A quantum bit and preparation method thereof, and quantum chip

Abstract

The present invention provides a quantum bit and a preparation method thereof, and a quantum chip, and relates to the field of quantum bit technology. Based on the target isotope with zero nuclear spin corresponding to the element in the first functional layer, the target isotope with zero nuclear spin corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the first functional layer; based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, the target isotope with zero nuclear spin corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the quantum well layer. In this way, the decoherence time of the quantum bit is comprehensively improved, thereby improving the performance and reliability of quantum computing.

Description

Technical Field

[0001] The present application relates to the field of quantum bit technology, and in particular to a quantum bit and a preparation method thereof, and a quantum chip. Background Art

[0002] In the field of quantum computing and quantum information processing, the long coherence time of quantum bits is the key to achieving reliable quantum computing. However, there are currently some challenges in achieving long coherence time of quantum bits in solid materials, one of which is the decoherence caused by impurities from non-zero nuclear spins. In solid materials, the spin quantum numbers of many nuclear spins are not zero, and these non-zero nuclear spins have an adverse effect on the coherence of quantum bits.

[0003] Therefore, how to reduce or remove non-zero nuclear spin elements is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] In view of the above problems, the present application provides a quantum bit and a preparation method thereof, and a quantum chip, which uses ion implantation based on a target isotope with zero nuclear spin to reduce or remove non-zero nuclear spin elements. The specific scheme is as follows:

[0005] A first aspect of the present application provides a method for preparing a quantum bit, the method comprising: providing a substrate;

[0006] forming a first functional layer on one side of the substrate;

[0007] Based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation;

[0008] forming a quantum well layer on a side of the first functional layer facing away from the substrate, wherein the quantum well layer is in contact with the first functional layer;

[0009] Based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, the target isotope with zero nuclear spin corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation.

[0010] Preferably, in the above-mentioned method for preparing a quantum bit, the quantum bit is a Ge quantum bit, and the forming of a first functional layer on one side of the substrate comprises:

[0011] A Ge 0.8 Si 0.2 Functional layer.

[0012] Preferably, in the above-mentioned method for preparing a quantum bit, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation, comprising:

[0013] Based on the Ge 0.8 Si 0.2 The nuclear spin corresponding to the Ge element in the functional layer is zero 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.8 Si 0.2 Functional layer 70 Ge 0.8 Si 0.2 Functional layer;

[0014] Based on the Ge 0.8 Si 0.2 The nuclear spin corresponding to the Si element in the functional layer is zero 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.8 Si 0.2 Functional layer 70 Ge 0.8 28 Si 0.2 Functional layer.

[0015] Preferably, in the above-mentioned method for preparing a quantum bit, the quantum well layer is a Ge quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising:

[0016] Based on the fact that the nuclear spin corresponding to the Ge element in the Ge quantum well layer is zero 70 Ge isotope, using ion implantation 70 Ge isotopes are implanted into the Ge quantum well layer to form 70 Ge quantum well layer.

[0017] Preferably, in the above-mentioned method for preparing a quantum bit, the quantum bit is a Si quantum bit, and the forming of a first functional layer on one side of the substrate comprises:

[0018] A Ge 0.3 Si 0.7 Functional layer.

[0019] Preferably, in the above-mentioned method for preparing a quantum bit, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation, comprising:

[0020] Based on the Ge 0.3 Si 0.7 The nuclear spin corresponding to the Ge element in the functional layer is zero 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.3 Si 0.7 Functional layer 70 Ge 0.3 Si 0.7 Functional layer;

[0021] Based on the Ge 0.3 Si 0.7 The nuclear spin corresponding to the Si element in the functional layer is zero 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.3 Si 0.7 Functional layer 70 Ge 0.3 28 Si 0.7 Functional layer.

[0022] Preferably, in the above-mentioned method for preparing a quantum bit, the quantum well layer is a Si quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising:

[0023] Based on the fact that the nuclear spin corresponding to the Si element in the Si quantum well layer is zero 28 Si isotope, using ion implantation 28 Si isotopes are implanted into the Si quantum well layer to form 28 Si quantum well layer.

