Ion transmission device and ion transmission method

Abstract

To provide an ion transmission device and an ion transmission method for speeding up quantum computation using ions.SOLUTION: An ion transmission device includes: a pre-shuttle processing unit that initializes a transmission ion and a retention ion, which are placed together with a data ion in a source trap, into a Bell state; a shuttling unit that transfers the transmission ion from the source trap to a destination trap; and a post-shuttle processing unit that determines, using a detection ion arranged in the destination trap, whether the transmission ion has leaked, and notifies the pre-shuttle processing unit of the determination result. When the transmission ion has not leaked, information on the data ion is teleported to the transmission ion by quantum teleportation.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to quantum computers that use ions as quantum bits. [Background technology]

[0002] Quantum computers are a technology that performs calculations by utilizing the principle of superposition in quantum mechanics, and are expected to be able to quickly solve problems such as prime factorization and quantum chemistry calculations, so their development is being actively pursued around the world. Bits, the elements that make up ordinary computers, take on values ​​of 0 or 1. On the other hand, qubits, the elements that make up quantum computers, can take on continuous superposition states of 0 and 1 in addition to 0 and 1. It is thought that quantum computers can perform high-speed calculations by utilizing this superposition state.

[0003] Ions captured in a vacuum are expected to be a medium capable of retaining quantum bit information for long periods of time. Quantum bits using ions typically use light to control the ion's two electronic states, which correspond to 0 and 1. Because ions carry an electric charge, if electrodes with appropriate potentials are placed around them and a potential is established that creates a minimum point at the desired coordinates, the ion can be fixed at the minimum point and used for long-term calculations.

[0004] This mechanism of electrically capturing ions at the desired coordinates is called a trap. Note that since such a potential cannot be created by combining only constant electric fields, designs such as a Paul trap, in which the potential of some electrodes is periodically changed, are common (Non-Patent Documents 1 and 2).

[0005] Because the potential of a trap has a finite height, ions that are overheated by external noise and gain energy greater than the height of the potential will exceed this edge and escape the trap. This is called ion leakage. If an ion carrying the information being calculated leaks out, it is difficult to capture the same ion again, and the calculation will fail. For this reason, a mechanism called cooperative cooling is used, in which ions are combined with other cooled ions to remove their energy, and ions are repeatedly cooled during the calculation so that their energy is sufficiently smaller than the height of the potential.

[0006] One of the weaknesses of quantum computers using ions is the difficulty in scaling up. Because ions repel each other due to Coulomb interactions, the number of ions that can be collected in a single trap with current technology is limited to a few dozen. On the other hand, the number of quantum bits required for useful calculations is estimated to be over 100,000, leaving a large gap. One method proposed to overcome this weakness of ions, which is the difficulty in scaling up, is to expand the system using a quantum charge-coupled device (QCCD) (Non-Patent Document 1).

[0007] In this method, an ion trap is first constructed using electrodes, and then the coordinates of the trap are slowly moved over time by gradually changing the voltage value applied to the electrodes over time. This allows the ion coordinates to move to follow the coordinates of the trapping point, and can be moved to the desired position. This operation of controlling the trap position and moving ions from one point to the desired position is called shuttling. Shuttling makes it possible to move ions from one trap to another, thereby expanding the quantum computer beyond the number of ions that can be captured in a single trap. This shuttling mechanism has been demonstrated in small-scale systems and is expected to be a useful technique for realizing quantum computers.

[0008] If the shuttling is performed too quickly, the trapped ions will gain energy during the shuttling process. When the energy gained approaches the height of the trap potential, combined with external disturbances, the ions will likely leak out. The simplest way to suppress this leakage is to slow down the shuttling speed, but this slows down the movement of ions between traps, which in turn slows down the quantum computing itself, making it less useful.

