Ion quantum state control method and control system

Abstract

The application discloses an ion quantum state control method and a control system. The control method comprises the following steps: applying a magnetic field with a set magnetic field intensity to a plurality of ions in a confinement region to split an initial state in each ion into a first Zeeman split state and a second Zeeman split state; applying an initial light to the plurality of ions to initialize each ion to the first Zeeman split state; applying an addressing light to at least one set ion in the plurality of ions to make the set ion transition from the first Zeeman split state to the second Zeeman split state or transition from the second Zeeman split state to the first Zeeman split state; and applying a manipulation light to the plurality of ions to make the set ion transition from the second Zeeman split state to a control state or make the set ion transition from the control state to the second Zeeman split state. The application provides an ion quantum state control method and a control system, which can achieve the purpose of independent addressing, can realize axial manipulation of ions, can inhibit the influence of radio frequency power fluctuation, and is also beneficial to the expansion of the number of ion bits.

Description

Technical Field

[0001] This invention relates to the field of quantum technology, and in particular to a method and control system for controlling ion quantum states. Background Technology

[0002] Ion trap quantum computing features indistinguishability, full connectivity, and long coherence time. The quantum state control of ions is usually achieved using optical addressing. However, as the number of ion qubits increases, radial phonon modes become denser, and these modes often overlap. Other phonon modes can interfere with the control of a specific phonon, affecting fidelity and gate depth. Another drawback is that the stability of radial modes is greatly affected by radio frequency power, requiring frequent parameter calibration, which is inefficient. Summary of the Invention

[0003] This invention provides an ion quantum state control method and control system, which can achieve independent addressing, axial manipulation of ions, suppress the influence of radio frequency power fluctuations, and also facilitate the expansion of the number of ion qubits.

[0004] According to one aspect of the present invention, a method for controlling ion quantum states is provided, the method comprising:

[0005] A magnetic field of a predetermined strength is applied to multiple ions in a confinement region to split the initial state of each ion into a first Zeeman splitting state and a second Zeeman splitting state, wherein each ion includes an initial state and a control state;

[0006] Initial light is applied to the plurality of ions to initialize each ion to the first Zeeman splitting state;

[0007] An addressing light is applied to at least one of the plurality of ions to cause the set ion to transition from the first Zeeman split state to the second Zeeman split state, or from the second Zeeman split state to the first Zeeman split state;

[0008] Manipulation light is applied to the plurality of ions to cause the selected ion to transition from the second Zeeman split state to the control state, or to cause the selected ion to transition from the control state to the second Zeeman split state, wherein the transmission direction of the manipulation light is parallel to the axis of the plurality of ions, and the axis of the plurality of ions is the direction of the DC electric field of the ion trap.

[0009] Optionally, the addressing light includes a first beam and a second beam;

[0010] The product of the difference between the frequency of the first beam and the frequency of the second beam and Planck's constant is the set energy level difference, wherein the energy level of the second Zeeman split state and the energy level of the first Zeeman split state is the set energy level difference.

[0011] Optionally, the first beam and the second beam are combined and applied to the designated ion.

[0012] Optionally, applying initial light to the plurality of ions to initialize each ion to the first Zeeman splitting state includes:

[0013] An initial light is applied to the plurality of ions to cause ions in the second Zeeman split state to transition to an excited state, and ions in the excited state spontaneously transition to the first Zeeman split state or the second Zeeman split state.

[0014] Optionally, applying addressing light to at least one of the plurality of ions to cause the designated ion to transition from the first Zeeman split state to the second Zeeman split state, or from the second Zeeman split state to the first Zeeman split state, includes:

[0015] A first light beam is applied to the selected ion to cause the selected ion to transition from the first Zeeman split state to a decorated state corresponding to the excited state; wherein the energy level of the decorated state is greater than the energy level of the second Zeeman split state; the selected ion in the decorated state spontaneously transitions to the second Zeeman split state or the first Zeeman split state.

[0016] A second beam is applied to the designated ion to cause the designated ion to transition from the second Zeeman split state to the decorated state;

[0017] The selected ion can be transitioned from the first Zeeman splitting state to the second Zeeman splitting state, or from the second Zeeman splitting state to the first Zeeman splitting state, by Raman manipulation.

[0018] Optionally, when the plurality of ions are located in a one-dimensional ion chain, the transmission direction of the control light is parallel to the arrangement direction of the ions in the one-dimensional ion chain; the angle between the transmission direction of the addressing light and the arrangement direction of the ions in the one-dimensional ion chain is greater than 0 and less than or equal to 90°.

[0019] When the plurality of ions are located in a two-dimensional ion array, the beam surface of the control light is coplanar with the two-dimensional ion array; the angle between the beam surface of the addressing light and the two-dimensional ion array is greater than 0 and less than or equal to 90°.