[0024] Preferably, in the above-mentioned method for preparing a quantum bit, the method for preparing a quantum bit further comprises:

[0025] A protection layer is formed on a side of the quantum well layer facing away from the substrate.

[0026] A second aspect of the present application provides a quantum bit, which is obtained by any of the quantum bit preparation methods described above.

[0027] A third aspect of the present application provides a quantum chip, which includes the quantum bits described above.

[0028] By means of the above technical scheme, the present application provides a quantum bit and a preparation method thereof, and a quantum chip, based on the target isotope with zero nuclear spin corresponding to the element in the first functional layer, the target isotope with zero nuclear spin corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the first functional layer; based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, the target isotope with zero nuclear spin corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the quantum well layer. In this way, the decoherence time of the quantum bit is comprehensively improved, thereby improving the performance and reliability of quantum computing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0030] Figure 1 A schematic diagram of a process for preparing a quantum bit provided by an embodiment of the present invention;

[0031] Figure 2 One of the partial structural schematic diagrams of a Ge quantum bit provided by an embodiment of the present invention;

[0032] Figure 3 A second schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention;

[0033] Figure 4 A third schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention;

[0034] Figure 5 A fourth schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention;

[0035] Figure 6 A fifth schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention;

[0036] Figure 7 A sixth schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention;

[0037] Figure 8One of the partial structural schematic diagrams of a Si quantum bit provided by an embodiment of the present invention;

[0038] Fig. 9 A second schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention;

[0039] Fig.10 A third schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention;

[0040] Fig.11 A fourth schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention;

[0041] Fig.12 A fifth schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention;

[0042] Fig.13 The sixth schematic diagram of the partial structure of a Si quantum bit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those of ordinary skill in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems. It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation on the present application.

[0044] Before introducing the technical solution of the present application and the technical effects that can be achieved by the technical solution of the present application, a brief introduction to some relevant background is first given.

[0045] Hyperfine Interaction: Non-zero nuclear spin (such as in Si 29 Si nuclear spins) are coupled to electron spins through hyperfine interactions. This interaction is due to the magnetic field generated by the nuclear spin affecting the electron spin, causing the energy level splitting and state mixing of the electron spin. The existence of this interaction will lead to the instability of the electron spin state, thus causing decoherence.

[0046] Effect of decoherence time: The decoherence time of electron spin is an important indicator for measuring the performance of quantum bits. A longer decoherence time means that the quantum bit can maintain its coherence for a longer time, thus being able to perform more quantum operations. In an environment with non-zero nuclear spin, the decoherence time is often significantly limited. Therefore, studying how to reduce or eliminate the influence of non-zero nuclear spin is crucial to extending the decoherence time and thus improving the performance of quantum bits.

[0047] The present application provides a quantum bit and a preparation method thereof, and a quantum chip. Based on the target isotope with zero nuclear spin corresponding to the element in the first functional layer, the target isotope with zero nuclear spin corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation to remove or reduce the content of the non-zero nuclear spin element in the first functional layer; based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, the target isotope with zero nuclear spin corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation to remove or reduce the content of the non-zero nuclear spin element in the quantum well layer. In this way, the decoherence time of the quantum bit is comprehensively improved, thereby improving the performance and stability of the quantum bit.

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] refer to Figure 1 , Figure 1 A schematic diagram of a process for preparing a quantum bit provided in an embodiment of the present invention. The process for preparing a quantum bit provided in an embodiment of the present invention comprises:

[0050] S101: providing a substrate.

[0051] S102: forming a first functional layer on one side of the substrate.

[0052] S103: Based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation.

[0053] S104: forming a quantum well layer on a side of the first functional layer facing away from the substrate, wherein the quantum well layer is in contact with the first functional layer.

[0054] S105: Based on the target isotopes with zero nuclear spin corresponding to the elements in the quantum well layer, inject the target isotopes with zero nuclear spin corresponding to the elements in the quantum well layer into the quantum well layer by ion implantation.

