Deflectors for individually addressing long ion chains

Abstract

Aspects of the present disclosure relate generally to systems and methods for use in implementing and / or operating quantum information processing (QIP) systems, and more particularly to the use of deflectors in ion-trap QIP systems to individually address long ion chains. Methods for implementing one-qubit and two-qubit gates using acousto-optical deflectors (AODs) in optical Raman transitions are described. QIP systems configured to implement one-qubit and two-qubit gates using AODs in optical Raman transitions are also described.

Description

[Technical field]

[0001] (Priority) This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 286,900, filed December 7, 2021, entitled "Acousto-Optic Deflectors for Individually Addressing Long Ion Chains," and U.S. Non-Provisional Patent Application No. 18 / 062,338, filed December 6, 2022, entitled "Deflectors for Individually Addressing Long Ion Chains," the entire contents of which are incorporated herein by reference.

[0002] Aspects of the present disclosure generally relate to systems and methods for use in implementing, operating, and / or using quantum information processing (QIP) systems. [Background technology]

[0003] Trapped atoms are one of the main implementations of quantum information processing or quantum computing. Atom-based qubits can be used as quantum memories, as quantum gates in quantum computers and quantum simulators, and can function as nodes in quantum communication networks. Qubits based on trapped atomic ions enjoy a rare combination of attributes. For example, qubits based on trapped atomic ions have very good coherence properties, can be prepared and measured with nearly 100% efficiency, and are easily entangled by modulating the Coulomb interaction with a suitable external control field, such as an optical or microwave field. These attributes make atom-based qubits attractive for extended quantum operations, such as quantum computation or quantum simulation. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore important to develop new techniques to improve the design, fabrication, implementation, control, and / or functionality of various QIP systems used as quantum computers or quantum simulators, particularly QIP systems that involve operations based on atomic-based qubits. [Means for solving the problem]

[0005] The following presents a simplified summary of one or more aspects to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is not intended to identify key or critical elements of all aspects or to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] This disclosure describes various aspects of the use of deflectors in an ion trap QIP system to individually address long ion chains. For example, a method for implementing a quantum gate is described, the method including steering a first light beam toward a first set of optical components at a first angle by a first optical deflector, and imaging the first light beam along a first direction by the first set of optical components onto a first ion in the ion chain. The method further includes steering a second light beam toward a second set of optical components at the first angle by a second optical deflector, and imaging the second light beam along a second direction, different from the first direction, onto the first ion by the second set of optical components. The method further includes implementing a quantum gate using the first ion based on the first light beam and the second light beam being imaged onto the first ion.

[0007] In connection with the above method, a quantum computer is also described, the quantum computer including a first set of optical components and a second set of optical components, an ion trap configured to trap an ion chain, a first optical deflector configured to steer a first light beam toward the first set of optical components at a first angle, and a second optical deflector configured to steer a second light beam toward the second set of optical components at a first angle. The first set of optical components is configured to image the first light beam onto a first ion in the ion chain along a first direction. The second set of optical components is configured to image the second light beam onto the first ion along a second direction different from the first direction. Furthermore, a one-qubit quantum gate is implemented using the first ion based on the first light beam and the second light beam being imaged onto the first ion.

[0008] Another method for implementing a quantum gate is described, the method including steering a first light beam toward a first set of optical components by a first optical deflector and imaging the first light beam onto a first ion in an ion chain along a first direction by the first set of optical components. The method further includes steering a second light beam toward a second set of optical components by a second optical deflector and imaging the second light beam onto a second ion in the ion chain along a second direction different from the first direction by the second set of optical components. The method further includes steering a third light beam toward a third set of optical components by a third optical deflector and imaging the third light beam onto a second ion along the first direction by the third set of optical components. The method further includes steering a fourth light beam toward a fourth set of optical components by a fourth optical deflector and imaging the fourth light beam onto the first ion along the second direction by the fourth set of optical components. The method further includes implementing a quantum gate using the first ions and the second ions based on the first light beam and the fourth light beam being imaged onto the first ions and the second light beam and the third light beam being imaged onto the second ions.

[0009] In connection with the above method, a quantum computer is also described, the quantum computer including a first set of optical components, a second set of optical components, a third set of optical components, and a fourth set of optical components, an ion trap configured to trap an ion chain, a first optical deflector configured to steer a first light beam towards the first set of optical components, a second optical deflector configured to steer a second light beam towards the second set of optical components, a third optical deflector configured to steer a third light beam towards the third set of optical components, and a fourth optical deflector configured to steer a fourth light beam towards the fourth set of optical components. The first set of optical components is configured to image the first light beam onto a first ion in the ion chain along a first direction. The second set of optical components is configured to image the second light beam onto a second ion in the ion chain along a second direction different from the first direction. The third set of optical components is configured to image the third light beam onto a second ion in the ion chain along the first direction. The fourth set of optical components is configured to image the fourth light beam along the second direction onto the first ion. Further, a two-qubit gate is implemented using the first ion and the second ion based on the first light beam and the fourth light beam being imaged onto the first ion and the second light beam and the third light beam being imaged onto the second ion.

[0010] In this disclosure, the term quantum computer may be used interchangeably with the term QIP system to mean a system or device capable of performing quantum operations and algorithms.

[0011] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of only a few of the various ways in which the principles of the various aspects may be employed, and the description is intended to include all such aspects and their equivalents.

