Preparation device and preparation method of identical single photon source and preparation method of entangled photon source

Abstract

The invention provides a preparation device and preparation method of an identical single photon source and a preparation method of an entangled photon source, and the preparation device of the identical single photon source comprises a first laser which is suitable for providing an initial laser beam; the magneto-optical trap is suitable for capturing and forming atomic groups; the modulation component is suitable for modulating the initial laser beam under the action of an external modulation signal to obtain a plurality of first laser beams; the first objective lens is suitable for focusing the plurality of first laser beams, so that the plurality of first laser beams form a plurality of first light spots at the focal point of the first objective lens, the plurality of first light spots form an optical dipole trap array, and the optical dipole trap array is suitable for capturing atoms in an atomic group to form a monatomic array; and the waveguide array is suitable for collecting fluorescence generated by exciting the monatomic array under the irradiation of a second laser beam input externally, so as to form an identical waveguide array-assisted collection single photon source array.

Description

Technical Field

[0001] At least one embodiment of the present disclosure relates to the field of quantum information processing technology, and more specifically to a preparation device and method for an identical single-photon source and a preparation method for an entangled photon source. Background Art

[0002] In the field of quantum information and quantum communication, single photon sources and entangled photon sources are both necessary components of quantum hardware. For linear optical quantum computing, there are extremely high requirements for the number and quality of single photons. Because the interaction between photons and the environment is very weak, it is difficult to achieve photon-photon interaction. At present, the HOM effect is used to achieve photon interference and realize double quantum gates in post-selection. The resource of the measurement-based optical quantum computing model is the cluster state, a highly entangled photon state, and then the calculation is realized through single-bit measurement and feedforward. In order to realize the calculation, the photons in the cluster state must be measured in a specific order and basis; for quantum communication, a deterministic and identical single photon source is required to realize a scalable quantum communication link. Quantum key distribution also places high requirements on the quality of single photon sources and entangled photon sources. Deterministic single photon sources can improve the security bit rate over long distances; and the development of single photon sources and entangled photon sources is also conducive to the development of quantum networks and promotes the development of distributed quantum computers.

[0003] A single-photon source refers to a light source that only emits one photon at a time. There are many technologies, materials and processes to produce single photons, which can be roughly divided into two categories, "natural" and "engineering". The "natural" type can be achieved using atoms or molecules, and the "engineering" type includes semiconductor quantum dots, two-dimensional material defects, etc. For the "engineering" type, it is difficult to obtain a large number of identical single-photon sources due to the limitations of the manufacturing process. The atoms of the "natural" type are identical, so using atoms and combining atomic array technology can realize a large-scale single-photon source array, and using such artificial materials such as two-dimensional materials, it is relatively simple to obtain low-dimensional photon entangled states, but it is difficult to obtain high-dimensional photon entangled states. In the atomic-like system, multiple atoms can be entangled first by using the interaction between single-atom-like atoms, and high-dimensional photon entangled states and optical cluster states can be obtained relatively easily.

[0004] It is difficult to obtain identical single-photon source arrays and high-dimensional entangled photon sources in the existing technology, and the efficiency of collecting and exporting single photons spontaneously radiated by atomic-like objects (single atoms, single ions, superatoms, atoms in one-dimensional optical lattices, or semiconductor quantum dots) in the single-photon source array in the existing technology is low. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present disclosure provides a device for preparing identical single-photon sources, which can prepare identical single-photon source arrays and improve the efficiency of collecting and exporting single photons spontaneously radiated by atoms in the single-photon source array.

[0006] According to a first aspect of the present disclosure, there is provided a device for preparing an identical single-photon source, comprising:

[0007] a first laser adapted to provide an initial laser beam;

[0008] Magneto-optical trap, suitable for obtaining atomic groups;

[0009] A modulation component, adapted to modulate the initial laser beam under the action of an external modulation signal to obtain a plurality of first laser beams;

[0010] a first objective lens, adapted to focus the plurality of first laser beams so that the plurality of first laser beams form a plurality of first light spots at the focus of the first objective lens, the plurality of first light spots form an optical dipole trap array, and the optical dipole trap array is adapted to capture atoms in the atomic group to form a single atom array; and

[0011] A waveguide array is used to collect the fluorescence generated by the above-mentioned single-atom array when it is excited by the irradiation of the second laser beam input from the outside, so as to form an identical single-photon source array assisted by the above-mentioned waveguide array;

[0012] Wherein, each of the above-mentioned single photon sources is independent of each other and presents a one-to-one mapping relationship with each waveguide in the above-mentioned waveguide array.

[0013] According to an embodiment of the present disclosure, the preparation device of the above-mentioned identical single-photon source also includes a calibration component, which is suitable for receiving a third laser beam from the above-mentioned waveguide array, so that the second light spot formed by the above-mentioned first laser beam on the imaging surface in the above-mentioned calibration component and the third light spot formed by the above-mentioned third laser beam on the imaging surface in the above-mentioned calibration component are in the same focal plane, so as to improve the efficiency of the above-mentioned waveguide array in collecting the above-mentioned fluorescence.

[0014] According to an embodiment of the present disclosure, the calibration component includes:

[0015] a second objective lens, adapted to collimate the third laser beam;

[0016] A first lens, adapted to focus the third laser beam collimated by the second objective lens; and

[0017] The camera is adapted to respectively image the first laser beam and the third laser beam to obtain the second light spot and the third light spot.