[0055] Specifically, in terms of etching, the focused ion beam (FIB) uses a high-energy ion beam to locally etch materials, which can achieve nano-level fine processing. This function is often used in sample preparation, such as cross-section preparation of electron microscope samples. In terms of material deposition, FIB can deposit metals or other materials on the surface of the sample. The commonly used method is gas-assisted deposition, which is to inject a gas containing the target element, and then use an ion beam to decompose the gas and deposit the material. In terms of ion implantation, FIB can implant specific ions into the material to change the physical and chemical properties of the material. This is very important in the manufacture of semiconductor devices and is used for doping and forming pn junctions.

[0056] In qubit manufacturing, ion implantation has been widely used to dope and modify semiconductor materials. However, ion implantation is not currently used in the process of purifying zero-spin elements in qubits.

[0057] In the invention process of the present application, it was found that FIB combined with Wien filter can achieve isotope separation. The selected isotope ion beam is focused and guided to the sample surface for injection, so as to achieve the purification of specific isotopes. For example, specific isotopes in natural Si, Ge or SiGe can be purified. 28 Si isotopes and 70 Ge isotope.

[0058] Based on this, the embodiment of the present application enriches zero nuclear spin elements by ion implantation, and by selecting appropriate ion species, accurate control and removal of non-zero nuclear spin elements in the material are achieved. The method of purifying zero nuclear spin elements by ion implantation can significantly improve the decoherence time of quantum bits, thereby improving the performance and reliability of quantum computing. In general, purifying zero nuclear spin elements in quantum bits by ion implantation is a relatively innovative method that can solve the problem of short coherence time of quantum bits in solid materials, and provides new ideas and methods for realizing reliable quantum computing.

[0059] Specifically, the method for preparing a quantum bit provided in an embodiment of the present application is based on the target isotope with zero nuclear spin corresponding to the element in the first functional layer, and the target isotope with zero nuclear spin corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the first functional layer; based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, the target isotope with zero nuclear spin corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation to remove or reduce the content of non-zero nuclear spin elements in the quantum well layer. In this way, the decoherence time of the quantum bit is comprehensively improved, thereby improving the performance and reliability of quantum computing.

[0060] The preparation processes of Ge quantum bits and Si quantum bits are explained below respectively.

[0061] The preparation process of Ge quantum bits is as follows:

[0062] The step of forming a first functional layer on one side of the substrate comprises:

[0063] like Figure 2 As shown, Figure 2 This is one of the partial structural diagrams of a Ge quantum bit provided by an embodiment of the present invention. A Ge 0.8 Si 0.2 Functional layer 15.

[0064] The substrate 11 includes but is not limited to a silicon substrate.

[0065] like Figure 2 As shown, the Ge quantum bit also includes: a first Ge layer 12, a second Ge layer 13 and a Ge layer with a gradient element content which are sequentially stacked in the first direction. x Si 1-x In layer 14, x gradually decreases in the first direction, from 1 to 0.8. The first direction is perpendicular to the plane where the substrate 11 is located, and points from the substrate 11 to the first functional layer.

[0066] The growth temperature of the first Ge layer 12 is lower than that of the second Ge layer 13. In the field, the first Ge layer 12 is also called low-temperature Ge, and the second Ge layer 13 is called high-temperature Ge layer. The two are mainly used to suppress dislocations caused by lattice mismatch, and the thickness range is about 1μm-2μm.

[0067] Ge with gradient element content x Si 1-x The thickness of layer 14 is in the range of about 1 μm to 2 μm, and is mainly used to further annihilate dislocations in the Ge with a gradient element content. x Si 1-x Layer 14.

[0068] Afterwards, in the Ge x Si 1-x Ge with a fixed composition is grown on layer 14 0.8 Si 0.2 The functional layer 15 is used to fully relax the GeSi layer and shield the noise interference under the quantum well layer. 0.8 Si 0.2 The thickness of the functional layer 15 is about 500 nm.

[0069] At this time, the obtained Ge 0.8 Si 0.2The functional layer 15 contains non-zero nuclear spin elements of Ge and Si, which may have an adverse effect on the coherence of the quantum bit.