[0020] Optionally, the initial state is the ground state;

[0021] The control state is a metastable state.

[0022] Optionally, the transmission direction of the initial light is parallel to the direction of the magnetic field of the set magnetic field strength.

[0023] Optionally, the ion is 40 Ca+ ions, the first Zeeman splitting state energy level is S 1 / 2 (-1 / 2), the second Zeeman splitting state energy level is S 1 / 2 (+1 / 2), the control state energy level is 3D 5 / 2 The excited state energy level is 4P. 1 / 2 .

[0024] Optionally, the initial light includes σ-light with a wavelength of 397 nm;

[0025] The wavelength of the addressing light includes 397 nm;

[0026] The wavelength of the control light includes 729 nm.

[0027] Optionally, the set magnetic field strength is less than 10 Gauss.

[0028] Optionally, the control light is used to perform phonon manipulation.

[0029] Optionally, the initial light is global light.

[0030] According to another aspect of the present invention, an ion quantum state control system is provided, which is used to implement the ion quantum state control method provided in any embodiment of the present invention;

[0031] The ion quantum state control system includes:

[0032] An ion trap chip for trapping the ion chain;

[0033] A control light emitting device for emitting the control light;

[0034] Addressing light emitting device for emitting the addressing light.

[0035] Optionally, the addressing optical emitting device includes a first laser emitting unit and a first acousto-optic deflection unit;

[0036] The first laser emitting unit is used to generate the addressing light;

[0037] The first acousto-optic deflection unit is used to control the emission direction of the addressing light so that the addressing light irradiates the set ion.

[0038] Optionally, the control light emitting device includes a second laser emitting unit, a second acousto-optic deflection unit, and a lens unit;

[0039] The second laser emitting unit is used to generate the control light;

[0040] The second acousto-optic deflection unit is used to control the transmission direction of the control light so that the control light illuminates the selected position;

[0041] The lens unit is used to make the control light emitted by the second acousto-optic deflection unit parallel to the direction of the DC electric field of the ion trap.

[0042] This invention provides a method for controlling ion quantum states. The method includes: first, applying a magnetic field of a predetermined strength to multiple ions in a confinement region to split the initial state of each ion into a first Zeeman split state and a second Zeeman split state; then, applying initial light to each ion in the confinement region to initialize all ions to the first Zeeman split state; next, applying addressing light to at least one designated ion among the multiple ions to cause the designated ion to transition from the first Zeeman split state to the second Zeeman split state, or vice versa, to address the ions to be manipulated; ions not addressed do not interact with the addressing light; finally, applying manipulation light to the multiple ions to cause the designated ion to transition from the second Zeeman split state to a control state, or vice versa. The manipulation light can illuminate each ion in the confinement region, and the transmission direction of the manipulation light is parallel to the axis of the multiple ions, which is the direction of the DC electric field of the ion trap. The manipulation light can achieve axial phonon mode control of the designated ions. In summary, this embodiment provides an ion quantum state control method that can achieve independent addressing, axial manipulation of ions, suppression of the influence of radio frequency power fluctuations, and expansion of the number of ion qubits.

[0043] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart illustrating an ion quantum state control method according to an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of a structure provided by an embodiment of the present invention, showing the controlled ion concentration in a confinement region.

[0047] Figure 3This is a method provided according to embodiments of the present invention. 40 Schematic diagram of the energy level distribution of Ca+ ions;

[0048] Figure 4 This is a schematic diagram of the structure of an ion quantum state control system provided in an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the structure of an addressing optical emitting device according to an embodiment of the present invention;

[0050] Figure 6 This is a schematic diagram of the structure of another ion quantum state control system provided in an embodiment of the present invention;

[0051] Figure 7 This is a schematic diagram of the structure of another addressing optical emitting device provided according to an embodiment of the present invention;

[0052] Figure 8 This is a schematic diagram of another ion quantum state control system provided according to an embodiment of the present invention. Detailed Implementation

[0053] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0054] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0055] Figure 1 This is a flowchart illustrating an ion quantum state control method according to an embodiment of the present invention. (Refer to...) Figure 1 The ion quantum state control method provided in this embodiment includes the following steps:

[0056] S110. Apply a magnetic field of a set magnetic field strength to multiple ions in the confinement region to split the initial state of each ion into a first Zeeman splitting state and a second Zeeman splitting state.

[0057] Each ion includes an initial state and a control state. The energy level of the initial state is lower than that of the control state. The energy level of the first Zeeman split state is lower than that of the second Zeeman split state, and the energy level of the second Zeeman split state is lower than that of the control state.

[0058] Specifically, before step S110, an ion trap chip is used to capture and confine a portion of ions (charged atoms or molecules) within a certain range, forming a confinement region. The confinement region includes multiple ions, and all multiple ions in the confinement region are confined.

