CN106683976A - Single photon source based on single trapped ion - Google Patents

Abstract

The invention discloses a single photon source based on a single trapped ion, including a vacuum chamber, an ion trap chip and a calcium atom furnace. The ion trap chip includes a silicon arsenic substrate, a first silicon dioxide layer and a second silicon dioxide layer. The arsenic-silicon substrate is provided with a substrate through hole, and the opposite side walls of the substrate through hole are respectively provided with optical fiber fixing grooves, and two multimode optical fibers with a common optical axis are respectively arranged in the two optical fiber fixing grooves. The opposite end face of the optical fiber is a concave surface, the surface of the concave surface is provided with a dielectric film, the focal points of the concave surfaces of the two multimode optical fibers coincide, and an optical microcavity is formed between the concave surfaces of the two multimode optical fibers. The present invention realizes the Doppler limit of a single ion. cool down. Single photon sources have high production efficiencies. Easy to connect with existing optical communication system. Make the prepared single photon linewidth reach the natural linewidth of ion energy level transition.

Description

Single-photon sources based on single trapped ions

technical field

The invention relates to the technical field of quantum information processing, in particular to a single-photon source based on a single trapped ion, which can generate a single-photon output device, which improves the single-photon output efficiency, narrows the single-photon linewidth, and improves the transmission of quantum communication distance, and improve the security of quantum communication.

Background technique

Quantum properties have unique functions in the field of information, which may break through the limits of existing classical information systems in terms of increasing computing speed, ensuring information security, increasing information capacity, and improving detection accuracy, so a new branch of discipline was born - Quantum information science. It is the product of the combination of quantum mechanics and information science, including: quantum cryptography, quantum communication, quantum computing and quantum measurement. world's high attention. People are increasingly convinced that quantum information science has created new principles and methods for the development of information science, and will exert great potential in the 21st century, and quantum cryptography is one of the most important application fields in quantum information science. Since the security of quantum cryptography is guaranteed by the principle of quantum mechanics, the measurable and unclonable properties ensure that quantum cryptography will not be eavesdropped without leaving traces, so it is very safe.

A single photon source refers to a light source that emits only one photon at a time, and is an ideal light source for quantum cryptography, quantum communication, and quantum computing. How to find an ideal and stable single photon source is an urgent problem for the current research of quantum cryptography, quantum communication and quantum computing. At present, the widely used single-photon light source is to attenuate the coherent light pulse to an average of only 0.1 photons per pulse. Due to the Poisson distribution characteristics of photons, in the single-photon source realized through such an attenuation path, there are 2 photons in a single pulse. The probability of is still not negligible, so this is an approximate single-photon source, and its efficiency is low, which not only affects the transmission distance of the quantum key, but also affects its security. Therefore, developing a real single-photon source has become a key issue in the research of quantum cryptography.

An effective way to improve the data rate and signal-to-noise ratio of quantum communication is to use a root single photon source, which not only increases the repetition rate of the entire system but also increases the probability that each trigger pulse contains a single photon. The ways are usually as follows:

1. Using quantum dots, although single photons generated by quantum dots have been used to demonstrate quantum key distribution experiments and generate polarization-entangled photon pairs, but because this technology requires a temperature below 10K, and the wavelength of the entangled photons generated In addition, it is difficult to efficiently couple such photons to single-mode fibers.

2. Utilize quantum-correlated photon pairs in the parametric down-conversion process based on the second-order nonlinear effect of crystals. Relatively speaking, this method is relatively simple in technology. The key index to describe this single photon source is the announced efficiency H, whose physical meaning is the probability that a twin photon appears in the idle light band when a photon appears in the signal light band. However, there are technical difficulties in efficiently coupling such photons into single-mode fibers due to mode matching. At present, the announced efficiency of this single photon source is relatively low, especially when the bandwidth is less than 1nm, and the current value of H is less than 0.5.

3. Using single atoms or molecules trapped in high-precision cavities, this technology can in principle produce single photons that are very close to the ideal state.

