Ultracold atom differential interferometer gyroscope based on time-orbit potential well

Abstract

This invention relates to an ultracold atom differential interferometric gyroscope based on a time-track potential well, belonging to the fields of ultracold atoms and angular velocity measurement. The invention comprises an optical platform, a cooled laser source, an optical trap source, a Bragg pulse source, a vacuum cavity, an arbitrary wave generator, a signal generator, and six magnetic field coils. The vacuum cavity is located above the optical platform; the six magnetic field coils are located around the vacuum cavity to generate an alternating magnetic field; the signal generator provides alternating current to the magnetic field coils; the cooled light is distributed in three orthogonal directions, with two opposing beams in each direction; the Bragg pulse is a one-dimensional standing wave; both the optical trap light and the Bragg pulse are two orthogonal beams, and their beam directions coincide; the arbitrary wave generator generates the pulse timing of the pulse light. This invention utilizes ultracold atoms at even lower temperatures, enabling the achievement of a large interference area and high angular velocity sensitivity within a relatively small volume, and is suitable for moving platforms.

Description

Technical Field

[0001] This invention relates to an ultracold atom differential interferometer gyroscope based on a time-orbit potential well, belonging to the fields of ultracold atoms and angular velocity measurement. Background Technology

[0002] Currently, besides rotor gyroscopes, optical gyroscopes, and vibrating gyroscopes, angular velocity measurement systems based on atomic interferometry are a key research focus in this field. Angular velocity measurement in atomic interferometry primarily utilizes the Sagnac interferometry method. This method manipulates the splitting of atomic wave packets, guiding them through two paths enclosing a region, and then recombines them. The resulting interference signal depends on the system's rotation rate and the area enclosed by the paths. While optical Sagnac interferometers are an important component of modern angular velocity measurement, their sensitivity and stability are limited. Up-throw, counter-throw, and continuous-beam atomic interferometers are inherently more sensitive and exhibit superior gyroscope performance. However, their advantages are insufficient to offset the significant increase in the size and complexity of the equipment required for atomic systems. These problems can be overcome using atoms confined within a guiding potential or potential well, as opposed to atoms falling into free space. The potential well can support atoms against gravity, thus enabling long measurement times without requiring large fall distances. The potential well can also control the trajectories of atoms, causing them to form closed interference loops, providing a large enclosed region for a given linear dimension, suitable for measurements on moving carriers. Furthermore, traditional atomic interferometers use cold atoms at temperatures on the order of 10 micro Kelvin, with lower temperatures resulting in higher measurement accuracy; however, this patent proposes using Bose-Einstein condensates, which can reach temperatures below 100 nano Kelvin, offering lower temperatures and higher coherence times, thus further improving measurement accuracy. Summary of the Invention

[0003] To address the issue that existing technologies cannot simultaneously achieve the required device size and complexity while maintaining the accuracy of angular velocity measurement, the present invention aims to provide an ultracold atom interferometer based on a time-orbit potential well. This interferometer utilizes ultracold atoms at even lower temperatures, resulting in longer coherence times and higher sensitivity than cold atoms. It can achieve a large interference area and high angular velocity sensitivity within a relatively small volume and is suitable for moving carriers.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] The ultracold atomic differential interferometer gyroscope based on time orbit potential well disclosed in this invention includes an optical platform, a cooled laser source, an optical trap source, a Bragg pulse source, a vacuum cavity, an arbitrary wave generator, a signal generator, and six magnetic field coils.

[0006] A vacuum cavity is located above an optical platform; six magnetic field coils are located around the vacuum cavity to generate an alternating magnetic field; a signal generator is used to provide alternating current to the magnetic field coils; a cooling laser source, an optical trap source, and a Bragg pulse source are used to generate cooling light, optical trap light, and Bragg pulse light, respectively; the cooling light has two opposing beams in each of three orthogonal directions; the Bragg pulse light is a one-dimensional standing wave light; both the optical trap light and the Bragg pulse light are two orthogonal beams, and the beam directions of the optical trap light and the Bragg pulse light coincide; an arbitrary wave generator is used to generate the pulse timing of the pulse light.