[0059] The energy level difference between the second Zeeman split state and the first Zeeman split state is the set energy level difference. This set energy level difference is related to the set magnetic field strength and is denoted as ΔE = m. l μ B B, where ΔE is the defined energy level difference, m l μ is the magnetic quantum number. B B represents the Bohr magneton, and B is the set magnetic field strength.

[0060] Figure 2 This is a schematic diagram of a structure provided by an embodiment of the present invention, showing the controlled ion formation in a confinement region. (Refer to...) Figure 2 The confinement region 110 may include an ion chain. Taking five ions in the confinement region 110 as an example, these five ions are sequentially numbered as ion 1, ion 2, ion 3, ion 4, and ion 5. A magnetic field 120 of a predetermined magnetic field strength is applied to each ion in the confinement region 110. The magnetic field 120 provides Zeeman splitting energy levels. The magnitude and direction of the magnetic field experienced by each ion in the multiple ions are consistent, typically several Gauss. After being subjected to the magnetic field 120 of the predetermined magnetic field strength, the initial state of the ion is split by the magnetic field into a first Zeeman splitting state and a second Zeeman splitting state. Figure 3 This is a method provided according to embodiments of the present invention. 40 A schematic diagram of the energy level distribution of Ca+ ions, for reference. Figure 3 ,by 40 Taking Ca+ ions as an example, 4S 1 / 2 The two energy levels 4S 1 / 2 (+1 / 2) and 4S 1 / 2 (-1 / 2) is produced by the Zeeman effect of the magnetic field, 4P 1 / 2 and 3D 5 / 2 The energy level will also undergo Zeeman splitting, which is not shown in the figure.

[0061] Among them, 4S 1 / 2 As the initial state, 4S 1 / 2(-1 / 2) represents the first Zeeman splitting state, 4S 1 / 2 (+1 / 2) represents the second Zeeman splitting state. 3D 5 / 2 In control state, 4P 1 / 2 It is an excited state.

[0062] S120. Apply initial light to multiple ions to initialize each ion to the first Zeeman splitting state.

[0063] For details, please refer to [link / reference]. Figure 2 Initial light 130 illuminates all ions in the confinement region 110. The transmission direction of initial light 130 can be parallel to the direction of magnetic field 120. Under the illumination of initial light 130, ions in the second Zeeman-splitter state can transition to the excited state. However, due to the short lifetime of the excited state, the ions will soon spontaneously radiate back to the first or second Zeeman-splitter state. Because initial light 130 is constantly pumping, after a period of time, all ions in the second Zeeman-splitter state will eventually be pumped to the first Zeeman-splitter state. (Continue to refer to...) Figure 2 and Figure 3 ,by 40 Taking Ca+ ions as an example, initial light of 130 can cause 4S 1 / 2 The ion in (+1 / 2) transitions to 4P 1 / 2 In the middle, but 4P 1 / 2 Its lifetime is on the order of nanoseconds, and it will soon fall to 4 seconds through spontaneous emission. 1 / 2 On the two energy levels, that is, falling to 4S 1 / 2 (+1 / 2) Medium or 4S 1 / 2 (-1 / 2), but because the initial light 130 has been pumping for 4S 1 / 2 The ions in (+1 / 2) will eventually reach a state of 4S after about several microseconds. 1 / 2 (-1 / 2), thus completing the optical pumping process.

[0064] It should be noted that, Figure 3 The direction of each arrow indicates the transition direction of the ion.

[0065] S130. Apply addressing light to at least one of the plurality of ions to cause the set ion to transition from a first Zeeman split state to a second Zeeman split state, or from a second Zeeman split state to a first Zeeman split state.

[0066] For details, please refer to [link / reference]. Figure 2 The addressing beam 140 illuminates only a portion of the multiple ions in the confinement region 110, achieving independent addressing. The ions illuminated by the addressing beam 140 undergo only spin manipulation, not phonon manipulation. The addressing beam 140 is a focused beam with a small spot size, capable of altering the initial state of the selected ions, placing them in a controllable quantum state. (Continue to refer to...) Figure 2and Figure 3 ,by 40 Taking Ca+ ions as an example, addressing light 140 only illuminates ions 2 and ions 5. Addressing light 140 can perform Raman manipulation, which can convert the S+ ions in ions 2 and ions 5 into Ca+ ions. 1 / 2 (-1 / 2) jump to S 1 / 2 (+1 / 2) can also remove S from ion 2 and / or ion 5. 1 / 2 (+1 / 2) jump to S 1 / 2 (-1 / 2), while ions 1, 3, and 4, which are not irradiated by addressing light 140, remain in S. 1 / 2 (-1 / 2) in.

[0067] It should be noted that the ions irradiated by the addressing light 140 are the designated ions. Figure 2 Ions 2 and 5 are designated ions.