[0009] Therefore, there is a trade-off between the shuttling speed and the leakage rate. Once an ion leaks, the information it possesses is permanently lost. Therefore, in typical quantum computing, the shuttling speed is slowed down so that the probability of ion leakage is negligible during the computation. This problem is particularly severe at points called junctions, where two shuttling paths intersect, because these locations restrict the movement of the ions and can result in unintended potential deformations (Non-Patent Documents 3, 4). As a result, in current ion-based computations, the shuttling time accounts for a major portion of the computation time, resulting in slower computation times compared to other quantum bit devices, such as superconducting qubits. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] Moses, SA, et al. "A race track trapped-ion quantum processor." arXiv preprint arXiv:2305.03828 (2023). [Non-patent document 2] Monroe, Christopher, et al. "Large-scale modular quantum-computer architecture with atomic memory and photonic interconnects." Physical Review A 89.2 (2014): 022317. [Non-patent document 3] Hucul, David, et al. "On the transport of atomic ions in linear and multidimensional ion trap arrays." arXiv preprint quant-ph / 0702175 (2007). [Non-patent document 4] Burton, William Cody, et al. "Transport of multispecies ion crystals through a junction in a radio-frequency paul trap." Physical Review Letters 130.17 (2023): 173202. Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, to perform reliable calculations using ions, the leakage rate must be negligibly small, which requires slow shuttling, resulting in the problem of slow calculations using ions.

[0012] The present invention has been made in view of the above points, and has an object to provide a technique for speeding up quantum computing using ions. [Means for solving the problem]

[0013] According to the disclosed technology, a pre-shuttle processing unit is provided that initializes the data ions, the transmission ions, and the retention ions in a source trap in which the data ions, the transmission ions, and the retention ions are arranged to a Bell state; a shuttling unit that moves the transmitted ions from the source trap to a destination trap; a post-shuttle processing unit that determines whether the transmitted ions have leaked using detected ions arranged in the destination trap and notifies the pre-shuttle processing unit of the determination result; When the transmission ions are not leaking, information of the data ions is teleported to the transmission ions by quantum teleportation. An ion transmission device is provided. [Effects of the Invention]

[0014] The disclosed technology provides a technology for speeding up quantum computing using ions. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 3 is a diagram illustrating an example of the configuration of a quantum computing device 300. [Figure 2] FIG. 4 is a diagram illustrating an example of the configuration of an ion transmission device 400. [Figure 3] 10 is a flowchart illustrating the operation of the ion transmission device 400. [Figure 4] FIG. 1 is a diagram for explaining an embodiment. [Figure 5] FIG. 1 is a diagram for explaining an embodiment. [Figure 6] FIG. 1 is a diagram for explaining an embodiment. [Figure 7] FIG. 2 illustrates an example of a hardware configuration of the apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0017] (Device configuration example) In this embodiment, the operation of the technology according to the present invention is performed by an ion transmission device 400, which is a device that transmits captured ions at high speed by shuttling with a messenger. The ion transmission device 400 has the configuration of the quantum computing device 300, so here we will first explain an example of the basic configuration of the quantum computing device 300.

[0018] 1 shows an example of the configuration of a quantum computing device 300 according to this embodiment. The "quantum computing device" may also be called a "quantum computer," a "quantum computer," or a "quantum computing system."

[0019] As shown in Fig. 1, the quantum computing device 300 includes a control device 100 and a quantum processor 200. The control device 100 performs quantum computation by transmitting control signals and the like to the quantum processor 200, instructing the quantum processor 200 to perform operations and measurements, and obtaining computation results (measurement results). The control device 100 can be realized by, for example, a classical computer. Hereinafter, "computer" means "classical computer."

[0020] The quantum processor 200 has quantum bits as physical quantum systems. In this embodiment, ions are used as quantum bits. The quantum processor 200 includes a device for realizing trapping, a light source and optical system for irradiating ions with light, a photodetector for measurement, and other devices / systems necessary for realizing the ion transmission device 400.

[0021] In this embodiment, the control device 100 and the quantum processor 200 in the quantum computing device 300 cooperate to realize the function of the ion transmission device 400.

