Ion quantum state control system and control method

Abstract

The invention discloses an ion quantum state control system and method, and the system comprises an ion trap chip which is used for trapping an ion chain, and the arrangement direction of ions in the ion chain is parallel to the direction of a DC electric field of the ion trap chip. The control light emitting device is used for emitting control light to perform spinning control and phonon control on the ion chain, and the control light irradiates the ion chain along the ion arrangement direction in the ion chain; the addressing light emitting device is used for emitting addressing light to carry out spinning control on set ions in the ion chain so that the set ions can be controlled or cannot be controlled by the control light, and an included angle which is not zero is formed between the direction in which the addressing light irradiates the ion chain and the arrangement direction of the ions in the ion chain. The invention 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, inhibits 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] The present invention relates to the field of quantum technology, and in particular to an ion quantum state control system and a control method. Background Art

[0002] Ion trap quantum computing is characterized by complete homogeneity, full connectivity, and long coherence time. Optical addressing is usually used to manipulate the quantum state of one-dimensional ions. However, as the number of ion quantum bits increases, the radial phonon modes become denser, and the radial modes are often doubly overlapped. Other phonon modes will interfere with the manipulation of a specific phonon, affecting the fidelity and gate depth. Another drawback is that the stability of the radial mode will be greatly affected by the RF power, requiring frequent parameter calibration, which is inefficient. Summary of the invention

[0003] The present invention provides an ion quantum state control system and control method, which can achieve the purpose of independent addressing, realize axial manipulation of ions, suppress the influence of radio frequency power fluctuations in the system, and is also conducive to the expansion of the number of ion bits.

[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 of the ions in the ion chain 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 control 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 is used to emit addressing light to control the spin of set ions in the ion chain so that they can or cannot be controlled by the control light, and the direction in which the addressing light irradiates the ion chain has an angle that is not zero with the direction in which the ions in the ion chain are arranged.

[0007] Optionally, the addressing light 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 ions.

[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 is used 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, the first acousto-optic modulation unit is used to divide the addressing light into a first light beam and a second light beam, the first light beam and the second light beam having a frequency difference;

[0014] The first acousto-optic deflection unit is used to control the emission directions of the first light beam and the second light beam so that the first light beam and the second light beam irradiate the set ions.

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

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

[0017] Optionally, the ion trap chip is used to trap multiple columns of ion chains, and the multiple columns of ion chains are arranged in the same plane;

[0018] The control light emitting device comprises 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 control light so that the control light irradiates the ion chain of the selected column;

[0021] The lens unit is used to make the manipulation 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 also 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 includes a first acousto-optic deflector and a second acousto-optic deflector;

[0024] The frequency shifts of the light beam caused by the first acousto-optic deflector and the second acousto-optic deflector 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 where the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are fixed, and the planes where 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 where the multiple columns of ion chains are located.

[0027] Optionally, the plane where the deflection direction of the first acousto-optic deflector lies is parallel to the ion arrangement direction in the ion chain and perpendicular to the plane where multiple columns of the ion chains lie, and the plane where the deflection direction of the second acousto-optic deflector lies is perpendicular to the ion arrangement direction in the ion chain and perpendicular to the plane where multiple columns of the ion chains lie.

[0028] Optionally, the direction of the manipulation light before entering the second acousto-optic deflection unit is parallel to the ion arrangement direction in the ion chain and is collinear with the optical axis of the lens unit.

[0029] According to another aspect of the present invention, a method for controlling an ion quantum state is provided. The control method applies the ion quantum state control system provided by 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 the initial state includes a first Zeeman splitting state and a second Zeeman splitting state;

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

[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, 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 manipulation light includes 729 nm.

[0036] An embodiment of the present invention 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 control and phonon control on the ion chain, and an addressing light emitting device for emitting addressing light to perform spin control on set ions in the ion chain so that they can or cannot be controlled by the control light. Among them, the ion arrangement direction in the ion chain is parallel to the DC electric field direction of the ion trap chip, and the control light irradiates the ion chain along the ion arrangement direction in the ion chain. The control light can perform phonon control and spin control on the set ions, thereby realizing axial phonon mode control. Ions are easier to distinguish in the phonon mode, which is conducive to the expansion of the number of ion bits and can also suppress the influence of radio frequency power fluctuations. The direction in which the addressing light irradiates the ion chain has an angle that is not zero with the ion arrangement direction in the ion chain, so that the addressing light can irradiate the ions to be controlled, avoiding the addressing light irradiating all ions in the ion chain, and achieving the purpose of independent addressing. In summary, the ion quantum state control system provided in this embodiment can achieve the purpose of independent addressing, realize axial manipulation of ions, suppress the influence of RF power fluctuations, and is also conducive to the expansion of the number of ion bits.