[0018] According to an embodiment of the present disclosure, the modulation component includes:

[0019] an acousto-optic modulation assembly adapted to modulate the initial laser beam under the action of an externally applied modulation signal to obtain a plurality of diffracted laser beams having the same number of frequencies as the modulation signal; and

[0020] The lens group is suitable for expanding the diffracted laser beam to obtain the first laser beam.

[0021] According to an embodiment of the present disclosure, by adjusting the angle of the acousto-optic modulation component and the frequency spacing in the modulation signal, each waveguide in the waveguide array corresponds to the optical dipole trap array one by one.

[0022] According to an embodiment of the present disclosure, the modulation component further includes:

[0023] a reflector, adapted to reflect the first laser sub-beam; and

[0024] The dichroic mirror is adapted to transmit the first sub-laser beam and reflect the fluorescence from the single atom array.

[0025] According to an embodiment of the present disclosure, the device for preparing the above-mentioned identical single-photon source also includes a second lens, which is suitable for focusing the above-mentioned fluorescence reflected by the above-mentioned dichroic mirror so that the above-mentioned fluorescence is collected by the above-mentioned waveguide array.

[0026] According to an embodiment of the present disclosure, the waveguide array includes any one or a combination of the following: a femtosecond laser direct writing waveguide array, a femtosecond laser etching waveguide array, a silicon nitride chip, and a lithium niobate chip.

[0027] According to a second aspect of the present disclosure, a method for preparing an identical single-photon source is provided, comprising:

[0028] providing an initial laser beam using a first laser;

[0029] Using magneto-optical traps to obtain atomic clusters;

[0030] Using a modulation component to modulate the initial laser beam under the action of an external modulation signal to obtain a plurality of first laser beams;

[0031] Focusing the plurality of first laser beams by using a first objective lens, so that the plurality of first laser beams form a plurality of first light spots at the focus of the first objective lens, and the plurality of first light spots form an optical dipole trap array, and the optical dipole trap array is suitable for capturing atoms in the atomic group to form a single atom array; and

[0032] The fluorescence generated by the single atom array when excited by the second laser beam input from the outside is collected by using a waveguide array, so as to form an identical single photon source array assisted by the waveguide array;

[0033] Wherein, each of the above-mentioned single photon sources is independent of each other and presents a one-to-one mapping relationship with each waveguide in the above-mentioned waveguide array.

[0034] According to a third aspect of the present disclosure, a method for preparing an entangled photon source is provided, comprising: using resonant light to excite multiple single atoms in an identical single-photon source obtained by the above-mentioned identical single-photon source preparation device to a Rydberg state, so that dipole interaction occurs between the multiple above-mentioned single-photon sources, thereby obtaining an entangled photon source.

[0035] According to an embodiment of the present disclosure, a first laser is used to provide an initial laser beam, a magneto-optical trap is used to obtain an atomic cluster, a modulation component is used to modulate the initial laser beam under the action of an external modulation signal, a plurality of first laser beams are obtained, and a first objective lens is used to focus the plurality of first laser beams so that the plurality of first laser beams form a plurality of first light spots at the focal point of the first objective lens, and the plurality of first light spots form an optical dipole trap array, the optical dipole trap array is used to capture atoms in the atomic cluster to form a single atom array, and a waveguide array is used to collect fluorescence generated by the single atom array when excited by an externally input second laser beam, so as to form an identical waveguide array-assisted single-photon source array for collection, wherein each single-photon source is independent of each other and has a one-to-one mapping relationship with each waveguide in the waveguide array, and an identical single-photon source array is successfully prepared, and the efficiency of collecting and exporting single photons spontaneously radiated by atoms in the single-photon source array is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0037] Figure 1 A schematic diagram showing the principle of a device for preparing an identical single-photon source according to an embodiment of the present disclosure is shown;

[0038] Figure 2 A schematic diagram showing the working principle of a waveguide array in a device for preparing an identical single-photon source according to an embodiment of the present disclosure is shown;

[0039] Figure 3 A schematic diagram showing a cavity array formed by a waveguide array and a single-photon source array in a device for preparing an identical single-photon source based on atoms or ions according to an embodiment of the present disclosure is shown;

[0040] Figure 4A schematic diagram showing a cavity array formed by a waveguide array and a single-photon source array in a preparation device for an identical single-photon source based on quantum dots or two-dimensional materials doping according to an embodiment of the present disclosure;

[0041] Figure 5 A curve relationship diagram of the coupling constant at different wavelengths and the spacing between two adjacent waveguides in the waveguide array in a manufacturing device for an identical single-photon source according to an embodiment of the present disclosure is shown;

[0042] Figure 6 The second-order correlation function g of a single atom obtained by the preparation device of an identical single-photon source according to an embodiment of the present disclosure is shown. (2) (τ) measurement diagram;

[0043] Figure 7 A flow chart showing a method for preparing an identical single-photon source according to an embodiment of the present disclosure; and

[0044] Figure 8 A flow chart of a method for preparing an entangled photon source according to an embodiment of the present disclosure is shown.

