技术领域technical field
本发明涉及激光冷却领域，特别涉及一种基于环形永磁铁的塞曼减速器。The invention relates to the field of laser cooling, in particular to a Zeeman reducer based on an annular permanent magnet.
背景技术Background technique
冷原子气体由于其量子特性受到科学界越来越多的重视，从而被广泛应用于诸如原子光学、超精细原子光谱、多体系统特性、原子干涉、玻色爱因斯坦凝聚和原子钟的研究中。根据热力学原理，气体原子分子的温度与其运动速度成正正比，因此对原子减速就达到了冷却的目的。如果用热传递的方式对气态原子进行冷却，当温度下降到使得原子的热运动速度小于1m/s时，气体将凝结成液体或固体，这时原子间会产生强烈的相互作用，介质的能级结构和性能也会发生显著变化。一种有效获得冷原子气体的方法就是利用激光冷却原子。激光冷却同传统热传递冷却的区别就是在冷却过程中，降低了原子的速度，使其等效温度远远低于原子的熔点或沸点，但由于原子的密度较小，并没有发生气态到液态或固态的相变。Due to their quantum properties, cold atomic gases have attracted more and more attention from the scientific community, and thus have been widely used in researches such as atomic optics, hyperfine atomic spectroscopy, many-body system properties, atomic interference, Bose-Einstein condensate, and atomic clocks. . According to the principle of thermodynamics, the temperature of gas atoms and molecules is directly proportional to their speed of motion, so decelerating the atoms achieves the purpose of cooling. If the gaseous atoms are cooled by heat transfer, the gas will condense into a liquid or a solid when the temperature drops to such that the thermal velocity of the atoms is less than 1m/s. At this time, there will be a strong interaction between the atoms, and the energy of the medium The level structure and performance will also change significantly. One efficient way to obtain a gas of cold atoms is to cool the atoms with a laser. The difference between laser cooling and traditional heat transfer cooling is that in the cooling process, the speed of atoms is reduced, making the equivalent temperature far lower than the melting point or boiling point of atoms, but due to the low density of atoms, there is no gaseous state to liquid state or solid phase transitions.
激光冷却原子的基本原理是动量守恒定律。在激光冷却过程中，原子吸收一个光子跃迁到高能级，然后再自发辐射一个光子回落到基态。自发辐射过程中，原子发出的光子方向是随机的。因此从大量原子和多次过程的统计结果上看，原子自发辐射光子的总动量的矢量和是0，所以整个过程的原子动量变化就是原子吸收光子过程的动量变化。最终表现为原子在激光传播方向上的减速。The fundamental principle behind laser cooling of atoms is the law of conservation of momentum. During laser cooling, the atom absorbs a photon to jump to a higher energy level, and then spontaneously emits a photon to fall back to the ground state. In the process of spontaneous emission, the direction of photons emitted by atoms is random. Therefore, from the statistical results of a large number of atoms and multiple processes, the vector sum of the total momentum of atomic spontaneously radiated photons is 0, so the atomic momentum change in the whole process is the momentum change in the process of atoms absorbing photons. The final performance is the deceleration of atoms in the direction of laser propagation.
原子冷却需要考虑多普勒效应。原子跃迁的频率是自然基准，只和原子的特性有关，不随外界环境的改变而改变。原子只能吸收和它本身跃迁频率一致光子发生跃迁。但是，当原子以一定的速度运动时，由于多普勒效应，原子感受到的光的频率会发生改变，其频移大小和速度成正比。当光和原子相对运动时，原子感受到的光的频率会比实际频率高，称为蓝移。所以要使原子跃迁发生，光的实际频率需要比原子跃迁频率低，称为红失谐。Atom cooling requires consideration of the Doppler effect. The frequency of atomic transition is a natural benchmark, which is only related to the characteristics of atoms and does not change with changes in the external environment. An atom can only absorb photons with the same transition frequency as itself to make a transition. However, when the atom moves at a certain speed, due to the Doppler effect, the frequency of the light felt by the atom will change, and the frequency shift is proportional to the speed. When light and atoms move relative to each other, the frequency of light perceived by atoms will be higher than the actual frequency, which is called blue shift. So for the atomic transition to occur, the actual frequency of the light needs to be lower than the atomic transition frequency, which is called red detuning.
由于塞曼效应，原子的跃迁谱线在外磁场中会产生分裂。裂距和磁场的大小成正比。塞曼效应有偏振特性。对于量子数+1的跃迁，原子倾向于吸收σ+的偏振光，以保持角动量守恒；同理，对于量子数-1的跃迁，原子倾向于吸收σ-偏振光；对于量子数变为为0的跃迁，原子倾向于吸收线偏振光。Due to the Zeeman effect, the transition lines of atoms will split in the external magnetic field. The crack distance is proportional to the magnitude of the magnetic field. The Zeeman effect has polarization properties. For the transition of quantum number +1, the atom tends to absorb the polarized light of σ+ , so as to keep the angular momentum conservation; similarly, for the transition of quantum number -1, the atom tends to absorb the σ- polarized light; for the quantum number becomes 0 transition, atoms tend to absorb linearly polarized light.