[0007] The method for measuring angular velocity using the aforementioned ultracold atom differential interferometer gyroscope includes the following steps:

[0008] Step 1: Initially cool the atoms using cooling light to obtain optical aggregates, and then use an optical trap for evaporation and cooling to obtain ultracold atoms;

[0009] Step 2: Slowly reduce the light intensity of the optical trap to thermally load the ultracold atoms into the time orbit potential trap;

[0010] Step 3: Apply orthogonal Bragg pulses twice to the ultracold atoms to divide them into four atomic clusters, so that each atomic cluster can make circular motion in the time orbit potential well; at the moment when the atomic clusters coincide, apply a third Bragg pulse, which has the same direction and timing as the second pulse, to obtain the interference result;

[0011] Step 4: Finally, the atomic density distribution information is obtained using absorption imaging, and the interference result S is calculated. Δ and Repeat steps one through three 10 times to obtain 10 sets of interference results S. Δ and Finally, using elliptic fitting with 10 sets of interference results, the Sagnac phase Φ was obtained. s Thus, the system angular velocity Ω is obtained:

[0012]

[0013] Where Ω is the system angular velocity; A is the area of ​​the Sagnac interference path; and m is the atomic mass. Here, k is the reduced Planck constant, k0 is the pulsed light lattice wave vector, and ω0 is the resonator trap frequency.

[0014] The specific implementation method of step three:

[0015] A. Cold atoms are obtained by using cooling light, then the cold atoms are loaded into an optical trap, and then ultracold atoms are obtained by evaporation and cooling.

[0016] Then, by linearly reducing the light intensity through the optical trap, the ultracold atoms achieve adiabatic transfer to the center of the time orbit potential trap.

[0017] B. At time t=0, Applying Bragg pulses to ultracold atoms in a direction that splits them into particles with velocities of ±v B The two groups, respectively along The direction is simple harmonic motion, and the velocity is... Where k0 is the Bragg pulsed lattice laser wave vector. To reduce Planck's constant, n is a positive integer, representing the number of counter-pulses applied to the atom by the Bragg pulse.

[0018] C. At time t = π / (2ω0), the two clusters of ultracold atoms move to the maximum displacement of their simple harmonic motion. A Bragg pulse is applied to two clusters of ultracold atoms in the direction of the pulse. Each cluster of ultracold atoms is in They also split into two groups in the direction.

[0019] D. There are four atomic clusters at this time. The two upper clusters of ultracold atoms interfere with each other, and the two lower clusters of ultracold atoms interfere with each other. The two upper clusters of atoms represent... The quantum state +|v generated by the directional Bragg pulse B , Δ> and -|v B Δ>, respectively, making circular motions in counterclockwise and clockwise directions. The two clusters of atoms below represent... Quantum states generated by directional Bragg pulses and It moves in a circular motion in both clockwise and counterclockwise directions respectively;

[0020] E. At time t = 2π / ω0, after the four clusters of atoms complete one revolution, they return to their initial positions. Using the third Bragg pulse, the interference results S of the proportions of the upper and lower zero-state atoms are obtained respectively. Δ and Repeat the above steps 10 times to obtain 10 sets of interference results, and then obtain the Sagnac phase Φ by ellipse fitting. s The system angular velocity is calculated based on step four.

[0021] The specific implementation method of step four:

[0022] A. Due to the Sagnac effect, after the two clusters of atoms move in opposite directions for one revolution, the phase difference between the two clusters will be supplemented by the Sagnac phase:

[0023]

[0024] in, To reduce Planck's constant, ΔL is the angular momentum difference of the quantum states, Ω is the system's angular velocity vector, m is the mass of the ultracold atom, Ω is the magnitude of the angular velocity in the system's rotational direction, and the area of ​​the atomic wave packet's motion loop is A = πR. 2 R is the radius of the circular interference loop. The phase difference between the two atomic clusters below will be supplemented by the Sagnac phase -Φ. s Due to system noise, the interference phases of the upper and lower interference processes will produce a certain deviation Φ′, so the phases of the two upper atomic clusters Φ′ will also be different. Δ Phase with the two clusters of atoms below They are respectively:

[0025] Φ Δ =Φ s +Φ′

[0026]

[0027] Differential processing is performed to obtain the differential phase δΦ:

[0028]

[0029] B. After the third Bragg pulse, the interference result S is obtained. Δ and The upper part of the atoms will have S Δ =cos 2 (Φ Δ The proportion of / 2) is transferred to a quantum state with zero momentum, and the lower part of the atoms will have The proportion is transferred to a quantum state with zero momentum, through this formula. Change to Repeat the measurement 10 times, combine the measurement results, and fit S. Δ , Regarding Φ s Φ Δ The elliptic parametric equations yield the Sagnac phase Φ. s And then through the formula The system angular velocity was calculated.

[0030] Beneficial effects:

[0031] 1. The ultracold atom differential interferometer gyroscope based on time orbit potential well disclosed in this invention uses ultracold atoms at a lower temperature to replace cold atoms. Compared with interferometers implemented with cold atoms, ultracold atoms have a longer coherence time, which is conducive to achieving interference for a longer time, thereby achieving a larger interference area and improving the accuracy of angular velocity measurement.

