Ion quantum state control system and control method

Abstract

The application discloses an ion quantum state control system and a control method. The control system comprises an ion trap chip for trapping an ion chain, wherein the arrangement direction of ions in the ion chain is parallel to the direction of a direct current electric field of the ion trap chip; a control light emitting device for emitting control light to perform spin control and phonon control on the ion chain, wherein the control light irradiates the ion chain along the arrangement direction of ions in the ion chain; and an addressing light emitting device for emitting addressing light to perform spin control on a set of ions in the ion chain so that the set of ions can be controlled or cannot be controlled by the control light, wherein the direction in which the addressing light irradiates the ion chain has a non-zero included angle with the arrangement direction of ions in the ion chain. The application provides an ion quantum state control system and a control method, which can achieve the purpose of independent addressing, can realize axial control on ions, can inhibit the influence of radio frequency power fluctuation in the system, 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 an ion quantum state control system and control method. Background Technology

[0002] Ion trap quantum computing features indistinguishability, full connectivity, and long coherence time. For the manipulation of quantum states of one-dimensional ions, optical addressing is usually used. However, as the number of ion qubits increases, radial phonon modes become more dense, and these radial modes often overlap twice. Other phonon modes can interfere with the manipulation 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 system and control method, which can achieve independent addressing, axial manipulation of ions, suppress the influence of radio frequency power fluctuations in the system, and also facilitate the expansion of the number of ion qubits.

[0004] According to one aspect of the present invention, an ion quantum state control system is provided, the control system comprising: an ion trap chip for trapping ion chains, wherein the ion arrangement direction in the ion chains is parallel to the DC electric field direction of the ion trap chip;

[0005] A control light emitting device for emitting control light to perform spin and phonon control on the ion chain, wherein the control light irradiates the ion chain along the ion arrangement direction in the ion chain;

[0006] An addressing light emitting device for emitting addressing light to spin-manipulate selected ions in the ion chain, making them either controllable or uncontrollable by the control light, wherein the direction in which the addressing light irradiates the ion chain has a non-zero angle with the ion arrangement direction in the ion chain.

[0007] Optionally, the addressing optical emitting device includes a first laser emitting unit and a first acousto-optic deflection unit;

[0008] The first laser emitting unit is used to generate the addressing light;

[0009] 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.

[0010] Optionally, the control system provided in this embodiment further includes:

[0011] A magnetic field generating device for applying a magnetic field to the ion chain to cause energy level splitting of the ions;

[0012] An initial light emitting device for emitting initial light to initialize the quantum state of the ion chain, wherein the direction in which the initial light irradiates the ion chain is the same as or opposite to the direction of the magnetic field.

[0013] Optionally, the addressing light emitting device further includes a first acousto-optic modulation unit, which is used to divide the addressing light into a first beam and a second beam, wherein the first beam and the second beam have a frequency difference;

[0014] The first acousto-optic deflection unit 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 ion.

[0015] Optionally, the addressing optical emitting device further includes a beam shaping unit, which is used to combine and shape the first beam and the second beam;

[0016] The first acousto-optic deflection unit is used to control the emission direction of the shaped beam of light so that the beam of light irradiates the set ion.

[0017] Optionally, the ion trap chip is used to trap multiple rows of the ion chains, and the multiple rows of ion chains are arranged in a coplanar manner;

[0018] The control light emitting device includes a second laser emitting unit, a second acousto-optic deflection unit, and a lens unit;

[0019] The second laser emitting unit is used to generate the control light;

[0020] The second acousto-optic deflection unit is used to control the transmission direction of the manipulation light so that the manipulation light irradiates the selected column of ion chains;

[0021] The lens unit is used to make the control light emitted by the second acousto-optic deflection unit collinear with the ion chains of the selected column.

[0022] Optionally, the control light emitting device further includes a second acousto-optic modulation unit, which is used to adjust the frequency of the control light incident on the second acousto-optic deflection unit so that the frequency of the control light output by the second acousto-optic deflection unit meets the requirements of spin control or phonon control.

[0023] Optionally, the first acousto-optic deflection unit and / or the second acousto-optic deflection unit may include a first acousto-optic deflector and a second acousto-optic deflector.

[0024] The frequency shifts of the light beam caused by the first and second acousto-optic deflectors cancel each other out.

[0025] Optionally, the first acousto-optic deflection unit includes a first acousto-optic deflector and a second acousto-optic deflector. The planes in which the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are fixed, and the planes in which the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are different from each other.