高速原子和一定频率的激光作用减速后，由于多普勒效应，原子便不再和这一频率的激光继续作用，造成原子不能够持续减速。After the high-speed atoms are decelerated by the action of a certain frequency of laser, due to the Doppler effect, the atoms will no longer continue to interact with the laser of this frequency, resulting in the inability of the atoms to continue to decelerate.
为解决这一问题，可以通过一个外加磁场，利用塞曼效应来补偿多普勒效应产生的频移，让二者相互抵消。这样，原子便能够持续和一固定频率的激光相互作用，原子就能够得到持续减速。其磁场分布必须和原子速度在空间上的分布一致。这种产生外磁场分布，使得塞曼效应抵消多普勒频移，能够对原子进行持续减速的装置被称为塞曼减速器。To solve this problem, an external magnetic field can be used to compensate the frequency shift caused by the Doppler effect by using the Zeeman effect, so that the two cancel each other out. In this way, the atoms can continue to interact with a fixed-frequency laser, and the atoms can be continuously decelerated. Its magnetic field distribution must be consistent with the distribution of atomic velocity in space. This kind of external magnetic field distribution makes the Zeeman effect cancel the Doppler frequency shift, and the device that can continuously decelerate atoms is called a Zeeman decelerator.
传统的塞曼减速器是利用通电线圈产生塞曼磁场，主要有一线式和分段式两种。对于一线式塞曼减速器，整个磁场由一段线圈产生，由于通电电流恒定，因此需要严格控制每一点处导线的层数，最终需要绕成特定的形状，才能够产生和理论比较接近的磁场。因此对绕线圈数层数都有很严格的要求，需要用软件进行仿真和计算，同时对绕线本身的精度也有很高的要求。对于分段式塞曼减速器，由于在每段可以应用不同的电流，因此对绕线的计算和绕线精度要求都有所降低。The traditional Zeeman reducer uses a energized coil to generate a Zeeman magnetic field, and there are mainly two types: one-line type and segmented type. For a one-line Zeeman reducer, the entire magnetic field is generated by a section of coil. Since the energizing current is constant, it is necessary to strictly control the number of layers of wire at each point, and finally need to be wound into a specific shape to generate a magnetic field that is closer to the theory. Therefore, there are very strict requirements on the number of winding coils and layers, which need to be simulated and calculated by software. At the same time, there are also high requirements on the accuracy of the winding itself. For the segmented Zeeman reducer, since different currents can be applied in each segment, the calculation and accuracy requirements for winding are reduced.
以上两种塞曼减速器的都是通电螺线管式，在工作的时候需要通以一定的电流，电流在流过导线产生磁场的同时，会产生热量，导致整个塞曼减速器温度升高。温度升高首先会影响线圈的电阻，会造成电流的不稳定，影响原子减速；其次温度升高会导致塞曼减速器内的真空度变差；第三，加热也会影响最终原子的冷却，会对原子样品产生热辐射，升高原子的温度。The above two Zeeman reducers are all electric solenoid type. When working, a certain current needs to be passed through. When the current flows through the wire to generate a magnetic field, it will generate heat, which will cause the temperature of the entire Zeeman reducer to rise. . The increase in temperature will first affect the resistance of the coil, which will cause the instability of the current and affect the deceleration of atoms; secondly, the increase in temperature will lead to the deterioration of the vacuum in the Zeeman reducer; thirdly, heating will also affect the cooling of the final atoms, Thermal radiation is generated on the atomic sample, raising the temperature of the atoms.
解决发热问题的一个方案是利用水冷系统来平衡线圈的发热。然而加入水冷系统以后，水的流动会有一定的振动，会对原子样品引入新的振动噪声；同时水冷并不能完全消除加热的影响，顺着水流的方向，也会在塞曼减速器中产生一定的温度梯度等。One solution to the heating problem is to use a water cooling system to balance the heating of the coils. However, after the water cooling system is added, the flow of water will have certain vibrations, which will introduce new vibration noise to the atomic sample; at the same time, water cooling can not completely eliminate the influence of heating, and along the direction of water flow, it will also be generated in the Zeeman reducer. A certain temperature gradient, etc.