Contents of the invention

The purpose of the present invention is to solve the above problems in the prior art, provide a single photon source based on a single trapped ion, and meet the needs of quantum communication and quantum computing. The single-photon output is generated by using the fluorescence emitted by a single trapped ion. The linewidth of the single-photon source is very narrow, and the output single-photon can be guaranteed to be an ideal single-photon. It can increase the transmission distance of quantum communication and improve the security of communication. At the same time, it can increase the fidelity and coherence time of quantum states in quantum computing.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

The single photon source based on a single trapped ion includes a vacuum chamber, an ion trap chip and a calcium atom furnace arranged in the vacuum chamber. The silicon dioxide layer and the second silicon dioxide layer are provided with substrate through holes on the silicon arsenic substrate, and optical fiber fixing grooves are respectively arranged on the opposite side walls of the substrate through holes, and the two optical fiber fixing grooves are respectively There are two multimode fibers, the opposite ends of the two multimode fibers have a common optical axis, the opposite end faces of the two multimode fibers are concave surfaces, the focal points of the concave surfaces of the two multimode fibers coincide, and the concave surfaces of the two multimode fibers An optical microcavity is formed between them, and the focus of the optical microcavity coincides with the focus of the concave surfaces of the two multimode optical fibers.

The part of the first silicon dioxide layer located in the substrate through hole is provided with a first silicon dioxide layer through hole, and the part of the second silicon dioxide layer located in the substrate through hole is provided with a second silicon dioxide layer through hole,

The first silicon dioxide layer and the second silicon dioxide layer are provided with a direct current electrode for forming a direct current control electric field in the optical microcavity, a radio frequency electrode for forming a radio frequency trapping electric field in the optical microcavity, and a A micro-motion compensation electrode that controls the compensation electric field with direct current is formed in the cavity.

There are 10 micro-motion compensation electrodes and DC electrodes as mentioned above, 2 radio-frequency electrodes, 5 DC electrodes are arranged on one side of the through hole in the first silicon dioxide layer, 5 micro-motion compensation electrodes and 1 radio frequency electrode The electrodes are set on the other side of the through hole in the first silicon dioxide layer, the other 5 DC electrodes are set on one side of the second silicon dioxide layer through hole, and the other 5 micro-motion compensation electrodes and another radio frequency electrode are set on the On the other side of the through hole in the second silicon dioxide layer, the 5 DC electrodes on one side of the through hole in the first silicon dioxide layer and the 5 DC electrodes on one side of the through hole in the second silicon dioxide layer are respectively located in the optical micrometer. sides of the cavity.

The cross-sections of the through-holes in the first silicon dioxide layer and the through-holes in the second silicon dioxide layer as described above are smaller than the cross-sections of the through-holes in the substrate.

The above-mentioned ion trap chip is fixed in the chip placement hole on the filter circuit board, the filter circuit board is fixed on the chip support frame, the calcium atom furnace is fixed on the chip support frame, the chip support frame is fixed on the DC feedthrough, and the filter circuit board is fixed on the chip support frame. The circuit board is provided with a first-order passive RC filter circuit and RF wires. Both the DC electrode and the micro-motion compensation electrode are connected to the DC feedthrough through the first-order passive RC filter circuit. The RF electrode is connected to the RF feedthrough through the RF wire. Two The multimode optical fibers are respectively connected with the optical fiber feedthroughs.

The first CF35 interface to the eighth CF35 interface are evenly arranged on the vacuum chamber as described above along the same distribution circle, the first CF100 interface and the second CF100 interface are also arranged on the vacuum chamber, and the first CF35 interface is provided with a photoelectric interface for incident photoelectricity. The optical window from the laser and the cooling laser to the focal point of the optical microcavity, the third CF35 interface is provided with an optical window for incident single photon generation laser to the focal point of the optical microcavity, the fifth CF35 interface and the seventh CF35 interface Install optical windows respectively, install fiber feedthrough on the fourth CF35 interface and the eighth CF35 interface, install radio frequency feedthrough on the second CF35 interface, and connect the sixth CF35 interface with the ion pump and sublimation pump respectively through 4-way vacuum connectors Connect with vacuum angle valve.