[0068] S140. Apply manipulation light to multiple ions to cause a set ion to transition from a second Zeeman splitting state to a control state, or to cause a set ion to transition from a control state to a second Zeeman splitting state.

[0069] Among them, continue to refer to Figure 2 The transmission direction of the control light 150 is parallel to the axis of the multiple ions, and the axis of the multiple ions is the direction of the DC electric field of the ion trap.

[0070] Specifically, the direction of the DC electric field in the ion trap is the direction in which the DC electric field is applied from the ion trap to the confinement region. The manipulation light 150 can illuminate all ions in the confinement region 110, performing spin manipulation and phonon manipulation (phonon manipulation is involved in quantum logic gate operations). In this embodiment, the transmission direction of the manipulation light 150 is set parallel to the axis of multiple ions, which can realize axial phonon mode manipulation of selected ions, suppress the influence of radio frequency power fluctuations, and make ions easier to distinguish in phonon mode, which is beneficial to the expansion of the number of ion qubits.

[0071] Ions are easier to distinguish in phonon modes because the complexity of distinguishing between phonon modes is lower than that of radial phonon modes as the number of ion qubits increases; it is also because axial modes are mainly affected by DC electric fields, and the stability of DC electric fields is higher than that of radio frequency electric fields, which is conducive to the expansion of the number of ion qubits.

[0072] The duration of the manipulator light 150 can be controlled according to the Rabi oscillation period, allowing the selected ion to transition from the second Zeeman splitting state to the control state, or vice versa. Ions in the first Zeeman splitting state do not react under the irradiation of the manipulator light 150. (Continue to refer to...) Figure 2 and Figure 3 ,by 40Taking Ca+ ions as an example, the control of light 150 performs electric quadrupole energy level control, coupling S 1 / 2 (+1 / 2) and D 5 / 2 The sub-level, while in S 1 / 2 (-1 / 2) ions do not react.

[0073] It should be noted that the set ion located in the first Zeeman split state does not undergo a transition under the irradiation of the control light 150 and remains in the first Zeeman split state. When it is necessary to control the set ion located in the first Zeeman split state, the control addressing light 140 irradiates the set ion, causing the set ion to transition from the first Zeeman split state to the second Zeeman split state.

[0074] This embodiment provides an ion quantum state control method. The method includes: first, applying a magnetic field of a predetermined strength to multiple ions in a confinement region to split the initial state of each ion into a first Zeeman split state and a second Zeeman split state; then, applying initial light to each ion in the confinement region to initialize all ions to the first Zeeman split state; next, applying addressing light to at least one designated ion among the multiple ions to cause the designated ion to transition from the first Zeeman split state to the second Zeeman split state, or vice versa, to address the ion to be manipulated; ions not addressed do not interact with the addressing light; finally, applying manipulation light to the multiple ions to cause the designated ion to transition from the second Zeeman split state to a control state, or vice versa. The manipulation light can illuminate each ion in the confinement region, and the transmission direction of the manipulation light is parallel to the axis of the multiple ions, which is the direction of the DC electric field of the ion trap. The manipulation light can achieve axial phonon mode control of the designated ions. In summary, this embodiment provides an ion quantum state control method that can achieve independent addressing, axial manipulation of ions, suppression of the influence of radio frequency power fluctuations, and expansion of the number of ion qubits.

[0075] Optionally, the addressing beam includes a first beam and a second beam. The product of the difference between the frequencies of the first and second beams and Planck's constant is the set energy level difference. The energy level difference between the second and first Zeeman-split states is also the set energy level difference. This configuration allows ions in the first and second Zeeman-split states to transition to the same energy level under the influence of the first and second beams, respectively. Both the first and second beams in the addressing beam irradiate the same ion, but the duration of their irradiation may differ.

[0076] Optionally, the wavelength of the first beam is equal to the wavelength of the second beam. This setting allows the first and second beams to exit from the same light emitter and reduces crosstalk between them. Furthermore, the first and second beams can be identical in all properties except for their frequencies. This setting ensures that the energy difference between the first and second beams is equal to the set energy level difference, ultimately guaranteeing that ions in the first Zeeman-split state transition to the same energy level under the influence of the first beam and ions in the second Zeeman-split state under the influence of the second beam.

[0077] Optionally, the first beam and the second beam are combined and applied to the target ion. This configuration can improve the brightness of the addressing light, ensure the quality of the addressing light, and also ensure that the first beam and the second beam have the same transmission path, ensuring that the first beam and the second beam illuminate the same target ion.

[0078] Optionally, applying initial light to multiple ions to initialize each ion to a first Zeeman split state includes: applying initial light to multiple ions to cause ions in a second Zeeman split state to transition to an excited state, and ions in the excited state to spontaneously transition to either the first Zeeman split state or the second Zeeman split state.