[0012] The disclosed aspects are described below in conjunction with the accompanying drawings, which are provided to illustrate but not to limit the disclosed aspects, and in which like reference numerals represent like elements. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram of atomic ions in a linear crystal or chain according to an aspect of the present disclosure. [Diagram 2] FIG. 1 illustrates an example of a quantum information processing (QIP) system according to an aspect of the present disclosure. [Diagram 3] FIG. 2 illustrates an example of a computing device according to an aspect of the present disclosure. [Figure 4A] FIG. 1 illustrates an example of a counter-propagating light beam scanning system according to aspects of the present disclosure. [Figure 4B] FIG. 1 illustrates an example of a counter-propagating light beam scanning system according to aspects of the present disclosure. [Diagram 5] FIG. 1 illustrates an example of a deflector-based Raman optical system according to aspects of the present disclosure. [Figure 6] FIG. 1 illustrates an example of a method for implementing and operating a one-qubit gate using deflector-based Raman optics, according to an embodiment of the present disclosure. [Figure 7] FIG. 1 illustrates an example of a method for implementing and operating a two-qubit gate using deflector-based Raman optics, according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The detailed description set forth below in conjunction with the accompanying drawings or figures is intended as a description of various configurations or implementations and is not intended to represent the only configurations or implementations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to one of ordinary skill in the art that these concepts may be practiced without these specific details or with variations of these specific details. In some instances, well-known components are shown in block diagram form, and some blocks may represent one or more well-known components.

[0015] Optical Raman operations are a typical means of performing or implementing one-qubit and two-qubit gates on trapped ions in quantum computers. Optical Raman operations are also used for laser cooling and system characterization and calibration. The speed at which operations and therefore algorithms can be performed is limited in many architectures by the optical power that can be delivered to the ions in a linear chain (see FIG. 1). For example, in a trapped ion quantum computer that uses an N-channel acousto-optic modulator (AOM) hardware approach to address the ions in the chain, the power output from the laser is typically split in N directions before the AOM, which means that a) the power delivered to each ion is 1 / N of the total power, and b) when performing gates on a small subset of n ions in the chain at a time, most of the power is wasted because the set of Nn beams that do not address ions is idle power.

[0016] An approach that may circumvent this problem is to use steering techniques to direct the laser intensity. One technique may be to use micro-electromechanical system (MEMS) based Raman light beam steering of M×M elements capable of delivering M pairs of Raman light beams to any M pairs of ions at once, where M is a number between 2 and N. For M=2, this allows for the most efficient use of laser power, at the expense of the ability to simultaneously address multiple pairs of ions. However, the power handling of MEMS mirrors for relevant wavelengths in ion-trapping quantum computers, such as 532 nanometer (nm) light, is currently believed to be on the order of only 100 milliwatts (mW) per light beam (and even less for typical UV light such as 355 nm), and thus is relatively low and may still limit the speed at which operations and therefore algorithms can be performed.

[0017] Electro-optic deflectors (EODs) are another steering technique that allows for directed laser intensity. In certain applications, EODs are desirable because they can have less noise and greater linearity. However, there are three main limitations that make this technique more challenging for trapped ion quantum computing. The first, and most important, is the deflection range. A typical ion chain holds many ions. In one example, a chain may hold 32 ions to implement 32 qubits. State-of-the-art (SoA) EODs can only address a small subset of that number, on the order of 2-3, using typical beam parameters in an ion chain. The second limitation is the purity and stability of the polarization. EOD crystals are typically sensitive to the environment and applied voltage, and trapped ions require very precise polarization control. The third limitation is the speed, which is limited by the ability to drive high voltage (HV) into a capacitive load and is on the order of a few milliseconds (ms) or more.

[0018] In this disclosure, we propose an alternative approach using acousto-optic deflectors (AODs) to steer pairs of Raman light beams in a manner that allows for delivery of significantly higher laser intensities than both MEMS and AOM (e.g., N-channel AOM) approaches, while having comparable functionality to the MEMS approach. Furthermore, using AODs leverages the fast (approximately 1-5 ms) optical switching times of acousto-optic devices and does not rely on mechanical action like MEMS, which may be prone to wear.

[0019] Solutions to the above problems are described in more detail in relation to FIGS. 1-7, which provide background on QIP systems or quantum computers, and more particularly atom-based QIP systems or quantum computers.

[0020] FIG. 1 shows a diagram 100 including a plurality of atomic ions or ions 106 (e.g., ions 106a, 106b, ..., 106c, and 106d) trapped in a linear crystal or chain 110 using a trap (not shown, but the trap can be in a vacuum chamber as shown in FIG. 2). The trap can be referred to as an ion trap. The illustrated ion trap can be constructed or fabricated on a semiconductor substrate, a dielectric substrate, or a glass die or wafer (also referred to as a glass substrate). The ions 106 can be provided to the trap as atomic species for ionization and confinement in the chain 110. Some or all of the ions 106 can be configured to operate as quantum bits in a QIP system. Additionally, a quantum processor, sometimes simply referred to as a processor, can represent a portion of a quantum computer or QIP system that includes the chain 110 and performs quantum operations using the ions 106 in the chain 110.