[0045] In the above drawings, the meanings of the reference numerals are as follows:

[0046] 1- first laser;

[0047] 2- Modulation component;

[0048] 21- Acousto-optic modulation component;

[0049] 22-reflector;

[0050] 23- dichroic mirror;

[0051] 24-lens group;

[0052] 241- third lens;

[0053] 242- fourth lens;

[0054] 3- Waveguide array;

[0055] 4- Second lens;

[0056] 5- first objective lens;

[0057] 6-optical dipole trap array;

[0058] 7- second laser beam;

[0059] 8- Second objective lens;

[0060] 9- first lens;

[0061] 10- Camera;

[0062] 11- third laser beam;

[0063] 12-single atom array;

[0064] 13-Multiple single photons emitted by a single atom array;

[0065] 14- Atom array or ion array;

[0066] 15-Quantum dot array or two-dimensional material doping system;

[0067] 16-Base. DETAILED DESCRIPTION

[0068] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0069] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0070] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0071] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0072] It is difficult to obtain identical single-photon source arrays and high-dimensional entangled photon sources in the related technology, and the efficiency of collecting and exporting single photons spontaneously radiated by atomic-like objects (single atoms, single ions, super atoms, atoms in one-dimensional optical lattices, or semiconductor quantum dots) in the single-photon source array in the related technology is low.

[0073] In view of this, the present disclosure provides a preparation device for an identical single-photon source, by using a first laser to provide an initial laser beam, using a magneto-optical trap to obtain an atomic cluster, using a modulation component to modulate the initial laser beam under the action of an external modulation signal to obtain multiple first laser beams, using a first objective lens to focus the multiple first laser beams, so that the multiple first laser beams form a plurality of first light spots at the focal point of the first objective lens, and the plurality of first light spots form an optical dipole trap array, the optical dipole trap array is used to capture atoms in the atomic cluster to form a single atom array, and a waveguide array is used to collect the fluorescence generated by the single atom array when excited by an externally input second laser beam, so as to form an identical single-photon source array assisted by the waveguide array, wherein each single-photon source is independent of each other and presents a one-to-one mapping relationship with each waveguide in the waveguide array, thereby successfully preparing an identical single-photon source array, and improving the collection and export efficiency of single photons spontaneously radiated by atoms in the single-photon source array.

[0074] Figure 1 A schematic diagram of the principle of a device for preparing an identical single-photon source according to an embodiment of the present disclosure is shown.

[0075] According to some embodiments of the present disclosure, Figure 1 As shown, the preparation device of the above-mentioned identical single-photon source includes a first laser 1, a magneto-optical trap, a modulation component 2, a first objective lens 5 and a waveguide array 3. The first laser 1 is suitable for providing an initial laser beam; the magneto-optical trap is suitable for obtaining an atomic group; the modulation component 2 is suitable for modulating the initial laser beam under the action of an external modulation signal to obtain multiple first laser beams; the first objective lens 5 is suitable for focusing multiple first laser beams, so that the multiple first laser beams form multiple first light spots at the focus of the first objective lens 5, and the multiple first light spots form an optical dipole trap array 6, which is suitable for capturing atoms in the atomic group to form a single-atom array; and the waveguide array 3 is suitable for collecting the fluorescence generated by the single-atom array when it is excited by the external second laser beam, so as to form an identical single-photon source array assisted by the waveguide array 3; wherein each single-photon source is independent of each other and presents a one-to-one mapping relationship with each waveguide in the waveguide array 3.

[0076] According to some embodiments of the present disclosure, a first laser 1 is used to provide an initial laser beam, a magneto-optical trap is used to obtain an atomic cluster, a modulation component 2 is used to modulate the initial laser beam under the action of an external modulation signal to obtain multiple first laser beams, and a first objective lens 5 is used to focus the multiple first laser beams so that the multiple first laser beams form multiple first light spots at the focal point of the first objective lens 5, and the multiple first light spots form an optical dipole trap array 6, which is used to capture atoms in the atomic cluster to form a single atom array, and a waveguide array 3 is used to collect fluorescence generated by the single atom array when excited by an externally input second laser beam, so as to form a single-photon source array assisted by the identical waveguide array 3 for collection, wherein each single-photon source is independent of each other and presents a one-to-one mapping relationship with each waveguide in the waveguide array 3, and an identical single-photon source array is successfully prepared, and the efficiency of collecting and exporting single photons spontaneously radiated by atoms in the single-photon source array is improved.

[0077] According to some embodiments of the present disclosure, an identical single-photon source refers to a light source that can deterministically generate single photons with high purity, high identity and high efficiency. This light source is characterized in that only one photon can be emitted at a time, and each photon has the same quantum state (such as polarization, frequency, phase, etc.).

[0078] According to some embodiments of the present disclosure, the preparation device of the above-mentioned identical single-photon source can not only be used under rubidium atoms, but is also compatible with neutral atoms such as cesium atoms. It only needs to change the wavelength of the cooling light and the back-pumping light of the magneto-optical trap, the wavelength of the far-infrared detuned light, and the wavelength of the excitation light of the resonant laser fluorescence according to the type of atoms.

[0079] According to some embodiments of the present disclosure, the initial laser beam needs to meet the far-infrared detuning condition. Different options are available for the transition energy levels of different atoms. For example, the laser wavelengths that meet the far-infrared detuning condition for rubidium atoms are 781nm, 785nm, 810nm, 830nm, 852nm, etc.; and the laser wavelengths that meet the far-infrared detuning condition for Cs atoms are 1064nm, 855nm, etc., wherein the types of atoms are not limited.

