam splitter PBS1, a second half-wave plate B2, a second polarization cube beam splitter PBS2, a third half-wave plate B3, and a prism, arranged in order from top to bottom along the same axis.

[0025] The atom detection laser emitted by the laser is connected to the laser collimator 2 through the polarization-maintaining optical fiber 1, and the laser collimator 2 is vertically mounted on the fixed frame 6; the laser collimator 2 collimates the atom detection laser into the first output light Y1 pointing vertically downward; the first output light Y1 is incident on the splitting surface of the first polarization cube beam splitter PBS1 after the laser polarization is optimized by the 1 / 2 wave plate B1, and the splitting surface of the first polarization cube beam splitter PBS1 is set at 45 degrees to the output light Y1, and the splitting surface of the first polarization cube beam splitter PBS1 completely transmits the first output light Y1, and the first output light Y After exiting the first polarization cube beam splitter PBS1, the laser polarization is optimized by the second half-wave plate B2 and reaches the second polarization cube beam splitter PBS2. The splitting surface of the second polarization cube beam splitter PBS2 is set at a 45-degree angle to the exit light Y1. Under the action of the splitting surface of the polarization cube beam splitter PBS2, the first exit light Y1 is split into the first detection light X1 that is horizontally directed to the right and the second exit light Y2 that is vertically directed downward. The second exit light Y2 passes through the third half-wave plate B3 and is incident on the prism 5. It is reflected by the reflective bevel of the prism 5 to form the second detection light X2 that is horizontally directed to the right.

[0026] The first detection light X1 and the second detection light X2 move horizontally to the right and pass through the vacuum chamber 3 of the atomic interferometer gravimeter. A first reflector M1 and a second reflector M2 are provided at positions on the right side of the vacuum chamber 3 corresponding to the first detection light X1 and the second detection light X2.

[0027] After passing through the vacuum chamber 3 of the atomic interferometer gravimeter, the first detection light X1 is incident on the first reflector M1. The first reflector M1 returns the first detection light X1 to its original path to form a third detection light X3 pointing horizontally to the left. The first detection light X1 and the third detection light X3 pointing horizontally to the left form a pair of standing waves, which can effectively offset the interference of the detection light itself on the cold atomic cluster during the detection process. The third detection light X3 pointing horizontally to the left passes through the first 1 / 4 wave plate C1 and is reflected by the splitting surface of the second polarization cube beam splitter PBS2 as the third detection light X3 pointing vertically upward. The third detection light X3 pointing vertically upward enters the first polarization cube beam splitter PBS1 and is reflected by the reflective surface of the first polarization cube beam splitter PBS1 as the first reflected light X5 pointing horizontally to the left. The first reflected light X5 is converged onto the first photoelectric probe PD1 through the first focusing lens L1. The first photoelectric probe PD1 is used to detect changes in the light intensity of the first detection light X1 and the third detection light X3.

[0028] After passing through the vacuum chamber of the atomic interferometer gravimeter, the second probe light X2 is incident on the second zero-degree reflector M2. This reflector returns the second probe light X2 along its original path, forming a fourth probe light X4 traveling horizontally to the left. The second and fourth probe lights X2 and X4 form a pair of standing waves, effectively canceling any interference from the probe light on the cold atomic clusters during detection. The fourth probe light X4 traveling horizontally to the left passes through the second quarter-wave plate C2 and is reflected by the prism as the fourth probe light X4 traveling vertically upward. The fourth probe light X4 traveling vertically upward enters the second polarization cube beam splitter PBS2 and is reflected by the reflective surface of the second polarization cube beam splitter PBS2 as the second reflected light X6 traveling horizontally to the left. The second reflected light X6 is focused by the second focusing lens L2 onto the second photoelectric probe PD2, which detects changes in the intensity of the second and fourth probe lights X2 and X4. The first photoelectric probe PD1 is connected to the positive input of the operational amplifier 7, and the second photoelectric probe PD2 is connected to the negative input of the operational amplifier.

[0029] In other embodiments of the present invention, a light shield 8 is provided on the left side of the first reflector M1. After the first detection light X1 passes through the vacuum chamber 3 of the atomic interferometer gravimeter, it is incident on the first reflector M1 through the light shield 8. The light shield 8 prevents 10% of the detection light X1 from being reflected, which is used to blow away the undetected 2-state atoms in the superposition state.