[0032] 2. The ultracold atom differential interferometric gyroscope based on time orbit potential well disclosed in this invention uses a differential method with two sets of ultracold atom interferometers to achieve common-mode suppression of phase noise that masks the rotation signal, improve the signal-to-noise ratio, and thus improve the accuracy of angular velocity signal extraction.

[0033] 3. The ultracold atom differential interferometric gyroscope based on a time-orbit potential well disclosed in this invention uses a time-orbit potential well to control the trajectory of ultracold atoms, causing them to form a closed interference loop, which significantly reduces the difficulty of calibrating the outer carrier plane perpendicular to gravity.

[0034] 4. The ultracold atom differential interferometric gyroscope based on time-track potential well disclosed in this invention uses the method of trapping ultracold atoms in a potential well. Compared with the traditional up-thrown cold atom interferometric gyroscope, this method can achieve a larger interference area and higher angular velocity sensitivity in a smaller volume.

[0035] 5. Traditional upward-thrown cold atom gyroscopes cannot function properly on moving platforms because the atoms encounter vacuum walls during motion, disrupting the interference process and resulting in no measurement results. The ultracold atom differential interferometric gyroscope based on a time-orbit potential well disclosed in this invention allows the interference process to occur within the potential field, and the measurement process is unaffected by the platform's motion, making it suitable for use on moving platforms. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the ultracold atom differential interferometer gyroscope based on a time-orbit potential well disclosed in this invention;

[0037] Figure 2 This is a flowchart of the ultracold atom differential interferometer gyroscope based on a time-orbit potential well disclosed in this invention.

[0038] Figure 3 This is a schematic diagram of the atomic interference process.

[0039] Among them: 1-Optical platform, 2-Cooled laser source, 3-Optical trap source, 4-Bragg pulse source, 5-Vacuum cavity, 6-Arbitrary wave generator, 7-Signal generator, 8-Magnetic field coil. Detailed Implementation

[0040] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0041] Example 1:

[0042] like Figure 1As shown, the ultracold atom differential interferometer gyroscope based on a time-track potential well disclosed in this embodiment mainly consists of an optical platform 1, a cooled laser source 2, an optical trap source 3, a Bragg pulse source 4, a vacuum cavity 5, an arbitrary wave generator 6, a signal generator 7, and magnetic field coils 8. The six magnetic field coils 8 are located around the vacuum cavity 5 and are used to generate an alternating magnetic field to form a time-track potential well; the signal generator 7 provides alternating current to the magnetic field coils 8; the cooled laser source 2, the optical trap source 3, and the Bragg pulse source 4 are used to generate cooled light, optical trap light, and Bragg pulse light, respectively; the arbitrary wave generator 7 is used to generate pulse timing for the Bragg pulse source; all of these are located on the optical platform 1.

[0043] like Figure 2 As shown in this embodiment, the method for measuring angular velocity using an ultracold atom differential interferometric gyroscope based on a time-orbit potential well is as follows: First, the atoms are initially cooled using cooling light generated by a cooling laser source 2 to obtain cold atoms. Then, they are evaporated and cooled using an orthogonal optical trap generated by an optical trap source 3 to obtain ultracold atoms with a temperature below 100 nK. The light intensity of the optical trap is then slowly reduced, and the atoms are adiabatically loaded into the time-orbit potential well. Next, an arbitrary wave generator 6 generates a pulse signal to a Bragg pulse source 4 to apply the first Bragg pulse to the ultracold atoms. Under the pulse, the ultracold atoms will split into two clusters of atoms with equal numbers and opposite velocities until the velocity of the clusters is consumed to zero by the potential well. At this point, the atoms will be separated by a distance. Then, the arbitrary wave generator 6 generates a second pulse signal to the Bragg pulse source 4, and each ultracold atom will split into two clusters of atoms with equal numbers and opposite velocities, resulting in a total of four clusters. Due to the effect of the time-orbit potential well, the four clusters will undergo circular motion. At this point, the relative phase control magnetic field coil 8 of the signal generator 7 is used to close the trajectory of the four atomic clusters. After the atomic clusters have completed one revolution, the arbitrary wave generator 6 generates a pulse signal to the Bragg pulse light source 4, producing a third Bragg pulse, and obtaining the interference result: the ratio S of the upper and lower zero-state atoms. Δ and Finally, phase information is obtained from the interference results, and the angular velocity is calculated. The interference process is as follows: Figure 3 As shown, the angular velocity of the system under test is Ω.