[0080] According to some embodiments of the present disclosure, different excitation lights are selected according to different types of atoms used. In the case of different atoms, the second laser beam needs to be close to the resonance energy level to be able to scatter photons. For example, rubidium atoms can select excitation light with a wavelength of 780nm, and cesium atoms can select excitation light with a wavelength of 852nm.

[0081] According to some embodiments of the present disclosure, the above-mentioned preparation device of the identical single-photon source also includes a vacuum system, and the vacuum system is suitable for providing a vacuum environment.

[0082] According to some optional embodiments of the present disclosure, the vacuum system is an ultra-high vacuum system assembled from SUS304 stainless steel components. The vacuum system uses a dry pump, a molecular pump, and an ion pump group, which can reach 10 -10 The vacuum is of the order of mbar. A special rubidium source is installed in the vacuum. The two electrodes of the rubidium source can be energized by the outside world to generate rubidium atomic vapor that meets the experimental needs. The function of this part is to produce cooled atomic groups. The second laser beam with a wavelength of 780nm is used. The cyclic transition red is detuned by 12MHz. Since the atom has a certain probability of falling into the dark state of the cooling light , an additional pump beam is required Pump the atoms that fell into the dark state back Finally, a cooled rubidium atom cluster is obtained at the center of the anti-Helmholtz coil, which can be used for single-atom trapping experiments.

[0083] According to some embodiments of the present disclosure, in a single-atom capture experiment, using the dipole force of far-detuned light, the first laser beam with a wavelength of 852nm in the far-red detuning will have an attraction on the atoms, and the atoms will be more inclined to stay at the position with the strongest light intensity. When the first laser beam is focused by a large numerical aperture objective to form an optical dipole trap with a beam waist size of less than 2 microns, there will be a photon blocking effect. It is precisely because of the existence of the photon blocking effect that if there are an even number of atoms in the trap, every two atoms will collide to form rubidium molecules and escape from the trap together. If there are an odd number of atoms, one atom will remain in the trap, and finally there will be only one or zero atoms in the tightly bound dipole trap. The technology of atomic array rearrangement makes up for this. Simply put, 2N dipole traps generally have N dipole traps that can be loaded with single atoms. By moving these N atoms to the target area required for the experiment, the atomic loading of the target position can be deterministically achieved, that is, a deterministic single-photon source is achieved. By increasing the number of optical dipole traps, a deterministic single-photon source can be achieved.

[0084] According to some optional embodiments of the present disclosure, the above-mentioned preparation device of the identical single-photon source further includes an aspherical lens ( Figure 1 (not shown in the figure), the aspheric lens is arranged between the first laser 1 and the modulation component 2, and the aspheric lens is suitable for collimating the initial laser beam emitted by the first laser 1.

[0085] According to some embodiments of the present disclosure, the preparation device of the above-mentioned identical single-photon source also includes a calibration component, which is suitable for receiving a third laser beam from the waveguide array 3, so that the second light spot formed by the first laser beam on the imaging surface in the calibration component and the third light spot formed by the third laser beam on the imaging surface in the calibration component are in the same focal plane, so as to improve the efficiency of the waveguide array 3 in collecting fluorescence.

[0086] According to some embodiments of the present disclosure, by utilizing a calibration component to receive a third laser beam from the waveguide array 3, a second light spot formed by the first laser beam on the imaging surface in the calibration component and a third light spot formed by the third laser beam on the imaging surface in the calibration component are in the same focal plane, thereby improving the efficiency of the waveguide array 3 in collecting fluorescence.

[0087] According to some embodiments of the present disclosure, the wavelength of the third laser beam is close to the wavelength of the fluorescent photons, so that there is almost no chromatic aberration between the wavelengths of the laser beam and the fluorescent photons. For example, in the case of rubidium atoms, the wavelength of the third laser beam is 780nm; in the case of cesium atoms, the wavelength of the third laser beam is 852nm.

[0088] According to some embodiments of the present disclosure, the calibration assembly includes a second objective lens 8, a first lens 9, and a camera 10. The second objective lens 8 is suitable for collimating the third laser beam; the first lens 9 is suitable for focusing the third laser beam collimated by the second objective lens 8; and the camera 10 is suitable for imaging the first laser beam and the third laser beam, respectively, to obtain the second light spot and the third light spot.

[0089] According to some embodiments of the present disclosure, a calibration component is used to receive a third laser beam from the waveguide array 3, so that a second light spot formed by the first laser beam on the imaging surface of the camera 10 in the calibration component and a third light spot formed by the third laser beam on the imaging surface of the camera 10 in the calibration component are in the same focal plane, thereby improving the efficiency of the waveguide array 3 in collecting fluorescence.

[0090] According to some embodiments of the present disclosure, the third laser beam is incident on the waveguide array 3, and the third laser beam is transmitted through the waveguide array 3, the second lens 4, the dichroic mirror 23, the lens group 24, the first objective lens 5, the second objective lens 8, the first lens 9 and the camera 10, wherein the second objective lens 8 collimates the third laser beam; the first lens 9 focuses the third laser beam collimated by the second objective lens 8; the camera 10 images the first laser beam and the third laser beam respectively to obtain the second light spot and the third light spot.