[0030] A second embodiment of the present invention provides a detection method for a cold atom interferometer gravimeter atomic number detection device, comprising the following steps:

[0031] Step 1: Turn on the laser. The first, third, second, and fourth probe lights X1, X3, X2, and X4 form a detection zone in the lower portion of the vacuum chamber of the cold atom interferometer gravimeter. After participating in the interference, the cold atom cluster 4 will be distributed in two ground state energy levels with a certain probability, that is, the cold atom cluster is in a superposition state.

[0032] Step 2: The cold atomic cluster 4 in the superposition state continues to fall under the action of gravity. When the cold atomic cluster falls to the first detection light X1, due to the photoelectric effect between the first detection light X1 and the cold atomic cluster, one of the ground-state atoms in the cold atomic cluster absorbs the photons in the first detection light X1, causing the intensity of the first reflected light X5 to decrease. The first photoelectric probe PD1 is used to detect the changes in the first detection light X1 and the third detection light X3.

[0033] When the cold atomic cluster passes through the first detection light X1 and the third detection light X3, the second detection light X2 and the fourth detection light X4 will not be affected by the cold atomic cluster. At this moment, the change detected by the second photoelectric probe PD2 is the background jitter of the detection light; the signals between the first photoelectric probe PD1 and the second photoelectric probe PD2 are differentially suppressed by the operational amplifier circuit to suppress the common-mode noise in the detection light path.

[0034] In step 3, when the cold atomic cluster in the superposition state falls to the second detection light X2, the atoms in the other ground state in the cold atomic cluster absorb the photons in the second detection light X2, causing the intensity of the second reflected light X6 to weaken. The changes in the second detection light X2 and the fourth detection light X4 can be detected by the second photoelectric probe PD2.

[0035] When the cold atomic cluster passes through the second detection light X2 and the fourth detection light X4, the first detection light X1 and the third detection light X3 will not be affected by the cold atomic cluster. At this moment, the change detected by the first photoelectric probe PD1 is the background jitter of the detection light; the signals between the first photoelectric probe PD1 and the second photoelectric probe PD2 are differentially suppressed by the operational amplifier circuit to suppress the common-mode noise in the detection light path.

