CN117454997A

CN117454997A - Ion trap chip parameter correction method and device, electronic equipment and medium

Info

Publication number: CN117454997A
Application number: CN202311444852.5A
Authority: CN
Inventors: 黄晨; 汪景波
Original assignee: Beijing Baidu Netcom Science and Technology Co Ltd
Current assignee: Beijing Baidu Netcom Science and Technology Co Ltd
Priority date: 2023-11-01
Filing date: 2023-11-01
Publication date: 2024-01-26

Abstract

The present disclosure provides a method, apparatus, electronic device, computer readable storage medium and computer program product for ion trap chip parameter correction, and relates to the field of quantum computers, in particular to the technical field of ion trap chips. The implementation scheme is as follows: determining an intrinsic phonon frequency of a first ion in the ion trap chip; the following operations are performed a plurality of times: adjusting the power value of the laser and determining the equivalent amplitude of the laser irradiated to the first ion under the current power value; acquiring and setting a second pulse duration of the laser, and changing the frequency difference between two laser beams divided by the beam splitter by the laser to determine a second probability that the first ion is in an excited state under each frequency difference; determining a first phonon frequency based on a change in the second probability with the frequency difference; determining a difference between the first phonon frequency and the eigen-phonon frequency; and performing function fitting based on the corresponding relation between the equivalent amplitude and the corresponding difference value, so as to correct the phonon frequency under the corresponding equivalent amplitude based on the fitting function.

Description

Ion trap chip parameter correction method and device, electronic equipment and medium

Technical Field

The present disclosure relates to the field of quantum computers, and in particular to the field of ion trap chip technology, and more particularly, to an ion trap chip parameter correction method, apparatus, electronic device, computer readable storage medium, and computer program product.

Background

The ion trap quantum calculation is a calculation method based on quantum mechanics, and the principle is that ions are used for processing information as quantum bits by utilizing stable movement of the ions in an electric field, and quantum gate operation can be realized through accurate regulation and control of laser and a microwave field, so that quantum calculation is performed. This approach is currently considered one of the promising approaches to quantum computing.

The basic process of ion trap quantum computation is to cool ions by laser, form a binding potential in space by direct current and alternating electric field, make the ions stand still at a point in three-dimensional space, and then realize quantum entanglement and operation between the ions by adjusting the laser. Since each ion can be abstracted as one qubit, many important tasks in quantum computing, such as quantum random walk, quantum simulation, and quantum search, can be achieved by manipulating them. The ion trap quantum calculation has high controllability, can realize high-efficiency quantum algorithm, and has wide application prospect. Meanwhile, the requirement of ion trap quantum calculation on the experimental technology is very high, the position, energy level and interaction of ions need to be precisely controlled, and high-precision measurement and control of the ions are also needed.

Disclosure of Invention

The present disclosure provides an ion trap chip parameter correction method, apparatus, electronic device, computer readable storage medium and computer program product.

According to an aspect of the present disclosure, there is provided an ion trap chip parameter correction method, including: determining the position of a first ion to be calibrated in the ion trap chip; acquiring and setting an initial power value of a laser so that the equivalent amplitude of the laser after irradiating the first ions is smaller than a first threshold value; acquiring and setting a first pulse duration of the laser, and changing a frequency difference between two laser beams split by a beam splitter of the laser to determine a first probability that the first ion is in an excited state at each frequency difference; determining an eigenphonon frequency based on a change in the first probability with the frequency difference; the following operations are performed N times, N being a positive integer of 2 or more: adjusting the power value of the laser, and determining the equivalent amplitude of the laser irradiated to the first ion under the current power value; acquiring and setting a second pulse duration of the laser, and changing a frequency difference between two laser beams split by the laser through a beam splitter to determine a second probability that the first ions are in an excited state at each frequency difference; determining a first phonon frequency based on a change in the second probability with the frequency difference; determining a difference between the first phonon frequency and the eigenphonon frequency; and performing function fitting based on the corresponding relation between the equivalent amplitude and the corresponding difference value, so that the phonon frequency under the corresponding equivalent amplitude is corrected based on the function obtained by fitting.

According to another aspect of the present disclosure, there is provided an ion trap chip parameter-correcting apparatus, comprising: a first determining unit configured to determine a position of a first ion to be calibrated in the ion trap chip; an acquisition unit configured to acquire and set an initial power value of a laser so that an equivalent amplitude of the laser after irradiating the first ion is smaller than a first threshold; a second determining unit configured to acquire and set a first pulse duration of the laser and change a frequency difference between two laser beams divided by a beam splitter by the laser to determine a first probability that the first ion is in an excited state at each frequency difference; a third determination unit configured to determine an eigenphonon frequency based on a variation of the first probability with the frequency difference; an execution unit configured to execute the following operations N times, N being a positive integer of 2 or more: adjusting the power value of the laser, and determining the equivalent amplitude of the laser irradiated to the first ion under the current power value; acquiring and setting a second pulse duration of the laser, and changing a frequency difference between two laser beams split by the laser through a beam splitter to determine a second probability that the first ions are in an excited state at each frequency difference; determining a first phonon frequency based on a change in the second probability with the frequency difference; determining a difference between the first phonon frequency and the eigenphonon frequency; and a correction unit configured to perform function fitting based on a correspondence between the equivalent amplitude and the corresponding difference value, so that the phonon frequency at the corresponding equivalent amplitude is corrected based on a function obtained by the fitting.