[0021] In the example shown in FIG. 1, the trap includes electrodes for trapping or confining a number of ions in chains 110 that are laser-cooled to be nearly stationary. The number of trapped ions can be configurable, and more or fewer ions can be trapped. The ions can be, for example, ytterbium ions ( 171 Yb + ions, etc.). The ions can be 171 Yb + The ions are illuminated with laser (light) radiation tuned to the resonance of the ions, and the fluorescence of the ions is imaged onto a camera or other type of detection device (e.g., a photomultiplier tube or PMT). In this example, the ions may be spaced apart from each other by a few microns (μm), but the separation may vary based on the configuration of the architecture. The separation of the ions is determined by a balance between external confinement forces and Coulomb repulsion, and need not be uniform. Furthermore, in addition to ytterbium ions, barium ions, neutral atoms, Rydberg atoms, or other types of atom-based qubit technology may also be used. Furthermore, ions of the same species, different species, and / or different isotopes of ions may be used. The trap may be a linear RF Paul trap, but other types of confinement devices may also be used, including optical confinement. Thus, the confinement device may be based on a variety of technologies, e.g., to hold ions, neutral atoms, or Rydberg atoms, with an ion trap being one example of such a confinement device. The ion trap may be, for example, a surface trap.

[0022] 2 shows a block diagram of an example of a QIP system 200. The QIP system 200 may also be referred to as a quantum computing system, a quantum computer, a computing device, an ion trap type system, etc. The QIP system 200 may be part of a hybrid computing system in which the QIP system 200 is used to perform quantum computations and operations, and the hybrid computing system also includes a classical computer to perform classical computations and operations. In such a hybrid system, quantum and classical computations and operations may interact.

[0023] 2 shows an overall controller 205 configured to perform various control operations of the QIP system 200. These control operations may be performed by an operator, may be automated, or may be a combination of both. Instructions for at least some of the control operations may be stored in a memory (not shown) in the overall controller 205 and may be updated over time via a communication interface (not shown). Although the overall controller 205 is shown separate from the QIP system 200, the overall controller 205 may be integrated with or may be a part of the QIP system 200. The overall controller 205 may include an automation and calibration controller 280 configured to perform various calibration, testing, and automation operations associated with the QIP system 200. These calibration, testing, and automation operations may involve, for example, all or a portion of the algorithm component 210, all or a portion of the optics and trap controller 220, and / or all or a portion of the chamber 250.

[0024] The QIP system 200 may include the algorithm component 210 described above, which may operate with other parts of the QIP system 200 to execute or implement a quantum algorithm, quantum application, or quantum operation. The algorithm component 210 may be used to execute or implement a stack or sequence of one-qubit and / or multi-qubit (e.g., two-qubit) operations as well as combinations of extended quantum computations. The algorithm component 210 may also include software tools (e.g., compilers) that facilitate such execution or implementation. Thus, the algorithm component 210 may directly or indirectly provide instructions to various components of the QIP system 200 (e.g., optical and trap controller 220) to execute or enable a quantum algorithm, quantum application, or quantum operation. The algorithm component 210 may receive information resulting from executing or performing a quantum algorithm, quantum application, or quantum operation, process the information, and / or forward the information to other components of the QIP system 200 or other devices (e.g., external devices connected to the QIP system 200) for further processing.

[0025] QIP system 200 may include optics and trap controller 220 as described above, which controls various aspects of trap 270 in chamber 250, including generating signals to control trap 270. Optics and trap controller 220 may also control operation of lasers, optics, and optical components used to provide a light beam that interacts with atoms or ions in the trap. An optical system including multiple components may be referred to as an optical assembly. The light beam is used to set up the ions, run or implement a quantum algorithm, quantum application, or quantum operation using the ions, and read results from the ions. Control of operation of lasers, optics, and optical components may include dynamic changes of operating parameters and / or settings, including controlling positioning using motorized mounts or holders. Trap 270 may be referred to as an ion trap when used to confine or trap ions. However, trap 270 may also be used to trap neutral atoms, Rydberg atoms, and other types of atom-based qubits. The laser, optics, and optical components may be at least partially located within the optics and trapping controller 220, the imaging system 230, and / or the chamber 250.

[0026] The QIP system 200 may include an imaging system 230. The imaging system 230 may include a high resolution imager (e.g., a CCD camera) or other type of detection device (e.g., a PMT) for monitoring the ions while they are being provided to the trap 270 and / or after they have been provided to the trap 270 (e.g., to read the results). In one aspect, the imaging system 230 may be implemented separately from the optics and trap controller 220, although detection, identification, and labeling of ions using fluorescence and with image processing algorithms may need to be coordinated with the optics and trap controller 220.

[0027] In addition to the above-mentioned components, QIP system 200 may include a source 260 that provides atomic species (e.g., a plume or flux of neutral atoms) to a chamber 250 having a trap 270. Where atomic ions are the basis of quantum operations, trap 270 confines the ionized (e.g., photoionized) atomic species. Trap 270 may be part of what may be referred to as the processor or processing portion of QIP system 200. That is, trap 270 may be considered to be the core of the processing operations of QIP system 200, as it holds the atomic-based qubits that are used to perform or implement quantum operations or simulations. At least a portion of source 260 may be implemented separately from chamber 250.

[0028] It should be understood that the various components of the QIP system 200 shown in Figure 2 are depicted at a high level for ease of understanding. Such components may include one or more subcomponents, details of which may be provided below as necessary to better understand certain aspects of the present disclosure.