[0037] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 is a schematic structural diagram of an ion quantum state control system provided according to an embodiment of the present invention;

[0040] Figure 2 is a schematic structural diagram of ions in a trapped ion chain being controlled according to an embodiment of the present invention;

[0041] Figure 3 is a schematic structural diagram of an addressing light emitting device provided according to an embodiment of the present invention;

[0042] Figure 4 is a schematic structural diagram of another ion quantum state control system provided according to an embodiment of the present invention;

[0043] Figure 5 According to an embodiment of the present invention, 40Schematic diagram of the energy level distribution of Ca+ ions;

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

[0045] Figure 7 is a schematic structural diagram of another ion quantum state control system provided according to an embodiment of the present invention;

[0046] Figure 8 is a schematic flow chart of an ion quantum state control method provided according to an embodiment of the present invention;

[0047] Fig. 9 It is a flow chart of another ion quantum state control method provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Figure 1 is a schematic diagram of the structure of an ion quantum state control system provided according to an embodiment of the present invention, Figure 2 is a schematic diagram of a structure when ions in a trapped ion chain are controlled according to an embodiment of the present invention, with reference to Figure 1 and Figure 2The ion quantum state control system provided in this embodiment includes: an ion trap chip 210 for trapping an ion chain 110, wherein the arrangement direction of ions in the ion chain 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 chain 110, wherein the control light 150 irradiates the ion chain 110 along the arrangement direction of ions in the ion chain 110; an addressing light emitting device 230 for emitting addressing light 140 to perform spin control on set ions in the ion chain 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 chain 110 has an angle that is not zero with the arrangement direction of ions in the ion chain 110.

[0051] Specifically, the ion trap chip 210 can apply a DC electric field to the ion chain 110 to trap the ion chain 110. The trapped ion chain 110 includes a plurality of ions. Figure 2 Taking the trapped ion chain 110 including 5 ions as an example, these 5 ions are numbered in sequence 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 part of the ions in the ion chain 110 , and the ions irradiated by the addressing light 140 are set ions. Figure 2 Ions 2 and 5 in the chain 110 are irradiated by the addressing light 140, that is, ions 2 and 5 are set ions. The direction in which the addressing light 140 irradiates the ion chain 110 is set to have an angle that is not 0 with the ion arrangement direction in the ion chain 110, so that the addressing light 140 can irradiate the set ions to be manipulated, and avoid the addressing light 140 irradiating all ions, thereby achieving the effect of independent addressing. The addressing light 140 can perform spin manipulation on the set ions. The addressing light 140 can control the set ions to transition from the first set state to the second set state, or from the second set state to the first set state.

[0053] The manipulation light 150 emitted by the manipulation light emitting device 220 can irradiate all ions in the trapped ion chain 110. The manipulation light 150 can manipulate the energy level position of the set ion in the second set state. For example, the manipulation light 150 can make the set ion in the second set state transition to the excited state, and can also make the set ion in the excited state transition to the second set state, thereby realizing the manipulation of the set ion by the manipulation light 150. When the manipulation 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 manipulated by the manipulation light 150.

[0054] The control light 150 emitted by the control light emitting device 220 can perform phonon control and spin control on the set ions, thereby realizing axial phonon mode control. Ions are easier to distinguish in the phonon mode, which is beneficial to the expansion of the number of ion bits and can also suppress the influence of RF power fluctuations. Ions are easier to distinguish in the phonon mode because the complexity of the distinction between axial phonon modes is lower than that of radial phonon modes as the number of ion quantum bits increases; it is also because the axial mode is mainly affected by the DC electric field, and the stability of the DC electric field is higher than that of the RF electric field, which is beneficial to the expansion of the number of ion bits.