According to another aspect of the present disclosure, there is provided an electronic device including: at least one processor; and a memory communicatively coupled to the at least one processor; the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the methods described in the present disclosure.

According to another aspect of the present disclosure, there is provided a non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the method described in the present disclosure.

According to another aspect of the present disclosure, there is provided a computer program product comprising a computer program which, when executed by a processor, implements the method described in the present disclosure.

According to one or more embodiments of the present disclosure, the equivalent amplitude and the phonon frequency are calibrated in an associated manner, and a relationship between the corresponding equivalent amplitude and the difference is fitted, so that the related phonon frequency can be corrected based on the difference, the phonon frequency calibration accuracy is higher, the corrected phonon frequency can be better suitable for ion trap experiments, and a guarantee is provided for the accuracy of experimental results.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following specification.

Drawings

The accompanying drawings illustrate exemplary embodiments and, together with the description, serve to explain exemplary implementations of the embodiments. The illustrated embodiments are for exemplary purposes only and do not limit the scope of the claims. Throughout the drawings, identical reference numerals designate similar, but not necessarily identical, elements.

Fig. 1 shows a flow chart of an ion trap chip parameter modification method according to an embodiment of the present disclosure;

FIG. 2 illustrates a schematic diagram of ion location determination by scanning laser and fluorescence imaging in accordance with an embodiment of the present disclosure;

FIG. 3 illustrates a schematic diagram of possible transitions after ion and phonon coupling according to an embodiment of the present disclosure;

FIG. 4 shows a schematic diagram of a blue sideband transition sweep result and a baseline model theoretical fit result in accordance with an embodiment of the present disclosure;

FIG. 5 illustrates a schematic diagram of determining phonon frequencies based on a sweep experiment in accordance with an embodiment of the present disclosure;

Fig. 6 shows a block diagram of a configuration of an ion trap chip parameter-correction apparatus in accordance with an embodiment of the present disclosure; and

fig. 7 illustrates a block diagram of an exemplary electronic device that can be used to implement embodiments of the present disclosure.

Detailed Description

Exemplary embodiments of the present disclosure are described below in conjunction with the accompanying drawings, which include various details of the embodiments of the present disclosure to facilitate understanding, and should be considered as merely exemplary. Accordingly, one of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the present disclosure. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.

In the present disclosure, the use of the terms "first," "second," and the like to describe various elements is not intended to limit the positional relationship, timing relationship, or importance relationship of the elements, unless otherwise indicated, and such terms are merely used to distinguish one element from another. In some examples, a first element and a second element may refer to the same instance of the element, and in some cases, they may also refer to different instances based on the description of the context.

The terminology used in the description of the various illustrated examples in this disclosure is for the purpose of describing particular examples only and is not intended to be limiting. Unless the context clearly indicates otherwise, the elements may be one or more if the number of the elements is not specifically limited. Furthermore, the term "and/or" as used in this disclosure encompasses any and all possible combinations of the listed items.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

To date, various types of computers in use are based on classical physics as the theoretical basis for information processing, known as traditional or classical computers. Classical information systems store data or programs using binary data bits that are physically easiest to implement, each binary data bit being represented by a 0 or a 1, called a bit or a bit, as the smallest unit of information. Classical computers themselves have the inevitable weakness: first, the most basic limitation of energy consumption in the calculation process. The minimum energy required by the logic element or the memory cell should be more than several times of kT to avoid malfunction under thermal expansion; secondly, information entropy and heating energy consumption; thirdly, when the wiring density of the computer chip is large, the uncertainty of momentum is large when the uncertainty of the electronic position is small according to the uncertainty relation of the Hessenberg. Electrons are no longer bound and there is a quantum interference effect that can even destroy the performance of the chip.

Quantum computers (QWs) are a class of physical devices that perform high-speed mathematical and logical operations, store and process quantum information, following quantum mechanical properties, laws. When a device processes and calculates quantum information and a quantum algorithm is operated, the device is a quantum computer. Quantum computers follow unique quantum dynamics (particularly quantum interferometry) to achieve a new model of information processing. For parallel processing of computational problems, quantum computers have an absolute advantage in speed over classical computers. The transformation implemented by the quantum computer on each superposition component is equivalent to a classical computation, all of which are completed simultaneously and are superimposed according to a certain probability amplitude to give the output result of the quantum computer, and the computation is called quantum parallel computation. Quantum parallel processing greatly improves the efficiency of quantum computers so that they can perform tasks that classical computers cannot do, such as factorization of a large natural number. Quantum coherence is essentially exploited in all quantum ultrafast algorithms. Therefore, quantum parallel computation with quantum state instead of classical state can reach incomparable operation speed and information processing function of classical computer, and save a large amount of operation resources.