Compared with the prior art, the present invention has the following beneficial effects:

1. The single ion trapping system of the present invention utilizes standard semiconductor micromachining technology to realize the processing of ion traps and the manufacture of optical microcavities. The ion traps have a pair of radio frequency electrodes, five pairs of DC control electrodes and five pairs of micro-motion compensation electrodes. The coupling between the ion and the optical microcavity can be precisely controlled in one-dimensional direction, and the precise micro-motion compensation in three-dimensional direction can realize the Doppler limit cooling of a single ion.

2. When the single ion trapping system of the present invention outputs single photons, the single ion is cooled to the Doppler limit through 397nm and 866nm cooling lasers, the 397nm laser is turned off, and the 732nm laser is turned on to realize the transition from 4S _1/2 state to 4P _{1/ 2} -state continuous pumping, so as to continuously output 397nm single photons, which are coupled to the optical fiber output under the action of optical microcavity and single ions; when working with a single light source, the wavelength of pump light (732nm and 866nm) and the wavelength of signal light (397nm) The difference is that the single photon impurity problem caused by the same frequency of the pump light and the signal light is avoided, and the continuous pumping and optical microcavity coupling output are realized at the same time, and the single photon source has a high production efficiency.

3. The single-photon output of the single-photon source based on a single trapped ion in the present invention is coupled and output by using a multimode optical fiber, which is convenient for connection with an existing optical communication system.

4. The present invention is based on the single photon source of a single trapped ion. When the single photon is output, the trapped single ion is cooled to the Doppler limit, which eliminates the effect of the single photon frequency broadening caused by the thermal motion of the ion, so that the prepared single photon The line width reaches the natural line width of ion energy level transition, which is an ideal single photon source for long-distance quantum communication.

Description of drawings

Fig. 1 is a schematic cross-sectional structure diagram of a vacuum chamber of the present invention.

Fig. 2 is a schematic diagram of the overall structure of the present invention.

Fig. 3a is a schematic diagram of the installation structure of the filter circuit board of the present invention.

Fig. 3b is a schematic plan view of the ion trap chip of the present invention.

Fig. 3c is a schematic diagram of the installation structure of the ion trap chip of the present invention.

Fig. 3d is a schematic structural view of the fiber fixing groove of the present invention.

Fig. 3e is an enlarged schematic view of part A in Fig. 3d.

Fig. 4 is a schematic diagram of the three-dimensional structure of the ion trap chip of the present invention.

Fig. 5 is a schematic diagram of the calcium ion energy level structure of the present invention.

Fig. 6 is a schematic diagram of the principle of the present invention.

In the figure: 1-photoionization laser and cooling laser; 2-RF feedthrough; 3-multimode fiber; 4-single photon generation laser; 5-optical window; 6-fiber feedthrough; 7-vacuum pipe connector; 8-vacuum chamber; 9-ion trap chip; 10-sublimation pump; 11-ion pump; 12-DC feedthrough; 13-chip support frame; 14-calcium atom furnace; 15-filter circuit board; 16-filter capacitor; 17-filter resistor; 18-DC electrode; 19-RF electrode; 20-fiber fixing slot; 21-optical microcavity; 22-calcium ion; 23-vacuum angle valve; 24-4-way vacuum connector; Compensation electrode; 26-through hole in the first silicon dioxide layer; 27-through hole in the substrate; 28-through hole in the second silicon dioxide layer; 29-chip placement hole; 30-arsenic silicon substrate; 31-first Silicon dioxide layer; 32 - second silicon dioxide layer.

detailed description

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

The single photon source based on a single trapped ion includes a vacuum chamber 8, and also includes an ion trap chip 9 and a calcium atom furnace 14 arranged in the vacuum chamber 8. The first silicon dioxide layer 31 and the second silicon dioxide layer 32 on both sides of the silicon substrate 30 are provided with a substrate through hole 27 on the silicon substrate 30, and on two opposite side walls of the substrate through hole 27 Optical fiber fixing grooves 20 are arranged respectively, and two multimode optical fibers 3 are respectively arranged in the two optical fiber fixing grooves 20. The opposite ends of the two multimode optical fibers 3 have a common optical axis, and the opposite end faces of the two multimode optical fibers 3 are concave surfaces. , the surface of the concave surface is provided with a dielectric film, the focal points of the concave surfaces of the two multimode optical fibers coincide, an optical microcavity 21 is formed between the concave surfaces of the two multimode optical fibers, and the focal point of the optical microcavity 21 is the focal point of the concave surfaces of the two multimode optical fibers coincide,