[0070] Therefore, in the embodiment of the present application, this Ge 0.8 Si 0.2 The non-zero nuclear spin elements in the functional layer 15 are purified to reduce or remove the non-zero nuclear spin elements.

[0071] The method of injecting the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer into the first functional layer by ion implantation based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer comprises:

[0072] like Figure 3 As shown, Figure 3 This is a schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention. 0.8 Si 0.2 The nuclear spin corresponding to the Ge element in the functional layer 15 is zero. 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.8 Si 0.2 The functional layer 15 is formed 70 Ge 0.8 Si 0.2 Functional layer 16.

[0073] That is, using a focused ion beam 70 Ge is used as the target material, and the ion implantation method is used to 70 Ge isotope is implanted into the Ge 0.8 Si 0.2 In the functional layer 15, other isotopes of Ge are removed as much as possible. Obviously, the content of non-zero nuclear spin elements of Ge will also be reduced, or even completely removed, so as to achieve 70 Purification of Ge isotopes to improve 70 The abundance of Ge isotopes forms the purified 70 Ge 0.8 Si 0.2 Functional layer 16.

[0074] Because in 70 After the purification of Ge isotopes, polycrystalline may occur. 28Before Si isotope purification, rapid thermal annealing can be used to perform solid phase epitaxial growth on the crystals after FIB bombardment to promote their single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time, the annealing temperature is about 1000°C, and the annealing time is about 5s. The optional parameters for solid phase epitaxial growth include processing temperature and processing time, the processing temperature is about 620°C, and the processing time is about 10min.

[0075] Further, such as Figure 4 As shown, Figure 4 This is a schematic diagram of a partial structure of a Ge quantum bit provided in an embodiment of the present invention. 0.8 Si 0.2 The nuclear spin corresponding to the Si element in the functional layer 15 is zero. 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.8 Si 0.2 The functional layer 16 is formed 70 Ge 0.8 28 Si 0.2 Functional layer 17.

[0076] That is, using a focused ion beam 28 Si is used as the target material, and ion implantation is used to 28 Si isotope implantation into the 70 Ge 0.8 Si 0.2 In the functional layer 16, other isotopes of Si are removed as much as possible. Obviously, the content of non-zero nuclear spin elements of Si will also be reduced, or even completely removed, so as to achieve 28 Purification of Si isotopes to improve 28 The abundance of Si isotopes forms the purified 70 Ge 0.8 28 Si 0.2 Functional layer 17.

[0077] Because in 28 After Si isotope purification, polycrystalline may also occur. 28 After Si isotope purification, rapid thermal annealing can be used to perform solid phase epitaxial growth on the FIB-bombarded crystal to promote its single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time. The annealing temperature is about 1000°C and the annealing time is about 5s. The optional solid phase epitaxial growth parameters include processing temperature and processing time. The processing temperature is about 620°C and the processing time is about 10min.

[0078] In order to improve the quality of the film layer of the subsequent quantum well layer, the Ge 0.8 Si 0.2 After the functional layer 15 is treated, a mixed cleaning solution consisting of hydrofluoric acid, sulfuric acid and hydrogen peroxide may be used to clean the functional layer 15. Figure 4 The structure shown is cleaned.

[0079] The quantum well layer is a Ge quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising:

[0080] Further, such as Figure 5 As shown, Figure 5 The fourth schematic diagram of a partial structure of a Ge quantum bit provided by an embodiment of the present invention. A Ge quantum well layer 18 is prepared, the thickness of the Ge quantum well layer 18 is less than 50nm, and a two-dimensional hole gas is formed therein. The Ge quantum well layer 18 obtained at this time contains non-zero nuclear spin elements of the Ge element. These non-zero nuclear spin elements will have an adverse effect on the coherence of the quantum bit.

[0081] Therefore, in the embodiment of the present application, the non-zero nuclear spin elements in the Ge quantum well layer 18 are purified to reduce or remove the non-zero nuclear spin elements.