In order to realize high-performance ion trap quantum computation, parameter calibration of an ion trap system is important. In order to achieve high fidelity quantum operations, researchers need to precisely calibrate parameters of ion trap systems, including lasers, phonon frequencies, ion-ion interactions, and the like.

In ion trap quantum control, each ion in the trap represents one qubit, and two internal states |Σ >, |Σ > of the ion can be just represented as the |0>, |1> state of the qubit. If two qubits need to be entangled, it is often necessary to direct laser light onto two ions, while the two lased ions share quantized phonon modes in the ion chain in charge coulomb interactions. Such experimental systems, the equivalent hamiltonian amount of which is generally related to parameters of the ion trap system, including laser frequency, amplitude and phase, phonon frequency, coupling strength, etc. The adjustment of the equivalent hamiltonian amount is generally achieved experimentally by adjusting the amplitude and phase of the laser pulses.

Thus, in quantum operations based on the ion trap system, corresponding quantum operations can be realized based on the calibrated parameters. For example, modulating the laser pulses based on more accurate system parameters, by applying the laser pulses to the respective ions, a more accurate quantum gate is obtained, thereby achieving a more accurate quantum computing operation based on the obtained quantum gate. Therefore, accurate calibration of these parameters can improve the efficiency and accuracy of quantum operations in the ion trap, thereby improving the performance of ion trap quantum computation.

Among these parameters to be calibrated, the collective vibration mode of the ion trap, phonon frequency, is of particular importance. This is because in ion trap quantum computation, accurate operation and control of ions are required for generating double-bit and multi-bit quantum gates, and after each operation of the quantum circuit is completed, cooling and resetting work is required by phonons, which are all independent of calibrating the phonon frequency.

Theoretically, the phonon frequency corresponding to the collective vibration of ions in the ion trap is limited. The confinement of phonon frequency is due to the coulomb interactions between ions and the interactions between the positions of the individual ions in steady state. These interactions cause the collective vibration of ions to form specific frequency modes that can be excited and tuned by precisely controlling the frequency and power of the laser. Thus, the value of the phonon frequency corresponding to the collective vibration of ions in the ion trap can be used to precisely control the position and momentum of the ions. Operation in ion trap quantum computing often requires precise control of interactions between ions and ion positions, and thus precise regulation of phonon frequencies in the ion trap. If the phonon frequency calibration is erroneous, interactions between ions will lead to errors and noise in the calculation, affecting the accuracy and reliability of the overall calculation. Therefore, the accurate value of phonon frequency is one of the keys to ensure high efficiency and accuracy in ion trap quantum computation.

In the ion trap experiment, the built ion trap system needs to be calibrated. A more accurate method is Ramsey interferometry. The Ramsey interferometry is a measurement method based on quantum interference, and can measure the energy difference between internal energy levels of atoms or ions by adjusting free evolution time and observing periodic changes of interference fringes. In ion trap experiments, ramsey interferometry can be used to measure the phonon frequency of ions. The specific operation method is as follows: an atom or ion is prepared from one energy level to another, then allowed to evolve freely for a period of time, and finally turned back to the prepared state. If two ions are at the same energy level, they interfere, creating interference fringes; if the two ions are at different energy levels, they do not interfere and do not produce interference fringes. By adjusting the free evolution time, a periodic variation of the interference fringes can be observed. From the period of the interference fringes, the phonon frequency of the ions can be calculated.

However, the sensitivity of Ramsey interferometry is limited by the free evolution time. Shorter free evolution times lead to reduced visibility of the interference fringes, while longer free evolution times lead to periodic variations of the interference fringes becoming less pronounced. The Ramsey interferometry requires high-precision laser and control systems and stable environmental conditions to obtain high-precision phonon frequency calibration results. Environmental noise or temperature variations may affect the experimental results. Ramsey interferometry requires multiple experiments to determine phonon frequencies, which adds complexity and time consuming to the experiment. In addition, the Ramsey interferometry requires ion traps with high quality factors and long lifetimes to ensure stability of interference fringes. This places certain demands on the preparation and tuning of the ion trap.