The part of the first silicon dioxide layer 31 located at the substrate through hole 27 is provided with a first silicon dioxide layer through hole 26, and the part of the second silicon dioxide layer 32 located at the substrate through hole 27 is provided with a second silicon dioxide layer. TSV 28,

The first silicon dioxide layer 31 and the second silicon dioxide layer 32 are provided with a DC electrode 18 for forming a DC control electric field in the optical microcavity 21, and a radio frequency electrode 19 for forming a radio frequency trapped electric field in the optical microcavity 21. And a micro-motion compensation electrode 25 for forming a DC control compensation electric field in the optical microcavity 21 .

The vacuum chamber 8 is evenly provided with the first CF35 interface to the eighth CF35 interface along the same distribution circle, the vacuum chamber 8 is also provided with the first CF100 interface and the second CF100 interface, and the first CF35 interface is provided with the incident photoionization laser. And cooling laser to the optical window 5 of the focus of the optical microcavity 21, the third CF35 interface is provided with the optical window 5 for incident single photon generation laser to the focal point of the optical microcavity 21, the fifth CF35 interface and the seventh CF35 A light-through window 5 is respectively installed on the interface, an optical fiber feedthrough 6 is installed on the fourth CF35 interface and the eighth CF35 interface, a radio frequency feedthrough 2 is installed on the second CF35 interface, and the sixth CF35 interface passes through a 4-way vacuum connector 24 respectively It is connected with ion pump 11, sublimation pump 10 and vacuum angle valve 23.

As a preferred solution, as shown in FIG. 2 , the vacuum degree in the vacuum chamber 8 is maintained at about 1.0×10 ⁻⁸ Pa through an ion pump 11 and a sublimation pump 10 . The vacuum chamber 8 has a decahedral structure. Eight CF35 interfaces are arranged at the center of the eight surfaces evenly distributed along the same distribution circle on the vacuum chamber 8. The first CF35 interface and the second CF35 interface are set in sequence along the distribution circle direction. , the third CF35 interface, the fourth CF35 interface, the fifth CF35 interface, the sixth CF35 interface, the seventh CF35 interface and the eighth CF35 interface (in Figure 2, the top is the first CF35 interface, clockwise along the distribution circle The first to eighth CF35 in sequence), the center of the distribution circle is at the same point as the center of the vacuum chamber 8, and the line connecting the center point of the first CF35 interface and the center point of the fifth CF35 interface passes through the center of the distribution circle and is located in the vertical direction, The first CF35 interface is located at the top, the fifth CF35 interface is located at the bottom, the connecting line between the center point of the third CF35 interface and the center point of the seventh CF35 interface passes through the center of the distribution circle and is perpendicular to the center point of the first CF35 interface and the center of the fifth CF35 interface The line connecting the points, the line connecting the center point of the second CF35 interface and the center point of the sixth CF35 interface passes through the center of the distribution circle and forms an angle of 45 degrees with the line connecting the center point of the first CF35 interface and the center point of the fifth CF35 interface. The connection line of the four CF35 interface center points and the eighth CF35 interface center point passes through the center of the distribution circle and forms an angle of 45 degrees with the connection line between the first CF35 interface center point and the fifth CF35 interface center point, and the other two surfaces of the vacuum chamber 8 A first CF100 interface and a second CF100 interface are respectively provided, and the connection line between the first CF100 interface and the second CF100 interface is perpendicular to the distribution circle. The first CF100 interface is installed with a 25-core DC feedthrough 12, and the second CF100 interface is installed with a detection window for detecting the fluorescence emitted by the trapped ions.