[0044] The method for measuring angular velocity using an ultracold atom differential interferometer gyroscope based on a time-track potential well disclosed in this embodiment is as follows:

[0045] A. First, cooling light is generated using a cooling laser source 2 to obtain cold atoms. Then, the atoms are loaded into an optical trap using an optical trap source 3. Next, ultracold atoms are obtained through evaporation cooling in the optical trap. Finally, the ultracold atoms are adiabatically transferred to the center of the time-orbit potential trap, as follows: Figure 3 As shown in a.

[0046] B. A pulse signal is generated using the arbitrary wave generator 6 and fed to the Bragg pulse light source 4 to achieve... A Bragg pulse is applied to the atom in the direction that splits the atom into particles with velocities of ±v. B The two groups, respectively along The direction is simple harmonic motion, and the velocity is... Where k0 is the Bragg pulsed lattice laser wave vector. is the reduced Planck constant; n is a positive integer representing the number of counter-pulses applied to the atom by the Bragg pulse. The trajectory equation y(t) of an ultracold atom in a certain direction is:

[0047] y(t)=±Rsin(ω0t),

[0048] Where the radius of rotational interference R = v B / ω0, where ω0 is the sink frequency.

[0049] C. At t = π / (2ω0), the two clusters of atoms move to their maximum displacements in simple harmonic motion. At this point, an arbitrary wave generator 6 generates a pulse signal and sends it to the Bragg pulse light source 4 to achieve... If Bragg pulses are applied simultaneously to two groups of atoms, the atoms will... They also split into two groups in the direction.

[0050] D. At this time there are four clusters of atoms, of which the top two clusters (in) Figure 3 (In d, marked with "Δ") The quantum state +|v generated by the directional Bragg pulse B Δ> (gray in the diagram) and -|v B Δ> (white in the diagram) moves in circles in counterclockwise and clockwise directions respectively, with trajectory equations y(t) = R cos(ω0t) and x(t) = ±R sin(ω0t). For the two clusters of atoms below... exist Figure 3 d in use (Marked), and move in circles in clockwise and counterclockwise directions respectively.

[0051] E. At time t = 2π / ω0, the four clusters of atoms return to their initial positions after completing one revolution (x = 0, y = ±R, e.g.) Figure 3 e). Using the arbitrary wave generator 6 to generate a pulse signal for the Bragg pulse light source 4, the third... When a directional Bragg pulse is applied to ultracold atoms, the upper atoms will exhibit S... Δ =cos 2 (Φ ΔThe proportion of / 2) is transferred to a quantum state with zero momentum, and the same is true for the lower atoms. And expressed as

[0052] F. Interference results S Δ and Construct the parametric equation of the ellipse, and with Φ Δ Φ s Related. Finally, the atomic density distribution information was obtained using absorption imaging, and the interference result S was calculated. Δ and The measurement was repeated 10 times. Using the 10 sets of interferometric data, the Sagnac phase Φ was obtained through ellipse fitting. s The relationship between the system's angular velocity Ω and the following formula can be used to calculate the system's angular velocity Ω.

[0053]

[0054] Where A is the Sagnac interference path area, and m is the atomic mass. To reduce Planck's constant, k0 is the pulsed optical lattice wave vector, ω0 is the trap frequency, and n is the number of back impulses applied to the atoms by the Bragg pulse. From the above equation, it can be seen that to improve the system's angular velocity sensitivity, a higher-order n-order back impulse pulse and a lower trap frequency ω0 are applied. This method differs from increasing the device height by increasing the atom fall time to improve gyroscope sensitivity; this method can improve sensitivity within a limited space and is unrestricted in moving vehicles.