Accordingly, embodiments in accordance with the present disclosure provide an ion trap chip parameter modification method. Fig. 1 shows a flowchart of an ion trap chip parameter modification method according to an embodiment of the present disclosure, as shown in fig. 1, a method 100 includes: determining a position of a first ion to be calibrated in the ion trap chip (step 110); acquiring and setting an initial power value of a laser so that an equivalent amplitude of the laser after the laser irradiates the first ions is smaller than a first threshold (step 120); acquiring and setting a first pulse duration of the laser and changing a frequency difference between two laser beams split by a beam splitter of the laser to determine a first probability that the first ion is in an excited state at each frequency difference (step 130); determining an eigenphonon frequency based on a variation of the first probability with the frequency difference (step 140); the following operations are performed N times, N being a positive integer of 2 or more (step 150): adjusting the power value of the laser and determining an equivalent amplitude of the laser after irradiating the first ion at the current power value (step 1501); acquiring and setting a second pulse duration of the laser and changing a frequency difference between two laser beams split by a beam splitter of the laser to determine a second probability that the first ion is in an excited state at each frequency difference (step 1502); determining a first phonon frequency based on the second probability as a function of the frequency difference (step 1503); determining a difference between the first phonon frequency and the eigenphonon frequency (step 1504); and performing a function fit based on the correspondence between the equivalent amplitudes and the corresponding differences, such that the phonon frequencies at the corresponding equivalent amplitudes are modified based on the function resulting from the fit (step 160).

According to the embodiment of the disclosure, the equivalent amplitude and the phonon frequency are subjected to associated calibration, and the corresponding relation between the equivalent amplitude and the difference value is fitted, so that the related phonon frequency can be corrected based on the difference value, the phonon frequency calibration accuracy is higher, the corrected phonon frequency can be better suitable for ion trap experiments, and the accuracy of experimental results is improved.

Because of the particularity of ion trap quantum computation, ions which are qubits float at a space of 10-100 μm above an ion trap chip, and the distance between every two ions is related to the total ion number, which is about 2-10 μm. The ions are generally not equidistant and have the characteristics of dense middle and sparse two sides. As a first step in ion trap quantum computation, the position of the qubit needs to be found in space to perform subsequent quantum operations.

In some embodiments, determining the location of the first ion to be calibrated in the ion trap chip comprises: and changing the incident angle of the laser according to a first preset step length within a first preset range so as to determine the position of the first ion through fluorescence imaging.

In some examples, the plurality of ions in the ion trap may be scanned one by a scanning laser method to find their respective locations. Scanning laser methods, i.e., if there are multiple ions in the ion trap, can use the laser to scan the ions one by one. By changing the incidence position of the laser beam and monitoring the fluorescence signal, the position of the ions can be found. When the laser beam coincides with an ion, the fluorescence signal changes significantly, thereby determining the ion's position. Fig. 2 shows a schematic diagram of ion (qubit) location determination by scanning laser and fluorescence imaging according to an embodiment of the disclosure.

In particular, ion location may be calibrated by means of fluorescence imaging and scanning of the laser beam. By laser cooling the ions and exciting them to a higher energy level, the ions emit fluorescent photons and flyback back to the ground state. These fluorescent photons can be collected and detected by imaging systems such as optical microscopes and photomultiplier tubes or charge-coupled device (CCD) cameras. Since the fluorescence signal intensity is related to the degree of overlap between the ion location and the laser beam, the location of the ion can be found by processing and analyzing the collected fluorescence images.

It will be appreciated that the ions have a slight movement in their respective positions, and thus the determined positions of the ions may also be referred to as central positions, without limitation.

In some embodiments, obtaining and setting the initial power value of the laser such that an equivalent amplitude of the laser after irradiating the first ions is less than a first threshold comprises: adjusting the power value of the laser until the determined equivalent amplitude is less than a first threshold value and determining the power value corresponding to the equivalent amplitude being less than the first threshold value as an initial power value: determining a frequency difference between the first ion g and e states to determine a frequency difference between two laser beams split by a beam splitter based on the frequency difference; adjusting pulse durations of the laser and determining a probability that the first ion is in an excited state after irradiation of the first ion by the laser at each pulse duration; determining a third pulse duration corresponding to when the probability of the first ion in the excited state is close to 1; and determining an equivalent amplitude of the laser after irradiating the first ion based on the third pulse duration.

According to some embodiments, the equivalent amplitude Ω of the laser after irradiating the first ion is determined based on the following formula:

Ω＝π/2τ

where τ is the third pulse duration.

In some examples, after the position of the first ion is determined, the frequency difference of the two opposite laser beams may be modulated to be the same as the frequency difference between the states |g > and |e > in the first ion, and by continuously changing the pulse duration τ of the laser action, the change over time in the number of layouts of the first ion in the state |e > (excited state) is observed until the probability of the first ion in the state |e > approaches 1 when the laser pulse duration τ passes. In this way, the equivalent amplitude (i.e., rabi drive intensity) of the laser light after it has been irradiated to the first ion can be calibrated to be Ω=pi/2τ.

According to some embodiments, the first threshold comprises 0.01MHz.

It will be appreciated that the corresponding first threshold may be set according to specific ion trap chips or practical requirements, so that when the equivalent amplitude is smaller than the threshold, the laser may default to have difficulty in coupling between the first ions and phonons, and the phonon frequency thereof is close to the eigenfrequency thereof.

According to some embodiments, the first pulse duration is greater than the second pulse duration.