[0022] It should be noted that the quantum bits (ions) in this embodiment are not limited to those using actual physical systems. For example, the quantum bits may be on a simulator realized by software. In this case, the quantum processor 200 functions as a quantum bit simulator. This simulator may be provided inside the control device 100. Alternatively, this simulator may be provided on the cloud.

[0023] (Configuration example of ion transmission device 400) 2 shows an example of the configuration of an ion transmission device 400 according to this embodiment. As shown in FIG. 2, the ion transmission device 400 includes an ion loading section 410, a pre-shuttle processing section 420, a shuttling section 430, and a post-shuttle processing section 440.

[0024] The ion loading unit 410 captures new ions from a vacuum and places the ions, whose information has been initialized, in a trap installed on an electrode.

[0025] The pre-shuttle processing unit 420 is a system that controls the trap from which the ions are transferred for shuttling. As shown in Figure 2, the trap from which the ions are transferred contains three types of ions: data ions carrying the data to be transferred, transfer ions that are actually shuttled, and retained ions that are quantum entangled with the transfer ions.

[0026] The pre-shuttle processing unit 420 has the function of initializing the "transmitted ions and retained ions" into a quantum entangled state called a Bell state, which is independent of the data to be transmitted. It also has the function of performing a measurement called a Bell measurement between the "data ions and retained ions" and transmitting the measurement results to the post-shuttle processing unit 440.

[0027] The shuttling unit 430 is a system that shuttles ions from a trap that is the source of the shuttling to a trap that is the destination of the shuttling. The shuttling unit 430 has a function of shuttling transmitted ions from the source of the shuttling to the destination.

[0028] The post-shuttle processing unit 440 is a system that controls the trap to which the shuttled ions are transferred. The trap to which the ions are transferred always holds detection ions that detect whether the transmitted ions have reached the trap without leaking due to repulsion caused by Coulomb interaction. The post-shuttle processing unit 440 has the function of detecting whether the transmitted ions have reached the trap as a result of the shuttled ions. The post-shuttle processing unit 440 also has the function of performing the Pauli operation.

[0029] (Example of operation of ion transmission device 400) An example of the operation performed using the ion loading unit 410, the pre-shuttle processing unit 420, the shuttling unit 430, and the post-shuttle processing unit 440 will be described with reference to the flowchart of FIG.

[0030] In the initial state, the trap from which the shuttle moves contains the transmitted ions and the retained ions, and the trap to which the shuttle moves contains the detected ions.

[0031] <s1> In S1 (step 1), the ion loading unit 410 moves data ions to the pre-shuttling treatment unit 420 and places them in the trap from which they were moved.

[0032] <s2> In S2, the pre-shuttle treatment unit 420 initializes the transmitted and retained ions to a Bell state.

[0033] <s3> In S3, the shuttling unit 430 performs shuttling to move the transmitted ions from the source trap to the destination trap, where there is a certain probability that the ions will leak out and escape from the shuttling trap.

[0034] <s4> In S4, the post-shuttle processing unit 440 uses the detected ions to determine whether or not the shuttling was successful. That is, the post-shuttle processing unit 440 uses the detected ions to determine whether or not the transmitted ions have leaked, and notifies the pre-shuttle processing unit 420 of the determination result. If there is no leak, the process proceeds to S5, and if there is a leak, the process proceeds to S7.

[0035] <s5> In S5, the pre-shuttle processing unit 420 performs a Bell measurement on the data ions and the retained ions, and notifies the post-shuttle processing unit 440 of the measurement results.

[0036] <s6> In S6, the post-shuttle processing unit 440 teleports the information carried by the data ions to the transmission ions by the quantum teleportation mechanism by performing a Pauli operation on the transmission ions in accordance with the value notified from the pre-shuttle processing unit 420. As a result, by treating the transmission ions as data ions, the data ions can be transmitted.