On the first CF35 interface and the fifth CF35 interface, the third CF35 interface and the seventh CF35 interface, the light-through window 5 for the laser light is respectively installed, and the light-through window 5 installed on the first CF35 interface is used for photoelectricity From the input of the laser and the cooling laser 1, the optical window 5 on the third CF35 interface is used for the input of the single photon generation laser, and the fiber feedthrough 6 is installed on the fourth CF35 interface and the eighth CF35 interface for optical For the single photon output coupled by the microcavity 21, a radio frequency feedthrough 2 is installed on the second CF35 interface for connecting the radio frequency electrode 19 of the ion trap chip 9, and the sixth CF35 interface is connected to the 4-way vacuum connector 24.

The ion trap chip 9 is fixed in the chip placement hole 29 on the filter circuit board 15, the filter circuit board 15 is fixed on the chip support frame 13, the calcium atom furnace 14 is fixed on the chip support frame 13, and the chip support frame 13 is fixed on the DC feeder. On the pass 12, a first-order passive RC filter circuit and a radio frequency wire are arranged on the filter circuit board 15, and the DC electrode 18 and the micro-motion compensation electrode 25 are connected to the DC feedthrough 12 through the first-order passive RC filter circuit, and the radio frequency electrode 19 passes through The radio frequency wire is connected to the radio frequency feedthrough 2, and the two multimode optical fibers are respectively connected to the optical fiber feedthrough 6.

As a preferred solution, as shown in Figure 3a, the ion trap chip 9 is fixed in the chip placement hole 29 on the filter circuit board 15 by vacuum glue, and the filter circuit board 15 passes through the small holes of 3 mm in diameter on the four corners , using M3 stainless steel screws to connect with the chip support frame 13, the chip support frame 13 is fixed on the DC feedthrough 12, and the chip support frame 13 is fixed with a calcium atom furnace 14.

As a preferred solution, as shown in Figure 3b, the filter circuit board 15 is provided with a first-order passive RC filter circuit, the first-order passive RC filter circuit includes a filter capacitor 16 and a filter resistor 17, the capacitance of the filter capacitor 16 The value is 820pF, the resistance value of the filter resistor 17 is 240Ω, and the corner frequency of the first-order passive RC filter circuit is 810KHz. The size of the filter circuit board 15 is 60mm×50mm×1.6mm, and there is a chip placement hole 29 for placing the ion trap chip 9 in the center. The chip placement hole 29 is a stepped through hole, and the size of one end of the chip placement hole 29 is 7mm×9mm ×0.8mm, the size of the other end of the chip placement hole 29 is 5mm×7mm×0.8mm.

As a preferred solution, as shown in Figure 3d, the ion trap chip 9 is stepped, the size of one side of the ion trap chip 9 is 5 mm × 7 mm, the size of the other side of the ion trap chip 9 is 7 mm × 9 mm, and the thickness is 330 μm. The surface-polished silicon arsenic substrate is thermally oxidized to form a first silicon dioxide layer and a second silicon dioxide layer with a thickness of 15 μm on the top surface and the bottom surface of the silicon arsenic substrate. In the ion trapping region, through etching, a substrate through-hole 27 is formed on the silicon-arsenic substrate, a first silicon dioxide layer through-hole 26 is opened on the first silicon dioxide layer, and a first silicon dioxide layer through-hole 26 is opened on the second silicon dioxide layer. A second silicon dioxide layer through hole 28 is opened, and the cross sections of the first silicon dioxide layer through hole 26 and the second silicon dioxide layer through hole 28 are smaller than the cross section of the substrate through hole 27 . The preferred substrate through hole 27 has a length × width × height of 2.84 mm × 640 μm × 330 μm, and the length × width × height of the first silicon dioxide layer through hole 26 and the second silicon dioxide layer through hole 28 is 2.54 mm × 340 μm×15 μm, the central axes of the first silicon dioxide layer through hole 26, the second silicon dioxide layer through hole 28, and the substrate through hole 27 are collinear, and the first silicon dioxide layer through hole 26, the second silicon dioxide layer through hole The length directions of the silicon layer through hole 28 and the substrate through hole 27 are consistent,