[0055] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring angular velocity using an ultracold atom differential interferometer gyroscope based on a time-track potential well, characterized in that: Includes the following steps, Step 1: Initially cool the atoms using cooling light to obtain optical aggregates, and then use an optical trap for evaporation cooling to obtain ultracold atoms; Step 2: Slowly reduce the light intensity of the optical trap to thermally load the ultracold atoms into the time orbit potential trap; Step 3: Apply orthogonal Bragg pulses twice to the ultracold atoms to divide them into four atomic clusters, so that each atomic cluster can make circular motion in the time orbit potential well; at the moment when the atomic clusters coincide, apply a third Bragg pulse, which has the same direction and timing as the second pulse, to obtain the interference result; Step 4: Process the interference results using absorption imaging to obtain atomic density distribution information. Repeat steps 1 to 3 10 times to obtain 10 sets of processed interference results. Use the 10 sets of interference results to perform ellipse fitting to obtain the Sagnac phase Φ. S Thus, the system angular velocity Ω is obtained: Where Ω is the system angular velocity; A is the area of ​​the Sagnac interference path; and m is the atomic mass. Here, k0 is the pulsed light lattice wave vector, and ω0 is the resonator trap frequency; The ultracold atomic differential interferometer gyroscope includes an optical platform, a cooled laser source, an optical trap source, a Bragg pulse source, a vacuum cavity, an arbitrary wave generator, a signal generator, and six magnetic field coils. A vacuum cavity is located above an optical platform; six magnetic field coils are located around the vacuum cavity to generate an alternating magnetic field; a signal generator is used to provide alternating current to the magnetic field coils; a cooling laser source, an optical trap source, and a Bragg pulse source are used to generate cooling light, optical trap light, and Bragg pulse light, respectively; the cooling light has two opposing beams in each of three orthogonal directions; the Bragg pulse light is a one-dimensional standing wave light; both the optical trap light and the Bragg pulse light are two orthogonal beams, and the beam directions of the optical trap light and the Bragg pulse light coincide; an arbitrary wave generator is used to generate the pulse timing of the pulse light.

2. The method as described in claim 1, characterized in that: The specific implementation method of step three: A. Cold atoms are obtained by using cooling light, then the cold atoms are loaded into an optical trap, and then ultracold atoms are obtained by evaporation and cooling. Then, by linearly reducing the light intensity through the optical trap, the ultracold atoms achieve adiabatic transfer to the center of the time orbit potential trap; B. At time t=0, Applying Bragg pulses to ultracold atoms in a direction that splits them into particles with velocities of ±v B The two groups, respectively along The direction is simple harmonic motion, and the velocity is... Where k0 is the Bragg pulsed lattice laser wave vector. To reduce Planck's constant, n is a positive integer, representing the number of counter-pulses applied to the atom by the Bragg pulse; C. At time t = π / (2ω0), the two clusters of ultracold atoms move to the maximum displacement of their simple harmonic motion; at this time... A Bragg pulse is applied to two clusters of ultracold atoms in the direction of the pulse. Each cluster of ultracold atoms is in It also split into two groups in the direction; D. At this time, there are four atomic clusters; the two upper clusters of ultracold atoms interfere with each other, and the two lower clusters of ultracold atoms interfere with each other; the two upper clusters of atoms represent The quantum state +|v generated by the directional Bragg pulse B ,Δ> and -|v B ,Δ>, respectively along counterclockwise and clockwise The needle moves in a circular motion; the two clusters of atoms below represent... Quantum states generated by directional Bragg pulses and It moves in a circular motion in both clockwise and counterclockwise directions respectively; E. At time t = 2π / ω0, after the four clusters of atoms complete one revolution, they return to their initial positions. Using the third Bragg pulse, the interference results S of the proportions of the upper and lower zero-state atoms are obtained respectively. Δ and Repeat the steps more than 10 times to obtain 10 sets of interference results S. Δ and The Sagnac phase Φ is then obtained through elliptic fitting. S The system angular velocity is calculated based on step four.

3. The method as described in claim 2, characterized in that: The specific implementation method of step four, A. Due to the Sagnac effect, after the two clusters of atoms move in opposite directions for one revolution, the phase difference between the two clusters will be supplemented by the Sagnac phase: in, To reduce Planck's constant, ΔL is the angular momentum difference of the quantum states, Ω is the system's angular velocity vector, m is the mass of the ultracold atom, Ω is the magnitude of the angular velocity in the system's rotational direction, and the area of ​​the atomic wave packet's motion loop is A = πR. 2 R is the radius of the circular interference loop; and the phase difference between the two atomic clusters below will add the Sagnac phase -Φ S Due to system noise, the interference phase will deviate by a certain Φ during the upper and lower interference processes. ' Therefore, the phase Φ of the two atomic clusters above Δ Phase with the two clusters of atoms below They are respectively: F Δ =Φ S +Φ′ Differential processing is performed to obtain the differential phase δΦ: B. After the third Bragg pulse, the interference result S is obtained. Δ and The upper part of the atoms will have S Δ =cos 2 (Φ Δ The proportion of / 2) is transferred to a quantum state with zero momentum, and the lower part of the atoms will have The proportion is transferred to a quantum state with zero momentum, through the formula Change to Repeat the same steps 10 times to obtain 10 sets of data; use the 10 sets of data to fit S. Δ , Regarding Φ S Φ Δ The elliptic parametric equations yield the Sagnac phase Φ. S And then through the formula The system angular velocity was calculated.

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