Deterministic ultra-cold single ion preparation device and method

Abstract

The invention provides a deterministic ultra-cold single ion preparation device and method, and relates to the field of ion source preparation. The preparation device comprises a magneto-optical trap system used for cooling and trapping neutral hot atomic gas to obtain a cold atomic group; the ionization laser system is used for ionizing the cold atomic group through the laser emitted by the continuous wavelength laser to obtain an electron-ion pair; the detection system is used for collecting electrons, ions and flight time information of the electrons and the ions; the acceleration extraction system is used for guiding electrons and ions to fly to the detection system in an acceleration manner; the vacuum system is used for providing a vacuum environment required by an experiment; the gating system is used for screening ions meeting a preset flight time condition to reach the detection system; and the coincidence measurement system is used for determining a target electron-target ion pair according to the flight time information. According to the invention, a high-flow-intensity single ion source can be obtained through photoionization of cold atomic groups, and deterministic control of single ions can be realized through a coincidence measurement technology and a gating system.

Description

Technical Field

[0001] The present application relates to the technical field of single ion source preparation, and in particular to a deterministic ultracold single ion preparation device and method. Background Art

[0002] The preparation, manipulation and detection of single particles is one of the key technologies in experimental physics. Research over the past few decades has shown that the manipulation of single particles such as ions, atoms or photons is a key driving force for promoting scientific and technological progress. Among them, single-ion technology is a novel ion beam technology that connects quantum optics and materials science applications. It has become an important tool for realizing applications such as nanostructure manufacturing and doping, and plays an important role in the study of the interaction between single ions and matter and quantum information processing.

[0003] There are many ion sources available, each with specific characteristics. There are three main types of traditional ion sources that have been successfully commercialized: liquid metal ion source (LMIS), gas field emission ion source (GFIS) and inductively coupled plasma ion source (ICPS). Liquid metal ion source LMIS uses a strong electric field to act on molten metal to produce ions, and has the advantages of stable performance and high repeatability. However, since the metal used must have high surface tension and low melting point when in liquid state, it can only provide a few ion beams mainly based on gallium. Gas field emission ion source GFIS uses a strong electric field to ionize gas atoms to prepare ions. The ion types are mainly light helium ions and neon ions, and it needs to be equipped with a low-temperature cooling system, which brings many inconveniences to operation and maintenance. Inductively coupled plasma ion source ICPS generates ions through inductively coupled radio frequency discharge, and can provide more ion types, but the brightness and energy dispersion are far inferior to the former two. Although the above ion sources have been commercialized, there are still problems such as single ion type, high energy dispersion, harsh preparation conditions and complex structure, which limit its application range. In particular, accurately controlling the number of ions in the ion beam in these ion sources is a huge challenge, making it difficult to meet the needs of single-ion preparation in new application scenarios.

[0004] The increasing maturity of laser cooling and trapping technology has provided a new solution for the development of new single ion sources. On the one hand, based on ion trap technology, the ions themselves are cooled and captured, and can be deterministically drawn out of the trap to achieve control over the number of ions. However, the current intensity that can be achieved by this single ion source is very limited. On the other hand, extremely bright ion sources can be prepared by photoionization laser-cooled atomic clusters or atomic beams, including magneto-optical trap ion sources and cold atom ion sources, but these ion sources do not inherently have deterministic characteristics. In addition, there are studies that use the Rydberg blockade mechanism to prepare single atoms from atomic clusters, and obtain deterministic single ion sources after photoionization, but this scheme has extremely high requirements on the laser line width and atomic cluster density, and the experiment has not yet been realized. Therefore, it is necessary to provide a solution to the above problems. Summary of the invention

[0005] The present application provides a deterministic ultracold single ion preparation device and method to solve the low current intensity problem of ultracold single ion sources based on ion traps in the prior art, as well as the uncertainty problem of traditional ion sources, cold atomic ion sources, etc.

[0006] The present application provides a deterministic ultracold single ion preparation device, comprising: Magneto-optical trap system, used to cool and trap neutral hot atomic gas to obtain cold atomic groups; An ionization laser system, used for ionizing the cold atomic group by laser light emitted by a continuous wavelength laser, to obtain a plurality of electrons and ions corresponding to each of the electrons, wherein each of the ions is an ultracold single ion; A detection system, used for collecting the electrons and the ions, and obtaining flight time information of the electrons and the ions based on their respective flight paths, wherein the starting point of the flight path is the magneto-optical trap system and the end point is the detection system; An acceleration extraction system, used for guiding the electrons and the ions to accelerate and fly toward the detection system; A vacuum system, used for providing a vacuum environment for the flight of the cold atoms, the electrons and the ions; A gating system, used for screening the ions so that the ions meeting the preset flight time conditions can reach the detection system; A coincidence measurement system is used to determine, based on the flight time information, that the target ion is the ion corresponding to the target electron, the target electron is one of the multiple electrons, and the target ion is one of the multiple ions when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within a preset time window.

[0007] According to the deterministic ultracold single ion preparation device provided in the present application, the coincidence measurement system comprises: a signal amplifying element, used to amplify the signal representing the time-of-flight information output by the detection system; A signal discrimination element is used to filter out invalid signals from the amplified signal; A signal delay and stretching element, used for performing coincidence measurement on the flight time information corresponding to the signal output by the signal discrimination element, and determining that the target ion is the ion corresponding to the target electron when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within the preset time window; The signal counter element is used to record the number of electrons collected by the detection system and the number of ions screened by the gating system.

[0008] According to the deterministic ultracold single ion preparation device provided by the present application, the vacuum system includes a vacuum chamber, the flight path is located in the vacuum chamber, and the magneto-optical trap system includes a first laser emitting device and a pair of anti-Helmholtz coils, and the anti-Helmholtz coils are symmetrically arranged outside the vacuum chamber; The magneto-optical trap system is used to obtain three pairs of counter-propagating and mutually orthogonal laser beams based on the first laser emitted by the first laser emitting device, construct a magneto-optical trap based on the laser field formed by the laser beam and the gradient magnetic field generated by the anti-Helmholtz coil, and cool and trap the neutral hot atomic gas through the magneto-optical trap to obtain the cold atomic cluster.