[0091] According to some embodiments of the present disclosure, the modulation component 2 includes an acousto-optic modulation component 21 and a lens group 24. The acousto-optic modulation component 21 is adapted to modulate the initial laser beam under the action of an externally applied modulation signal to obtain a plurality of diffracted laser beams having the same number of frequencies as the modulation signal; and the lens group 24 is adapted to expand the diffracted laser beam to obtain a first laser beam.

[0092] According to some embodiments of the present disclosure, the initial laser beam is modulated by using an acousto-optic modulation component 21 under the action of an externally applied modulation signal to obtain a plurality of diffracted laser beams having the same number of frequencies as the modulation signal; the diffracted laser beam is expanded by using a lens group 24 to obtain a first laser beam, and the initial laser beam can be modulated according to actual experimental needs to obtain the first laser beam.

[0093] According to some embodiments of the present disclosure, each waveguide in the waveguide array 3 corresponds to the optical dipole trap array 6 one by one by adjusting the angle of the acousto-optic modulation component 21 and the frequency spacing in the modulation signal.

[0094] According to some embodiments of the present disclosure, by adjusting the angle of the acousto-optic modulation component 21 and the frequency spacing in the modulation signal, each waveguide in the waveguide array 3 corresponds one-to-one to the optical dipole trap array 6, thereby enabling targeted modulation of each optical dipole trap in the optical dipole trap array 6, so that different optical dipole traps can obtain different single atoms.

[0095] According to some optional embodiments of the present disclosure, the AOM component 21 includes any one of an AOM and an AOD deflector.

[0096] According to some embodiments of the present disclosure, the modulation component 2 further includes a reflector 22 and a dichroic mirror 23. The reflector 22 is adapted to reflect the first sub-laser beam; and the dichroic mirror 23 is adapted to transmit the first sub-laser beam and reflect the fluorescence from the single atom array.

[0097] According to some embodiments of the present disclosure, the apparatus for preparing the identical single-photon source further includes a second lens 4 , which is adapted to focus the fluorescence reflected by the dichroic mirror 23 so that the fluorescence is collected by the waveguide array 3 .

[0098] According to some embodiments of the present disclosure, the waveguide array 3 includes any one or a combination of the following: a femtosecond laser direct writing waveguide array, a femtosecond laser etching waveguide array, a silicon nitride chip, and a lithium niobate chip.

[0099] According to some optional embodiments of the present disclosure, the waveguide array 3 is a combination of a femtosecond laser direct writing waveguide array and a lithium niobate chip. The femtosecond laser direct writing waveguide array collects single photons from a completely identical single photon source. At this time, it is also necessary to perform some nonlinear operations on the single photons, such as using a micro-ring cavity to implement a controlled-Z gate (CZ). These require materials to have nonlinearity, which can be achieved with a lithium niobate chip. Assuming that a femtosecond laser direct writing waveguide is used to collect photons, the femtosecond laser direct writing waveguide chip can be used as an interface for the lithium niobate chip. The photons are output from the femtosecond laser direct writing waveguide to the lithium niobate chip to achieve modulation of the photons.

[0100] According to some optional embodiments of the present disclosure, femtosecond laser direct writing technology is used to achieve material modification in a specific area of ​​a glass substrate (including but not limited to boroaluminosilicate materials), so that the refractive index of the material in this area increases to form a refractive index difference, and an optical waveguide is engraved on the glass substrate, thereby realizing the transmission of laser light and ensuring that the transmitted laser light is still a single-mode laser. By engraving multiple optical waveguides on the glass substrate according to required parameters including waveguide spacing, coupling strength between waveguides, and different dimensions (one-dimensional, two-dimensional, and three-dimensional), it can be used to realize photon collection of a single atom and execute linear optical quantum computing circuits.

[0101] Using femtosecond laser direct writing technology, the signal input port can realize waveguide arrangement of any configuration, and can realize one-to-one mapping between the photon collection port and the atoms (single photon source) in the atomic array of any configuration, so that a single waveguide can collect the photons emitted by a single atom (single photon source) in the atomic array without crosstalk, thereby realizing the independent collection of photons emitted by all atoms in the atomic array (single photon source array). The signal output port can also be designed into various configurations, which can be adapted to include but not limited to one-dimensional and multi-dimensional optical fiber arrays to derive single photons from the single photon source array; or directly write quantum circuits for photon quantum computing or quantum simulation on the chip to realize tasks such as optical quantum computing or optical quantum simulation.

[0102] According to some optional embodiments of the present disclosure, an initial laser beam with a wavelength of 852 nm is passed through an aspherical lens with a focal length of f=13.86 mm ( Figure 1The laser beam is collimated into a light beam with an output diameter of d=3mm, and then passes through the acousto-optic modulation component 21. Multi-beam diffraction is achieved by inputting a multi-tone signal into the acousto-optic modulation component 21. The initial laser beam is then expanded into a first laser beam with a diameter of D=22.5mm through a third lens 241 with a focal length of f1=-20mm and a fourth lens 242 with a focal length of f2=150mm. The first laser beam is then incident on a first objective lens 5 with a numerical aperture of 0.5 to focus the first laser beam onto an optical dipole trap array 6 with a beam waist size of 1.2um to achieve capture of a single atom array. While the optical fiber array and the waveguide array 3 achieve the maximum coupling efficiency, the first and last optical fibers in the optical fiber array are connected to the third laser beam of 780nm. Since the dichroic mirror 23 allows 852nm light to pass through and reflects 780nm light, the 852nm spot array generated by the acousto-optic modulation component 21 can be seen in the imaging camera 10, and the 780nm spot reflected by the optical waveguide can also be seen. The angle of the acousto-optic modulation component 21 and the frequency spacing in the multi-tone signal are adjusted to achieve a one-to-one alignment between the waveguide array 3 and the optical dipole trap array 6, and it is necessary to ensure that the 780nm spot and the 852nm spot are in the same focal plane. The purpose here is to achieve a one-to-one mapping between a single atom in the atomic array and a single waveguide in the waveguide array and to achieve the maximum collection efficiency of atomic fluorescence. Through this type of operation, the waveguide array can be used to collect atomic fluorescence, and each atom is an independent single-photon source. A large-scale single-photon source array is realized through the optical waveguide array, and each single-photon source is independent of each other. At the same time, atoms are naturally existing particles with identical properties, so an identical single-photon source array can be formed.