From the above, it can be seen that the equivalent amplitude (i.e., rabi drive strength) is inversely proportional to the laser pulse duration. Thus, when the equivalent amplitude is small, a longer pulse duration τ may be selected to change the frequency difference between the two laser beams split by the beam splitter, determine a first probability that the first ion is in an excited state at each frequency difference, and thus determine the eigenphonon frequency.

Because of the problems of complicated operation, large time consumption and the like of the Ramsey interferometry, in the embodiment according to the disclosure, the phonon frequency of ions is measured by adopting a laser sweep method. Specifically, the frequency of an excitation signal (namely, the frequency difference between two laser beams) is adjusted through a laser scanner, and the change of the fluorescence of ions is observed, so that the number of the arrangement of the ions in an excited state can be obtained.

In the example of determining the phonon frequency by sweep experiments, a significant peak occurs when the frequency difference between the two laser beams split by the beam splitter approaches the phonon frequency. Thus, the frequency difference corresponding to the occurrence of the peak of the first probability can be determined as the corresponding phonon frequency.

Similarly, according to some embodiments, determining the equivalent amplitude of the laser after irradiating the first ion at the current power value comprises: determining a frequency difference between the first ion g and e states to determine a frequency difference between two laser beams split by a beam splitter based on the frequency difference; adjusting pulse durations of the laser and determining a probability that the first ion is in an excited state after irradiation of the first ion by the laser at each pulse duration; determining a fourth pulse duration corresponding to when the probability of the first ion in the excited state is close to 1; and determining an equivalent amplitude of the laser after irradiating the first ion based on the fourth pulse duration.

Ω＝π/2τ

here τ is the fourth pulse duration.

According to some embodiments, acquiring and setting the second pulse duration of the laser comprises: setting the second pulse duration equal to the fourth pulse duration or close to the fourth pulse duration within a preset error range.

In some embodiments, after one ion (i.e., the first ion) is calibrated, the incident angle of the laser may be changed to address the next first ion to be calibrated, and the corresponding calibration procedure is repeated to complete the functional relationship between the equivalent amplitude of the next ion and the corresponding phonon frequency difference until all ions are calibrated.

In some examples, after obtaining a functional relationship between the equivalent amplitudes obtained by fitting and the corresponding differences, the quantum frequencies corresponding to the corresponding ions in the same or similar ion trap chips may be modified based on the functional relationship. For example, in some experiments, the eigen-phonon frequency is required, but the phonon frequency calibrated by the user is not the eigen-frequency. In ion trap chip parameter calibration, it is generally necessary to calibrate equivalent amplitude and further calibrate the phonon frequency on the basis of the equivalent amplitude, so that a frequency difference corresponding to the equivalent amplitude calibrated by the user can be determined according to the equivalent amplitude calibrated by the user and the functional relationship obtained according to the embodiment of the present disclosure, and then the phonon frequency calibrated by the user is subtracted from the frequency difference to obtain a corresponding eigenfrequency. As another example, a manufacturer has given a corresponding phonon frequency, but in a user experiment, due to the influence of the laser power, phase, amplitude, etc. used, there is a certain difference in the actual phonon frequency from the given phonon frequency. Therefore, according to the equivalent amplitude calibrated in the user experiment and the functional relationship obtained according to the embodiment of the present disclosure, the frequency difference corresponding to the equivalent amplitude calibrated by the user can be determined, and then the actual phonon frequency in the current user experiment can be obtained by adding the given phonon frequency to the frequency difference.

It will be appreciated that the above correction of quantum frequencies corresponding to respective ions in the same or similar ion trap chips based on this functional relationship is merely exemplary. In a real physical experiment, a user can obtain a more accurate phonon frequency under the corresponding equivalent amplitude based on the functional relation according to the practical requirement of the user, and the method is not limited.

In some sweep experiments, when determining the phonon frequency based on the number of layouts (i.e., probabilities) of ions in an excited state, the difference between the observed frequency corresponding to the first blue sideband transition peak (i.e., the frequency difference between the two lasers split by the beam splitter) and the frequency corresponding to the main transition peak is typically considered as the phonon frequency. However, only the blue sideband transition is considered at this time, and the effect of the main transition and the red sideband transition on the result is ignored; also, only two energy level systems, i.e., |g > |n > and |g > |n+1>, are considered, while actual ion trap systems have multiple energy levels.

Thus, in some embodiments, a method according to the present disclosure further comprises: and determining a Hamiltonian amount representation of a quantum system corresponding to the first ion, so as to determine each probability that the first ion is in an excited state based on the Hamiltonian amount representation. The Hamiltonian representation includes an item corresponding to a blue sideband transition, an item corresponding to a red sideband transition, and an item corresponding to a main transition.

As described above, it is common to use the difference between the direct reading first blue sideband transition frequency and the main transition frequency as the phonon frequency. However, in practice, only the blue sideband transition is considered, and the presence of the main transition and the red sideband transition is ignored, so that a deviation is generated between the calibrated phonon frequency and the actual value.