[0037] This completes the protocol, and the data and retained ions in the source trap can be used as the transmitted and retained ions for the next iteration of this protocol.

[0038] <s7> If the shuttling is not successful, in S7, the pre-shuttle processing unit 420 notifies the ion loading unit 410, and the ion loading unit 410, upon receiving the notification, loads the newly transmitted ions into the source trap. After that, the protocol is executed again from S2.

[0039] <Summary of the protocol> The mechanism by which data can be essentially moved in the above protocol without shuttling the data ions themselves that actually hold the data is based on the mechanism of quantum teleportation. Quantum teleportation is a protocol that can transfer one quantum bit of information by generating a state called quantum entanglement at the source and destination that is independent of the data being sent and consuming this state. In this case, even if the transmission of one of the quantum entangled quantum bits fails, the ion can be shuttled again, so it is possible to tolerate shuttling with a non-negligible leak probability.

[0040] In other words, in the above protocol, when shuttling an ion, the desired ion is not directly transported by shuttling, but rather quantum entanglement is generated and shuttled first, and then the shuttled quantum entanglement is consumed to transmit the ion by quantum teleportation. With this method, even if the first stage of quantum entanglement shuttling fails, the entire protocol can be restarted without affecting the desired ion. Therefore, ions can be effectively transmitted to maximize efficiency while accepting a certain shuttling failure probability.

[0041] (Example) An embodiment according to the above protocol will be described with reference to Figures 4 to 6. Figures 4 and 5 show a successful case of the above protocol, and Figure 6 shows a failed case.

[0042] In steps S1 and S2 shown in Figure 4, data ions, retained ions, and transmitted ions are placed in the source trap, and the retained ions and transmitted ions are initialized to a Bell state. In step S3, the transmitted ions are transferred from the source trap to the destination trap by shuttling. As a result of the determination in step S4, it is assumed that the transmitted ions are not leaking.

[0043] In S5 of Fig. 5, Bell measurements are performed on the data ions and the retained ions, and the measurement results are notified to the destination trap. In S6, a Pauli operation based on the measurement results is performed on the transmitted ions in the destination trap, and the information contained in the data ions is teleported to the transmitted ions.

[0044] On the other hand, in the failure case shown in Figure 6, the determination in S4 reveals that transmitted ions are leaking. In this case, as shown in S7, new transmitted ions are loaded into the source trap.

[0045] (Example of hardware configuration) The control device 100 described in this embodiment can be realized, for example, by causing a computer to execute a program. Furthermore, when quantum bits on a simulator are used as quantum bits, the ion transmission device 400 can also be realized by causing a computer to execute a program. This computer may be a physical computer or a virtual machine on the cloud.

[0046] That is, the device (control device 100, ion transmission device 400, etc.) can be realized by executing a program corresponding to the processing performed by the device using hardware resources such as a CPU and memory built into a computer. The program can be recorded on a computer-readable recording medium (such as a portable memory) and stored or distributed. The program can also be provided via a network such as the Internet or email.

[0047] Fig. 7 is a diagram showing an example of the hardware configuration of the computer. The computer in Fig. 7 includes a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, an output device 1008, and the like, all of which are interconnected via a bus B. The computer may further include a GPU.

[0048] A program for realizing processing on the computer is provided by a recording medium 1001 such as a CD-ROM or a memory card. When the recording medium 1001 storing the program is set in the drive device 1000, the program is installed from the recording medium 1001 to the auxiliary storage device 1002 via the drive device 1000. However, the program does not necessarily have to be installed from the recording medium 1001, but may be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files, data, etc.

[0049] The memory device 1003 reads and stores the program from the auxiliary storage device 1002 when an instruction to start the program is received. The CPU 1004 realizes the functions related to the device in accordance with the program stored in the memory device 1003. The interface device 1005 is used as an interface for connecting to the quantum processor 200, etc. The display device 1006 displays a GUI (Graphical User Interface) etc. according to the program. The input device 1007 is composed of a keyboard and mouse, buttons, a touch panel etc., and is used to input various operation instructions. The output device 1008 outputs the calculation results.