目前国际上有利用永磁铁实现塞曼减速器的尝试。其中有的是利用和原子运动方向垂直的磁场，称为横向塞曼减速器，如英国NPL实验室。此类减速器磁场非轴对称，均匀性差，会对原子的减速产生不利影响。另一些是利用减速器中心轴对称的几条磁铁产生的同原子运动方向相同的磁场，成为纵向塞曼减速器，如德国的PTB等。这种磁场虽然是关于塞曼减速器纵轴对称分布，然而由有限几条磁铁产生的磁场终究无法做到关于纵轴的柱对称。在横向不同分布点的原子所处的磁场不同，其塞曼分裂不同，原子的谐振频率便不同，因此所有原子无法实现同样的冷却效果。At present, there are attempts to use permanent magnets to realize Zeeman reducers in the world. Some of them use a magnetic field perpendicular to the direction of atomic motion, called a transverse Zeeman reducer, such as the British NPL laboratory. The magnetic field of this kind of reducer is non-axisymmetric and has poor uniformity, which will have an adverse effect on the deceleration of atoms. Others are longitudinal Zeeman reducers, such as PTB in Germany, which use the magnetic field generated by several magnets symmetrical to the central axis of the reducer in the same direction as the atomic movement. Although this magnetic field is distributed symmetrically about the longitudinal axis of the Zeeman reducer, the magnetic field generated by a limited number of magnets cannot achieve columnar symmetry about the longitudinal axis after all. Atoms at different distribution points in the horizontal direction are in different magnetic fields, and their Zeeman splits are different, and the resonant frequencies of the atoms are different, so all atoms cannot achieve the same cooling effect.
发明内容Contents of the invention
本发明实施例提供一种基于环形永磁铁的塞曼减速器，通过提供能够匹配理想磁场模型的实际磁场，有效地补偿原子在激光冷却过程总多普勒频移的变化，使激光频率和原子在减速器中始终保持谐振。An embodiment of the present invention provides a Zeeman reducer based on a ring-shaped permanent magnet. By providing an actual magnetic field that can match the ideal magnetic field model, it can effectively compensate for the change of the total Doppler frequency shift of the atom during the laser cooling process, so that the laser frequency and the atomic Resonance is always maintained in the reducer.
根据本发明的一个方面，提供一种基于环形永磁铁的塞曼减速器，包括多个环形永磁铁，其中：According to one aspect of the present invention, there is provided a Zeeman reducer based on annular permanent magnets, comprising a plurality of annular permanent magnets, wherein:
多个环形永磁铁同轴排列，以便形成用于放置减速腔的腔室；A plurality of annular permanent magnets are coaxially arranged to form a chamber for placing the deceleration chamber;
通过控制各环形永磁铁所产生的磁场，以便在减速腔中形成特定的磁场分布，且沿减速腔的轴线呈柱对称。By controlling the magnetic fields generated by the ring-shaped permanent magnets, a specific magnetic field distribution is formed in the deceleration cavity, and the axis of the deceleration cavity is column-symmetric.
在一个实施例中，环形永磁铁上的单个磁偶极子对空间中P点所产生的磁场强度为：In one embodiment, the magnetic field intensity produced by a single magnetic dipole on the annular permanent magnet to point P in space is:
其中，Bx、By、Bz是单个磁偶极子在空间中P点所产生的磁场在三个坐标轴上的分量，μ0表示真空中的磁导率，m为磁偶极子的磁矩，r表示单个磁偶极子与空间中点P的距离，Among them, Bx , Byy , and Bz are the components of the magnetic field generated by a single magnetic dipole at point P in space on three coordinate axes, μ0 represents the magnetic permeability in vacuum, and m is the magnetic dipole The magnetic moment of , r represents the distance of a single magnetic dipole from the point P in space,
在一个实施例中，减速腔出口处的最大磁场不大于预定的磁场门限B(z)，其中：In one embodiment, the maximum magnetic field at the exit of the deceleration chamber is not greater than a predetermined magnetic field threshold B(z), wherein:
其中，h表示普朗克常数，δ表示激光频率相对于原子跃迁频率的失谐量，μB表示磁导率，λ表示激光波长，vi表示原子进入塞曼减速器的初速度大小，a表示原子在塞曼减速器中获得的加速度，z表示原子在塞曼减速器轴向上的位置。Among them, h represents Planck's constant, δ represents the detuning of the laser frequency relative to the atomic transition frequency, μB represents the magnetic permeability, λ represents the laser wavelength, vi represents the initial velocity of the atom entering the Zeeman reducer, a Indicates the acceleration obtained by the atom in the Zeeman reducer, and z represents the axial position of the atom in the Zeeman reducer.
在一个实施例中，在各环形永磁铁外设置磁屏蔽层，以便防止磁场泄露。In one embodiment, a magnetic shielding layer is provided outside each annular permanent magnet to prevent leakage of the magnetic field.
在一个实施例中，磁屏蔽层由软铁材料构成。In one embodiment, the magnetic shielding layer is composed of a soft iron material.