[0079] For details, please refer to [link / reference]. Figure 3 Under the initial light 130, the ions in the second Zeeman split state will not directly jump to the first Zeeman split state, but will first jump to the excited state. However, due to the short lifetime of the excited state, the ions will soon spontaneously radiate to the first Zeeman split state or the second Zeeman split state.

[0080] Optionally, applying an addressing light to at least one selected ion among a plurality of ions to cause the selected ion to transition from a first Zeeman split state to a second Zeeman split state, or from a second Zeeman split state to a first Zeeman split state, includes: applying a first light beam to the selected ion to cause the selected ion to transition from the first Zeeman split state to a decorated state corresponding to the excited state; wherein the energy level of the decorated state is greater than the energy level of the second Zeeman split state; the selected ion in the decorated state spontaneously transitions to the second Zeeman split state or the first Zeeman split state; applying a second light beam to the selected ion to cause the selected ion to transition from the second Zeeman split state to the decorated state; or causing the selected ion to transition from the first Zeeman split state to the second Zeeman split state, or from the second Zeeman split state to the first Zeeman split state, by Raman manipulation.

[0081] For details, please refer to [link / reference]. Figure 3 ,by 40 Taking Ca+ ions as an example, the first beam can direct the selected ions from S... 1 / 2 (-1 / 2) transition to the decorated state; the second beam can transfer the selected ion from S 1 / 2(+1 / 2) transitions to the decorated state, which has a lifetime on the order of nanoseconds. The ion in the decorated state quickly falls to 4 s⁻¹ via spontaneous emission. 1 / 2 At the two energy levels, the set ion can eventually be transitioned to the second Zeeman split state or the first Zeeman split state through Raman manipulation.

[0082] Optionally, when multiple ions are located in a one-dimensional ion chain, the transmission direction of the control light is parallel to the arrangement direction of the ions in the one-dimensional ion chain. This setting allows the control light to be the ion chain axial control light, with the axial direction being the direction of the DC electric field of the ion trap, thereby enabling the selected ion receiving the control light to perform spin control and phonon control.

[0083] Optionally, the angle between the transmission direction of the addressing light and the arrangement direction of the ions in the one-dimensional ion chain is greater than 0 and less than or equal to 90°. This setting can achieve the purpose of independent addressing.

[0084] Optionally, the angle between the transmission direction of the addressing light and the arrangement direction of the ions in the one-dimensional ion chain is equal to 90°. This setting facilitates calculation and addressing operations.

[0085] Optionally, when multiple ions are located in a two-dimensional ion array, the beam surface of the control light is coplanar with the two-dimensional ion array; the angle between the beam surface of the addressing light and the two-dimensional ion array is greater than 0 and less than or equal to 90°. With this setting, the set ions receiving the control light can perform spin control and phonon control, and independent addressing can also be achieved.

[0086] Optionally, the initial state is the ground state; the control state is the metastable state.

[0087] Specifically, the ground state and metastable state have relatively long durations. Setting the initial state as the ground state ensures that unaddressed ions are stably located in the first Zeeman split state, preventing unaddressed ions from interfering with addressed ions. Setting the initial state as the ground state and the control state as metastable states ensures that the control state and the second Zeeman split state are stable for a longer period of time. This prevents ions in the control state from rapidly and spontaneously transitioning to other states, and also prevents ions in the second Zeeman split state from rapidly and spontaneously transitioning to other states.

[0088] Optional, continue to refer to Figure 2 The transmission direction of the initial light 130 is parallel to the direction of the magnetic field 120 with the set magnetic field strength.

[0089] Specifically, the transmission direction of the initial light 130 can be the same as or opposite to the direction of the magnetic field 120 with the set magnetic field strength. Setting the transmission direction of the initial light 130 to be parallel to the direction of the magnetic field 120 with the set magnetic field strength can make the ions in the second Zeeman split state completely jump to the first Zeeman split state.

[0090] Optionally, the ions are40 The first Zeeman splitting state energy level of the Ca+ ion is S. 1 / 2 (-1 / 2), the second Zeeman splitting state energy level is S 1 / 2 (+1 / 2), the control state energy level is 3D 5 / 2 The excited state energy level is 4P. 1 / 2 .

[0091] Specifically, 40 Ca+ ions possess characteristics such as simple energy level structure, long metastable lifetime, and narrow natural linewidth. The control method provided in this embodiment can be used to... 40 Ca+ ions are controlled, in order to 40 When Ca+ ions are used in the field of quantum computing, they can further improve the performance of quantum computers.

[0092] Optionally, the initial light includes σ-light with a wavelength of 397 nm. This setting allows ions irradiated by the initial light to transition from the second Zeeman splitting state to the first Zeeman splitting state, achieving the effect of optical pumping.