[0009] According to the deterministic ultracold single ion preparation device provided in the present application, the ionization laser system includes a second laser emitting device, and the ionization laser system ionizes the cold atomic group by a second laser emitted by a continuous wavelength laser in the second laser emitting device to obtain multiple electrons and ions corresponding to each of the electrons, and the wavelength of the second laser is different from the wavelength of the first laser.

[0010] According to the deterministic ultracold single ion preparation device provided in the present application, the first laser is also used to make atoms transition from a ground state to an excited state, and the second laser is used to ionize cold atomic clusters in the excited state to obtain multiple electrons and ions corresponding to each of the electrons.

[0011] According to the deterministic ultracold single ion preparation device provided in the present application, the detection system includes an electron detection system and an ion detection system, the electron detection system is used to collect the flight time information of each of the electrons, and the ion detection system is used to collect the flight time information of each of the ions.

[0012] According to the deterministic ultracold single ion preparation device provided in the present application, the gating system is located between the acceleration extraction system and the ion detection system, and the gating system includes a pair of metal plates, which are parallel to the flight path and symmetrically arranged on both sides of the flight path; The gating system is used to provide a channel for the ions to fly along the flight path to the ion detection system when the ions meet the preset flight time condition, so that the ions reach the ion detection system; and to make the ions deviate from the flight path when the ions do not meet the preset flight time condition, so that the ions cannot reach the ion detection system.

[0013] According to the deterministic ultracold single ion preparation device provided in the present application, the gating system determines that the ion meets the preset flight time condition when an electronic trigger signal is detected, and the delay time and width of the electronic trigger signal are determined based on the historical flight time information obtained by the compliance measurement system.

[0014] According to the deterministic ultracold single ion preparation device provided in the present application, the detection system is a two-dimensional position-sensitive detector.

[0015] The present application also provides a deterministic ultracold single ion preparation method, which is applied to a deterministic ultracold single ion preparation device provided in the present application, and the deterministic ultracold single ion preparation method comprises: The neutral hot atomic gas is cooled and trapped by the magneto-optical trap system to obtain cold atomic groups; The cold atomic group is ionized by the ionization laser system using laser light emitted by a continuous wavelength laser to obtain a plurality of electrons and ions corresponding to each of the electrons, wherein each of the ions is an ultracold single ion; The electrons and the ions are collected by the detection system, and flight time information of the electrons and the ions based on their respective flight paths is obtained, wherein the starting point of the flight path is the magneto-optical trap system and the end point is the detection system; Guiding the electrons and the ions to accelerate toward the detection system through the acceleration extraction system; Providing a vacuum environment for the flight of the cold atoms, the electrons and the ions through the vacuum system; The ions are screened by the gating system so that the ions meeting the preset flight time conditions can reach the detection system; Through the coincidence measurement system, according to the flight time information, when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within a preset time window, it is determined that the target ion is the ion corresponding to the target electron, the target electron is one of the multiple electrons, and the target ion is one of the multiple ions.

[0016] In the present application, a laser ionization cold atomic group generated by a continuous wavelength laser is used to generate a high-intensity single ion source, which effectively solves the low-intensity problem in the related technology caused by the slow loading rate of the ion trap and the constraint of the Coulomb interaction between ions in the trap; secondly, by utilizing the coincidence measurement technology and introducing a gating system, deterministic control of each ion in the ion beam can be achieved. For example, ions can be screened through the gating system so that ions that meet the preset flight time conditions reach the detection system, and the ions corresponding to each electron can be accurately determined, laying the foundation for the development of new nano-ion beam technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic diagram of the working principle of a deterministic ultracold single ion preparation device shown in one embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] The present application provides a deterministic ultracold single ion preparation device, which is based on coincidence measurement technology and expands the magneto-optical trap ion source, and can solve the low current problem of ultracold single ion sources based on ion traps, as well as the uncertainty problem of traditional ion sources, cold atomic ion sources, etc. Among them, ultracold means that the temperature of the ion is in an extremely low temperature state, usually in the micro-Kelvin (μK) order. Ultracold refers to an extremely low temperature relative to normal temperature (about 300K), at which the thermal motion energy of the ion is extremely small.

[0021] In this application, the uncertainty of the ion source refers to the fact that in the process of ion generation, parameters such as the time of ion generation, the flight trajectory of ions, and the number of ions cannot be accurately controlled or predicted. For example, in some traditional ion sources, when ions are generated by thermal ionization or electron impact ionization, the ionization of atoms is a relatively random process. Ions may be generated at different times, and the number of ions generated each time may fluctuate due to factors such as ionization probability and uneven atomic density distribution.

[0022] The deterministic ultracold single ion preparation device of the present application may include a magneto-optical trap system, a vacuum system, an ionization laser system, an acceleration extraction system, a detection system, a coincidence measurement system, and a gating system.

[0023] Magneto-optical trap system, used to cool and trap neutral hot atomic gas to obtain cold atomic groups; An ionization laser system is used to ionize cold atomic groups using laser light emitted by a continuous wavelength laser to obtain multiple electrons and ions corresponding to each electron, each of which is an ultracold single ion; A detection system for collecting electrons and ions and obtaining flight time information of the electrons and ions based on their respective flight paths, the flight path starting from the magneto-optical trap system and ending at the detection system; An acceleration and extraction system is used to accelerate electrons and ions and guide them to fly to the detection system; Vacuum system, used to provide vacuum environment for the flight of electrons and ions; A gating system is used to screen the ions so that the ions that meet the preset flight time conditions can reach the detection system; A coincidence measurement system is used to determine, based on flight time information, that a target ion is an ion corresponding to a target electron, that a target electron is one of multiple electrons, and that a target ion is one of multiple ions when the difference between the times when the target electron and the target ion respectively arrive at a detection system is within a preset time window.