[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 control and phonon control on the ion chain, and an addressing light emitting device for emitting addressing light to perform spin control on set ions in the ion chain so that they can or cannot be controlled by the control light. Among them, the ion arrangement direction in the ion chain is parallel to the DC electric field direction of the ion trap chip, and the control light irradiates the ion chain along the ion arrangement direction in the ion chain. The control light can perform phonon control and spin control on the set ions, thereby realizing axial phonon mode control. Ions are easier to distinguish in the phonon mode, which is conducive to the expansion of the number of ion bits and can also suppress the influence of RF power fluctuations. The direction in which the addressing light irradiates the ion chain has an angle that is not zero with the ion arrangement direction in the ion chain, so that the addressing light can irradiate the ions to be controlled, avoiding the addressing light irradiating all ions in the ion chain, and achieving the purpose of independent addressing. In summary, the ion quantum state control system provided in this embodiment can achieve the purpose of independent addressing, realize axial manipulation of ions, suppress the influence of RF power fluctuations, and is also conducive to the expansion of the number of ion bits.

[0056] Optional, Figure 3 is a schematic diagram of the structure of an addressing light emitting device provided according to an embodiment of the present invention, with reference 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 for generating Raman manipulation light.

[0058] Optional, Figure 4 is a schematic diagram of the structure 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 also 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; an initial light emitting device 250 for emitting initial light 130 to initialize the quantum state of the ion chain 110, and the direction in which the initial light 130 irradiates 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 to which each ion in the ion chain 110 is subjected are consistent, and the magnetic field strength is usually several Gauss. After the ions are subjected to the magnetic field 120, the initial state of the ions is split by the magnetic field into a first Zeeman split state and a second Zeeman split state. Figure 5 According to an embodiment of the present invention, 40 Schematic diagram of the energy level distribution of Ca+ ions, see Figure 5 ,by 40 For example, Ca+ ions, 4S 1 / 2 Two energy levels of 4S 1 / 2 (+1 / 2) and 4S 1 / 2 (-1 / 2) is produced by the Zeeman effect of the magnetic field, that is, 40 After 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 of the second Zeeman splitting state will also produce Zeeman splitting, which is not shown in the figure. The energy level difference between the energy level of the second Zeeman splitting state and the energy level of the first Zeeman splitting state can be a set energy level difference. The set energy level difference is related to the magnetic field strength of the magnetic field 120, and the set energy level difference is ΔE=m l μ B B, where △E is the set energy level difference, m l is the magnetic quantum number, μ B is the Bohr magneton, and B is the magnetic field intensity. It should be noted that the first setting state in the above embodiment may be the first Zeeman splitting state, and the second setting state may be the second Zeeman splitting state.

[0060] Continue to refer Figure 2 , the initial light 130 irradiates all the ions in the ion chain 110. Under the irradiation of the initial light 130, the ions in the second Zeeman splitting state can transition to the excited state, but due to the short lifetime of the excited state, the ions will soon spontaneously radiate and fall to the first Zeeman splitting state or the second Zeeman splitting state. Since the initial light 130 is always pumping, after a period of time, all the ions in the second Zeeman splitting state will eventually be pumped to the first Zeeman splitting state, so as to complete the quantum state initialization operation of the ion chain 110. Continue to refer to Figure 2 and Figure 5 ,by 40For example, the initial light 130 can make 4S 1 / 2 The ions in (+1 / 2) transition to 4P 1 / 2 In, but 4P 1 / 2 The lifetime is in the nanosecond range and will soon drop to 4 seconds through spontaneous radiation. 1 / 2 The two energy levels of 4S 1 / 2 (+1 / 2) Medium or 4S 1 / 2 (-1 / 2), but since the initial light 130 has been pumping 4S 1 / 2 Ions in (+1 / 2) will eventually be in 4S after about a few us. 1 / 2 (-1 / 2), thus completing the optical pumping process. It should be noted that Figure 5 The direction of each arrow in the figure indicates the transition direction of the ion. 1 / 2 Can be the initial state, 4S 1 / 2 (-1 / 2) can be the first Zeeman splitting state, 4S 1 / 2 (+1 / 2) can be the second Zeeman splitting state. 3D 5 / 2 Can be controlled, 4P 1 / 2 Can be an excited state.

[0061] Optional, Figure 6 is a schematic diagram of the structure of another addressing light emitting device provided 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 light beam and a second light beam, and the first light beam and the second light beam have a frequency difference; the first acousto-optic deflection unit 232 is used to control the emission directions of the first light beam and the second light beam so that the first light beam and the second light beam irradiate the set ions.

[0062] Specifically, the product of the frequency difference between the first light beam and the second light beam and the Planck constant is the set energy level difference, wherein the difference between the energy level of the second Zeeman splitting state and the energy level of the first Zeeman splitting state is the set energy level difference, and such a setting can make the ions in the first Zeeman splitting state and the ions in the second Zeeman splitting state transition to the same energy level under the action of the first light beam and the ions in the second Zeeman splitting state under the action of the second light beam. The first acousto-optic modulation unit 233 is set to divide the addressing light into the first light beam and the second light beam, so that the first light beam and the second light beam can perform Raman manipulation on the set ions.