[0026] Optionally, the direction of the addressing light before entering the first acousto-optic deflection unit is perpendicular to the plane containing the multiple columns of ion chains.

[0027] 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 columns of the ion chain, 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 columns of the ion chain.

[0028] 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.

[0029] According to another aspect of the present invention, an ion quantum state control method is provided. The control method applies the ion quantum state control system provided in any embodiment of the present invention, and the control method includes:

[0030] Each ion in the ion chain includes an initial state and a control state, and each initial state includes a first Zeeman splitting state and a second Zeeman splitting state;

[0031] The addressing light, through Raman manipulation, causes the target 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;

[0032] The manipulation light causes each ion in the ion chain to transition from the second Zeeman splitting state to the control state, or from the control state to the second Zeeman splitting state, through Raman manipulation.

[0033] Optionally, 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 .

[0034] Optionally, the wavelength of the addressing light includes 397 nm;

[0035] The wavelength of the control light includes 729 nm.

[0036] This invention provides an ion quantum state control system, comprising an ion trap chip for trapping ion chains, a control light emitting device for emitting control light to perform spin and phonon manipulation on the ion chains, and an addressing light emitting device for emitting addressing light to perform spin manipulation on selected ions in the ion chains, enabling or preventing them from being manipulated by the control light. The ion arrangement direction in the ion chain is parallel to the DC electric field direction of the ion trap chip. The control light irradiates the ion chain along the ion arrangement direction, allowing for phonon and spin manipulation of the selected ions, thereby achieving axial phonon mode control. Ions are more easily distinguishable in phonon mode, which is beneficial for expanding the number of ion qubits and suppressing the influence of radio frequency power fluctuations. The direction of the addressing light irradiating the ion chain has a non-zero angle with the ion arrangement direction, allowing the addressing light to irradiate the desired ion and avoiding irradiation of all ions in the ion chain, thus achieving independent addressing. In summary, the ion quantum state control system provided in this embodiment 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.

[0037] 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

[0038] 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.

[0039] Figure 1 This is a schematic diagram of the structure of an ion quantum state control system provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of a trapped ion chain when ions are controlled, according to an embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the structure of an addressing optical emitting device according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the structure of another ion quantum state control system provided in an embodiment of the present invention;

[0043] Figure 5 This is a method provided according to embodiments of the present invention. 40Schematic diagram of the energy level distribution of Ca+ ions;

[0044] Figure 6 This is a schematic diagram of the structure of another addressing optical emitting device provided according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of the structure of another ion quantum state control system provided in an embodiment of the present invention;

[0046] Figure 8 This is a flowchart illustrating an ion quantum state control method according to an embodiment of the present invention;

[0047] Figure 9 This is a flowchart illustrating another method for controlling ion quantum states according to an embodiment of the present invention. Detailed Implementation

[0048] 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.

[0049] 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.

[0050] Figure 1 This is a schematic diagram of the structure of an ion quantum state control system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a trapped ion chain under controlled conditions according to an embodiment of the present invention. (Refer to...) Figure 1 and Figure 2The ion quantum state control system provided in this embodiment includes: an ion trap chip 210 for trapping ion chains 110, wherein the ion arrangement direction in the ion chains 110 is parallel to the DC electric field direction of the ion trap chip 210; a control light emitting device 220 for emitting control light 150 to perform spin control and phonon control on the ion chains 110, wherein the control light 150 irradiates the ion chains 110 along the ion arrangement direction in the ion chains 110; and an addressing light emitting device 230 for emitting addressing light 140 to perform spin control on selected ions in the ion chains 110 so that they can or cannot be controlled by the control light 150, wherein the direction in which the addressing light 140 irradiates the ion chains 110 has a non-zero angle with the ion arrangement direction in the ion chains 110.

[0051] Specifically, the ion trap chip 210 can apply a DC electric field to the ion chain 110 to trap it. The trapped ion chain 110 comprises multiple ions. (Continue to the previous section) Figure 2 Taking the trapped ion chain 110, which includes 5 ions, as an example, these 5 ions are sequentially numbered to form ion 1, ion 2, ion 3, ion 4 and ion 5.

[0052] The addressing light 140 emitted by the addressing light emitting device 230 irradiates at least a portion of the ions in the ion chain 110, and the ions irradiated by the addressing light 140 are designated ions. Figure 2 Ions 2 and 5 in the ion chain 110 are irradiated by addressing light 140, meaning ions 2 and 5 are designated ions. The direction in which the addressing light 140 irradiates the ion chain 110 forms a non-zero angle with the ion arrangement direction within the ion chain 110. This allows the addressing light 140 to irradiate only the designated ions to be controlled, preventing it from irradiating all ions, thus achieving independent addressing. The addressing light 140 can perform spin manipulation on the designated ions. The addressing light 140 can control the designated ions to transition from a first designated state to a second designated state, or from a second designated state to a first designated state.