[0024] The following sections will introduce each part in turn: (1) Magneto-optical trap system In the present application, the vacuum system includes a vacuum chamber, the flight path is located in the vacuum chamber, and the magneto-optical trap system includes a first laser emitting device and a pair of anti-Helmholtz coils, which are symmetrically arranged outside the vacuum chamber.

[0025] The magneto-optical trap system is used to obtain three pairs of counter-propagating and mutually orthogonal laser beams based on the first laser emitted by the first laser emitting device, and to construct a magneto-optical trap based on the laser field formed by the laser beam and the gradient magnetic field generated by the anti-Helmholtz coil, and to cool and trap the neutral hot atomic gas generated by the atomic furnace through the magneto-optical trap to obtain cold atomic clusters of a certain density.

[0026] The first laser may be a 780 nm laser, or a laser of other wavelengths set according to actual needs.

[0027] After the first laser is split by optical fiber, three pairs of mutually orthogonal laser beams that propagate in opposite directions can be obtained. These three pairs of laser beams can form a laser field. A pair of anti-Helmholtz coils are symmetrically placed outside the vacuum chamber to generate a gradient magnetic field. Therefore, a classic three-dimensional atomic cooling and trapping device, the magneto-optical trap, can be constructed through the laser field and the gradient magnetic field. The magneto-optical trap can slow down the cooling of atoms above room temperature to the order of hundreds of μK and stably trap them in the trap, thereby obtaining cold atomic clusters. The order of hundreds of μK refers to a temperature in the range of several hundred microkelvins, for example, a temperature value between 100μK and 999μK.

[0028] In the laser field, the laser beam interacts with atoms, and the momentum exchange between photons and atoms slows down the cooling of atoms above room temperature. In the process of absorbing and spontaneously radiating photons, the momentum of atoms gradually decreases from a statistical perspective, thereby cooling the atoms to the order of hundreds of μK.

[0029] In a gradient magnetic field, atoms will be affected by a force related to the magnetic field gradient and the atomic magnetic moment. This force will push the atoms to the central area where the magnetic field is weaker, and work together with the laser field to stably trap the cooled atoms in the trap, forming a cold atomic cluster of a certain density, providing a basis for subsequent processes such as ionization.

[0030] (2) Vacuum system In the present application, the vacuum system is used to provide a vacuum environment during the preparation of cold atoms and the subsequent extraction of electrons and ions.

[0031] Specifically, the vacuum system includes a series of vacuum components such as a vacuum chamber, a vacuum pump group (molecular pump and mechanical pump, etc.), an ionization gauge, a bellows, a molecular pump controller, and a beam pipeline.

[0032] The vacuum system can control the vacuum degree index of the vacuum chamber (or the absolute pressure in the vacuum chamber) to provide a vacuum environment for the operation of the deterministic ultracold single ion preparation device, thereby greatly reducing the collision between atoms or ions and other gas molecules, avoiding problems such as increased atomic thermal motion and ion scattering caused by collisions, and ensuring that the cooling, trapping, ionization of atoms, and the extraction of electrons and ions can proceed smoothly and stably. The higher the vacuum degree of the vacuum chamber, the lower the gas pressure in the vacuum chamber and the rarer the gas molecules.

[0033] In actual implementation, the vacuum degree of the vacuum chamber can be set according to actual needs to obtain the required vacuum environment. For example, the vacuum environment can be an ultra-high vacuum environment (UHV). An ultra-high vacuum environment refers to a vacuum environment with a pressure lower than Vacuum environment, or pressure range The vacuum environment between.

[0034] The vacuum pump group is responsible for extracting the gas in the vacuum chamber.

[0035] The molecular pump uses high-speed rotating blades or turbines to push gas molecules from one end of the vacuum chamber to the other end, thereby extracting the gas.

[0036] Mechanical pumps are mainly used to initially evacuate the vacuum chamber.

[0037] The ionization gauge is used to detect the vacuum degree in the vacuum chamber in real time and accurately.

[0038] In the vacuum system, bellows are used to connect different vacuum components, such as connecting the vacuum pump group and the vacuum chamber, connecting the ionization gauge and the vacuum chamber, etc.

[0039] Molecular pump controller is mainly used to accurately control the operation of molecular pump.

[0040] A beam pipe is a smooth internal pipe structure used to guide ions from the generation area (such as the ion source in a vacuum chamber) to subsequent application equipment (such as the mass analyzer of a mass spectrometer, the implantation target chamber of an ion implanter, etc.).

[0041] (3) Ionization laser system In the present application, the ionization laser system includes a second laser emitting device. The ionization laser system ionizes the cold atomic clusters by emitting a second laser through a continuous wavelength laser in the second laser emitting device to obtain a plurality of electrons and ions corresponding to each electron. The wavelength of the second laser is different from that of the first laser.

[0042] In the present application, an ionization laser system is used to ionize cold atomic radicals to generate electron-ion pairs.

[0043] The second laser can be a 423nm laser, or a laser of other wavelengths set according to actual needs. The wavelength of the second laser is different from the wavelength of the first laser. The second laser emitting device can be the same device as the first laser emitting device, or can be a different device.