[0082] like Figure 6 As shown, Figure 6 A schematic diagram of a partial structure of a Ge quantum bit provided by an embodiment of the present invention. Based on the fact that the nuclear spin corresponding to the Ge element in the Ge quantum well layer 18 is zero 70 Ge isotope, using ion implantation 70 Ge isotopes are injected into the Ge quantum well layer 18 to form 70 Ge quantum well layer 19.

[0083] That is, using a focused ion beam 70 Ge is used as the target material, and the ion implantation method is used to 70 Ge isotopes are injected into the Ge quantum well layer 18 to remove other isotopes of Ge as much as possible. Obviously, the content of non-zero nuclear spin elements of Ge will also be reduced, or even completely removed, so as to achieve 70 Purification of Ge isotopes to improve 70 The abundance of Ge isotopes forms the purified 70 Ge quantum well layer 19.

[0084] Because in 70After the purification of Ge isotopes, polycrystalline may occur. Therefore, after the Ge quantum well layer 18 is processed, rapid thermal annealing can be used to perform solid phase epitaxial growth on the crystals after FIB bombardment to promote its single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time. The annealing temperature is about 1000°C and the annealing time is about 5s. The optional solid phase epitaxial growth parameters include processing temperature and processing time. The processing temperature is about 620°C and the processing time is about 10min.

[0085] Furthermore, in order to improve the quality of the film layer prepared subsequently, after the Ge quantum well layer 18 is treated, a mixed cleaning solution consisting of hydrofluoric acid, sulfuric acid and hydrogen peroxide may be used to clean the Ge quantum well layer 18. Figure 6 The structure shown is cleaned.

[0086] In an optional embodiment of the present invention, a protection layer may be formed on a side of the quantum well layer facing away from the substrate.

[0087] like Figure 7 As shown, Figure 7 The sixth schematic diagram of a partial structure of a Ge quantum bit provided by an embodiment of the present invention. The protective layer includes a thickness ranging from 10nm to 100nm. 70 Ge 0.8 28 Si 0.2 The top shielding layer 20 is used to isolate the impurities and noise from the upper part. The protective layer can also include a Si cap layer 21 with a thickness of about several nanometers to provide a more stable interface for the Ge quantum bit, solve the problem of instability of the germanium silicon material when encountering water vapor, and improve the service life and performance of the Ge quantum bit.

[0088] The preparation process of Si quantum bits is as follows:

[0089] The step of forming a first functional layer on one side of the substrate comprises:

[0090] like Figure 8 As shown, Figure 8 This is one of the partial structural diagrams of a Si quantum bit provided by an embodiment of the present invention. Ge is formed on one side of the substrate 11. 0.3 Si 0.7 Functional layer 22.

[0091] The substrate 11 includes but is not limited to a silicon substrate. Figure 8 As shown, Si quantum bits also include: Ge with gradient element content y Si 1-y In the layer 23, y gradually increases in the first direction, from 0 to 0.3. The first direction is perpendicular to the plane where the substrate 11 is located, and points from the substrate 11 to the first functional layer.

[0092] Ge with gradient element content y Si 1-y The thickness of layer 23 is about 2 μm-3 μm, which is mainly used to further annihilate dislocations in the Ge with gradient element content. y Si 1-y Layer 23.

[0093] After that, by reducing the surface roughness and chemical cleaning, the Ge y Si 1-y Ge with a fixed composition is grown on layer 23 0.3 Si 0.7 The functional layer 22 is used to fully relax the GeSi layer and shield the noise interference under the quantum well layer. 0.3 Si 0.7 The thickness of the functional layer 22 is about 500 nm.

[0094] At this time, the obtained Ge 0.3 Si 0.7 The functional layer 22 contains non-zero nuclear spin elements of Ge and non-zero nuclear spin elements of Si. These non-zero nuclear spin elements may have an adverse effect on the coherence of the quantum bit.

[0095] Therefore, in the embodiment of the present application, this Ge 0.3 Si 0.7 The non-zero nuclear spin elements in the functional layer 22 are purified to reduce or remove the non-zero nuclear spin elements.

[0096] The method of injecting the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer into the first functional layer by ion implantation based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer comprises:

[0097] like Fig. 9 As shown, Fig. 9 This is a schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention. 0.3 Si 0.7 The nuclear spin corresponding to the Ge element in the functional layer 22 is zero. 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.3 Si 0.7 The functional layer 22 is formed 70 Ge 0.3 Si 0.7 Functional layer 24.