While in embodiments according to the present disclosure, the effects of three transitions are considered simultaneously, their corresponding full hamiltonian amounts are as follows:

wherein j and k are respectively ion and phonon indexes, and Ω _j Is the equivalent Rabi drive frequency (i.e. equivalent amplitude),is the j ion from |g>Transfer to |e>State ascending operator->Representing a large detuning of the two lasers, i.e. the frequency difference between the two lasers, into which the lasers are split by the beam splitter, is also generally a controllable variable in sweep experiments. η (eta) _j,k Is the strength of the coupling between ions and phonons, a _k Annihilation operator, ω, of phonons _k The frequency of phonons, which is also the object to be calibrated, h.c represents the conjugate term.

The Hamiltonian quantity is eta _j,k Less often, the expansion can be expressed in the following form:

when delta _j When=0, one will generally ignore the following high frequency term, and only the hamiltonian remainsAn item is called a main transition. When delta _j ≈ω _k At the same time, the Hamiltonian amount is approximately left only +.>The term is called the blue sideband transition. When delta _j ≈-ω _k At the same time, the Hamiltonian amount is approximately left only +.>The term is called the red sideband transition. The above three transitions are generally all items one presently considers. The corresponding transition diagram is shown in fig. 3.

When only blue sideband transition is considered, after the interaction Hamiltonian quantity of the laser and the two-level system is evolved in t time, the probability of the ion in the state of |e > can be conveniently obtained based on the corresponding Hamiltonian calculation:

the result of the sweep frequency deviates from the actual situation, which is called "frequency drift", as shown in fig. 4.

In the above embodiment, however, the hamiltonian amount expression used takes three kinds of transitions into consideration, and therefore the variation of the number of layouts in the excited state with the laser frequency difference can be calculated based on the hamiltonian amount. It should be noted that an apparatus for observing the number of layouts (probability) that ions are in an excited state (e.g., a fluorescence detection apparatus) can be conveniently obtained. In the simulation experiment, the distribution number change of ions in an excited state under different laser parameters can be calculated based on the determined Hamiltonian amount. Therefore, by calculating the change in the number of excited state layouts with the frequency, three layout numbers of the dominant red blue |e > |n >, |e > |n-1>, |e > |n+1> and the total |e > state layout number can be recorded, as shown in fig. 5.

As described above, in the above example of determining the phonon frequency through the sweep experiment, the frequency difference corresponding to when the peak occurs in the first probability may be determined as the corresponding phonon frequency. Whereas in the example shown in fig. 5, the first probability peaks generally corresponding to the peak corresponding to the Lan Biandai transition. Therefore, a frequency difference corresponding to a peak in which the frequency difference is larger than the 0 region (i.e., a peak corresponding to the blue sideband transition) can be read as the corresponding phonon frequency.

In the embodiment, the influence of main transition, red transition and blue transition is reserved in the Hamiltonian expression, the calibration result is more in accordance with the actual experimental condition, and the calibrated parameters are more close to the actual experimental parameters.

As shown in fig. 6, there is also provided an ion trap chip parameter-correction apparatus 600 according to an embodiment of the present disclosure, including: a first determining unit 610 configured to determine a position of a first ion to be calibrated in the ion trap chip; an acquisition unit 620 configured to acquire and set an initial power value of a laser so that an equivalent amplitude of the laser after irradiating the first ion is smaller than a first threshold; a second determining unit 630 configured to acquire and set a first pulse duration of the laser and change a frequency difference between two laser beams divided by a beam splitter by the laser to determine a first probability that the first ion is in an excited state at each frequency difference; a third determining unit 640 configured to determine an eigenphonon frequency based on a variation of the first probability with the frequency difference; an execution unit 650 configured to execute the following operations N times, N being a positive integer of 2 or more: adjusting the power value of the laser, and determining the equivalent amplitude of the laser irradiated to the first ion under the current power value; acquiring and setting a second pulse duration of the laser, and changing a frequency difference between two laser beams split by the laser through a beam splitter to determine a second probability that the first ions are in an excited state at each frequency difference; and determining a first phonon frequency based on a variation of the second probability with the frequency difference; determining a difference between the first phonon frequency and the eigenphonon frequency; and a correction unit 660 configured to perform function fitting based on the correspondence between the equivalent amplitudes and the respective differences, such that the phonon frequencies at the respective equivalent amplitudes are corrected based on the fitted function.

Here, the operations of the above units 610 to 660 of the ion trap chip parameter-correcting apparatus 600 are similar to the operations of the steps 110 to 160 described above, respectively, and are not repeated here.

According to embodiments of the present disclosure, there is also provided an electronic device, a readable storage medium and a computer program product.

Referring to fig. 7, a block diagram of an electronic device 700 that may be a server or a client of the present disclosure, which is an example of a hardware device that may be applied to aspects of the present disclosure, will now be described. Electronic devices are intended to represent various forms of digital electronic computer devices, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular telephones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be exemplary only, and are not meant to limit implementations of the disclosure described and/or claimed herein.