[0044] Figure 1 This is a schematic diagram of the working principle of a deterministic ultracold single ion preparation device shown in an embodiment of the present application. The first laser emitting device is used to emit 780nm laser (i.e. Figure 1 The second laser emitting device is used to emit a 423nm laser (i.e. Figure 1 423nm ionization laser in Figure 1 In the figure, the two circles above and below the cold atom cluster represent a pair of anti-Helmholtz coils. The arrow pointing to the upper anti-Helmholtz coil indicates the direction of the 780nm cooling laser, which can pass through the anti-Helmholtz coil, but does not mean that it must be above the anti-Helmholtz coil. The arrow pointing to the lower anti-Helmholtz coil also indicates the direction of the 780nm cooling laser, which can pass through the anti-Helmholtz coil, but does not mean that it must be below the anti-Helmholtz coil.

[0045] The second laser emission device is mainly composed of a continuous wavelength laser, which is used for the photoionization process of cold atomic groups to produce electron-ion pairs. A continuous wavelength laser refers to a device that can continuously output a laser with a fixed wavelength (or with very small fluctuations in a very narrow wavelength range). Unlike a pulsed laser, the output of a continuous wavelength laser is continuous in time, with no obvious pulse intervals.

[0046] In the present application, the first laser is also used to provide energy for the energy level transition of the cold atomic cluster, so that each cold atom in the cold atomic cluster transitions to an excited state, and the second laser is used to ionize each cold atom in the excited state to obtain multiple electrons and ions corresponding to each electron.

[0047] In the present application, the process of photoionization of cold atom groups can adopt a two-color two-photon resonant ionization method, which includes two steps: the first step is to prepare the atoms in the vacuum chamber from the ground state to the excited state through the resonance transition using the first laser in the process of obtaining the cold atom groups through the magneto-optical trap system; the second step is to ionize the atoms in the excited state through the second laser. The present application can efficiently convert the cold atom groups into electrons and ions through this precisely controlled two-step ionization process.

[0048] (4) Accelerated extraction system In this application, the acceleration extraction system is used to achieve the acceleration and efficient output of electrons and ions. Specifically, the acceleration extraction system mainly consists of a series of parallel plate electrodes with circular holes in the middle (i.e. Figure 1These electrode sheets are arranged parallel to each other in space, and there is a circular hole in the middle of each electrode sheet. Through careful electromagnetic field simulation and screening of appropriate loading voltage, electrons and ions can pass smoothly between the electrode sheets, while ensuring that the distribution of the electric field can guide the movement of electrons and ions along the axial direction to a certain extent.

[0049] In order to enable the acceleration extraction system to work effectively, this application also requires detailed electromagnetic field simulation. Since the electric field distribution between the electrode sheets is affected by various factors such as the shape, size, spacing and applied voltage of the electrode sheets, the electromagnetic field simulation software can simulate the electric field distribution under different voltage loading conditions and electrode sheet geometric parameters. During the simulation process, by continuously adjusting the voltage value and the relevant parameters of the electrode sheets, a solution that can produce the electric field distribution that is most conducive to the acceleration and extraction of electrons and ions is found, and the electric field distribution must ensure that the direction of the electric field force received by electrons and ions when passing between the electrode sheets can accelerate them in the desired direction, and minimize the scattering and loss of electrons and ions.

[0050] (5) Detection system In this application, there are two detection systems, one for collecting electrons and outputting the flight time spectrum and spatial distribution information of electrons, which is called the electron detection system (corresponding to Figure 1 The other is used to collect ions and output the flight time spectrum (i.e., flight time information) and spatial distribution information of the ions, which is called the ion detection system (corresponding to Figure 1 The detection system generally uses a two-dimensional position sensitive detector.

[0051] The two-dimensional position-sensitive detector consists of two microchannel plates, a fluorescent screen and a charge-coupled device camera (CCD camera), which is used to record and output the flight time spectrum and spatial distribution information of electrons and ions.

[0052] A microchannel plate is a thin plate-like structure with many tiny channels, and the inner wall of the internal channel is coated with secondary electron emission material. In a two-dimensional position sensitive detector, the main function of the two microchannel plates is to amplify the electron and ion signals.

[0053] A phosphor screen is a screen that emits visible light after being hit by electrons. In a two-dimensional position-sensitive detector, the main function of the phosphor screen is to convert the electronic signal amplified by the microchannel plate into a visible light signal, so as to convert the invisible electronic signal into a light signal that is easy to observe and record.

[0054] CCD camera is mainly composed of CCD chip, optical lens and related electronic circuit. CCD chip is a semiconductor device, which is composed of many photosensitive units (pixels). CCD camera is used to record the light signal on the fluorescent screen. It can convert the light signal into digital image signal, so as to accurately record the position information of electrons and ions on the fluorescent screen. By analyzing the digital image, the spatial distribution of electrons and ions can be obtained.

[0055] (6) Compliance with measurement system In this application, compliance measurement systems include: A signal amplifying element, used for amplifying the signal representing the time-of-flight information output by the detection system; A signal discrimination element is used to filter out invalid signals from the amplified signal; A signal delay and stretching element is used to perform coincidence measurement on the flight time information corresponding to the signal output by the signal discrimination element, and determine that the target ion is the ion corresponding to the target electron when the difference between the time when the target electron and the target ion arrive at the detection system is within a preset time window; The signal counter element is used to record the number of electrons collected by the detection system and the number of ions filtered by the gating system.

[0056] In the present application, the coincidence measurement system processes the signal output by the detection system and uses the electronic signal as a trigger to predict the generation of relevant ions.

[0057] The signal amplifier is used to amplify the signal output by the detection system. Since the original signal output by the detection system may be very weak and difficult to directly process, the signal can be amplified by the signal amplifier first.

[0058] The signal discrimination component discriminates the amplified signal by adjusting and setting the threshold of the component. The threshold determines which signals are considered valid signals and which are filtered as noise or irrelevant signals. That is, only signals with intensity exceeding the threshold are identified as valid signals. For example, if the threshold is set to a certain voltage value, signals below this voltage value will be ignored, and signals above this voltage value will continue to enter the subsequent processing flow. In this way, the noise signals that may be introduced by the detection system during the collection process can be effectively removed, thereby improving the reliability of the signal.