[0093] Optionally, the wavelength of the addressing light includes 397nm. This shorter wavelength allows for a smaller focused spot of the addressing light. When the addressing light irradiates the target ion, it prevents the spot from overlapping with non-target ions, thus enabling the 397nm ultraviolet light to address individual ions. The maximum diameter of the spot of the addressing light irradiating the target ion is smaller than the distance between the ions.

[0094] Optionally, the wavelength of the control light can be 729 nm, which allows the selected ions irradiated by the control light to perform electric quadrupole level control.

[0095] Optionally, the magnetic field strength is set to be less than 10 Gauss. It can be seen that the magnetic field strength applied to the multiple ions in the trapped region is not too large. This can ensure that the initial state of the ions is split into the first Zeeman splitting state and the second Zeeman splitting state under the action of the magnetic field, and also avoid other phenomena of the ions under the action of a large magnetic field.

[0096] Optionally, the control light is used to perform phonon manipulation.

[0097] Optionally, the initial light can be global light. This setting ensures that every ion in the trapped region is illuminated by the initial light, thereby ensuring that all ions in the trapped region are initialized to the first Zeeman splitting state.

[0098] This embodiment also provides an ion quantum state control system, which is used to implement the ion quantum state control method provided in any embodiment of the present invention. Figure 4 A schematic diagram of the ion quantum state control system provided in an embodiment of the present invention is shown below. Figure 4The ion quantum state control system includes: an ion trap chip 210 for trapping ion chains; a control light emitting device 220 for emitting control light; and an address light emitting device 230 for emitting address light.

[0099] This embodiment provides an ion quantum state control system that can achieve independent addressing, axial manipulation of ions, suppress the influence of radio frequency power fluctuations, and also facilitate the expansion of the number of ion qubits.

[0100] Optional, Figure 5 This is a schematic diagram of an addressing optical emitting device according to an embodiment of the present invention. (Refer to...) Figure 5 The addressing light emitting device 230 provided in this embodiment includes a first laser emitting unit 231 and a first acousto-optic deflection unit 232; the first laser emitting unit 231 is used to generate addressing light; the first acousto-optic deflection unit 232 is used to control the emission direction of the addressing light so that the addressing light irradiates the set ions.

[0101] Specifically, the first laser emitting unit 231 includes a laser, which is a laser source that generates Raman-manipulated light.

[0102] Optional, Figure 6 This is a schematic diagram of another ion quantum state control system provided according to an embodiment of the present invention, with reference to... Figure 6 and Figure 2 The ion quantum state control system provided in this embodiment further includes: a magnetic field generating device 240 for applying a magnetic field 120 to the ion chain 110 to cause energy level splitting of the ions; and an initial light emitting device 250 for emitting initial light 130 to initialize the quantum state of the ion chain 110, wherein the direction of the initial light 130 irradiating the ion chain 110 is the same as or opposite to the direction of the magnetic field 120.

[0103] Optional, Figure 7 This is a schematic diagram of another addressing optical emitting device according to an embodiment of the present invention, with reference to... Figure 7 The addressing light emitting device 230 also includes a first acousto-optic modulation unit 233, which is used to divide the addressing light into a first beam and a second beam, the first beam and the second beam having a frequency difference; and a first acousto-optic deflection unit 232, which is used to control the emission direction of the first beam and the second beam, so that the first beam and the second beam irradiate the set ions.

[0104] Optional, continue to refer to Figure 7 The addressing light emitting device 230 also includes a beam shaping unit 234, which is used to combine and shape the first beam and the second beam; the first acousto-optic deflection unit 232 is used to control the emission direction of the combined beam after shaping so that the combined beam irradiates the set ions.

[0105] Optional, Figure 8 This is a schematic diagram of another ion quantum state control system provided according to an embodiment of the present invention, with reference to... Figure 8 The control light emitting device 220 includes a second laser emitting unit ( Figure 7 (Not shown in the image) Second acousto-optic deflection unit 221 and lens unit 222; Second laser emitting unit is used to generate control light; Second acousto-optic deflection unit 221 is used to control the transmission direction of control light so that control light irradiates a selected position; Lens unit 222 is used to make the control light emitted by the second acousto-optic deflection unit 221 parallel to the DC electric field direction of the ion trap.

[0106] Specifically, the ion trap chip provided in this embodiment is used to trap multiple rows of ion chains, which are arranged coplanarly. The ion quantum state control system provided in this embodiment can perform quantum state manipulation on a two-dimensional ion array. The second acousto-optic deflection unit 221 is used to control the transmission direction of the manipulation light, so that the manipulation light irradiates the selected row of ion chains; the lens unit 222 is used to make the manipulation light emitted from the second acousto-optic deflection unit 221 collinear with the selected row of ion chains. After the manipulation light is deflected by the second acousto-optic deflection unit 221, it passes through a lens unit 222 to further change the direction of the light path, ultimately making the manipulation light output by the manipulation light emitting device 220 collinear with the selected row of ion chains, thereby enabling spin manipulation and phonon manipulation of multiple ions in the selected row of ion chains. The lens unit 222 includes a lens, the focal point of which is located at the convergence point of the emitted light from the second acousto-optic deflection unit 221.