在一个实施例中，各环形永磁铁由两部分构成，以便能够沿减速腔的轴线分为两部分。In one embodiment, each annular permanent magnet consists of two parts so as to be able to be divided into two parts along the axis of the deceleration chamber.
在一个实施例中，各环形永磁铁的极性方向相同。In one embodiment, the polarity directions of the ring-shaped permanent magnets are the same.
在一个实施例中，在减速腔轴线上指定位置一侧的环形永磁铁具有第一极性方向，在指定位置另一侧的环形永磁铁具有第二极性方向，第一极性方向和第二极性方向相反。In one embodiment, the ring-shaped permanent magnet on one side of the specified position on the axis of the deceleration chamber has a first polarity direction, and the ring-shaped permanent magnet on the other side of the specified position has a second polarity direction, the first polarity direction and the second polarity direction. The dipoles are opposite in direction.
通过以下参照附图对本发明的示例性实施例的详细描述，本发明的其它特征及其优点将会变得清楚。Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.
附图说明Description of drawings
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative efforts.
图1为本发明塞曼减速器一个实施例的示意图。Fig. 1 is a schematic diagram of an embodiment of the Zeeman speed reducer of the present invention.
图2为本发明不同极性方向情况下的磁场强度示意图。Fig. 2 is a schematic diagram of the magnetic field strength in different polar directions according to the present invention.
图3为本发明实际磁场分布与理论磁场分布对比示意图。Fig. 3 is a schematic diagram of the comparison between the actual magnetic field distribution and the theoretical magnetic field distribution of the present invention.
图4为本发明塞曼减速器距离中心轴线5mm处的磁场强度的轴向分布示意图。Fig. 4 is a schematic diagram of the axial distribution of the magnetic field intensity at a distance of 5 mm from the central axis of the Zeeman reducer of the present invention.
具体实施方式detailed description
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本发明及其应用或使用的任何限制。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way taken as limiting the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.
除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本发明的范围。The relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
同时，应当明白，为了便于描述，附图中所示出的各个部分的尺寸并不是按照实际的比例关系绘制的。At the same time, it should be understood that, for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为授权说明书的一部分。Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the Authorized Specification.
在这里示出和讨论的所有示例中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它示例可以具有不同的值。In all examples shown and discussed herein, any specific values should be construed as exemplary only, and not as limitations. Therefore, other examples of the exemplary embodiment may have different values.
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.
需要说明的是，当原子处在塞曼减速器中，激光行进方向和原子的运动方向相反，激光频率相对原子跃迁频率的实际失谐量可以表示为：It should be noted that when the atoms are in the Zeeman reducer, the direction of laser travel is opposite to that of the atoms, and the actual detuning of the laser frequency relative to the atomic transition frequency can be expressed as:
其中δ0为激光频率相对原子静共振频率的失谐量(δ0＝ωlaser-ωatom)；k*v(z)表示原子在塞曼减速器内z点由于速度造成的多普勒频移，k为光波矢，v(z)为原子在z点的速度。Where δ0 is the detuning of the laser frequency relative to the static resonance frequency of the atom (δ0 =ωlaser -ωatom ); k*v(z) represents the Doppler frequency of the atom at point z in the Zeeman reducer due to its velocity shift, k is the light wave vector, and v(z) is the velocity of the atom at point z.
表示在塞曼减速器内z点处的磁场引起的塞曼频移，μB为磁导率，为约化普朗克常数。 Indicates the Zeeman frequency shift caused by the magnetic field at point z in the Zeeman reducer, μB is the magnetic permeability, is the reduced Planck constant.
“-”和“+”分别对应塞曼分裂中量子数变化为+1和-1的跃迁，分别需要利用σ+光和σ-光进行激发。"-" and "+" correspond to the transitions whose quantum numbers change to +1 and -1 in the Zeeman splitting, respectively, which need to be excited by σ+ light and σ- light, respectively.
要使原子束持续有效地在减速器中被减速，激光频率与原子跃迁应始终谐振，即应使总失谐量在塞曼减速器内轴上任意点δ＝0。To make the atomic beam continuously and effectively decelerated in the reducer, the laser frequency and the atomic transition should always be in resonance, that is, the total detuning should be δ=0 at any point on the inner axis of the Zeeman reducer.
因此塞曼减速器的轴向磁场分布为：Therefore, the axial magnetic field distribution of the Zeeman reducer is:
B(z)＝±Bb±Bd(z) (2)B(z)＝±Bb ±Bd (z) (2)
其中Bb是偏置磁场，可根据实际情况选择，和δ0的大小相关，其中“+”表示和原子运动方向同向的磁场，“-”表示和原子运动方向相反的磁场。Bd(z)为随塞曼减速器轴向位置而变化的磁场。Among them, Bb is the bias magnetic field, which can be selected according to the actual situation, and is related to the size of δ0 , where "+" indicates the magnetic field in the same direction as the atomic movement direction, and "-" indicates the magnetic field in the opposite direction to the atomic movement direction. Bd (z) is the magnetic field that changes with the axial position of the Zeeman reducer.