[0059] Signal delay and broadening element: Due to the obvious difference in mass between electrons and ions formed by photoionized atoms, electrons from the same photoionization event will reach the detector first. In order to achieve event-by-event (photoionization event) recording, the electron-ion coincidence signal from the same photoionization event needs to be used as a trigger signal for coincidence measurement. The basic principle is to delay the fast signal (electron signal), broaden the slow signal (ion signal), and then make the two coincide to form a trigger signal. When the trigger signal arrives, the particle information begins to be recorded. The signal counter element records and monitors the electronic trigger signal count and the single ion count after gated screening respectively. The electronic trigger signal count reflects the number of electrons detected by the detection system, and the count can be used to understand the frequency of electrons generated in the photoionization process and other information. The single ion count after gated screening counts the single ions screened by the gated system, which can be used to determine the preparation effect of single ions. In the present application, an electron-ion pair can be obtained after a photoionization operation is performed on an atom. Therefore, when an electron and an ion both come from the same atom, it means that the electron and the ion come from the same photoionization event, and the electron and the ion correspond to each other and are an electron-ion pair.

[0060] On the basis of the delayed and stretched signal, coincidence measurement can be performed. Coincidence measurement is based on the time correlation between electrons and ions. Within a preset time window (i.e., coincidence window), the coincidence measurement system determines whether the electron signal and the ion signal appear at the same time. If both appear within the time range of the coincidence window, they appear at the same time. Assuming that the width of the coincidence window is set to Δt nanoseconds, if the electron (e.g., target electron) signal arrives at time t1 and the ion (e.g., target ion) signal arrives at time t2, as long as |t2-t1|≤Δt, it can be determined as a coincidence event, indicating that this is a pair of coincident electron-ion pairs (target electron-target ion pair), that is, from the same photoionization event. The width of the coincidence window is pre-set based on factors such as experimental requirements and system performance.

[0061] (7) Door control system In the present application, the gating system is located between the acceleration extraction system and the ion detection system, and the gating system includes a pair of metal plates, which are parallel to the flight path and symmetrically arranged on both sides of the flight path.

[0062] The gating system is used to provide a channel for ions to fly along a flight path to the ion detection system when the ions meet the preset flight time conditions, so that the ions reach the ion detection system; and to make the ions deviate from the flight path when the ions do not meet the preset flight time conditions, so that the ions cannot reach the ion detection system.

[0063] In the present application, when the gating system detects the electronic trigger signal, it determines that the ion meets the preset flight time condition, and the delay time of the electronic trigger signal (i.e. Figure 1 In ) and width (i.e. Figure 1 In , also known as gate time, refers to the length of time the gate system is in the open state) is determined according to the electronic trigger signal. For example, the gate system detects the electronic trigger signal at time t1, then the gate system waits for t1 based on the time. Turn on after a certain time, and keep it on after turning on The duration of the on state allows ions to reach the ion detector.

[0064] In this application, a gating system is used for deterministic single ion preparation, allowing ions with a specific flight time to pass when an electronic trigger signal is detected.

[0065] In the present application, by loading a pulse voltage of appropriate amplitude, when an electronic signal is triggered, the metal plate generates a channel that allows ions to pass through. The ions fly along the channel under the action of the electric field and reach the ion detection system through the gating system. At this time, the gating system is in an open state; when there is no electronic signal trigger, all ions deviate from the flight trajectory, and the ion detection system cannot collect ion signals. At this time, the gating system is in a closed state, thereby ensuring that only single ions that meet the preset flight time conditions can be collected by the detector, thereby realizing the preparation of deterministic single ions.

[0066] In this application, the purpose of obtaining flight time information is mainly to collect the initial state information of electrons and ions and analyze their motion characteristics. The function of the gating system is to control the flight trajectory of subsequent ions to ensure that only ions that meet specific conditions (preset flight time conditions) can reach the ion detection system. In other words, the gating system dynamically screens and controls the ions during their subsequent flight based on the results of previous measurements and analyses, such as reasonably setting the delay time and width of the trigger signal, thereby achieving deterministic single ion preparation.

[0067] Specifically, refer to Figure 1 After the electron reaches the electron detector, the signal representing the electron's flight time information will be collected by the coincidence measurement system. After the coincidence measurement system processes the electron's flight time information, it obtains an electronic trigger signal and sends the electronic trigger signal to the gating system. The gating system obtains the delay time according to the electronic trigger signal and gate time , based on the moment of receiving the electronic trigger signal, the delay Turn on after a certain period of time, and keep it after turning on The gated system is turned on for a certain period of time, so that ions can only reach the ion detector during the period of time when the gated system is turned on, thereby screening the ions. After the ions reach the ion detector, the signal representing the flight time information of the ions can be collected by the coincidence measurement system. At this time, the coincidence measurement system can conduct a comprehensive analysis of the flight time information of the electrons and the ions, thereby , Gate time , Δt, etc., so that in the subsequent process, the optimized delay time is used. , Gate time , Δt, etc. can more accurately obtain the ions corresponding to the electrons. In other words, the flight time information of the ions collected this time is used to calculate the delay time. , Gate time , Δt and other parameters are optimized to improve the control accuracy of subsequent ions. Even if the flight time information of the ions is not collected, the gating system will screen the ions according to the existing control strategy. Figure 1 The dotted line connects the coincidence measurement system and the ion detector, while the solid line connects the coincidence measurement system and the electron detector, indicating that the coincidence measurement system needs to collect the flight time information of the electrons in real time.