[0050] (Summary of the embodiment and its effects) As explained above, by performing additional processing before and after shuttling, a shuttling method that allows recovery even if a leak occurs is realized. This makes it possible to shuttling with a certain leakage rate allowed, and even when taking into account the processing before and after, faster shuttling than conventional methods is possible. This makes it possible to speed up quantum computing using ions.

[0051] The following additional notes are provided regarding the above-described embodiments.

[0052] <Additional Notes> (Additional note 1) a pre-shuttle processing unit that initializes the data ions, the transmitted ions, and the retained ions in a source trap into a Bell state; a shuttling unit that moves the transmitted ions from the source trap to a destination trap; a post-shuttle processing unit that determines whether the transmitted ions have leaked using detected ions arranged in the destination trap and notifies the pre-shuttle processing unit of the determination result; When the transmission ions are not leaking, information of the data ions is teleported to the transmission ions by quantum teleportation. Ion transmission device. (Additional note 2) When the transmission ions are not leaking, the pre-shuttle processing unit performs a Pauli measurement on the data ions and the retained ions, and notifies the measurement result to the post-shuttle processing unit, and the post-shuttle processing unit performs a Pauli operation on the transmission ions according to the measurement result. 10. The ion transmission device of claim 1. (Additional note 3) When the transmitted ions are leaking, new transmitted ions are loaded into the source trap. 3. The ion transmission device according to claim 1 or 2. (Additional note 4) An ion transmission method performed by an ion transmission device, comprising: initializing the data ions, the transmit ions, and the retained ions to a Bell state in a source trap in which the data ions, the transmit ions, and the retained ions are located; transferring the transmitted ions from the source trap to a destination trap; determining whether the transmitted ions have leaked using detected ions arranged in the destination trap, and notifying the source trap of the determination result; teleporting information of the data ions to the transmit ions by quantum teleportation if the transmit ions are not leaking; An ion transmission method comprising:

[0053] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0054] 100 control device 200 quantum processors 300 Quantum computing device 400 Ion Transmission Device 410 Ion Road Section 420 Shuttling pre-treatment section 430 Shuttling Department 440 Shuttling post-processing section 1000 Drive Device 1001 Recording media 1002 Auxiliary storage 1003 Memory device 1004 CPU 1005 Interface device 1006 Display device 1007 Input Device 1008 Output Device

Claims

1. a pre-shuttle processing unit that initializes the data ions, the transmitted ions, and the retained ions in a source trap into a Bell state; a shuttling unit that moves the transmitted ions from the source trap to a destination trap; a post-shuttle processing unit that determines whether the transmitted ions have leaked using detected ions arranged in the destination trap and notifies the pre-shuttle processing unit of the determination result; When the transmission ions are not leaking, information of the data ions is teleported to the transmission ions by quantum teleportation. Ion transmission device.

2. When the transmission ions are not leaking, the pre-shuttle processing unit performs a Pauli measurement on the data ions and the retained ions, and notifies the measurement result to the post-shuttle processing unit, and the post-shuttle processing unit performs a Pauli operation on the transmission ions according to the measurement result.

10. The ion transmission device of claim 1.

3. When the transmitted ions are leaking, new transmitted ions are loaded into the source trap.

3. An ion transmission device according to claim 1 or 2.

4. An ion transmission method performed by an ion transmission device, comprising: initializing the data ions, the transmit ions, and the retained ions to a Bell state in a source trap in which the data ions, the transmit ions, and the retained ions are located; transferring the transmitted ions from the source trap to a destination trap; determining whether the transmitted ions have leaked using detected ions arranged in the destination trap, and notifying the source trap of the determination result; teleporting information of the data ions to the transmit ions by quantum teleportation if the transmit ions are not leaking; An ion transmission method comprising:

Images