[0063] Optionally, the wavelength of the first light beam is equal to the wavelength of the second light beam. This arrangement allows the first light beam and the second light beam to be emitted from the same light emitter, and can also reduce the crosstalk between the first light beam and the second light beam. Furthermore, the first light beam and the second light beam can have the same properties except for the frequency. This arrangement can ensure that the energy difference between the first light beam and the second light beam is the set energy level difference, thereby ultimately ensuring that the ions in the first Zeeman splitting state under the action of the first light beam and the ions in the second Zeeman splitting state under the action of the second light beam transition to the same energy level.

[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 light beam and the second light beam; the first acousto-optic deflection unit 232 is used to control the emission direction of the combined light after shaping so that the combined light irradiates the set ions.

[0065] Specifically, the beam shaping unit 234 can make the transmission paths of the first beam and the second beam in the same addressing light beam the same, ensuring that the first beam and the second beam corresponding to the same addressing light beam are irradiated on the same set ions. The beam shaping unit 233 can include a single-mode polarization-maintaining fiber, a fiber coupling device, a beam expander, a collimator, a focusing mirror, a wave plate, etc., to ensure the purity of laser polarization and transverse mode.

[0066] Optional, Figure 7 is a schematic diagram of the structure 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 ion chains, and the multiple ion chains are arranged in the same plane; the control light emitting device 220 includes a second laser emitting unit ( Figure 7 ), a second acousto-optic deflection unit 221 and a lens unit 222; a second laser emitting unit is used to generate control light; the second acousto-optic deflection unit 221 is used to control the transmission direction of the control light so that the control light illuminates the selected column of ion chains; the lens unit 222 is used to make the control light emitted by the second acousto-optic deflection unit 221 colinear with the selected column of ion chains.

[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 changes the direction of the light path through a lens unit 222, so that the manipulation light output by the manipulation light emitting device 220 is collinear with the ion chain of the selected column, thereby performing spin manipulation and phonon manipulation on multiple ions in the ion chain of the selected column. The lens unit 222 includes a lens, and the focus of the lens is located at the convergence point of the outgoing light of 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 it is necessary to perform spin manipulation on the ion chain, the second acousto-optic modulation unit 223 adjusts the frequency of the manipulation light incident to the second acousto-optic deflection unit 222 to the target frequency required for spin manipulation. When it is necessary to perform phonon manipulation on the ion chain, the second acousto-optic modulation unit 223 adjusts the frequency of the manipulation light incident to the second acousto-optic deflection unit 222 to the target frequency required for phonon manipulation, thereby improving the manipulation effect of the manipulation 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 shifts of the light beam caused by the first acousto-optic deflector 2321 and the second acousto-optic deflector 2322 cancel each other.

[0071] Specifically, the frequency shifts of the light beam caused by the first acousto-optic deflector 2321 and the second acousto-optic deflector 2322 in the first acousto-optic deflection unit 232 cancel each other, so 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. The frequency shifts of the light beam caused by the first acousto-optic deflector and the second acousto-optic deflector in the second acousto-optic deflection unit 221 cancel each other, so 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 acousto-optic deflection unit 232 includes a first acousto-optic deflector 2321 and a second acousto-optic deflector 2322, the planes where the deflection directions of the first acousto-optic deflector 2321 and the second acousto-optic deflector 2322 are located are fixed, and the planes where the deflection directions of the first acousto-optic deflector 2321 and the second acousto-optic deflector 2322 are located are different from each other.

[0073] Specifically, the plane where the deflection direction is located refers to the plane where the fan-shaped light beams with different deflection angles are located. The plane where the deflection direction of the light beam is located by the first acousto-optic deflector 2321 and the plane where the deflection direction of the light beam is located by the second acousto-optic deflector 2322 have an angle that is not zero, and the angle can be 90°, so that the first acousto-optic deflection unit 232 can 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 where the multiple columns of ion chains are located. This arrangement can expand the angle range of the first acousto-optic deflection unit's deflection of the addressing light.

[0075] Optionally, the plane where the deflection direction of the first acousto-optic deflector lies is parallel to the ion arrangement direction in the ion chain and perpendicular to the plane where the multiple columns of ion chains lie, and the plane where the deflection direction of the second acousto-optic deflector lies is perpendicular to the ion arrangement direction in the ion chain and perpendicular to the plane where the multiple columns of ion chains lie.