[0068] exist Figure 1 In the field of digital logic, TTL is a digital logic level standard used to transmit control signals and status information in the circuit. Its level state (high level or low level) represents different logic instructions. The high-voltage pulse switch is used to control the on and off of the high-voltage pulse according to the received control signal (such as TTL signal). When a specific TTL signal is received, the high-voltage pulse switch will turn on or off, thereby controlling the voltage state of the subsequent circuit. -HV (negative high voltage) is used to provide a negative high voltage, which is used in conjunction with the high-voltage pulse switch to generate an electric field during the ion extraction and control process to achieve operations such as acceleration and deflection of ions.

[0069] The deterministic ultracold single ion preparation device in this application can achieve deterministic control of each ion in the ion beam. The determinism here is at least reflected in: (1) The determinism of ion-electron pairing: Through the coincidence measurement technology, the pairing relationship between each electron and the corresponding ion can be clearly determined, that is, each detected electron can accurately correspond to the ion it produces. (2) The determinism of ion trajectory control: Based on the results of the coincidence measurement, the delay time of the gate trigger signal is reasonably set. and width , triggering hardware gating to control the trajectory of ions during flight, so that the movement path of ions during flight can be precisely controlled, and only ions that meet specific conditions can fly along the expected trajectory and reach the ion detection system. (3) Deterministic single ion preparation: Through a series of signal processing (amplification, screening, compliance measurement, etc.), only single ions that meet specific conditions will be counted and used, realizing deterministic single ion preparation, ensuring that each single ion prepared meets specific requirements rather than being randomly generated.

[0070] Next, we take the rubidium atom in the alkali metal atom system as an example. Taking this as an example, the process of preparing a single ion by the deterministic ultracold single ion preparation device of the present application is described in detail: Step 1: Place the rubidium bulb in the metal valve, wrap the metal valve with a heating tape, and heat it to about 45°C. The atomic elements evaporate to form a diffuse hot neutral atomic gas.

[0071] Step 2: The ECDL semiconductor laser outputs a 780nm continuous light, which is split by the optical fiber to form a "three-beam six-path" cooling light path, forming a laser field, and cooperating with a pair of anti-Helmholtz coils to generate a gradient magnetic field (10G / cm in the longitudinal direction and 5G / cm in the transverse direction) to construct a classic atomic three-dimensional cooling and trapping device - a magneto-optical trap. Achieve cyclic cooling, trapping atoms in the trap The diameter and temperature of the cold atom cluster are 1.4 mm and 500 μK respectively. represents the electronic state of the atom, F represents the total angular momentum quantum number of the atom in the initial state, and F=2 represents the total angular momentum quantum number of the atom in the initial state is 2. represents the electronic state after the transition, F' represents the total angular momentum quantum number of the atom in the electronic state after the transition, and F'=3 represents the total angular momentum quantum number of the atom in the electronic state after the transition is 3. In the figure, 5 indicates that the principal quantum number of the electron in the atom is 5, the 2 in the upper right corner of 5 is the multiplicity in spectroscopy, indicating that the electron spin has two possible orientations, S is the spectroscopy symbol, indicating the value of the orbital angular quantum number L of the electron in the atom, S corresponds to L = 0, indicating that the electron cloud is spherically symmetrically distributed, and 1 / 2 indicates that the total angular momentum quantum number of the electron in the atom is 1 / 2. In the figure, 5 indicates that the principal quantum number of the electron in the atom is 5. The 2 in the upper right corner of 5 is the multiplicity in spectroscopy, indicating that the electron's spin has two possible orientations. P is the spectroscopy symbol, corresponding to the orbital angular quantum number L = 1, indicating that the electron cloud is dumbbell-shaped. 3 / 2 indicates that the total angular momentum quantum number of the electron in the atom is 3 / 2.

[0072] Step 3: The ECDL semiconductor laser outputs continuous light with a wavelength of 423nm, which acts on the cold atom group after passing through the focal lens (f=75cm) to generate electron-ion pairs. The generated electrons can be one electron or multiple electrons. If there are multiple electrons, when the electron detector receives any one of them, the gating system can be controlled by the coincidence measurement system (sending an electronic trigger signal) to make the gating system screen the ions corresponding to the electron, thereby obtaining the single ion corresponding to the electron.

[0073] Step 4: The acceleration extraction system consists of 20 electrode plates, which are placed symmetrically along the ionization zone. Through detailed electromagnetic field simulation calculations, the electrode plates are loaded with appropriate voltages to form an electric field. Under the action of the electric field, electrons and ions are accelerated to fly to their corresponding two-dimensional position-sensitive detectors. The two-dimensional position-sensitive detectors simultaneously output the flight time spectra and spatial distribution information of the electrons and ions.

[0074] Step 5: The coincidence measurement system obtains the flight time spectrum output by the detection system, amplifies the signal through the signal amplifier element, discriminates the amplified signal through the signal discrimination element, performs coincidence measurement on the discriminated signal through the signal delay broadening element, and counts the counts of electrons and ions respectively through the signal counter element. For example: when the ionization laser intensity is 0.36mW, the electron count rate is 3500 / s and the ion count rate is 40000 / s.

[0075] Step 6: Introduce the gating system. When the electronic signal is triggered, the gating system works and outputs high-voltage pulses, allowing ions with a specific flight time (i.e., meeting the preset flight time conditions) to pass through, thereby predicting the generation of related ions.

[0076] The specific values ​​of the parameters in the above steps 1 to 6 are for illustration only. In actual implementation, the values ​​of the parameters can be set according to actual needs.

[0077] The deterministic ultracold single ion preparation device of the present application is applicable to all cold atomic systems, not limited to the research of ultracold Rb single ions. For those skilled in the art, some improvements and modifications are made to the present application according to the different target atomic systems selected in the experiment, the different wavelengths of the ionization laser used, and the replacement of the microchannel plate detector (MCP) with a channel electron multiplier (CEM), and these improvements and modifications are also considered to be within the scope of protection of the present application. It should be particularly pointed out that for those skilled in the art, if a cold atomic system is not used, a single ion source prepared by using techniques such as light excitation and photoionization processes and electron beam collision with target atoms is also within the scope of protection of the present application.