There are 10 micro-motion compensation electrodes 25 and DC electrodes 18, 2 radio-frequency electrodes 19, 5 DC electrodes 18 are arranged on one side of the first silicon dioxide layer through hole 26, and 5 micro-motion compensation electrodes 25 and 1 A radio frequency electrode 19 is arranged on the other side of the first silicon dioxide layer through hole 26, and another 5 DC electrodes 18 are arranged on one side of the second silicon dioxide layer through hole 28, and another 5 micro-motion compensation electrodes 25 and Another radio frequency electrode 19 is arranged on the other side of the second silicon dioxide layer through hole 28, and the five DC electrodes 18 on one side of the first silicon dioxide layer through hole 26 and the second silicon dioxide layer through hole 28 The five DC electrodes 18 on one side of the optical microcavity 21 are located on both sides of the optical microcavity 21 respectively.

As a preferred solution, a 5-micron-thick gold layer electrode is formed on the surface of the first silicon dioxide layer and the second silicon dioxide layer by thermal evaporation and electroplating, and these gold layer electrodes include 10 DC electrodes 18 and 2 radio frequency electrodes. The electrodes 19 and 10 micro-motion compensation electrodes 25, the widths of the 10 DC electrodes 18 and the 10 micro-motion compensation electrodes 25 are all 340 μm, and the widths of the two radio frequency electrodes 19 are both 50 μm. There are 5 DC electrodes 18 arranged on one side of the through hole 26 in the first silicon dioxide layer, and 5 micro-motion compensation electrodes 25 and 1 radio frequency electrode 19 are arranged on the other side of the through hole 26 in the first silicon dioxide layer , the other five DC electrodes 18 are on one side of the second silicon dioxide layer through hole 28, and the other five micro-motion compensation electrodes 25 and another radio frequency electrode 19 are on the other side of the second silicon dioxide layer through hole 28 , the above-mentioned 10 DC electrodes 18 are divided into two parts and are respectively located on both sides of the substrate through hole 27, the distance between the RF electrode 19 on the first silicon dioxide layer or the second silicon dioxide layer and the micro-motion compensation electrode 25 is 50 μm. The distance between the DC electrodes 18 on the first silicon dioxide layer or the second silicon dioxide layer is 10 μm, and the distance between the micro-motion compensation electrodes 25 on the first silicon dioxide layer or the second silicon dioxide layer is 10 μm. 10 μm. In addition, fiber fixing grooves 20 with a length of 3.18 mm, a width of 200 μm, and a depth of 900 μm are respectively etched on both sides of the substrate through hole 27 on the arsenic silicon substrate 9, and the length direction of the two fiber fixing grooves 20 is aligned with the substrate through hole. The length direction of 27 is vertical and located on the same straight line, and two multimode optical fibers are respectively placed in the two optical fiber fixing grooves 20 . The ion trap chip 9 is vacuum glued to the chip placement hole 29 in the center of the filter circuit 15, and each DC electrode 18 and each micro-motion compensation electrode 25 of the ion trap chip 9 are respectively connected to the filter circuit through gold wires with a diameter of 25.4 μm. A first-order passive RC filter circuit on the board 15 is connected at one end. The capacitance value of the filter capacitor 16 of the first-order passive RC filter circuit is 820pF, the resistance value of the filter resistor 17 is 240Ω, and its corner frequency is 810KHz. The other end of the first-order passive RC filter circuit is connected to a DC feedthrough 12 through a vacuum wire, and the DC feedthrough 12 is connected to a DC voltage source. Each RF electrode 19 of the ion trap chip 9 is connected to one end of the RF wire on the filter circuit board 15 through a gold wire with a diameter of 25.4 μm, and then the other end of the RF wire is connected to the RF feedthrough 13 through a vacuum wire, and the RF feedthrough Connect to 13 and then connect to the RF source.