[0053] The control light 150 emitted by the control light emitting device 220 can irradiate all ions in the trapped ion chain 110. The control light 150 can manipulate the energy level position of the set ion in the second set state. For example, the control light 150 can cause the set ion in the second set state to transition to the excited state, or it can cause the set ion in the excited state to transition to the second set state, thereby realizing the control of the set ion by the control light 150. When the control light 150 irradiates the set ion in the first set state, the set ion does not transition, that is, the set ion in the first set state cannot be controlled by the control light 150.

[0054] The control light 150 emitted by the control light emitting device 220 can perform phonon and spin manipulation on the selected ions, thereby achieving axial phonon mode control. Ions are easier to distinguish in phonon mode, which is beneficial for expanding the number of ion qubits and suppressing the influence of radio frequency power fluctuations. Ions are easier to distinguish in phonon mode because the complexity of distinguishing between different phonon modes is lower in axial phonon mode than in radial phonon mode as the number of ion qubits increases; it is also because axial mode is mainly affected by DC electric field, and the stability of DC electric field is higher than that of radio frequency electric field, which is beneficial for expanding the number of ion qubits.

[0055] This embodiment provides an ion quantum state control system, which includes an ion trap chip for trapping ion chains, a control light emitting device for emitting control light to perform spin and phonon manipulation on the ion chains, and an addressing light emitting device for emitting addressing light to perform spin manipulation on selected ions in the ion chains, enabling or preventing them from being manipulated by the control light. The ion arrangement direction in the ion chain is parallel to the DC electric field direction of the ion trap chip. The control light irradiates the ion chain along the ion arrangement direction, allowing for phonon and spin manipulation of the selected ions, thereby achieving axial phonon mode control. Ions are more easily distinguishable in phonon mode, which is beneficial for expanding the number of ion qubits and suppressing the influence of radio frequency power fluctuations. The direction of the addressing light irradiating the ion chain has a non-zero angle with the ion arrangement direction, allowing the addressing light to irradiate the desired ion and avoiding irradiation of all ions in the ion chain, thus achieving independent addressing. In summary, the ion quantum state control system provided in this embodiment 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.

[0056] Optional, Figure 3 This is a schematic diagram of an addressing optical emitting device according to an embodiment of the present invention. (Refer to...) Figure 3 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.

[0057] Specifically, the first laser emitting unit 231 includes a laser, which is a laser source that generates Raman-manipulated light.

[0058] Optional, Figure 4 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 4 and Figure 2The 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.

[0059] Specifically, the magnitude and direction of the magnetic field 120 experienced by each ion in the ion chain 110 are consistent, and the magnetic field strength can typically be several Gauss. After being subjected to the magnetic field 120, 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 5 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 5 ,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, that is, towards 40 When Ca+ ions are subjected to a magnetic field of 120°, 4S 1 / 2 Split into 4S 1 / 2 (+1 / 2) and 4S 1 / 2 (-1 / 2). 4P 1 / 2 and 3D 5 / 2 The energy level will also undergo Zeeman splitting, which is not shown in the diagram. The energy level difference between the second Zeeman splitting state and the first Zeeman splitting state can be defined as the set energy level difference. The set energy level difference is related to the magnetic field strength of magnetic field 120, and is defined 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 represents the magnetic field strength. It should be noted that the first set state in the above embodiments can be a first Zeeman splitting state, and the second set state can be a second Zeeman splitting state.

[0060] Continue to refer to Figure 2 Initial light 130 irradiates all ions in ion chain 110. Under the irradiation of initial light 130, ions in the second Zeeman-splitter state can transition to an excited state, but due to the short lifetime of the excited state, the ions will soon spontaneously radiate to either the first or second Zeeman-splitter state. Since initial light 130 is continuously pumping, after a period of time, all ions in the second Zeeman-splitter state will eventually be pumped to the first Zeeman-splitter state, thus completing the quantum state initialization operation of ion chain 110. (Continue to refer to...) Figure 2 and Figure 5 ,by 40Taking 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. It should be noted that... Figure 5 The arrows indicate the direction of ion transitions. Specifically, 4S... 1 / 2 This can be the initial state, 4S 1 / 2 (-1 / 2) can be the first Zeeman splitting state, 4S 1 / 2 (+1 / 2) could be the second Zeeman splitting state. 3D 5 / 2 Can be in control state, 4P 1 / 2 It can be an excited state.