As shown in fig. 7, the electronic device 700 includes a computing unit 701 that can perform various appropriate actions and processes according to a computer program stored in a Read Only Memory (ROM) 702 or a computer program loaded from a storage unit 708 into a Random Access Memory (RAM) 703. In the RAM 703, various programs and data required for the operation of the electronic device 700 may also be stored. The computing unit 701, the ROM 702, and the RAM 703 are connected to each other through a bus 704. An input/output (I/O) interface 705 is also connected to bus 704.

Various components in the electronic device 700 are connected to the I/O interface 705, including: an input unit 706, an output unit 707, a storage unit 708, and a communication unit 709. The input unit 706 may be any type of device capable of inputting information to the electronic device 700, the input unit 706 may receive input numeric or character information and generate key signal inputs related to user settings and/or function control of the electronic device, and may include, but is not limited to, a mouse, a keyboard, a touch screen, a trackpad, a trackball, a joystick, a microphone, and/or a remote control. The output unit 707 may be any type of device capable of presenting information and may include, but is not limited to, a display, speakers, video/audio output terminals, vibrators, and/or printers. Storage unit 708 may include, but is not limited to, magnetic disks, optical disks. The communication unit 709 allows the electronic device 700 to exchange information/data with other devices through computer networks, such as the internet, and/or various telecommunications networks, and may include, but is not limited to, modems, network cards, infrared communication devices, wireless communication transceivers and/or chipsets, such as bluetooth devices, 802.11 devices, wiFi devices, wiMax devices, cellular communication devices, and/or the like.

The computing unit 701 may be a variety of general and/or special purpose processing components having processing and computing capabilities. Some examples of computing unit 701 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various specialized Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 701 performs the various methods and processes described above, such as method 100. For example, in some embodiments, the method 100 may be implemented as a computer software program tangibly embodied on a machine-readable medium, such as the storage unit 708. In some embodiments, part or all of the computer program may be loaded and/or installed onto the electronic device 700 via the ROM 702 and/or the communication unit 709. When the computer program is loaded into RAM 703 and executed by computing unit 701, one or more steps of method 100 described above may be performed. Alternatively, in other embodiments, the computing unit 701 may be configured to perform the method 100 by any other suitable means (e.g., by means of firmware).

Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuit systems, field Programmable Gate Arrays (FPGAs), application Specific Integrated Circuits (ASICs), application Specific Standard Products (ASSPs), systems On Chip (SOCs), complex Programmable Logic Devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs, the one or more computer programs may be executed and/or interpreted on a programmable system including at least one programmable processor, which may be a special purpose or general-purpose programmable processor, that may receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to a user; and a keyboard and pointing device (e.g., a mouse or trackball) by which a user can provide input to the computer. Other kinds of devices may also be used to provide for interaction with a user; for example, feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form, including acoustic input, speech input, or tactile input.

The systems and techniques described here can be implemented in a computing system that includes a background component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such background, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local Area Networks (LANs), wide Area Networks (WANs), the internet, and blockchain networks.

The computer system may include a client and a server. The client and server are typically remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. The server may be a cloud server, a server of a distributed system, or a server incorporating a blockchain.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps recited in the present disclosure may be performed in parallel, sequentially or in a different order, provided that the desired results of the disclosed aspects are achieved, and are not limited herein.

Although embodiments or examples of the present disclosure have been described with reference to the accompanying drawings, it is to be understood that the foregoing methods, systems, and apparatus are merely exemplary embodiments or examples, and that the scope of the present invention is not limited by these embodiments or examples but only by the claims following the grant and their equivalents. Various elements of the embodiments or examples may be omitted or replaced with equivalent elements thereof. Furthermore, the steps may be performed in a different order than described in the present disclosure. Further, various elements of the embodiments or examples may be combined in various ways. It is important that as technology evolves, many of the elements described herein may be replaced by equivalent elements that appear after the disclosure.

Claims

1. An ion trap chip parameter correction method, comprising:

Determining the position of a first ion to be calibrated in the ion trap chip;

acquiring and setting an initial power value of a laser so that the equivalent amplitude of the laser after irradiating the first ions is smaller than a first threshold value;

acquiring and setting a first pulse duration of the laser, and changing a frequency difference between two laser beams split by a beam splitter of the laser to determine a first probability that the first ion is in an excited state at each frequency difference;

determining an eigenphonon frequency based on a change in the first probability with the frequency difference;

the following operations are performed N times, N being a positive integer of 2 or more:

adjusting the power value of the laser, and determining the equivalent amplitude of the laser irradiated to the first ion under the current power value;

acquiring and setting a second pulse duration of the laser, and changing a frequency difference between two laser beams split by the laser through a beam splitter to determine a second probability that the first ions are in an excited state at each frequency difference;

determining a first phonon frequency based on a change in the second probability with the frequency difference;

determining a difference between the first phonon frequency and the eigenphonon frequency; and performing function fitting based on the corresponding relation between the equivalent amplitude and the corresponding difference value, so that the phonon frequency under the corresponding equivalent amplitude is corrected based on the function obtained by fitting.