[0036] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The scope of protection of the present invention should not be regarded as limited to the specific forms described in the embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A detection method for an atomic number detection device of a cold atom interferometer gravimeter, characterized by: The atomic number detection device for a cold atom interferometer gravimeter comprises a laser, a polarization-maintaining optical fiber, a laser collimator, a first half-wave plate (B1), a first polarization cube beam splitter (PBS1), a second half-wave plate (B2), a second polarization cube beam splitter (PBS2), a third half-wave plate (B3), and a prism, which are arranged in sequence from top to bottom along the same axis; The atom detection laser emitted by the laser is connected to the laser collimator through a polarization-maintaining optical fiber. The laser collimator collimates the atom detection laser into a first output light (Y1) directed vertically downward. The first output light (Y1) passes through a 1 / 2 wave plate (B1) and is incident on a beam splitting surface of a first polarization cube beam splitter (PBS1). The beam splitting surface of the first polarization cube beam splitter (PBS1) is set at 45 degrees to the first output light (Y1). The beam splitting surface of the first polarization cube beam splitter (PBS1) completely transmits the first output light (Y1). The first output light (Y1) passes through the first polarization cube beam splitter (P After being emitted from the first output light (BS1), the light passes through the second half-wave plate (B2) and reaches the second polarization cube beam splitter (PBS2); the splitting surface of the second polarization cube beam splitter (PBS2) is set at 45 degrees to the first output light (Y1). Under the action of the splitting surface of the polarization cube beam splitter (PBS2), the first output light (Y1) is split into a first detection light (X1) directed horizontally to the right and a second output light (Y2) directed vertically downward; the second output light (Y2) passes through the third half-wave plate (B3) and is incident on the prism, and is reflected by the reflective oblique surface of the prism to form a second detection light (X2) directed horizontally to the right. The first detection light (X1) and the second detection light (X2) are horizontally directed to the right and pass through the vacuum chamber of the atomic interferometer gravimeter, and a first reflecting mirror (M1) and a second reflecting mirror (M2) are provided at positions on the right side of the vacuum chamber corresponding to the first detection light (X1) and the second detection light (X2); The first detection light (X1) passes through the vacuum chamber of the atomic interferometer gravimeter and is incident on the first reflector (M1). The first reflector (M1) returns the first detection light (X1) along its original path to form a third detection light (X3) directed horizontally to the left. The third detection light (X3) directed horizontally to the left passes through the first quarter-wave plate (C1) and is reflected by the beam splitting surface of the second polarization cube beam splitter (PBS2) to form a third detection light (X3) directed vertically upward. The third detection light (X3) directed vertically upward enters the first polarization cube beam splitter (PBS1) and is reflected by the reflective surface of the first polarization cube beam splitter (PBS1) to form a first reflected light (X5) directed horizontally to the left. The first reflected light (X5) is converged onto the first photoelectric probe (PD1) through the first focusing lens (L1). The first photoelectric probe (PD1) is used to detect changes in the light intensities of the first detection light (X1) and the third detection light (X3). The second detection light (X2) passes through the vacuum chamber of the atomic interferometer gravimeter and is incident on the second reflector (M2). The second reflector (M2) returns the second detection light (X2) along its original path to form a fourth detection light (X4) directed horizontally to the left. The fourth detection light (X4) directed horizontally to the left passes through a second quarter-wave plate (C2) and is reflected by a prism to form a fourth detection light (X4) directed vertically upward. The fourth detection light (X4) directed vertically upward enters a second polarization cube beam splitter (PBS2) and is reflected by a reflective surface of the second polarization cube beam splitter (PBS2) to form a second reflected light (X6) directed horizontally to the left. The second reflected light (X6) is converged onto a second photoelectric probe (PD2) through a second focusing lens (L2). The second photoelectric probe (PD2) is used to detect changes in the light intensities of the second detection light (X2) and the fourth detection light (X4). The first photoelectric probe (PD1) is connected to the positive input terminal of the operational amplifier, and the second photoelectric probe (PD2) is connected to the negative input terminal of the operational amplifier; The detection method comprises the following steps: Step 1: Turn on the laser. The first probe light (X1), the third probe light (X3), the second probe light (X2), and the fourth probe light (X4) form a detection area below the vacuum chamber of the cold atom interferometer gravimeter. After the cold atom cluster participates in the interference, it is distributed in two ground state energy levels, that is, the cold atom cluster is in a superposition state. Step 2: The cold atomic cluster in the superposition state continues to fall under the action of gravity. When the cold atomic cluster falls to the first detection light (X1), due to the photoelectric effect between the first detection light (X1) and the cold atomic cluster, one of the atoms in the ground state of the cold atomic cluster absorbs the photons in the first detection light (X1), causing the intensity of the first reflected light (X5) to decrease. The first photoelectric probe (PD1) is used to detect changes in the first detection light (X1) and the third detection light (X3); Step 3: When the cold atomic cluster in the superposition state falls onto the second detection light (X2), another ground-state atom in the cold atomic cluster absorbs photons in the second detection light (X2), causing the intensity of the second reflected light (X6) to decrease. The second photoelectric probe (PD2) can detect changes in the second detection light (X2) and the fourth detection light (X4). In step 2, when the cold atomic cluster passes through the first detection light (X1) and the third detection light (X3), the second detection light (X2) and the fourth detection light (X4) are not affected by the cold atomic cluster, and the change detected by the second photoelectric probe (PD2) at this moment is the background jitter of the detection light; the signals between the first photoelectric probe (PD1) and the second photoelectric probe (PD2) are differentially controlled by the operational amplifier circuit to suppress common mode noise in the detection light path; In step 3, when the cold atomic cluster passes through the second detection light (X2) and the fourth detection light (X4), the first detection light (X1) and the third detection light (X3) are not affected by the cold atomic cluster. At this moment, the change detected by the first photoelectric probe (PD1) is the background jitter of the detection light; the signals between the first photoelectric probe (PD1) and the second photoelectric probe (PD2) are differentially suppressed by the operational amplifier circuit to suppress the common mode noise in the detection light path.

Images