[0061] Optional, Figure 6 This is a schematic diagram of another addressing optical emitting device according to an embodiment of the present invention, with reference to... Figure 6 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.

[0062] Specifically, the product of the frequency difference between the first beam and the second beam and Planck's constant is the set energy level difference. The energy level difference between the second Zeeman-splitter state and the first Zeeman-splitter state is the set energy level difference. This configuration allows ions in the first Zeeman-splitter state to transition to the same energy level under the influence of the first beam and ions in the second Zeeman-splitter state under the influence of the second beam. The first acousto-optic modulation unit 233 splits the addressing light into a first beam and a second beam, enabling the first and second beams to perform Raman manipulation on the set ions.

[0063] 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.

[0064] Optional, continue to refer to Figure 6 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.

[0065] Specifically, beam shaping unit 234 ensures that the first and second beams in the same addressing beam have the same transmission path, guaranteeing that the first and second beams corresponding to the same addressing beam illuminate the same set ion. Beam shaping unit 233 may include single-mode polarization-maintaining fiber, fiber coupling device, beam expander, collimator, focusing lens, waveplate, etc., to ensure the purity of laser polarization and transverse mode.

[0066] Optional, Figure 7 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 7 The ion trap chip provided in this embodiment is used to trap multiple rows of ion chains, and the multiple rows of ion chains are arranged in a coplanar manner; 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 the ion chain of the selected column; Lens unit 222 is used to make the control light emitted by the second acousto-optic deflection unit 221 collinear with the ion chain of the selected column.

[0067] Specifically, the ion quantum state control system provided in this embodiment can perform quantum state manipulation on a two-dimensional ion array. The manipulation light is deflected by the second acousto-optic deflection unit 221 and then further altered by a lens unit 222, ultimately ensuring that the manipulation light output by the manipulation light emitting device 220 is collinear with the ion chain of the selected column. This allows for spin and phonon manipulation of multiple ions in the selected column of the ion chain. 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.

[0068] Optional, continue to refer to Figure 7 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.

[0069] 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.

[0070] Optional, continue to refer to Figure 7 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.

[0071] 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.

[0072] Optional, continue to refer to Figure 7 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] This embodiment also provides an ion quantum state control method, which can be applied to the ion quantum state control system provided in any embodiment of the present invention. Figure 8 This is a flowchart illustrating an ion quantum state control method according to an embodiment of the present invention. (Refer to...) Figure 8 This embodiment provides a method for controlling ion quantum states, which includes the following steps:

[0079] S210. The addressing light, through Raman manipulation, causes the set ion to transition 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.

[0080] In this ion chain, each ion includes an initial state and a control state, and the initial state includes a first Zeeman split state and a second Zeeman split state. The energy level of the initial state is lower than the energy level of the control state, the energy level of the first Zeeman split state is lower than the energy level of the second Zeeman split state, and the energy level of the second Zeeman split state is lower than the energy level of the control state.

[0081] S220. The manipulating light causes each ion in the ion chain to transition from the second Zeeman splitting state to the control state, or from the control state to the second Zeeman splitting state, through Raman manipulation.

[0082] Specifically, the duration of the manipulator light can be controlled according to the Rabi oscillation period, which can cause the target 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.

[0083] The ion quantum state control method provided in this embodiment can achieve independent addressing, axial manipulation of ions, suppress the influence of radio frequency power fluctuations, and is also conducive to the expansion of the number of ion qubits.

[0084] Figure 9 This is a flowchart illustrating another method for controlling ion quantum states according to an embodiment of the present invention. (Refer to...) Figure 9 The ion quantum state control method provided in this embodiment includes the following steps:

[0085] 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.

[0086] 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.

[0087] S120. Apply initial light to multiple ions to initialize each ion to the first Zeeman splitting state.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] For details, please refer to [link / reference]. Figure 5 Under initial light 130, the second Zeeman split state (4S) 1 / 2 The ions in (+1 / 2) will not directly transition to the first Zeeman split state (4S). 1 / 2 (-1 / 2)), but instead first transitions to the excited state (4P). 1 / 2 However, due to the short lifetime of the excited state, the ion will soon spontaneously radiate to the first Zeeman split state or the second Zeeman split state.

[0092] 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.

[0093] For details, please refer to [link / reference]. Figure 5 ,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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] Optionally, the initial state is the ground state; the control state is the metastable state.