[0029] Aspects of the present disclosure may be implemented at least in part using optical components within QIP system 200, including those that are part of and controlled by optics and trapping controller 220, imaging system 230, and / or chamber 250.

[0030] Referring now to FIG. 3, an example of a computer system or device 300 is shown. The computer device 300 may represent, for example, a single computing device, multiple computing devices, or a distributed computing system. The computer device 300 may be configured as a quantum computer (e.g., a QIP system), a classical computer, or to perform a combination of quantum and classical computing functions, sometimes referred to as hybrid functions or operations. For example, the computer device 300 may be used to process information using quantum algorithms, classical computer data processing operations, or a combination of both. In some cases, the results of one set of operations (e.g., a quantum algorithm) are shared with other sets of operations (e.g., classical computer data processing). A typical example of a computer device 300 implemented as a QIP system capable of performing quantum computations and simulations is, for example, the QIP system 200 shown in FIG. 2.

[0031] The computing device 300 may include a processor 310 for performing processing functions related to one or more of the functions described herein. The processor 310 may include a single processor, a set of processors, or one or more multi-core processors. Furthermore, the processor 310 may be implemented as an integrated and / or distributed processing system. The processor 310 may include one or more central processing units (CPUs) 310a, one or more graphics processing units (GPUs) 310b, one or more quantum processing units (QPUs) 310c, one or more intelligence processing units (IPUs) 310d (e.g., artificial intelligence or AI processors), or a combination of some or all of these types of processors. In one aspect, the processor 310 may refer to a general-purpose processor of the computing device 300, and the computing device 300 may also include additional processors 310 for performing further specific functions (e.g., including functions for controlling the operation of the computing device 300). Quantum operations may be performed by the QPU 310c. Some or all of the QPUs 310c may use atom-based qubits, although different QPUs may be based on different qubit technologies.

[0032] The computing device 300 may include a memory 320 for storing instructions executable by the processor 310 to perform operations. The memory 320 may also store data to be processed by the processor 310 and / or data resulting from processing by the processor 310. In one implementation, for example, the memory 320 may correspond to a computer-readable storage medium that stores code or instructions for performing one or more functions or operations. As with the processor 310, the memory 320 may refer to a general-purpose memory of the computing device 300, and the computing device 300 may also include additional memory 320 for storing instructions and / or data for further specific functions.

[0033] It will be appreciated that the processor 310 and memory 320 may be used in connection with a variety of operations, including, but not limited to, computing, calculation, simulation, control, calibration, system management, and other operations of the computing device 300, including the methods or processes described herein.

[0034] Additionally, the computing device 300 may include a communications component 330 that utilizes hardware, software, and services to enable the computing device 300 to establish and maintain communications with one or more entities. The communications component 330 may also be used to communicate between components of the computing device 300 and between the computing device 300 and external devices, such as devices located across a communications network and / or devices serially or locally connected to the computing device 300. For example, the communications component 330 may include one or more buses and may further include transmit and receive chain components associated with transmitters and receivers, respectively, operable to interface with external devices. The communications component 330 may be used to receive updates regarding the operation or functionality of the computing device 300.

[0035] Additionally, computing device 300 may include data store 340, which may be any suitable combination of hardware and / or software that provides mass storage of information, databases, and programs used in connection with the operation of computing device 300 and / or any method or process described herein. For example, data store 340 may be a data repository for operating system 360 (e.g., a classical OS, a quantum OS, or both). In one implementation, data store 340 may include memory 320. In one implementation, processor 310 may execute, and memory 320 or data store 340 may store, operating system 360 and / or applications or programs.

[0036] The computing device 300 may also include a user interface component 350 configured to receive input from a user of the computing device 300 and further configured to generate output for presentation to the user or for provision (directly or indirectly) to a different system. The user interface component 350 may include one or more input devices, including but not limited to a keyboard, a numeric keypad, a mouse, a touch-sensitive display, a digitizer, navigation keys, function keys, a microphone, a voice recognition component, any other mechanism capable of receiving input from a user, or any combination thereof. Additionally, the user interface component 350 may include one or more output devices, including but not limited to a display, a speaker, a haptic feedback mechanism, a printer, any other mechanism capable of presenting output to a user, or any combination thereof. In one implementation, the user interface component 350 may send and / or receive messages corresponding to operations of the operating system 360. When the computing device 300 is implemented as part of a cloud-based infrastructure solution, the user interface component 350 may be used to enable a user of the cloud-based infrastructure solution to remotely interact with the computing device 300.

[0037] A method and system for steering a pair of Raman light beams using an AOD is described in more detail below in relation to the system described in Figures 1-3.

[0038] 4A and 4B show diagrams 400 and 460, respectively, illustrating an example of a counter-propagating optical beam scanning system using deflectors (e.g., AODs) for optical beam steering. The general concept is to use symmetric optics in each propagation direction (dual individual addressing configuration) to cancel the position-dependent frequency of the AODs and keep the difference frequency Df between the beams from different propagation directions constant. In this example, a pair of optical beams can be directed at different ions in an ion chain, with each ion being used to implement a one-qubit or two-qubit gate.