本发明所提出的塞曼减速器可包括多个环形永磁铁，其中，如图1所示，多个环形永磁铁1同轴排列，以便形成用于放置减速腔的腔室2。通过控制各环形永磁铁所产生的磁场，以便在减速腔中形成特定的磁场分布，且沿减速腔的轴线呈柱对称。The Zeeman speed reducer proposed by the present invention may include a plurality of ring-shaped permanent magnets, wherein, as shown in FIG. 1 , a plurality of ring-shaped permanent magnets 1 are coaxially arranged to form a chamber 2 for placing a reduction chamber. By controlling the magnetic fields generated by the ring-shaped permanent magnets, a specific magnetic field distribution is formed in the deceleration cavity, and the axis of the deceleration cavity is column-symmetric.
其中，减速腔与多个环形永磁铁同轴，同时通过控制各环形永磁铁的内外径和厚度，可控制其所产生的磁场。Wherein, the deceleration cavity is coaxial with multiple ring permanent magnets, and the magnetic field generated by each ring permanent magnet can be controlled by controlling the inner and outer diameters and thicknesses of each ring permanent magnet.
基于本发明上述实施例提供的塞曼减速器，由于横向磁场分布均匀，呈柱对称，且均匀区域较大，有利于所有原子的共同减速。Based on the Zeeman reducer provided by the above-mentioned embodiments of the present invention, since the transverse magnetic field is uniformly distributed and column-symmetric, and the uniform area is relatively large, it is beneficial for the common deceleration of all atoms.
优选的，在各环形永磁铁外设置磁屏蔽层3，以便防止磁场泄露。例如，磁屏蔽层2可由软铁材料构成。Preferably, a magnetic shielding layer 3 is provided outside each annular permanent magnet, so as to prevent leakage of the magnetic field. For example, the magnetic shielding layer 2 may be composed of a soft iron material.
优选的，各环形永磁铁可由两部分构成，以便能够沿减速腔的轴线分为两部分，从而便于安装和移动。Preferably, each annular permanent magnet can be composed of two parts, so that it can be divided into two parts along the axis of the deceleration chamber, so as to facilitate installation and movement.
由于本发明提出的塞曼减速器由多块环形永磁铁组合而成，因此永磁铁的极性安装方向可根据实际磁场需求情况加以改变。Since the Zeeman speed reducer proposed by the present invention is composed of a plurality of annular permanent magnets, the installation direction of the polarity of the permanent magnets can be changed according to the actual magnetic field requirements.
在一个实施例中，各环形永磁铁的极性方向相同。在另一实施例中，各环形永磁铁的极性方向可不相同。例如，在减速腔轴线上指定位置一侧的环形永磁铁具有第一极性方向，在指定位置另一侧的环形永磁铁具有第二极性方向，第一极性方向和第二极性方向相反。In one embodiment, the polarity directions of the ring-shaped permanent magnets are the same. In another embodiment, the polarity directions of the ring-shaped permanent magnets may be different. For example, the ring-shaped permanent magnet on one side of the designated position on the axis of the reduction chamber has a first polarity direction, and the ring-shaped permanent magnet on the other side of the designated position has a second polarity direction, the first polarity direction and the second polarity direction on the contrary.
相应的磁场示意图如图2所示。从图2中可以看到，在全部永磁铁极性方向相同的情况下(即单向磁场)，无论是左旋光还是右旋光，磁场曲线均不过零。而在永磁铁极性方向不相同的情况下(即自旋反转)，无论是左旋光还是右旋光，会出现磁场曲线过零的情况。The corresponding magnetic field schematic diagram is shown in Fig. 2 . It can be seen from Figure 2 that when all the permanent magnets have the same polarity direction (that is, a unidirectional magnetic field), the magnetic field curve does not exceed zero no matter whether it is left-handed light or right-handed light. However, when the polarity directions of the permanent magnets are different (that is, the spin is reversed), whether it is left-handed light or right-handed light, the magnetic field curve will cross zero.
若原子(例如锶原子)在塞曼减速器里面匀减速运动，理论最大加速度可由公式确定：If the atoms (such as strontium atoms) are uniformly decelerated in the Zeeman reducer, the theoretical maximum acceleration can be determined by the formula:
其中Γ为原子的跃迁几率，和光强相关，M为锶原子质量。对于锶原子1S0-1P1跃迁，amax＝9.83*105m/s2，例如设计加速度为最大加速度的一半，即a＝4.915*105m/s2，以保证在当前塞曼光强的前提下，原子速度变化足够快，能够将绝大多数原子的速度从初始状态的500m/s降低至80m/s。Among them, Γ is the transition probability of the atom, which is related to the light intensity, and M is the mass of the strontium atom. For strontium atom1 S0 -1 P1 transition, amax =9.83*105 m/s2 , for example, the design acceleration is half of the maximum acceleration, that is, a=4.915*105 m/s2 , to ensure Under the premise of Mann light intensity, the atomic speed changes fast enough to reduce the speed of most atoms from the initial state of 500m/s to 80m/s.