[0076] Specifically, the first acousto-optic deflector can deflect the addressing light up and down, and the second acousto-optic deflector can deflect the addressing light left and right, thereby achieving addressing of a two-dimensional ion array.

[0077] Optionally, the direction of the manipulation light before entering the second acousto-optic deflection unit is parallel to the ion arrangement direction in the ion chain and is collinear with the optical axis of the lens unit. This arrangement can expand the angle range of the second acousto-optic deflection unit's deflection of the manipulation light.

[0078] This embodiment also provides an ion quantum state control method, which is applied to the ion quantum state control system provided by any embodiment of the present invention. Figure 8 is a flow chart of a method for controlling an ion quantum state according to an embodiment of the present invention, with reference to Figure 8 The present embodiment provides an ion quantum state control method comprising the following steps:

[0079] S210 , the addressing light 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 through Raman manipulation.

[0080] Wherein, each ion in the ion chain includes an initial state and a control state, and the initial state includes a first Zeeman splitting state and a second Zeeman splitting 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 splitting state is lower than the energy level of the second Zeeman splitting state, and the energy level of the second Zeeman splitting state is lower than the energy level of the control state.

[0081] S220, 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.

[0082] Specifically, the duration of the control light can be controlled according to the Rabi oscillation period, so that the set ion can be made to transition from the second Zeeman splitting state to the control state, or the set ion can be made to transition from the control state to the second Zeeman splitting state. The ions in the first Zeeman splitting state do not react under the irradiation of the control light.

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

[0084] Fig. 9 is a flow chart of another ion quantum state control method provided according to an embodiment of the present invention, with reference to Fig. 9 The ion quantum state control method provided in this embodiment includes the following steps:

[0085] S110 , applying a magnetic field of a set magnetic field strength to the plurality of ions in the confinement region so that the initial state of each ion is split into a first Zeeman split state and a second Zeeman split 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 to form a confinement region, which includes a plurality of ions, and the plurality of ions in the confinement region are all trapped.

[0087] S120, applying initial light to the plurality of ions so that each ion is initialized to a first Zeeman splitting state.

[0088] S130 , applying addressing light to at least one set ion among the plurality of ions to make the set ion transition from a first Zeeman splitting state to a second Zeeman splitting state, or transition from the second Zeeman splitting state to the first Zeeman splitting state.

[0089] S140, applying manipulation light to the plurality of ions to make the set ions transition from the second Zeeman splitting state to the control state, or to make the set ions transition from the control state to the second Zeeman splitting state.

[0090] Optionally, applying initial light to multiple ions so that each ion is initialized to the first Zeeman splitting state includes: applying initial light to multiple ions so that ions in the second Zeeman splitting state transition to an excited state, and the ions in the excited state spontaneously radiate and transition to the first Zeeman splitting state or the second Zeeman splitting state.

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

[0092] Optionally, applying addressing light to at least one set ion among a plurality of ions so that the set ion transitions from a first Zeeman splitting state to a second Zeeman splitting state, or from a second Zeeman splitting state to a first Zeeman splitting state, comprises: applying a first light beam to the set ion so that the set ion transitions from the first Zeeman splitting 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 splitting state; the set ion in the decorated state transitions to the second Zeeman splitting state or the first Zeeman splitting state by spontaneous radiation; applying a second light beam to the set ion so that the set ion transitions from the second Zeeman splitting state to the decorated state; and causing 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, through Raman manipulation.

[0093] For details, please refer to Figure 5 ,by 40 For example, Ca+ ions, the first beam can set the ions from S 1 / 2 (-1 / 2) transition to the dressed state, and the second beam can set the ion from S 1 / 2 (+1 / 2) transitions to the decorated state, the lifetime of the decorated state is in the order of ns, and the set ion in the decorated state will soon fall to 4S through spontaneous radiation. 1 / 2 At two energy levels, Raman manipulation can ultimately be used to make the set ion finally transition to the second Zeeman splitting state or the first Zeeman splitting state.

[0094] Optionally, when multiple ions are located in a one-dimensional ion chain, the transmission direction of the manipulation light is parallel to the arrangement direction of the ions in the one-dimensional ion chain. This arrangement can make the manipulation light axial manipulation light of the ion chain, and the axial direction is the direction of the DC electric field of the ion trap, so that the set ions receiving the manipulation light perform spin manipulation and phonon manipulation.