[0103] According to some embodiments of the present disclosure, the single-photon source array in the above-mentioned device for preparing identical single-photon sources is compatible with other micro-nano chips, including but not limited to femtosecond laser direct writing chips, silicon nitride chips and lithium niobate chips, and can be used to realize linear optical quantum computing.

[0104] Figure 2 A schematic diagram of the working principle of the waveguide array in the device for preparing an identical single-photon source according to an embodiment of the present disclosure is shown.

[0105] According to some embodiments of the present disclosure, Figure 2 As shown, the single atom array 12 is excited to generate multiple single photons, and the multiple single photons 13 emitted by the single atom array 12 are transmitted to the waveguide array 3 through the first objective lens 5, the lens group 24 and the second lens 4, and the multiple single photons 13 are collected by the waveguide array 3.

[0106] According to some embodiments of the present disclosure, the waveguide array 3 is an optical waveguide array, which is used to realize a one-to-one mapping between a single photon emission point in a single photon source array and a single waveguide. The single photon emission point is a single photon source, and the optical waveguide can collect and export photons scattered by the single photon source.

[0107] Figure 3 A schematic diagram of the principle of a cavity array formed by a waveguide array and a single-photon source array in a device for preparing an identical single-photon source based on atoms or ions according to an embodiment of the present disclosure is shown.

[0108] According to some embodiments of the present disclosure, Figure 3 As shown, two waveguide arrays 3 are symmetrically arranged at the two ends of the atomic array or the ion array. At this time, the relative positions of the two waveguide arrays 3 to the atomic array or the ion array can be constructed into a cavity array, which can improve the collection efficiency of the single photon source.

[0109] According to some optional embodiments of the present disclosure, the waveguide array 3 is a femtosecond laser direct writing waveguide array. After being polished and coated, the femtosecond laser direct writing waveguide array can be constructed into a cavity array with the bottom of the single photon source, thereby improving the collection efficiency of the single photon source.

[0110] According to some embodiments of the present disclosure, the specific operation of constructing a cavity array for an atomic array or an ion array requires two waveguide arrays 3 (i.e., two waveguide chips), both of which need to be polished and then coated, and the fluorescence emitted by the atoms or ions is collected together at both ends of the vacuum glass cavity. The cavity length can be locked at a reference of 810nm (light of this wavelength has no effect on 780nm lasers and 852nm lasers and is easily filtered out), and the two waveguide chips need to be strictly aligned and can be regarded as mirror devices.

[0111] Figure 4 A schematic diagram of the principle of a cavity array formed by a waveguide array and a single-photon source array in a device for preparing an identical single-photon source based on quantum dots or two-dimensional materials doping according to an embodiment of the present disclosure is shown.

[0112] According to some embodiments of the present disclosure, Figure 4 As shown, the cavity array formed by the waveguide array doped with quantum dots or two-dimensional materials and the single photon source array includes a waveguide array 3, a quantum dot array or a two-dimensional material doping system 15, and a substrate 16. The quantum dot array or the two-dimensional material doping system 15 is arranged above the substrate 16, and the waveguide array 3 is arranged at one end of the quantum dot array or the two-dimensional material doping system 15.

[0113] According to some embodiments of the present disclosure, the specific operation of constructing a cavity array for a quantum dot system or a two-dimensional material doped system is: since the quantum dot system or the two-dimensional material doped system is arranged on a substrate 16, and the substrate 16 includes sapphire or other materials, it is only necessary to coat the substrate 16, and then polish the coated waveguide chip to achieve cavity enhanced collection, thereby improving the collection efficiency of the single photon source.

[0114] According to some embodiments of the present disclosure, when a large-scale single-photon source array is implemented by combining atoms, ions or quantum dots with an optical waveguide array, each single-photon source is independent of each other.

[0115] Figure 5 A curve relationship diagram of the coupling constant at different wavelengths in a preparation device for an identical single-photon source according to an embodiment of the present disclosure and the spacing between two adjacent waveguides in a waveguide array is shown.

[0116] According to some embodiments of the present disclosure, Figure 5 The horizontal axis in the middle represents the waveguide array spacing in μm. Figure 5 The vertical axis represents the coupling constant in mm. Figure 5 It can be seen that the relationship between the initial laser beam, waveguide array spacing and coupling constant for different wavelengths is Figure 5 The waveguide array spacing that meets the actual experimental needs can be designed. When the wavelength of the initial laser beam is determined, different waveguide array spacings have different coupling constants.