根据公式：According to the formula:
可计算理论需要的磁场。h表示普朗克常数，δ表示激光频率相对于原子跃迁频率的失谐量，μB表示磁导率，λ表示激光波长，vi表示原子进入塞曼减速器的初速度大小，a表示原子在塞曼减速器中获得的加速度，z表示原子在塞曼减速器轴向上的位置。The theoretically required magnetic field can be calculated. h represents Planck's constant, δ represents the detuning of the laser frequency relative to the atomic transition frequency, μB represents the magnetic permeability, λ represents the laser wavelength, vi represents the initial velocity of the atom entering the Zeeman reducer, and a represents the atom The acceleration obtained in the Zeeman reducer, z represents the position of the atom in the axial direction of the Zeeman reducer.
在一个实施例中，单个环形永磁铁上的单个磁偶极子对空间中P点所产生的磁场强度为：In one embodiment, the magnetic field intensity produced by a single magnetic dipole on a single annular permanent magnet to point P in space is:
其中，Bx、By、Bz是单个磁偶极子在空间中P点所产生的磁场在三个坐标轴上的分量，μ0表示真空中的磁导率，m为磁偶极子的磁矩，r表示单个磁偶极子与空间中点P的距离，Among them, Bx , Byy , and Bz are the components of the magnetic field generated by a single magnetic dipole at point P in space on three coordinate axes, μ0 represents the magnetic permeability in vacuum, and m is the magnetic dipole The magnetic moment of , r represents the distance of a single magnetic dipole from the point P in space,
根据实际需要，可对环形永磁铁的内外径和厚度进行相应调整，得到的实际磁场分布和理论计算磁场分布比较如图3所示，可以看到实际磁场分布与理论磁场分布拟合得非常好。偏差最大处为0.5mT，小于2％。这里末端的实际磁场比理论磁场低且变化缓慢，是由于实际磁场的控制无法做到磁场快速降低到0，必须缓变降低，因此实际磁场变化速度要比理论磁场缓慢。同时为了防止原子到达塞曼减速器末端时速度低于期望，甚至获得了反向的速度又飞回原子炉中，因此塞曼减速器在出口处的最大磁场不能大于理论磁场。即，减速腔出口处的最大磁场不大于预定的磁场门限B(z)(如公式4所示)，也就是不大于该处的理论磁场。According to actual needs, the inner and outer diameters and thickness of the annular permanent magnet can be adjusted accordingly. The comparison between the obtained actual magnetic field distribution and the theoretically calculated magnetic field distribution is shown in Figure 3. It can be seen that the actual magnetic field distribution and the theoretical magnetic field distribution fit very well. . The maximum deviation is 0.5mT, less than 2%. The actual magnetic field at the end here is lower than the theoretical magnetic field and changes slowly, because the control of the actual magnetic field cannot quickly reduce the magnetic field to 0, and must be slowly reduced, so the actual magnetic field changes slower than the theoretical magnetic field. At the same time, in order to prevent the atoms from reaching the end of the Zeeman reducer at a lower speed than expected, and even obtain the reverse speed and fly back into the atomic furnace, the maximum magnetic field at the exit of the Zeeman reducer cannot be greater than the theoretical magnetic field. That is, the maximum magnetic field at the exit of the deceleration chamber is not greater than the predetermined magnetic field threshold B(z) (as shown in formula 4), that is, not greater than the theoretical magnetic field there.
在塞曼减速器中，磁场变缓相当于设计加速度变小，因此不影响实际使用。In the Zeeman reducer, the slowing of the magnetic field is equivalent to the reduction of the design acceleration, so it does not affect the actual use.
由于在本发明中横向磁场分布均匀，呈柱对称，且均匀区较大，有利于所有原子的共同减速。在径向距离为5mm的时候，在减速器的绝大部分区域中实际磁场与理论值的偏差小于0.1mT，最大处为入口处的0.5mT，小于1％。图4所示为本发明塞曼减速器距离中心轴线5mm处的磁场强度的轴向分布。In the present invention, the transverse magnetic field is evenly distributed, column-symmetric, and the uniform area is relatively large, which is beneficial to the common deceleration of all atoms. When the radial distance is 5mm, the deviation between the actual magnetic field and the theoretical value in most areas of the reducer is less than 0.1mT, and the maximum is 0.5mT at the entrance, which is less than 1%. Fig. 4 shows the axial distribution of the magnetic field intensity at a distance of 5 mm from the central axis of the Zeeman reducer of the present invention.