[0039] Diagram 400 shows a left system including a light beam source 405a, a deflector 410a, and a set of optical components 440a with imaging optics 425a, 430a, and 435a. Diagram 400 also shows a right system including a light beam source 405b, a deflector 410b, and a set of optical components 440b with imaging optics 425b, 430b, and 435b. Deflectors 410a and 410b may be implemented using AODs to steer light beams (based on control signals) from the left and right systems onto an ion plane 450 having multiple ions (e.g., ions 106 in chain 110). Thus, the left and right systems and their AODs may be used as counter-propagating beam scanning or beam steering systems, where the optical projection operation translates the frequency input to each AOD to a specific location (i.e., a specific ion position) in the ion plane 450. However, the left and right systems may have a non-zero angle between them.

[0040] In diagram 400, different light beams from the AODs represent different frequencies from the AODs (e.g., dashed lines can be lower frequencies and solid lines can be higher frequencies). As shown, AODs 410a and 410b are generating the same high frequency tone (solid lines) that is projected or imaged onto the same ion at the bottom of the chain in ion plane 450. For example, light beam 420a and light beam 420b are imaged onto the same lower ion in the chain from opposite directions. To address a different ion at the top of the chain in ion plane 450, a lower frequency tone (dashed line) can be turned on instead. For example, light beam 415a and light beam 415b are imaged together onto the same upper ion in the chain from opposite directions.

[0041] In ion manipulation, only the frequency difference (Df) is important, so if the applied frequency of the higher (or lower) frequency tone from the left system matches that from the right system, the frequency difference becomes zero, effectively removing the frequency dependence of the AOD on beam position.

[0042] In one example, a chain of ions having 32 ions with 3 mm spacing between ions (see, e.g., FIG. 1) may typically use an individually addressable laser waist (i.e., optical beam waist) of 1 micron (mm). To address each of the ions in the entire chain, the AOD optical beam scanning system requires a minimum of N=32 resolvable spots (one per ion in this example) and a field of view (FOV) of 93 mm. The number of resolvable spots is given by: N=Δθ / ΔΘ where Δθ is the angular extent of the AOD (in radians) and ΔΘ is the Gaussian divergence (or 1 / D) of the input beam.

[0043] Commercially available AODs typically have an angular range of 3 degrees and apertures of over 1 mm. This allows, for example, about 100 resolvable spots for an input light beam of 1 mm diameter at a laser wavelength of 532 nm and ±1.5 degrees. Each resolvable spot corresponds to one of several supported angles at which the AOD can steer or deflect the input light beam. For comparison, a MEMS with a beam diameter of 250 mm and ±6 degrees at a wavelength of 532 nm allows about 100 resolvable spots. The FOV can be evaluated by calculating the effective focal length (EFL) of the optical projection system, which converts a Gaussian waist at the AOD, here 0.5 mm, to another Gaussian waist at the ion, here 1 mm. The formula for EFL is: EFL=π×w AOD ×w ion / λ For 532 nm light, the EFL is 2.95 mm. Then, the FOV is: FOV=EFL×Δθ which gives FOV=2.95mm×3°=155mm. For comparison, for the MEMS system, EFL=1.48mm and FOV=1.48mm×12°=310mm.

[0044] Diagram 460 of FIG. 4B shows an example of the calculation of EFL and FOV. In this example, w AOD =w 0 and w ion =w 1 and the input light beam 465 to the AOD470 has a Gaussian waist w 0 and the light beams 480a and 480b imaged onto the ions by optics 475 have a Gaussian waist w 1 In this example, f is the focal length between AOD 470 and optics 475, and also the focal length between optics 475 and the ion plane.

[0045] AODs can also be used to overcome the power limitations of MEMS devices. The SoA AOD used in the example above can handle optical powers of approximately 10 W or more, whereas an equivalent MEMS mirror can handle optical powers of approximately 100 mW. This 100-fold increase in power handling capability has a significant impact on gate speed and therefore fidelity and error, so being able to handle higher powers is preferable.

[0046] 5 shows a diagram 500 illustrating an example of a schematic of a deflector-based Raman optical system according to an embodiment of the present disclosure. In this example, four deflectors (e.g., AODs) are used to generate two pairs of Raman light beams. Having two pairs of light beams allows for the implementation of a two-qubit gate in this system.

[0047] Diagram 500 shows a first combination of AODs including AOD 510a and AOD 510b, and a second combination of AODs including AOD 510c and AOD 510d. For AOD devices, the frequency of the steered light beam (such as by Bragg diffraction) is Doppler shifted based on the frequency of the acoustic wave used in the deflector. The frequency into AOD 510a can be expressed as f1L+df1Lm, and the output frequency can be expressed as f1L+df1Lm+df1Ld1. The frequency into AOD 510b can be expressed as f1R+df1Rm, and the output frequency can be expressed as f1R+df1Rm+df1Rd1. The frequency into AOD 510c can be expressed as f2L+df2Lm, and the output frequency can be expressed as f2L+df2Lm+df2Ld2. The frequency to AOD 510d can be expressed as f2R+df2Rm, and the output frequency can be expressed as f2R+df2Rm+df2Rd2.

[0048] Changing the frequency sent to the AODs in the form of a control signal (e.g., df1Ld1 to AOD 510a) changes the beam deflection angle, and a subsequent imaging system converts the angular deflection into a beam translation along the ion chain axis. Due to the ideal symmetry of the optical configuration, and because the Raman transition depends only on the frequency difference between the two beams of a pair (e.g., between the dashed or solid lines), this system can take advantage of a "dual individual" addressability (and associated low crosstalk) where the frequency shift complexity is low, e.g., df1Ld1=df1Rd1 and df2Ld2=df1Rd2. If there is a small left-right asymmetry in the optical system, then small deviations from these equations are necessary, and a small correction can be made via an upstream modulation AOM (not shown) to compensate for the frequency offset observed at the quantum bit, thereby shifting the frequencies df1Lm, df1Rm, df2Lm, and df2Rm and restoring and correcting the above equations, for example, to df1Ld1+df1Lm=df1Rd1+df1Rm and df2Ld2+df2Lm=df1Rd2+df2Rm.