The core diameters of the two multimode optical fibers 3 are both 200 μm, and the opposite end faces of the two multimode optical fibers 3 form a concave surface with a radius of curvature of 320 μm by laser thermal fusion, and the surface of the concave surface is coated with 397nm reflectance of 99%. medium film. As shown in Figure 4, the multimode optical fiber 3 is fixed in the optical fiber fixing groove 20 by insulating heat-conducting adhesive N353ND, and the two concave surfaces of the two multimode optical fibers 3 are placed oppositely, and the edges of the concave surfaces of the multimode optical fiber 3 are in contact with the optical fiber fixing groove. The grooves of the grooves are flush with each other, and the focal points of the concave surfaces of the two multimode optical fibers coincide, so that an optical microcavity 21 is formed between the concave surfaces of the two multimode optical fibers, and the focal point of the optical microcavity 21 is the focal point of the concave surfaces of the two multimode optical fibers , the optical axes of the concave surfaces of the two multimode fibers coincide and serve as the optical axis of the optical microcavity 21, the photoionization laser and the cooling laser incident from the vertical direction of the optical window 5 of the first CF35 interface pass through the focal point of the optical microcavity 21, The single-photon laser light incident from the horizontal direction of the light-through window 5 of the third CF35 interface passes through the focus of the optical microcavity 21, the optical axis of the optical microcavity 21, the single-photon laser light, and the vertical direction are perpendicular to each other, and its optical microcavity 21 The fineness F=312. Trapped calcium ions 22 are at the center of the optical microcavity 21 . The other ends of the two multimode fibers are standard SMA connectors, and the standard SMA connectors of the two multimode fibers are respectively connected to the fiber feedthrough 6 installed on the fourth CF35 interface and the eighth CF35 interface.

As shown in Figure 5, the single-photon source laser pumping process of this implementation example based on a single trapped ion is as follows:

Step 1, electrifying and heating the calcium atom furnace 14, the calcium atom furnace 14 generates calcium atom vapor, and the calcium atom vapor diffuses into the optical microcavity 21;

Step 2, incident photoionization laser (423nm and 375nm) and cooling laser (397nm and 866nm) from the light-through window 5 (vertical direction) of the first CF35 interface to the optical microcavity 21, under the interaction between the photoionization laser and calcium atoms, Generate monovalent calcium ions ( ⁴⁰ Ca ⁺ );

Step 3. The radio frequency source loads the two radio frequency electrodes 19 with a frequency ranging from 15 MHz to 30 MHz and a peak-to-peak voltage ranging from 100 V _pp to 400 V _pp . The DC voltage applied to the DC electrode 18 by the DC voltage source ranges from 20V to 60V. Under the action of the RF trapping electric field generated by the RF electrode 19 and the DC control electric field generated by the DC electrode 18, a trapping field is generated in the optical microcavity 21, and the generated monovalent calcium ions are trapped in the trapping field. The imprisoned monovalent calcium ions are under the action of cooling laser light (397nm and 866nm) incident on the optical window 5 (vertical direction) of the first CF35 interface. The compensating DC control electric field in the optical microcavity 21 adjusts the monovalent calcium ions to the focus of the optical microcavity 21 and cools the monovalent calcium ions to below 5mK.

Step 4. Turn off the photoionization laser and cooling laser incident from the light-transmitting window 5 (vertical direction) of the first CF35 interface, and inject the single-photon generated laser (732nm and 866nm) into the optical microcavity 21 through the third CF35 interface, The trapped monovalent calcium ions spontaneously radiate single photons with a wavelength of 397nm, and the single photons with a wavelength of 397nm are coupled out through the multimode fiber under the action of the optical microcavity.

The single photon prepared by the above steps is narrowed to the natural linewidth of the ion after eliminating the Doppler effect, that is, a narrow linewidth single photon source with a linewidth of the order of megahertz, which is suitable for long-distance quantum communication.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (5)

1. the single-photon source based on single trapped ion, including vacuum chamber（8）, it is characterised in that also including being arranged on vacuum chamber （8）Interior ion trap chip（9）With calcium atom stove（14）, ion trap chip（9）Including ginseng arsenic silicon chip（30）Be respectively provided with In ginseng arsenic silicon chip（30）First silicon dioxide layer on two sides（31）With the second silicon dioxide layer（32）, join arsenic silicon chip（30）On It is provided with substrate through-hole（27）, substrate through-hole（27）Relative two side wall on be respectively arranged with optical fiber fixing groove（20）, two Individual optical fiber fixing groove（20）Inside it is respectively arranged with two multimode fibres（3）, two multimode fibres（3）Opposite end common optical axis, two Individual multimode fibre（3）Relative end face be concave surface, the focus of the concave surface of two multimode fibres overlaps, two multimode fibres it is recessed Optical microcavity is formed between face（21）, optical microcavity（21）Focus overlap with the focus of the concave surface of two multimode fibres,