通过使用环形永磁铁，从而本发明所给出的塞曼减速器磁场是关于中心轴线旋转对称的，因为热原子束和冷却激光都具有一定的横截面积，中心对称的磁场可以确保所有的热原子经历相同的塞曼效应，进而达到同时减速的目的。By using ring-shaped permanent magnets, the Zeeman reducer magnetic field provided by the present invention is rotationally symmetric about the central axis, because both the hot atom beam and the cooling laser have a certain cross-sectional area, and the centrosymmetric magnetic field can ensure that all heat Atoms experience the same Zeeman effect, which slows down simultaneously.
通过实施本发明，可以得到以下有益效果：By implementing the present invention, the following beneficial effects can be obtained:
本发明利用环形永磁铁产生塞曼减速其所需磁场，在轴向上的磁力线关于中心轴线旋转对称，磁场强度在减速器截面上分布均匀，保证了轴向上同一空间位置的原子被同时减速。而且该塞曼减速器在使用过程中无功耗，属于清洁设备，不会发生发热的情况，有利于实验安全，也提高了冷却效率。另外，该环形永磁铁塞曼减速器还具有小型化的潜力。The present invention utilizes ring-shaped permanent magnets to generate the required magnetic field for Zeeman deceleration. The magnetic field lines in the axial direction are rotationally symmetrical about the central axis, and the magnetic field strength is evenly distributed on the cross-section of the reducer, which ensures that the atoms at the same spatial position in the axial direction are decelerated simultaneously. . Moreover, the Zeeman reducer has no power consumption during use, is a clean device, and does not generate heat, which is conducive to the safety of the experiment and improves the cooling efficiency. In addition, the annular permanent magnet Zeeman reducer also has the potential of miniaturization.
本发明的描述是为了示例和描述起见而给出的，而并不是无遗漏的或者将本发明限于所公开的形式。很多修改和变化对于本领域的普通技术人员而言是显然的。选择和描述实施例是为了更好说明本发明的原理和实际应用，并且使本领域的普通技术人员能够理解本发明从而设计适于特定用途的带有各种修改的各种实施例。The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and changes will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to better explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention and design various embodiments with various modifications as are suited to the particular use.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510938958.XACN106888546A (en) | 2015-12-16 | 2015-12-16 | Zeeman decelerator based on annular permanent magnet |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510938958.XACN106888546A (en) | 2015-12-16 | 2015-12-16 | Zeeman decelerator based on annular permanent magnet |
| Publication Number | Publication Date |
|---|---|
| CN106888546Atrue CN106888546A (en) | 2017-06-23 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510938958.XAPendingCN106888546A (en) | 2015-12-16 | 2015-12-16 | Zeeman decelerator based on annular permanent magnet |
| Country | Link |
|---|---|
| CN (1) | CN106888546A (en) |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110780585A (en)* | 2019-10-11 | 2020-02-11 | 北京大学 | Optical pumping cesium atomic clock applying axisymmetric multistage magnets and implementation method |
| CN111312497A (en)* | 2020-03-24 | 2020-06-19 | 中国科学院上海天文台 | Multi-section coil type ultra-uniform C field generating device of hydrogen atomic clock and manufacturing method thereof |
| RU2752462C1 (en)* | 2020-12-15 | 2021-07-28 | Российская Федерация, от имени которой выступает Федеральное агентство по техническому регулированию и метрологии (Росстандарт) | Atomic beam zeeman moderator |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6476383B1 (en)* | 1999-08-31 | 2002-11-05 | Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. | Device and method for generating and manipulating coherent matter waves |
| WO2007147477A1 (en)* | 2006-06-22 | 2007-12-27 | Sony Deutschland Gmbh | Zeeman-slower, coil for a zeeman-slower device and a method for cooling an atom beam |
| CN103528681A (en)* | 2013-10-12 | 2014-01-22 | 中国科学院上海高等研究院 | Cavity for magneto-optical trap reaction microscope imaging spectrometers |
| US20150200029A1 (en)* | 2014-01-13 | 2015-07-16 | ColdQuanta, Inc. | Ultra-Cold-Matter System with Thermally-Isolated Nested Source Cell |
| CN104833690A (en)* | 2015-06-04 | 2015-08-12 | 中国人民解放军国防科学技术大学 | Method for measuring alkali metal atomic polarizability of nuclear magnetic resonance gyro in real time |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6476383B1 (en)* | 1999-08-31 | 2002-11-05 | Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. | Device and method for generating and manipulating coherent matter waves |
| WO2007147477A1 (en)* | 2006-06-22 | 2007-12-27 | Sony Deutschland Gmbh | Zeeman-slower, coil for a zeeman-slower device and a method for cooling an atom beam |