[0098] That is, using a focused ion beam70 Ge is used as the target material, and the ion implantation method is used to 70 Ge isotope is implanted into the Ge 0.3 Si 0.7 In the functional layer 22, other isotopes of Ge are removed as much as possible. Obviously, the content of non-zero nuclear spin elements of Ge will also be reduced, or even completely removed, so as to achieve 70 Purification of Ge isotopes to improve 70 The abundance of Ge isotopes forms the purified 70 Ge 0.3 Si 0.7 Functional layer 24.

[0099] Because in 70 After the purification of Ge isotopes, polycrystalline may occur. 28 Before Si isotope purification, rapid thermal annealing can be used to perform solid phase epitaxial growth on the crystals after FIB bombardment to promote their single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time, the annealing temperature is about 1000°C, and the annealing time is about 5s. The optional parameters for solid phase epitaxial growth include processing temperature and processing time, the processing temperature is about 620°C, and the processing time is about 10min.

[0100] Further, such as Fig.10 As shown, Fig.10 This is a schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention. 0.3 Si 0.7 The nuclear spin corresponding to the Si element in the functional layer 22 is zero. 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.3 Si 0.7 The functional layer 24 is formed 70 Ge 0.3 28 Si 0.7 Functional layer 25.

[0101] That is, using a focused ion beam 28 Si is used as the target material, and ion implantation is used to 28 Si isotope implantation into the 70 Ge 0.3 Si 0.7 In the functional layer 24, other isotopes of Si are removed as much as possible. Obviously, the content of non-zero nuclear spin elements of Si will also be reduced, or even completely removed, so as to achieve 28 Purification of Si isotopes to improve28 The abundance of Si isotopes forms the purified 70 Ge 0.3 28 Si 0.7 Functional layer 25.

[0102] Because in 28 After Si isotope purification, polycrystalline may also occur. 28 After Si isotope purification, rapid thermal annealing can be used to perform solid phase epitaxial growth on the FIB-bombarded crystal to promote its single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time. The annealing temperature is about 1000°C and the annealing time is about 5s. The optional solid phase epitaxial growth parameters include processing temperature and processing time. The processing temperature is about 620°C and the processing time is about 10min.

[0103] In order to improve the quality of the film layer of the subsequent quantum well layer, the Ge 0.3 Si 0.7 After the functional layer 22 is treated, a mixed cleaning solution consisting of hydrofluoric acid, sulfuric acid and hydrogen peroxide may be used to clean the functional layer 22. Fig.10 The structure shown is cleaned.

[0104] The quantum well layer is a Si quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising:

[0105] Further, such as Fig.11 As shown, Fig.11 The fourth schematic diagram of a partial structure of a Si quantum bit provided by an embodiment of the present invention. A Si quantum well layer 26 is prepared, the thickness of the Si quantum well layer 26 is less than 50nm, and a two-dimensional hole gas is formed therein. The Si quantum well layer 26 obtained at this time contains non-zero nuclear spin elements of the Si element. These non-zero nuclear spin elements will have an adverse effect on the coherence of the quantum bit.

[0106] Therefore, in the embodiment of the present application, the non-zero nuclear spin elements in the Si quantum well layer 26 are purified to reduce or remove the non-zero nuclear spin elements.

[0107] like Fig.12 As shown, Fig.12 A schematic diagram of a partial structure of a Si quantum bit provided in an embodiment of the present invention. Based on the fact that the nuclear spin corresponding to the Si element in the Si quantum well layer 26 is zero 28 Si isotope, using ion implantation 28Si isotopes are implanted into the Si quantum well layer 26 to form 28 Si quantum well layer 27 .

[0108] That is, using a focused ion beam 28 Si is used as the target material, and ion implantation is used to 28 Si isotopes are injected into the Si quantum well layer 26 to remove other isotopes of Si as much as possible. Obviously, the content of non-zero nuclear spin elements of Si will also be reduced, or even completely removed, to achieve 28 Purification of Si isotopes to improve 28 The abundance of Si isotopes forms the purified 28 Si quantum well layer 27 .