[0078] In the present application, after electrons and ions are generated, they will fly to their respective corresponding detectors under the action of the acceleration extraction system. Since the mass of electrons is much smaller than that of ions, electrons will reach the electron detector before ions. Although it is impossible to accurately know in which time period the ions will reach the ion detector at the beginning, it is certain that ions can only reach the ion detector within a future period of time after the electrons reach the detector. This is an inevitable objective fact. The present application refers to the time relationship between the arrival of electrons and ions at the detector as the time correlation between electrons and corresponding ions. In this way, after detecting that an electron has arrived at the electron detector, a future time period can be assumed. This future time period is also the time period when the ion arrives at the ion detector (in fact, the future time period minus the time it takes for the ion to reach the ion detector from the gated system can obtain the time period when the ion arrives at the gated system. The delay time mentioned above can be determined based on the time period when the ion arrives at the gated system). , Gate time ), the present application controls the gating system so that only ions that can reach the ion detector within this future time period can be received by the ion detector, otherwise the trajectory will be deviated and cannot be received by the ion detector. If the ion detector does not receive any ions within this future time period, then the range of the time period is readjusted until the ion detector can receive ions. After the ion detector can receive the ions, it is determined whether the electron and the ion come from the same photoionization event based on whether the difference between the arrival time t1 of the electron and the arrival time t2 of the ion is less than Δt. If so, the ion and the electron correspond to each other and come from the same atom. The initial Δt may be an undesirable estimate, but by repeating the above-mentioned operation countless times, a relatively ideal Δt can be obtained. Therefore, the present application can obtain an ideal time period and Δt by repeatedly performing the above-mentioned operation (adjusting the time period and Δt). Finally, based on the ideal time period and Δt, the present application can know which ion corresponds to which electron. Among them, the preset flight time condition is determined based on the ideal time period.

[0079] In summary, the working principle of the deterministic ultracold single ion preparation device of the present application is: based on the electron-coincidence measurement technology, utilizing the time correlation between electrons and corresponding ions after photoionization of atoms, utilizing electronic information to predict the time information of the corresponding ions arriving at the ion detection system, obtaining the preset flight time conditions based on the time information, and regulating the trajectory of the ions during the flight according to the preset flight time conditions, thereby realizing deterministic single ion manipulation. Specifically, the steps of preparing deterministic ultracold single ions in the present application include: using a magneto-optical trap system to cool trapped neutral hot atomic gas to form a cold atomic cluster with a certain density; introducing a continuous wavelength laser to photoionize the cold atomic cluster after focusing to generate electron-ion pairs; using an acceleration extraction system to accelerate and extract the prepared electrons and ions respectively; using a two-dimensional position-sensitive detector to collect and record the flight time spectra and spatial distribution information of electrons and ions respectively; using a signal amplification element to amplify the flight time spectra of electrons and ions output by the detection system respectively; adjusting and setting the threshold of the signal discrimination element to perform discrimination processing on the amplified signal; using a delay broadening element to perform coincidence measurement on the discriminated signal; using a counter element to record and monitor the electronic trigger signal count and the single ion count after gated screening respectively; reasonably setting the delay time and width of the gated trigger signal to trigger hardware gating to achieve the preparation of deterministic single ions. The scheme of this application is applicable to a variety of atomic samples, has a rich variety of selectable ions, and has the advantages of simple device structure and high controllability. It can achieve deterministic control of each ion in the ion beam, laying the foundation for the development of new nano-ion beam technology, and will further have an important impact on the development of quantum information science and nanomaterials science. Compared with existing ion source technology, the scheme of this application has at least the following advantages: (1) Using a continuous wavelength laser to ionize cold atomic clusters can produce a high-current single ion source, effectively solving the low-current problem of ultracold single ion sources based on ion traps. Current refers to the number of ions passing through a certain cross section per unit time, that is, the ion number density. In the related art, the ion trap loading rate is slow and is constrained by the Coulomb interaction between ions in the trap, so there is a problem of low current. A continuous wavelength laser refers to a laser that can continuously output with a fixed wavelength and can continuously and stably output energy. Secondly, a continuous wavelength laser has the function of precise control and adjustment of frequency. By precisely tuning the laser frequency to a state that matches the specific energy level transition of the cold atom, it can achieve resonant excitation and ionization of the atom, thereby maximizing the use of laser energy to promote atomic ionization, reducing energy waste, and increasing the number of ions produced. Therefore, the present application uses a laser generated by a continuous wavelength laser to ionize cold atomic clusters, which can solve the problem of low current.

[0080] (2) By utilizing coincidence measurement technology and introducing a gating system, the number of ions in the ion beam can be precisely controlled, effectively solving the problem of uncertainty in the number of ions during the extraction process of traditional ion sources and cold atomic ion sources.

[0081] (3) The perfect combination of cold atom technology and coincidence measurement technology has greatly expanded the application scope of cold atoms and provided a new research plan for the development of nano-ion beam technology.

[0082] The present application also provides a deterministic ultracold single ion preparation method, which is applied to a deterministic ultracold single ion preparation device provided in the present application, and the deterministic ultracold single ion preparation method comprises: The neutral hot atomic gas is cooled and trapped by the magneto-optical trap system to obtain cold atomic groups; The cold atomic group is ionized by the ionization laser system using laser light emitted by a continuous wavelength laser to obtain a plurality of electrons and ions corresponding to each of the electrons, wherein each of the ions is an ultracold single ion; The electrons and the ions are collected by the detection system, and flight time information of the electrons and the ions based on their respective flight paths is obtained, wherein the starting point of the flight path is the magneto-optical trap system and the end point is the detection system; Guiding the electrons and the ions to accelerate toward the detection system through the acceleration extraction system; Providing a vacuum environment for the flight of the electrons and the ions through the vacuum system; The ions are screened by the gating system so that the ions meeting the preset flight time conditions can reach the detection system; Through the coincidence measurement system, according to the flight time information, when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within a preset time window, it is determined that the target ion is the ion corresponding to the target electron, the target electron is one of the multiple electrons, and the target ion is one of the multiple ions.