[0049] To drive multiple two-qubit gates simultaneously, multiple pairs of AODs can be combined to increase the number of independent manipulations of light beams by replicating the AOD unit cell of diagram 500. To address multiple chains, upstream combining optics and final projection optics can be accommodated, and the two AODs described in connection with diagram 500 can be replicated to provide scalability.

[0050] In the example shown in diagram 500, a left-hand system is shown that includes a light beam source 505a, a deflector or AOD 510a, a set of optical components with imaging optics 525a, 530a, 535a, and a beam splitter 540a. Diagram 500 also shows a right-hand system that includes a light beam source 505b, a deflector or AOD 510b, a set of optical components with imaging optics 525b, 530b, 535b, and a beam splitter 540b. Also shown is a bottom system that includes a light beam source 505c, a deflector or AOD 510c, a set of optical components with imaging optics 525c and 530c, and a beam splitter 540a and optical component 535a that are shared with the left-hand system. Additionally, the other lower system includes a light beam source 505d, a deflector or AOD 510d, a set of optical components with imaging optics 525d and 530d, and a beam splitter 540b and optical component 535b shared with the right system. The AODs are configured to steer the light beams (based on control signals) from the left, right, and lower systems onto an ion plane 550 having a number of ions (e.g., ions 106 in chain 110). Thus, the left, right, and lower systems and their AODs can be used to provide a counter-propagating beam scanning or beam steering system, where the optical projection operation translates the frequency input to each AOD to a specific location (i.e., a specific ion position) in the ion plane 550.

[0051] AODs also have the unique advantage over other beam scanning systems such as MEMS or EODs in that multiple tones and therefore multiple beams can be driven simultaneously, allowing parallel and even global operation in a software defined manner. For example, such an approach can be used to generate multiple beams by sending multiple RF tones. Nonlinearities can lead to mixing of the tones, resulting in extra beams. This can be avoided by operating deep within the linear region of the AOD device, by active phase control on the tones, by using splines or arbitrary waveform generators (AWGs), etc. This type of phase control can be used to implement gating and can also be used for sideband cooling.

[0052] Scanning systems, which are different from the fixed imaging systems typically used in most ion trap quantum computers, can have other general advantages. For example, scanning systems such as AODs and MEMS can address non-uniformly or arbitrarily spaced ions. If a multi-channel AOM is using only two channels, the other channels are turned off (wasted power). AOD systems with two channels use 100% of the power. Furthermore, multi-channel AOM systems are discrete and aberrations can cause ion beam overlap errors, which can lead to infidelity. AOD systems can be calibrated to eliminate this error.

[0053] It should be understood that aspects of the system described above in connection with Figures 4A, 4B, and 5 may be implemented at least in part using the optics and trap controller 220, imaging system 230, and / or chamber 250 of the QIP system 200 described above in connection with Figure 2.

[0054] FIG. 6 illustrates one example of a method 600 for implementing and operating a one-qubit gate using deflector-based (eg, AOD-based) Raman optics.

[0055] At 610, a first optical deflector (e.g., AOD 410a in FIG. 4A) steers a first light beam (e.g., light beam 420a) at a first angle toward a first set of optical components (e.g., optical components 525a, 430a, and 435a).

[0056] At 620, a first set of optical components images or projects a first light beam along a first direction (e.g., from the left) onto a first ion in the ion chain (e.g., an ion in the ion chain on ion plane 450).

[0057] At 630, a second optical deflector (e.g., AOD 410b) steers a second optical beam (e.g., optical beam 420b) at a first angle toward a second set of optical components (e.g., optical components 425, 430b, and 435b).

[0058] At 640, a second set of optics images or projects a second light beam onto the first ion along a second direction different from the first direction (eg, from the right).

[0059] At 650, a quantum gate is implemented using the first ion based on imaging a first light beam (e.g., light beam 420a) and a second light beam (e.g., light beam 420b) onto the first ion.

[0060] In one aspect of method 600, the first optical deflector is an AOD for steering the first optical beam to any one of a plurality of angles (e.g., resolvable spots) supported by the first optical deflector, including the first angle. Additionally, the second optical deflector is an AOD for steering the second optical beam to any one of a plurality of angles supported by the second optical deflector, including the first angle. Method 600 further includes selecting the first angle from the plurality of angles supported by the first optical deflector (e.g., by applying an input control signal of a particular frequency to the first deflector) and selecting the first angle from the plurality of angles supported by the second optical deflector (e.g., by applying an input control signal of a particular frequency to the second deflector). The AOD may support a continuous range of angles at which the optical beam can be steered or directed, so that a particular angle from the range may be used to achieve a particular resolvable spot that coincides with the position or location of a particular ion in the chain.

[0061] In one aspect of the method 600, the first direction and the second direction are opposite directions (e.g., opposite propagation directions). In other scenarios, the directions need not be opposite and may be, for example, 90 degrees apart.