[0109] Because in 28 After the Si isotope is purified, polycrystalline may occur. Therefore, after the Si quantum well layer is processed, rapid thermal annealing can be used to perform solid phase epitaxial growth on the crystal after FIB bombardment to promote its single crystalization. The optional rapid thermal annealing parameters include annealing temperature and annealing time. The annealing temperature is about 1000℃ and the annealing time is about 5s. The optional solid phase epitaxial growth parameters include processing temperature and processing time. The processing temperature is about 620℃ and the processing time is about 10min.

[0110] Furthermore, in order to improve the quality of the film layer prepared subsequently, after the Si quantum well layer 26 is treated, a mixed cleaning solution consisting of hydrofluoric acid, sulfuric acid and hydrogen peroxide may be used to clean the Si quantum well layer 26. Fig.12 The structure shown is cleaned.

[0111] In an optional embodiment of the present invention, a protection layer may be formed on a side of the quantum well layer facing away from the substrate.

[0112] like Fig.13 As shown, Fig.13 The sixth schematic diagram of a partial structure of a Si quantum bit provided by an embodiment of the present invention. The protective layer includes a thickness ranging from 10nm to 100nm. 70 Ge 0.3 28 Si 0.7 The top shielding layer 28 is used to isolate the impurities and noise from the upper part. The protective layer can also include a Si cap layer 21 with a thickness of about several nanometers to provide a relatively stable interface for the Si quantum bit, solve the problem of instability of the germanium silicon material when encountering water vapor, and improve the service life and performance of the Si quantum bit.

[0113] It can be seen from the above description that the method for preparing quantum bits provided by the embodiment of the present invention enriches zero nuclear spin elements by ion implantation, and by selecting suitable ion species, accurate control and removal of non-zero nuclear spin elements in the material are achieved. The method of purifying zero nuclear spin elements by ion implantation can significantly improve the decoherence time of quantum bits, thereby improving the performance and reliability of quantum computing. In general, purifying zero nuclear spin elements in quantum bits by ion implantation is a relatively innovative method that can solve the problem of short coherence time of quantum bits in solid materials, and provides new ideas and methods for realizing reliable quantum computing. It has the advantages of low cost, simple operation, and can achieve localized improvement of the abundance of zero nuclear spin elements.

[0114] Based on the above embodiment of the present invention, a quantum bit is further provided in another embodiment of the present invention. The quantum bit is obtained by the method for preparing the quantum bit described in the above embodiment.

[0115] Based on the above embodiments of the present invention, a quantum chip is provided in another embodiment of the present invention. The quantum chip includes the quantum bits described in the above embodiments.

[0116] It should be noted that the technical means for purifying specific isotopes in the method for preparing quantum bits provided in the embodiment of the present invention can also be applied to the preparation process of other devices, such as the preparation process of Si MOS devices.

[0117] The above is a detailed introduction to a quantum bit, a preparation method thereof, and a quantum chip provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0118] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0119] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0120] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a quantum bit, characterized in that: The method for preparing a quantum bit includes: providing a substrate; forming a first functional layer on one side of the substrate; Based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation; forming a quantum well layer on a side of the first functional layer facing away from the substrate, wherein the quantum well layer is in contact with the first functional layer; Based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, injecting the target isotope with zero nuclear spin corresponding to the element in the quantum well layer into the quantum well layer by ion implantation; The quantum bit is a Ge quantum bit, and the first functional layer is formed on one side of the substrate, including: A Ge 0.8 Si 0.2 Functional layer; The method of injecting the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer into the first functional layer by ion implantation based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer comprises: Based on the Ge 0.8 Si 0.2 The nuclear spin corresponding to the Ge element in the functional layer is zero 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.8 Si 0.2 Functional layer 70 Ge 0.8 Si 0.2 Functional layer; Based on the Ge 0.8 Si 0.2 The nuclear spin corresponding to the Si element in the functional layer is zero 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.8 Si 0.2 Functional layer 70 Ge 0.8 28 Si 0.2 Functional layer; The quantum well layer is a Ge quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising: Based on the fact that the nuclear spin corresponding to the Ge element in the Ge quantum well layer is zero 70 Ge isotope, using ion implantation 70 Ge isotopes are implanted into the Ge quantum well layer to form 70 Ge quantum well layer; The Ge quantum bit also includes: a first Ge layer, a second Ge layer, and a Ge layer with a gradient element content, which are sequentially stacked in the first direction. x Si 1-x layer, x gradually decreases in a first direction, changing from 1 to 0.8; the first direction is perpendicular to the plane where the substrate is located, and points from the substrate to the first functional layer; The growth temperature of the first Ge layer is lower than the growth temperature of the second Ge layer, and the first Ge layer and the second Ge layer are mainly used to suppress dislocation caused by lattice mismatch; The element content gradient Ge x Si 1-x The thickness of the layer ranges from about 1 μm to 2 μm, which is mainly used to further annihilate the dislocations in the Ge layer with a gradient content of the element. x Si 1-x Layer.