[0083] Regarding the description of the method part, please refer to the previous description of the deterministic ultracold single ion preparation device, and this application will not go into details here.

[0084] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A deterministic ultracold single ion preparation device, characterized in that: include: Magneto-optical trap system, used to cool and trap neutral hot atomic gas to obtain cold atomic groups; An ionization laser system, used for ionizing the cold atomic group by laser light emitted by a continuous wavelength laser, to obtain a plurality of electrons and ions corresponding to each of the electrons, wherein each of the ions is an ultracold single ion; A detection system, used for collecting the electrons and the ions, and obtaining flight time information of the electrons and the ions based on their respective flight paths, wherein the starting point of the flight path is the magneto-optical trap system and the end point is the detection system; An acceleration extraction system, used for guiding the electrons and the ions to accelerate and fly toward the detection system; A vacuum system, used for providing a vacuum environment for the flight of the cold atoms, the electrons and the ions; A gating system, used for screening the ions so that the ions meeting the preset flight time conditions can reach the detection system; A coincidence measurement system is used to determine, based on the flight time information, that the target ion is the ion corresponding to the target electron, the target electron is one of the multiple electrons, and the target ion is one of the multiple ions when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within a preset time window.

2. The deterministic ultracold single ion preparation device according to claim 1, characterized in that: The compliance measurement system comprises: a signal amplifying element, used to amplify the signal representing the time-of-flight information output by the detection system; A signal discrimination element is used to filter out invalid signals from the amplified signal; A signal delay and stretching element, used for performing coincidence measurement on the flight time information corresponding to the signal output by the signal discrimination element, and determining that the target ion is the ion corresponding to the target electron when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within the preset time window; The signal counter element is used to record the number of electrons collected by the detection system and the number of ions screened by the gating system.

3. The deterministic ultracold single ion preparation device according to claim 1, characterized in that: The vacuum system comprises a vacuum chamber, the flight path is located in the vacuum chamber, the magneto-optical trap system comprises a first laser emitting device and a pair of anti-Helmholtz coils, and the anti-Helmholtz coils are symmetrically arranged outside the vacuum chamber; The magneto-optical trap system is used to obtain three pairs of counter-propagating and mutually orthogonal laser beams based on the first laser emitted by the first laser emitting device, construct a magneto-optical trap based on the laser field formed by the laser beam and the gradient magnetic field generated by the anti-Helmholtz coil, and cool and trap the neutral hot atomic gas through the magneto-optical trap to obtain the cold atomic cluster.

4. The deterministic ultracold single ion preparation device according to claim 3, characterized in that: The ionization laser system includes a second laser emitting device. The ionization laser system ionizes the cold atomic group by a second laser emitted by a continuous wavelength laser in the second laser emitting device to obtain a plurality of electrons and ions corresponding to each of the electrons. The wavelength of the second laser is different from that of the first laser.

5. The deterministic ultracold single ion preparation device according to claim 4, characterized in that: The first laser is also used to make atoms transition from a ground state to an excited state, and the second laser is used to ionize cold atomic groups in the excited state to obtain a plurality of electrons and ions corresponding to each of the electrons.

6. The deterministic ultracold single ion preparation device according to claim 1, characterized in that: The detection system comprises an electron detection system and an ion detection system. The electron detection system is used to collect the flight time information of each of the electrons, and the ion detection system is used to collect the flight time information of each of the ions.

7. The deterministic ultracold single ion preparation device according to claim 6, characterized in that: The gating system is located between the acceleration extraction system and the ion detection system, and the gating system includes a pair of metal plates, which are parallel to the flight path and symmetrically arranged on both sides of the flight path; The gating system is used to provide a channel for the ions to fly along the flight path to the ion detection system when the ions meet the preset flight time condition, so that the ions reach the ion detection system; and to make the ions deviate from the flight path when the ions do not meet the preset flight time condition, so that the ions cannot reach the ion detection system.

8. The deterministic ultracold single ion preparation device according to claim 7, characterized in that: The gating system determines that the ions meet the preset flight time condition when the electronic trigger signal is detected, and the delay time and width of the electronic trigger signal are determined according to the historical flight time information obtained by the coincidence measurement system.

9. The deterministic ultracold single ion preparation device according to claim 1, characterized in that: The detection system is a two-dimensional position sensitive detector.

10. A method for preparing a deterministic ultracold single ion, characterized in that: Applied to the deterministic ultracold single ion preparation device according to any one of claims 1 to 9, the deterministic ultracold single ion preparation method comprises: The neutral hot atomic gas is cooled and trapped by the magneto-optical trap system to obtain cold atomic groups; The cold atomic group is ionized by the ionization laser system using laser light emitted by a continuous wavelength laser to obtain a plurality of electrons and ions corresponding to each of the electrons, wherein each of the ions is an ultracold single ion; The electrons and the ions are collected by the detection system, and flight time information of the electrons and the ions based on their respective flight paths is obtained, wherein the starting point of the flight path is the magneto-optical trap system and the end point is the detection system; Guiding the electrons and the ions to accelerate toward the detection system through the acceleration extraction system; Providing a vacuum environment for the flight of the cold atoms, the electrons and the ions through the vacuum system; The ions are screened by the gating system so that the ions meeting the preset flight time conditions can reach the detection system; Through the coincidence measurement system, according to the flight time information, when the difference between the times when the target electron and the target ion respectively arrive at the detection system is within a preset time window, it is determined that the target ion is the ion corresponding to the target electron, the target electron is one of the multiple electrons, and the target ion is one of the multiple ions.

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