First silicon dioxide layer（31）It is upper to be located at substrate through-hole（27）Part offer the first silicon dioxide layer through hole（26）, the Two silicon dioxide layers（32）It is upper to be located at substrate through-hole（27）Part offer the second silicon dioxide layer through hole（28）,

First silicon dioxide layer（31）With the second silicon dioxide layer（32）On be provided with optical microcavity（21）It is interior to form straight The DC electrode of flow control electric field（18）, in optical microcavity（21）It is interior to form the radio-frequency electrode that radio frequency imprisons electric field（19）With And in optical microcavity（21）The interior micromotion compensating electrode for forming DC control compensating electric field（25）.

2. the single-photon source based on single trapped ion according to claim 1, it is characterised in that described micromotion is mended Repay electrode（25）And DC electrode（18）10 are, radio-frequency electrode（19）For 2,5 DC electrode（18）It is arranged on first Silicon dioxide layer through hole（26）Side, 5 micromotion compensating electrodes（25）With 1 radio-frequency electrode（19）It is arranged on the first dioxy SiClx layer through hole（26）Opposite side, 5 DC electrode in addition（18）It is arranged on the second silicon dioxide layer through hole（28）Side, Other 5 micromotion compensating electrodes（25）With other 1 radio-frequency electrode（19）It is arranged on the second silicon dioxide layer through hole（28）'s Opposite side, the first silicon dioxide layer through hole（26）Side 5 DC electrode（18）With the second silicon dioxide layer through hole（28） Side 5 DC electrode（18）Optical microcavity is located at respectively（21）Both sides.

3. the single-photon source based on single trapped ion according to claim 1, it is characterised in that the first described dioxy SiClx layer through hole（26）With the second silicon dioxide layer through hole（28）Cross section be less than substrate through-hole（27）Cross section.

4. the single-photon source based on single trapped ion according to claim 1, it is characterised in that described ion trap core Piece（9）It is fixed on filter circuit plate（15）On chip putting hole（29）It is interior, filter circuit plate（15）It is fixed on wafer support frame （13）On, calcium atom stove（14）It is fixed on wafer support frame（13）On, wafer support frame（13）It is fixed on direct current feedthrough（12）On, Filter circuit plate（15）On be provided with the passive RC filter circuits of single order and radio-frequency wires, DC electrode（18）With micromotion compensation electricity Pole（25）By the passive RC filter circuits of single order and direct current feedthrough（12）Connection, radio-frequency electrode（19）By radio-frequency wires with penetrate Frequency feedthrough（2）Connection, two multimode fibres respectively with optical fiber feed-through（6）Connection.

5. the single-photon source based on single trapped ion according to claim 4, it is characterised in that described vacuum chamber （8）On be evenly arranged with a CF35 interfaces~the 8th CF35 interfaces, vacuum chamber along same circumferential spread（8）On be additionally provided with One CF100 interfaces and the 2nd CF100 interfaces, are provided with a CF35 interfaces and are arrived for incident photo-ionisation laser and cooling laser Optical microcavity（21）Focus thang-kng window（5）, it is provided with the 3rd CF35 interfaces and is arrived for incident single photon generation laser Optical microcavity（21）Focus thang-kng window（5）, on the 5th CF35 interfaces and the 7th CF35 interfaces thang-kng window is respectively mounted （5）, on the 4th CF35 interfaces and the 8th CF35 interfaces optical fiber feed-through is respectively mounted（6）, radio-frequency feed is installed on the 2nd CF35 interfaces It is logical（2）, the 6th CF35 interfaces are by 4 logical vacuum couplings（24）Respectively with ionic pump（11）, sublimation pump（10）And vacuum corner valve （23）Connection.