[0117] Figure 6 The second-order correlation function g of a single atom obtained by the preparation device of an identical single-photon source according to an embodiment of the present disclosure is shown. (2) (τ) measurement diagram.

[0118] According to some embodiments of the present disclosure, Figure 6 The horizontal axis represents the delay time in ns; the vertical axis represents the second-order correlation function. The delay time refers to the time difference between the signal being sent and the signal being received. In quantum optics experiments, the delay time may involve multiple aspects such as the transmission of photons and the response time of the detector. The second-order correlation function g (2) (τ) is one of the important indicators to describe the performance of a single photon source. It reflects the statistical distribution characteristics of photons in time. Specifically, the second-order correlation function measures the ratio of the probability of detecting two photons at different time points τ to the probability of detecting two photons under random distribution. By measuring the second-order correlation function, it can be determined whether the single-photon source really only emits a single photon. When g (2) When (0)≪1, it indicates that the probability of detecting two photons at the same time point is extremely low, that is, the light source has a good single-photon property. Figure 6The changes in the second-order correlation function at different delay times can be intuitively displayed, thus helping to judge the performance of the single-photon source.

[0119] Figure 7 A flow chart of a method for preparing an identical single-photon source according to an embodiment of the present disclosure is shown.

[0120] According to a second aspect of the present disclosure, a method for preparing an identical single-photon source is provided, such as Figure 7 As shown, the preparation method includes operations S101 to S105.

[0121] In operation S101, an initial laser beam is provided using a first laser.

[0122] In operation S102 , atomic clusters are obtained using a magneto-optical trap.

[0123] In operation S103, the initial laser beam is modulated by a modulation component under the action of an external modulation signal to obtain a plurality of first laser beams.

[0124] In operation S104, a first objective lens is used to focus a plurality of first laser beams, so that the plurality of first laser beams form a plurality of first light spots at the focus of the first objective lens, and the plurality of first light spots form an optical dipole trap array, which is suitable for capturing atoms in an atomic group to form a single atom array.

[0125] In operation S105, the fluorescence generated by the single atom array when excited by the externally input second laser beam is collected by using a waveguide array to form an identical single photon source array assisted by the waveguide array.

[0126] According to some embodiments of the present disclosure, each single photon source is independent of each other and has a one-to-one mapping relationship with each waveguide in the waveguide array 3 .

[0127] According to some embodiments of the present disclosure, the readout method based on the waveguide array is also compatible with the ion trap system and the semiconductor quantum dot system, and can collect the ions in the ion trap system and the semiconductor quantum dot system and the fluorescent photons radiated by the quantum dots.

[0128] According to some embodiments of the present disclosure, a first laser is used to provide an initial laser beam, a magneto-optical trap is used to obtain an atomic cluster, a modulation component is used to modulate the initial laser beam under the action of an external modulation signal, a plurality of first laser beams are obtained, and a first objective lens is used to focus the plurality of first laser beams so that the plurality of first laser beams form a plurality of first light spots at the focal point of the first objective lens, the plurality of first light spots form an optical dipole trap array, the optical dipole trap array is used to capture atoms in the atomic cluster to form a single atom array, a waveguide array is used to collect fluorescence generated by the single atom array when excited by an externally input second laser beam, so as to form a single-photon source array that is completely identical and collected with the assistance of a waveguide array, the single-photon source array is successfully prepared, and the efficiency of collecting and exporting single photons spontaneously radiated by atoms-like substances in the single-photon source array is improved.

[0129] Figure 8 A flow chart of a method for preparing an entangled photon source according to an embodiment of the present disclosure is shown.

[0130] According to a third aspect of the present disclosure, a method for preparing an entangled photon source is provided, such as Figure 8 As shown, the preparation method of the entangled photon source includes operation S201. In operation S201, multiple single atoms in the identical single-photon source obtained by the preparation device of the above-mentioned identical single-photon source are excited to Rydberg states using resonant light, so that dipole interaction occurs between the multiple single-photon sources, thereby obtaining an entangled photon source.

[0131] According to some embodiments of the present disclosure, an entangled photon source is successfully prepared by utilizing resonant light to excite multiple single atoms in an identical single-photon source obtained by the above-mentioned identical single-photon source preparation device to Rydberg states, so that dipole interaction occurs between the multiple single-photon sources.

[0132] According to some embodiments of the present disclosure, resonant light is light that can resonate with a material system (such as atoms, ions, quantum dot arrays, and two-dimensional material doping systems) in an identical single-photon source at a specific frequency. This resonance phenomenon refers to a state in which the energy exchange between light and the material system reaches maximum efficiency. In the resonant state, the absorption, emission, or scattering of light by the material system is significantly enhanced.

[0133] According to some embodiments of the present disclosure, based on the Rydberg interaction, adjacent atoms in identical single-photon sources can achieve entanglement between atoms by implementing a controlled phase gate of the two atoms because one atom is excited to a Rydberg state while the other atom cannot be excited to the same Rydberg state. As mentioned above, each atom is an independent single-photon source, and different single-photon sources are coupled together through interaction to form an entangled photon source, which can promote the development of quantum networks and quantum communications, and improve the capabilities of linear optical quantum computing.

[0134] According to some embodiments of the present disclosure, an ion trap is an entangled photon source obtained by interaction of modes (common vibration modes). Semiconductor quantum dots usually interact with each other by controlling an external electric field to obtain an entangled photon source.