[0062] In another aspect of the method 600, the quantum gate implemented using the first ion is a one-qubit quantum gate.

[0063] In another aspect of method 600, method 600 includes generating a first control signal provided to a first optical deflector to change the steering of a first optical beam toward the first set of optical components from a first angle to a second angle different from the first angle (e.g., as indicated by a different steering direction of optical beam 415a compared to optical beam 420a). Method 600 also includes generating a second control signal provided to a second optical deflector to change the steering of a second optical beam from the first angle to a second angle (e.g., as indicated by a different steering direction of optical beam 415b compared to optical beam 420b). Method 600 further includes imaging the first optical beam onto a second ion in the ion chain along a first direction by the first set of optical components, imaging the second optical beam onto the second ion along a second direction by the second set of optical components, and implementing a quantum gate using the second ion based on the first optical beam and the second optical beam being imaged onto the second ion. The quantum gate implemented using the second ion is a one qubit quantum gate.

[0064] A QIP system for performing method 600 may be based on the Raman configuration described in FIG. 4A and the QIP system 200 described in relation to FIG.

[0065] FIG. 7 illustrates one example of a method 700 for implementing and operating a two-qubit gate using deflector-based (eg, AOD-based) Raman optics.

[0066] At 710, a first optical deflector (e.g., AOD 510a in FIG. 5) steers a first light beam (e.g., light beam 520a) toward a first set of optical components (e.g., optical components 525a, 530a, 540a, and / or 535a).

[0067] At 720, a first set of optics images, projects, or translates the first light beam along a first direction (e.g., from the left) onto a first ion in the ion chain (e.g., an ion in the ion chain on ion plane 550).

[0068] At 730, a second optical deflector (e.g., AOD 510b) steers a second optical beam (e.g., optical beam 515b) toward a second set of optical components (e.g., optical components 525b, 530b, 540b, and / or 535b).

[0069] At 740, a second set of optics images, projects, or translates the second light beam along a second direction different from the first direction (e.g., from the right) onto a second ion in the ion chain.

[0070] At 750, a third optical deflector (eg, AOD 510c) steers a third optical beam (eg, optical beam 515c) toward a third set of optical components (eg, optical components 525c, 530c, 540a, and / or 535a).

[0071] At 760, a third set of optics images, projects, or transforms the third light beam along a first direction (eg, from the left) onto a second ion.

[0072] At 770, a fourth optical deflector (eg, AOD 510d) steers a fourth optical beam (eg, optical beam 520d) toward a fourth set of optical components (eg, optical components 525d, 530d, 540b, and / or 535b).

[0073] At 780, a fourth set of optics images, projects, or transforms the fourth light beam along a second direction (eg, from the right) onto the first ion.

[0074] At 790, a quantum gate is implemented using the first ions and the second ions based on the first light beam and the fourth light beam being imaged onto the first ions and the second light beam and the third light beam being imaged onto the second ions.

[0075] In one aspect of method 700, each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector is an AOD for steering a respective optical beam to any one of a plurality of angles (e.g., a resolvable spot of the AOD).

[0076] In another aspect of method 700, method 700 includes selecting, for each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector, a respective steering angle from a plurality of supported pre-set steering angles (e.g., by applying an input control signal of a particular frequency to the respective deflector).

[0077] In another aspect of the method 700, the first direction and the second direction are opposing directions (eg, opposing propagation directions).

[0078] In another aspect of method 700, the steering of the first and fourth optical beams is performed at a steering angle set to enable the first and fourth optical beams to be imaged or projected onto a first ion by a first set of optical components and a fourth set of optical components, respectively, and the steering of the second and third optical beams is performed at a steering angle set to enable the second and third optical beams to be imaged or projected onto a second ion by a second and third set of optical components, respectively.

[0079] In another aspect of the method 700, the quantum gate implemented using the first ion and the second ion is a two-qubit quantum gate.

[0080] A QIP system for performing the method 700 may be based on the Raman configuration described in FIG. 5 and the QIP system 200 described in relation to FIG.

[0081] The preceding description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the scope of the disclosure. Furthermore, although elements of the described aspects may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is expressly stated. Furthermore, unless otherwise stated, all or a portion of any aspect may be utilized with all or a portion of any other aspect. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A method for implementing a quantum gate, comprising: steering a first light beam at a first angle toward a first set of optical components with a first optical deflector; imaging the first light beam along a first direction onto a first ion in an ion chain with the first set of optics; steering a second light beam by a second optical deflector toward a second set of optical components at the first angle; imaging the second light beam onto the first ions along a second direction different from the first direction with the second set of optics; using the first ion to implement a quantum gate based on imaging the first light beam and the second light beam onto the first ion; A method comprising:

2. the first optical deflector is an acousto-optic deflector (AOD) for steering the first optical beam to any one of a plurality of angles supported by the first optical deflector, including the first angle; the second optical deflector is an AOD for steering the second optical beam to any one of a plurality of angles supported by the second optical deflector, including the first angle; The method of claim 1.

3. selecting the first angle from the plurality of angles supported by the first optical deflector; selecting the first angle from the plurality of angles supported by the second optical deflector; The method of claim 2 , further comprising:

4. The method of claim 1 , wherein the first direction and the second direction are opposing directions.

5. 2. The method of claim 1 , wherein the quantum gate implemented using the first ion is one.