2. The method of claim 1, wherein obtaining and setting an initial power value of a laser such that an equivalent amplitude of the laser after irradiating the first ions is less than a first threshold comprises:

adjusting the power value of the laser until the determined equivalent amplitude is less than a first threshold value and determining the power value corresponding to the equivalent amplitude being less than the first threshold value as an initial power value:

determining a frequency difference between the first ion g and e states to determine a frequency difference between two laser beams split by a beam splitter based on the frequency difference;

adjusting pulse durations of the laser and determining a probability that the first ion is in an excited state after irradiation of the first ion by the laser at each pulse duration;

determining a third pulse duration corresponding to when the probability of the first ion in the excited state is close to 1; and

an equivalent amplitude of the laser after irradiating the first ion is determined based on the third pulse duration.

3. The method of claim 1, wherein the first pulse duration is greater than the second pulse duration.

4. The method of claim 1, wherein the first threshold comprises 0.01MHz.

5. The method of claim 1, wherein determining the location of the first ion to be calibrated in the ion trap chip comprises: and changing the incident angle of the laser according to a first preset step length within a first preset range so as to determine the position of the first ion through fluorescence imaging.

6. The method of claim 1, further comprising: determining Hamiltonian amount representation of the quantum system corresponding to the first ion, determining each probability that the first ion is in an excited state based on the Hamiltonian amount representation,

the Hamiltonian representation comprises an item corresponding to a blue sideband transition, an item corresponding to a red sideband transition and an item corresponding to a main transition.

7. The method of claim 1, wherein determining an equivalent amplitude of the laser after irradiating the first ion at a current power value comprises:

Determining a fourth pulse duration corresponding to when the probability of the first ion in the excited state is close to 1; and

an equivalent amplitude of the laser after irradiating the first ion is determined based on the fourth pulse duration.

8. The method of claim 7, wherein acquiring and setting the second pulse duration of the laser comprises: setting the second pulse duration equal to the fourth pulse duration or close to the fourth pulse duration within a preset error range.

9. The method of claim 2 or 7, wherein the equivalent amplitude Ω of the laser after irradiation with the first ion is determined based on the following formula:

Ω＝π/2τ

where τ is the corresponding pulse duration when the probability of the first ion being in the excited state is close to 1.

10. An ion trap chip parameter correction apparatus comprising:

a first determining unit configured to determine a position of a first ion to be calibrated in the ion trap chip;

an acquisition unit configured to acquire and set an initial power value of a laser so that an equivalent amplitude of the laser after irradiating the first ion is smaller than a first threshold;

A second determining unit configured to acquire and set a first pulse duration of the laser and change a frequency difference between two laser beams divided by a beam splitter by the laser to determine a first probability that the first ion is in an excited state at each frequency difference;

a third determination unit configured to determine an eigenphonon frequency based on a variation of the first probability with the frequency difference;

an execution unit configured to execute the following operations N times, N being a positive integer of 2 or more:

determining a difference between the first phonon frequency and the eigenphonon frequency; and

and the correction unit is configured to perform function fitting based on the corresponding relation between the equivalent amplitude and the corresponding difference value, so that the phonon frequency under the corresponding equivalent amplitude is corrected based on the function obtained by fitting.

11. The apparatus of claim 10, wherein the acquisition unit comprises an adjustment subunit configured to: adjusting the power value of the laser until the determined equivalent amplitude is less than a first threshold value and determining the power value corresponding to the equivalent amplitude being less than the first threshold value as an initial power value:

12. The apparatus of claim 10, wherein the first pulse duration is greater than the second pulse duration.

13. The apparatus of claim 10, wherein the first threshold comprises 0.01MHz.

14. The apparatus of claim 10, wherein the first determination unit comprises a determination subunit configured to: and changing the incident angle of the laser according to a first preset step length within a first preset range so as to determine the position of the first ion through fluorescence imaging.

15. The apparatus of claim 10, further comprising a fourth determination unit configured to:

determining Hamiltonian amount representation of the quantum system corresponding to the first ion, determining each probability that the first ion is in an excited state based on the Hamiltonian amount representation,

16. The apparatus of claim 11, wherein the equivalent amplitude Ω of the laser after irradiation with the first ion is determined based on the following formula:

Ω＝π/2τ

where τ is the third pulse duration.

17. An electronic device, comprising:

at least one processor; and

a memory communicatively coupled to the at least one processor; wherein the method comprises the steps of

The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-9.

18. A non-transitory computer readable storage medium storing computer instructions for causing the computer to perform the method of any one of claims 1-9.

19. A computer program product comprising a computer program, wherein the computer program, when executed by a processor, implements the method of any of claims 1-9.