[0135] According to some embodiments of the present disclosure, multiple single-photon sources can be entangled by using the interaction between single-photon sources of different systems such as atoms, ions or quantum dots to construct an entangled photon source, which can be used to achieve, including but not limited to, optical cluster states.

[0136] According to some embodiments of the present disclosure, the use of atoms, ions, etc. as single photon sources to realize entangled photon sources can be based on the interaction between atoms. Through the controlled phase gate, entanglement including but not limited to single atoms, super atoms, or one-dimensional optical lattices can be first realized, and entangled photons can be directly obtained using entangled photon sources. Similarly, using femtosecond laser direct writing waveguides, entangled photon derivation in an entangled photon source array of any configuration can be realized.

[0137] According to some embodiments of the present disclosure, single photon sources and entangled photon source arrays can be used in scalable quantum networks and quantum repeaters, and can further perform error correction in repeaters, extend photon coherence time, and promote the realization of distributed quantum computers; single photon sources and entangled photon source arrays can be used to realize full-link quantum communication and improve the communication efficiency of quantum communication; single photon sources and entangled photon source arrays can serve quantum key distribution, improve the distribution efficiency of quantum cryptography and increase the security bit rate.

[0138] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0139] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A device for preparing an identical single-photon source, comprising: a first laser adapted to provide an initial laser beam; Magneto-optical trap, suitable for obtaining atomic groups; A modulation component, adapted to modulate the initial laser beam under the action of an external modulation signal to obtain a plurality of first laser beams; a first objective lens, adapted to focus the plurality of the first laser beams, so that the plurality of the first laser beams form a plurality of first light spots at the focus of the first objective lens, the plurality of the first light spots form an optical dipole trap array, and the optical dipole trap array is adapted to capture atoms in the atomic group to form a single atom array; as well as A waveguide array is used to collect the fluorescence generated by the single atom array when excited by the second laser beam input from the outside, so as to form an identical single photon source array assisted by the waveguide array; Wherein, each single photon source is independent of each other and has a one-to-one mapping relationship with each waveguide in the waveguide array 3 .

2. The preparation device of the identical single-photon source according to claim 1 further includes a calibration component, which is suitable for receiving a third laser beam from the waveguide array, so that a second light spot formed by the first laser beam on the imaging surface of the calibration component and a third light spot formed by the third laser beam on the imaging surface of the calibration component are in the same focal plane, so as to improve the efficiency of the waveguide array in collecting the fluorescence.

3. The preparation device of the identical single photon source according to claim 2, wherein: The calibration assembly comprises: a second objective lens, adapted to collimate the third laser beam; a first lens, adapted to focus the third laser beam collimated by the second objective lens; and The camera is adapted to respectively image the first laser beam and the third laser beam to obtain the second light spot and the third light spot.

4. The device for preparing an identical single photon source according to claim 1, wherein: The modulation component comprises: an acousto-optic modulation assembly adapted to modulate the initial laser beam under the action of an externally applied modulation signal to obtain a plurality of diffracted laser beams having the same number of frequencies as that in the modulation signal; and The lens group is suitable for expanding the diffracted laser beam to obtain the first laser beam.

5. The device for preparing an identical single photon source according to claim 4, wherein: By adjusting the angle of the acousto-optic modulation component and the frequency spacing in the modulation signal, each waveguide in the waveguide array corresponds to the optical dipole trap array one by one.

6. The device for preparing an identical single photon source according to claim 5, wherein: The modulation component also includes: a reflector, adapted to reflect the first laser sub-beam; and A dichroic mirror is used to transmit the first sub-laser beam and reflect the fluorescence from the single atom array.

7. The device for preparing an identical single-photon source according to any one of claims 1 to 6, wherein: A second lens is also included, which is adapted to focus the fluorescent light reflected by the dichroic mirror so that the fluorescent light is collected by the waveguide array.

8. The device for preparing an identical single photon source according to claim 1, wherein: The waveguide array includes any one or a combination of the following: a femtosecond laser direct writing waveguide array, a femtosecond laser etching waveguide array, a silicon nitride chip, and a lithium niobate chip.

9. A method for preparing an identical single-photon source, comprising: providing an initial laser beam using a first laser; Using magneto-optical traps to obtain atomic clusters; Using a modulation component to modulate the initial laser beam under the action of an external modulation signal to obtain a plurality of first laser beams; Focusing the plurality of the first laser beams by using a first objective lens, so that the plurality of the first laser beams form a plurality of first light spots at the focus of the first objective lens, and the plurality of the first light spots form an optical dipole trap array, and the optical dipole trap array is suitable for capturing atoms in the atomic group to form a single atom array; as well as Using a waveguide array to collect the fluorescence generated by the single atom array when excited by the second laser beam input from the outside, so as to form an identical single photon source array assisted by the waveguide array for collection; Wherein, each single photon source is independent of each other and presents a one-to-one mapping relationship with each waveguide in the waveguide array.

10. A method for preparing an entangled photon source, comprising: Resonant light is used to excite multiple single atoms in the identical single-photon source obtained by the preparation device of the identical single-photon source as described in any one of claims 1 to 8 to Rydberg states, so that dipole interaction occurs between the multiple single-photon sources, thereby obtaining an entangled photon source.

Images