[0107] Optional, continue to refer to Figure 8 The control light emitting device 220 also includes a second acousto-optic modulation unit 223, which is used to adjust the frequency of the control light incident on the second acousto-optic deflection unit 222 so that the frequency of the control light output by the second acousto-optic deflection unit 222 meets the requirements of spin control or phonon control.

[0108] Specifically, when spin manipulation of the ion chain is required, the second acousto-optic modulation unit 223 adjusts the frequency of the control light incident on the second acousto-optic deflection unit 222 to the target frequency required for spin manipulation. When phonon manipulation of the ion chain is required, the second acousto-optic modulation unit 223 adjusts the frequency of the control light incident on the second acousto-optic deflection unit 222 to the target frequency required for phonon manipulation, thereby improving the control effect of the control light on the ion chain.

[0109] Optional, continue to refer to Figure 8 The first acousto-optic deflection unit 232 and / or the second acousto-optic deflection unit includes a first acousto-optic deflector 2321 and a second acousto-optic deflector 2322, and the frequency shift of the light beam by the first acousto-optic deflector 2321 and the second acousto-optic deflector 2322 cancels each other out.

[0110] Specifically, the frequency shifts of the light beam caused by the first and second acousto-optic deflectors 2321 and 2322 in the first acousto-optic deflection unit 232 cancel each other out, ensuring that the frequency of the addressing light emitted from the first acousto-optic deflection unit 232 is equal to the target frequency corresponding to the addressing light. Similarly, the frequency shifts of the light beam caused by the first and second acousto-optic deflectors in the second acousto-optic deflection unit 221 cancel each other out, ensuring that the frequency of the control light emitted from the second acousto-optic deflection unit 221 is equal to the target frequency corresponding to the control light.

[0111] Optional, continue to refer to Figure 8 The first acoustic-optical deflection unit 232 includes a first acoustic-optical deflector 2321 and a second acoustic-optical deflector 2322. The planes in which the deflection directions of the first acoustic-optical deflector 2321 and the second acoustic-optical deflector 2322 are located are fixed, and the planes in which the deflection directions of the first acoustic-optical deflector 2321 and the second acoustic-optical deflector 2322 are located are different from each other.

[0112] Specifically, the plane containing the deflection direction refers to the plane containing the fan-shaped area formed by beams with different deflection angles. The plane containing the deflection direction of the beam by the first acousto-optic deflector 2321 and the plane containing the deflection direction of the beam by the second acousto-optic deflector 2322 have a non-zero angle, which can be 90°, thereby enabling the first acousto-optic deflection unit 232 to address the set ions in the two-dimensional ion array.

[0113] Optionally, the direction of the addressing light before entering the first acousto-optic deflection unit is perpendicular to the plane containing the multiple ion chains. This setting can expand the deflection angle range of the addressing light by the first acousto-optic deflection unit.

[0114] Optionally, the plane containing the deflection direction of the first acousto-optic deflector is parallel to the ion arrangement direction in the ion chain and perpendicular to the plane containing the multiple ion chains, and the plane containing the deflection direction of the second acousto-optic deflector is perpendicular to the ion arrangement direction in the ion chain and perpendicular to the plane containing the multiple ion chains.

[0115] Specifically, the first acousto-optic deflector can deflect the addressing light vertically, and the second acousto-optic deflector can deflect the addressing light horizontally, thereby enabling addressing of the two-dimensional ion array.

[0116] Optionally, the direction of the control light before entering the second acousto-optic deflection unit is parallel to the ion arrangement direction in the ion chain and collinear with the optical axis of the lens unit. This setting can expand the deflection angle range of the control light by the second acousto-optic deflection unit.

[0117] The ion quantum state control system provided in this embodiment has the same beneficial effects as the ion quantum state control method provided in any embodiment of the present invention. For technical details not covered in this embodiment, please refer to the ion quantum state control method provided in any embodiment of the present invention.