[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 plane of the manipulation light is coplanar with the two-dimensional ion array; the angle between the beam plane of the addressing light and the two-dimensional ion array is greater than 0 and less than or equal to 90°. With this arrangement, the set ions receiving the manipulation light can perform spin manipulation and phonon manipulation, and the purpose of 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 duration of the ground state and the metastable state is relatively long. Setting the initial state as the ground state can ensure that the unaddressed ions are stably located in the first Zeeman splitting state, and prevent the unaddressed ions from interfering with the addressed ions. Setting the initial state as the ground state and the control state as the metastable state can ensure that the control state and the second Zeeman splitting state are stable for a relatively long time, thereby preventing the ions in the control state from spontaneously transitioning to other states quickly, and preventing the ions in the second Zeeman splitting state from spontaneously transitioning to other states quickly.

[0100] Optionally, ions are 40 Ca+ ion, 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 .

[0101] Specifically, 40 Ca+ ions have the characteristics of simple energy level structure, long metastable lifetime and narrow natural line width. The control method provided in this embodiment can be used for 40 Ca+ ions are controlled. 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 arrangement can make the ions irradiated by the initial light transition from the second Zeeman splitting state to the first Zeeman splitting state, thereby achieving an optical pumping effect.

[0103] Optionally, the wavelength of the addressing light includes 397nm, which is shorter and can make the focused spot of the addressing light smaller. When the addressing light is irradiated on the set ions, the spot of the addressing light can be prevented from overlapping with the non-set ions, so that the 397nm ultraviolet light can address a single ion. The maximum diameter of the spot of the addressing light irradiated on the set ions is smaller than the spacing between the ions.

[0104] Optionally, the wavelength of the manipulation light includes 729 nm, and such a setting enables the set ions irradiated by the manipulation light to perform electric quadrupole energy level manipulation.

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

[0106] Optionally, the initial light is global light. This arrangement can ensure that each ion in the trapped region is irradiated by the initial light, thereby ensuring that each ion in the trapped region is initialized to the first Zeeman splitting state.

[0107] The ion quantum state control method provided in this embodiment has corresponding beneficial effects as the ion quantum state control system provided in any embodiment of the present invention. For technical details not detailed 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 to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0109] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present 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 of the ions in the ion chain 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 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; An addressing light emitting device is used to emit addressing light to control the spin of set ions in the ion chain so that they can or cannot be controlled by the control light, and the direction in which the addressing light irradiates the ion chain has an angle that is not zero with the direction in which the ions in the ion chain are arranged.

2. The ion quantum state control system according to claim 1, characterized in that: The addressing light emitting device comprises 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 ions.

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 is used 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 comprises a first acousto-optic modulation unit, the first acousto-optic modulation unit being used to divide the addressing light into a first light beam and a second light beam, the first light beam and the second light beam having a frequency difference; The first acousto-optic deflection unit is used to control the emission directions of the first light beam and the second light beam so that the first light beam and the second light beam irradiate the set ions.

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

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 ion chains, and the multiple columns of ion chains are arranged in the same plane; The control light emitting device comprises 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 irradiates the ion chain of the selected column; The lens unit is used to make the manipulation 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 also 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 comprises a first acousto-optic deflector and a second acousto-optic deflector; The frequency shifts of the light beam caused by the first acousto-optic deflector and the second acousto-optic deflector 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 where the deflection directions of the first acousto-optic deflector and the second acousto-optic deflector are located are fixed, and the planes where 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 where the multiple columns of ion chains are located.

11. The ion quantum state control system according to claim 10, characterized in that: The plane where the deflection direction of the first acousto-optic deflector lies is parallel to the ion arrangement direction in the ion chain and perpendicular to the plane where the multiple columns of the ion chains lie. The plane where the deflection direction of the second acousto-optic deflector lies is perpendicular to the ion arrangement direction in the ion chain and perpendicular to the plane where the multiple columns of the ion chains lie.

12. The ion quantum state control system according to claim 6, characterized in that: The direction of the manipulation light before entering the second acousto-optic deflection unit is parallel to the ion arrangement direction in the ion chain and is collinear with the optical axis of the lens unit.

13. A method for controlling ion quantum states, characterized in that: An ion quantum state control system according to any one of claims 1 to 12 is used, and comprises: Each ion in the ion chain includes an initial state and a control state, and the initial state includes a first Zeeman splitting state and a second Zeeman splitting state; The addressing light causes the setting 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, through Raman manipulation; 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 397nm; The wavelength of the manipulation light includes 729 nm.

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