| CN103528681A (en)* | 2013-10-12 | 2014-01-22 | 中国科学院上海高等研究院 | Cavity for magneto-optical trap reaction microscope imaging spectrometers |
| US20150200029A1 (en)* | 2014-01-13 | 2015-07-16 | ColdQuanta, Inc. | Ultra-Cold-Matter System with Thermally-Isolated Nested Source Cell |
| CN104833690A (en)* | 2015-06-04 | 2015-08-12 | 中国人民解放军国防科学技术大学 | Method for measuring alkali metal atomic polarizability of nuclear magnetic resonance gyro in real time |
| Title |
|---|
| IAN R. HILL ET.AL.: "Zeeman Slowers for Strontium based on Permanent Magnets", 《[PHYSICS.ATOM-PH》* |
| WANG QIANG 等: "A Longitudinal Zeeman Slower Based on Ring-Shaped Permanent Magnets for a Strontium Optical Lattice Clock", 《CHIN. PHYS. LETT.》* |
| YURI B. OVCHINNIKOV: "Longitudinal Zeeman slowers based on permanent magnetic dipoles", 《OPTICS COMMUNICATIONS》* |
| 谢玉林 等: "用于锶原子光钟永磁体塞曼减速器设计", 《时间频率学报》* |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110780585A (en)* | 2019-10-11 | 2020-02-11 | 北京大学 | Optical pumping cesium atomic clock applying axisymmetric multistage magnets and implementation method |
| CN110780585B (en)* | 2019-10-11 | 2021-01-26 | 北京大学 | Optical pumping cesium atomic clock applying axisymmetric multistage magnets and implementation method |
| CN111312497A (en)* | 2020-03-24 | 2020-06-19 | 中国科学院上海天文台 | Multi-section coil type ultra-uniform C field generating device of hydrogen atomic clock and manufacturing method thereof |
| RU2752462C1 (en)* | 2020-12-15 | 2021-07-28 | Российская Федерация, от имени которой выступает Федеральное агентство по техническому регулированию и метрологии (Росстандарт) | Atomic beam zeeman moderator |
| Publication | Publication Date | Title |
|---|---|---|
| Tuchin | Electromagnetic field and the chiral magnetic effect in the quark-gluon plasma | |
| Yakimenko et al. | Vortices in a toroidal Bose-Einstein condensate with a rotating weak link | |
| Yan et al. | Spin-Cherenkov effect and magnonic Mach cones | |
| Yamamoto | Photonic chiral vortical effect | |
| Kolmakov et al. | Wave turbulence in quantum fluids | |
| Ghorui et al. | Head on collision of dust ion acoustic solitary waves in magnetized quantum dusty plasmas | |
| Maiden et al. | Attraction, merger, reflection, and annihilation in magnetic droplet soliton scattering | |
| Yuan et al. | Classification of magnetic forces acting on an antiferromagnetic domain wall | |
| CN106888546A (en) | Zeeman decelerator based on annular permanent magnet | |
| JP2022500904A (en) | Non-reciprocal quantum devices that utilize quantum wave decay, interference, and selective absorption | |
| Fallah et al. | Nonreciprocal guided waves in the presence of swift electron beams | |
| Ali et al. | Magnetoacoustic waves with effect of arbitrary degree of temperature and spin degeneracy in electron‐positron‐ion plasmas | |
| Khanum et al. | Hydrodynamic analysis of electrostatic counter‐streaming instability in a spin‐polarized electron–positron–ion plasma | |
| CN103050166A (en) | Method capable of realizing neutral cold atom laser guidance with nano-scale cross section | |
| Abdoli-Arani et al. | Influence of electron–ion collisions in plasma on the electron energy gain using the TE11 mode inside an elliptical waveguide | |
| Sangtawee et al. | Coaxial quantum well wires in magnetic/nonmagnetic heterostructures | |
| Kozlov et al. | Dispersion equation for ballooning modes in two-component plasma | |
| Gomonay | Crystals with defects may be good for spintronics | |
| Dong et al. | Gyrokinetic study of the electron temperature gradient instability in plasmas with slightly hollow density profiles | |
| Takeuchi et al. | Tachyon condensation and brane annihilation in Bose-Einstein condensates: spontaneous symmetry breaking in restricted lower-dimensional subspace | |
| Khaetskii et al. | Unitarity of scattering and edge spin accumulation | |
| Suzuki et al. | Collisionless damping of fast magnetohydrodynamic waves in magnetorotational winds | |
| Kumar | Quantum Plasma in Astrophysics | |
| Nakata | Thermal spin pumping mediated by magnons in the semiclassical regime | |
| Lezhnin et al. | Evolution of relativistic electron vortices in laser plasmas |
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | Application publication date:20170623 | |
| WD01 | Invention patent application deemed withdrawn after publication |