6. generating a first control signal to be provided to the first optical deflector to change the steering of the first optical beam toward the first set of optical components from the first angle to a second angle different from the first angle; generating a second control signal provided to the second optical deflector to change the steering of the second optical beam from the first angle to the second angle; imaging the first light beam along the first direction onto a second ion in the ion chain with the first set of optics; imaging the second light beam along the second direction onto the second ions with the second set of optics; using the second ions to implement the quantum gate based on the first light beam and the second light beam being imaged or transformed onto the second ions; The method of claim 1 further comprising:

7. 7. The method of claim 6, wherein the quantum gate implemented using the second ion is a one qubit quantum gate.

8. 1. A method for implementing a quantum gate, comprising: steering a first light beam toward a first set of optical components with a first optical deflector; imaging the first light beam along a first direction onto a first ion in an ion chain with the first set of optics; steering the second light beam toward a second set of optical components with a second optical deflector; imaging the second light beam along a second direction, different from the first direction, onto a second ion in the ion chain with the second set of optics; steering the third light beam toward a third set of optical components with a third optical deflector; imaging the third light beam along the first direction onto the second ions with the third set of optics; steering the fourth light beam toward a fourth set of optical components by a fourth optical deflector; imaging the fourth light beam along the second direction onto the first ion with the fourth set of optics; implementing a quantum gate using the first ions and the second ions based on the first light beam and the fourth light beam being imaged onto the first ions and the second light beam and the third light beam being imaged onto the second ions; A method comprising:

9. 9. The method of claim 8, wherein each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector is an acousto-optical deflector (AOD) for steering a respective optical beam to any one of a plurality of angles.

10. 9. The method of claim 8, further comprising the step of selecting, for each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector, a respective steering angle from a plurality of supported pre-set steering angles.

11. The method of claim 8 , wherein the first direction and the second direction are opposing directions.

12. the steering of the first light beam and the fourth light beam is performed at a steering angle that is set to enable the first light beam and the fourth light beam to be imaged or transformed onto the first ion by the first set of optical components and the fourth set of optical components, respectively; the steering of the second light beam and the third light beam is performed at a steering angle set to enable the imaging or transforming of the second light beam and the third light beam onto the second ion by the second set of optical components and the third set of optical components, respectively. The method according to claim 8.

13. 10. The method of claim 8, wherein the quantum gate implemented using the first ion and the second ion is a two-qubit quantum gate.

14. a first set of optical components and a second set of optical components; an ion trap configured to trap an ion chain; a first optical deflector configured to steer a first optical beam toward the first set of optical components at a first angle; a second optical deflector configured to steer a second optical beam toward the second set of optical components at the first angle; Equipped with the first set of optics is configured to image the first light beam along a first direction onto a first ion in the ion chain; the second set of optics is configured to image the second light beam onto the first ions along a second direction different from the first direction; using the first ion to implement a one-qubit quantum gate based on imaging the first light beam and the second light beam onto the first ion. Quantum computer.

15. the first optical deflector is an acousto-optic deflector (AOD) and is configured to steer the first optical beam to any one of a plurality of angles supported by the first optical deflector, including the first angle; the second optical deflector is an AOD and is configured to steer the second optical beam to any one of a plurality of angles supported by the second optical deflector, including the first angle; 15. The quantum computer of claim 14.

16. The controller further comprises: selecting the first angle from the plurality of angles supported by the first optical deflector; Selecting the first angle from the plurality of angles supported by the second optical deflector.

16. The quantum computer of claim 15 configured to:

17. The controller further comprises: changing the steering of the first light beam toward the first set of optical components from the first angle to a second angle different from the first angle; Changing the steering of the second light beam from the first angle to the second angle. It is configured as follows: the first set of optics is configured to image the first light beam along the first direction onto a second ion in the ion chain; the second set of optics is configured to image the second light beam along the second direction onto the second ions; using the second ion to implement and operate a one-qubit quantum gate based on imaging the first light beam and the second light beam onto the second ion.

15. The quantum computer of claim 14.

18. a first set of optical components, a second set of optical components, a third set of optical components, and a fourth set of optical components; an ion trap configured to trap an ion chain; a first optical deflector configured to steer a first optical beam toward the first set of optical components; a second optical deflector configured to steer a second optical beam toward the second set of optical components; a third optical deflector configured to steer a third optical beam toward the third set of optical components; a fourth optical deflector configured to steer a fourth optical beam toward the fourth set of optical components; Equipped with the first set of optics is configured to image the first light beam along a first direction onto a first ion in an ion chain; the second set of optics is configured to image the second light beam onto a second ion in the ion chain along a second direction different from the first direction; the third set of optics is configured to image the third light beam along the first direction onto the second ions; the fourth set of optics configured to image the fourth light beam along the second direction onto the first ion; using the first ion and the second ion to implement a two-qubit gate based on the first light beam and the fourth light beam being imaged onto the first ion and the second light beam and the third light beam being imaged onto the second ion. Quantum computer.

19. 20. The quantum computer of claim 18, wherein each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector is an acousto-optical deflector (AOD) configured to steer a respective optical beam to any one of a plurality of angles.

20. a controller configured to select, for each of the first optical deflector, the second optical deflector, the third optical deflector, and the fourth optical deflector, a respective steering angle from a plurality of supported pre-set steering angles.

20. The quantum computer of claim 18, further comprising:

Images