[0099] 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.

[0100] Optionally, the ions are 40 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 .

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] Optionally, the control light is used to perform phonon manipulation.

[0106] 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.

[0107] The ion quantum state control method provided in this embodiment has the same beneficial effects as the ion quantum state control system provided in any embodiment of the present invention. For technical details not covered in this embodiment, please refer to the ion quantum state control system provided in any embodiment of the present invention.

[0108] 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.

[0109] 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. An ion quantum state control system, characterized in that, include: An ion trap chip for trapping ion chains, wherein the ion arrangement direction in the ion chains is parallel to the DC electric field direction of the ion trap chip. A control light emitting device for emitting control light to perform spin and phonon control on the ion chain, wherein the control light irradiates the ion chain along the ion arrangement direction in the ion chain; An addressing light emitting device for emitting addressing light to spin-manipulate selected ions in the ion chain so that they can or cannot be manipulated by the manipulation light, wherein the direction in which the addressing light irradiates the ion chain has a non-zero angle with the ion arrangement direction in the ion chain. The addressing light emitted by the addressing light irradiates at least a portion of the ions in the ion chain, and the ions irradiated by the addressing light are designated ions.

2. The ion quantum state control system according to claim 1, 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.

3. The ion quantum state control system according to claim 2, characterized in that, Also includes: A magnetic field generating device for applying a magnetic field to the ion chain to cause energy level splitting of the ions; An initial light emitting device for emitting initial light to initialize the quantum state of the ion chain, wherein the direction in which the initial light irradiates the ion chain is the same as or opposite to the direction of the magnetic field.

4. The ion quantum state control system according to claim 3, characterized in that, The addressing light emitting device further includes a first acousto-optic modulation unit, which is used to divide the addressing light into a first beam and a second beam, wherein the first beam and the second beam have a frequency difference. The first acousto-optic deflection unit 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 ion.

5. The ion quantum state control system according to claim 4, characterized in that, The addressing optical emitting device further includes a beam shaping unit, which is used to combine and shape the first beam and the second beam; The first acousto-optic deflection unit is used to control the emission direction of the shaped beam of light so that the beam of light irradiates the set ion.

6. The ion quantum state control system according to claim 2, characterized in that, The ion trap chip is used to trap multiple columns of the ion chains, and the multiple columns of the ion chains are arranged in a coplanar manner; 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 manipulation light so that the manipulation light irradiates the selected column of ion chains; The lens unit is used to make the control light emitted by the second acousto-optic deflection unit collinear with the ion chains of the selected column.

7. The ion quantum state control system according to claim 6, characterized in that, The control light emitting device further includes a second acousto-optic modulation unit, which is used to adjust the frequency of the control light incident on the second acousto-optic deflection unit so that the frequency of the control light output by the second acousto-optic deflection unit meets the requirements of spin control or phonon control.

8. The ion quantum state control system according to claim 6, characterized in that, The first acousto-optic deflection unit and / or the second acousto-optic deflection unit include a first acousto-optic deflector and a second acousto-optic deflector. The frequency shifts of the light beam caused by the first and second acousto-optic deflectors cancel each other out.

9. The ion quantum state control system according to claim 6, characterized in that, The first acousto-optic deflection unit includes a first acousto-optic deflector and a second acousto-optic deflector. The planes in which the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are fixed, and the planes in which the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are different from each other.

10. The ion quantum state control system according to claim 9, characterized in that, The direction of the addressing light before entering the first acousto-optic deflection unit is perpendicular to the plane containing the multiple columns of ion chains.

11. The ion quantum state control system according to claim 10, characterized in that, 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 columns of the ion chain. 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 columns of the ion chain.

12. The ion quantum state control system according to claim 6, characterized in that, The direction of the control light before it enters 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.

13. A method for controlling ion quantum states, characterized in that, The ion quantum state control system according to any one of claims 1-12 is further comprising: Each ion in the ion chain includes an initial state and a control state, and each initial state includes a first Zeeman splitting state and a second Zeeman splitting state; The addressing light, through Raman manipulation, causes the target 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; The manipulation light causes each ion in the ion chain to transition from the second Zeeman splitting state to the control state, or from the control state to the second Zeeman splitting state, through Raman manipulation.

14. The ion quantum state control method according to claim 13, characterized in that, 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 .

15. The ion quantum state control method according to claim 14, characterized in that, The wavelength of the addressing light includes 397 nm; The wavelength of the control light includes 729 nm.

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