2. The method for preparing a quantum bit according to claim 1, characterized in that: The method for preparing the quantum bit also includes: A protection layer is formed on a side of the quantum well layer facing away from the substrate.

3. A method for preparing a quantum bit, characterized in that: The method for preparing a quantum bit includes: providing a substrate; forming a first functional layer on one side of the substrate; Based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer, the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer is injected into the first functional layer by ion implantation; forming a quantum well layer on a side of the first functional layer facing away from the substrate, wherein the quantum well layer is in contact with the first functional layer; Based on the target isotope with zero nuclear spin corresponding to the element in the quantum well layer, injecting the target isotope with zero nuclear spin corresponding to the element in the quantum well layer into the quantum well layer by ion implantation; The quantum bit is a Si quantum bit, and the first functional layer is formed on one side of the substrate, including: A Ge 0.3 Si 0.7 Functional layer; The method of injecting the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer into the first functional layer by ion implantation based on the target isotope with a nuclear spin of zero corresponding to the element in the first functional layer comprises: Based on the Ge 0.3 Si 0.7 The nuclear spin corresponding to the Ge element in the functional layer is zero 70 Ge isotope, using ion implantation 70 Ge isotope is implanted into the Ge 0.3 Si 0.7 Functional layer 70 Ge 0.3 Si 0.7 Functional layer; Based on the Ge 0.3 Si 0.7 The nuclear spin corresponding to the Si element in the functional layer is zero 28 Si isotope, using ion implantation 28 Si isotope implantation into the 70 Ge 0.3 Si 0.7 Functional layer 70 Ge 0.3 28 Si 0.7 Functional layer; The quantum well layer is a Si quantum well layer, and the target isotope with a nuclear spin of zero corresponding to the element in the quantum well layer is injected into the quantum well layer by ion implantation, comprising: Based on the fact that the nuclear spin corresponding to the Si element in the Si quantum well layer is zero 28 Si isotope, using ion implantation 28 Si isotopes are implanted into the Si quantum well layer to form 28 Si quantum well layer; The Si quantum bit also includes: Ge with a gradient element content y Si 1-y layer, y gradually increases in a first direction, changing from 0 to 0.3; the first direction is perpendicular to the plane where the substrate is located, and points from the substrate to the first functional layer; The element content gradient Ge y Si 1-y The thickness of the layer ranges from about 2 μm to 3 μm, which is mainly used to further annihilate the dislocations in the Ge layer with a gradient element content. y Si 1-y in the layer; The Ge 0.3 Si 0.7 The thickness of the functional layer is about 500 nm.

4. The method for preparing a quantum bit according to claim 3, characterized in that: The method for preparing the quantum bit also includes: A protection layer is formed on a side of the quantum well layer facing away from the substrate.

5. A quantum bit, characterized in that: The quantum bit is obtained by the method for preparing the quantum bit according to claim 1 or 2; Or, the quantum bit is obtained by the quantum bit preparation method described in claim 3 or 4.

6. A quantum chip, characterized in that: The quantum chip comprises the quantum bit described in claim 5.

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