[0118] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0119] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for controlling ion quantum states, characterized in that, include: A magnetic field of a predetermined strength is applied to multiple ions in a confinement region to split the initial state of each ion into a first Zeeman splitting state and a second Zeeman splitting state, wherein each ion includes an initial state and a control state; Initial light is applied to the plurality of ions to initialize each ion to the first Zeeman splitting state; An addressing light is applied to at least one of the plurality of ions to cause the set ion to transition from the first Zeeman split state to the second Zeeman split state, or from the second Zeeman split state to the first Zeeman split state; Manipulation light is applied to the plurality of ions to cause the selected ion to transition from the second Zeeman split state to the control state, or to cause the selected ion to transition from the control state to the second Zeeman split state, wherein the transmission direction of the manipulation light is parallel to the axis of the plurality of ions to achieve axial phonon mode manipulation of the selected ion, and the axis of the plurality of ions is the direction of the DC electric field of the ion trap. The addressing light includes a first beam and a second beam; The wavelength of the first beam is equal to the wavelength of the second beam, and the product of the difference between the frequency of the first beam and the frequency of the second beam and Planck's constant is the set energy level difference, wherein the energy level of the second Zeeman split state and the energy level of the first Zeeman split state is the set energy level difference. When the plurality of ions are located in a one-dimensional ion chain, the transmission direction of the control light is parallel to the arrangement direction of the ions in the one-dimensional ion chain; the angle between the transmission direction of the addressing light and the arrangement direction of the ions in the one-dimensional ion chain is greater than 0 and less than or equal to 90°. When the plurality of ions are located in a two-dimensional ion array, the beam surface of the control light is coplanar with the two-dimensional ion array; the angle between the beam surface of the addressing light and the two-dimensional ion array is greater than 0 and less than or equal to 90°.

2. The ion quantum state control method according to claim 1, characterized in that, The first beam and the second beam are combined and applied to the designated ion.

3. The ion quantum state control method according to claim 1, characterized in that, The step of applying initial light to the plurality of ions to initialize each ion to the first Zeeman splitting state includes: An initial light is applied to the plurality of ions to cause ions in the second Zeeman split state to transition to an excited state, and ions in the excited state spontaneously transition to the first Zeeman split state or the second Zeeman split state.

4. The ion quantum state control method according to claim 3, characterized in that, Applying addressing light to at least one designated ion among the plurality of ions to cause the designated ion to transition from the first Zeeman split state to the second Zeeman split state, or from the second Zeeman split state to the first Zeeman split state, includes: A first light beam is applied to the selected ion to cause the selected ion to transition from the first Zeeman split state to a decorated state corresponding to the excited state; wherein the energy level of the decorated state is greater than the energy level of the second Zeeman split state; the selected ion in the decorated state spontaneously transitions to the second Zeeman split state or the first Zeeman split state. A second beam is applied to the designated ion to cause the designated ion to transition from the second Zeeman split state to the decorated state; The selected ion can be transitioned from the first Zeeman splitting state to the second Zeeman splitting state, or from the second Zeeman splitting state to the first Zeeman splitting state, by Raman manipulation.

5. The ion quantum state control method according to claim 1, characterized in that, The initial state is the ground state; The control state is a metastable state.

6. The ion quantum state control method according to claim 1, characterized in that, The transmission direction of the initial light is parallel to the direction of the magnetic field with the set magnetic field strength.

7. The ion quantum state control method according to claim 3, characterized in that, The ions are 40 Ca+ ions, the first Zeeman splitting state energy level is S 1 / 2 (-1 / 2), the second Zeeman splitting state energy level is S 1 / 2 (+1 / 2), the control state energy level is 3D 5 / 2 The excited state energy level is 4P. 1 / 2 .

8. The ion quantum state control method according to claim 7, characterized in that, The initial light includes σ-light with a wavelength of 397 nm; The wavelength of the addressing light includes 397 nm; The wavelength of the control light includes 729 nm.

9. The ion quantum state control method according to claim 1, characterized in that, The set magnetic field strength is less than 10 Gauss.

10. The ion quantum state control method according to claim 1, characterized in that, The control light is used to perform phonon manipulation.

11. The ion quantum state control method according to claim 1, characterized in that, The initial light is global light.

12. An ion quantum state control system, characterized in that, The ion quantum state control system is used to implement the ion quantum state control method according to any one of claims 1-11; The ion quantum state control system includes: An ion trap chip for trapping the ion chain; A control light emitting device for emitting the control light; Addressing light emitting device for emitting the addressing light.

13. The control system according to claim 12, characterized in that, The addressing optical emitting device includes a first laser emitting unit and a first acousto-optic deflection unit; The first laser emitting unit is used to generate the addressing light; The first acousto-optic deflection unit is used to control the emission direction of the addressing light so that the addressing light irradiates the set ion.

14. The control system according to claim 12, characterized in that, The control light emitting device includes a second laser emitting unit, a second acousto-optic deflection unit, and a lens unit; The second laser emitting unit is used to generate the control light; The second acousto-optic deflection unit is used to control the transmission direction of the control light so that the control light illuminates the selected position; The lens unit is used to make the control light emitted by the second acousto-optic deflection unit parallel to the direction of the DC electric field of the ion trap.

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