Modulation and demodulation method based on heteronuclear ions, ion trap system and quantum computer

Abstract

The application discloses a modulation and demodulation method based on heteronuclear ions, and discloses an ion trap system and a quantum computer. The method modulates and demodulates information through Rabi oscillation of the heteronuclear ions. When the signal is intercepted, the intercepting party only obtains a laser with power changing in a microsecond scale. Existing power detection equipment cannot accurately respond to the power change in the microsecond level, and it is difficult to decipher, thereby ensuring the accuracy and security of information transmission. Compared with the traditional single-probe modulation and demodulation method, the application has higher efficiency on the quantum channel, higher quantum resource utilization rate, and higher information transmission rate. The light path of the application is easier to build than the light path of the homonuclear ions, and the crosstalk rate of the laser of the heteronuclear ions and the ions is lower than the crosstalk rate of the homonuclear ions and the ions through the addressing light path.

Description

Technical Field

[0001] This invention belongs to the field of quantum communication technology based on trapped ions, specifically relating to modulation and demodulation methods based on heteronuclear ions, as well as ion trap systems and quantum computers. Background Technology

[0002] With the rapid development of quantum information science, quantum communication has become an important direction for future information transmission. In particular, in application scenarios such as quantum key distribution, quantum networks, and quantum satellite communication, higher technical requirements have been put forward for the efficient modulation and accurate demodulation of quantum states.

[0003] Quantum modulation and demodulation technology plays a crucial role in quantum communication. In quantum communication, demodulation technology is used to extract information from the received quantum signal to ensure the accuracy and security of information transmission. Traditional demodulation methods are inefficient on quantum channels and cannot make full use of quantum resources, resulting in a limited information extraction rate. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a modulation and demodulation method based on heteronuclear ions, as well as an ion trap system and a quantum computer.

[0005] The above-mentioned objectives of the present invention are achieved by the following technical means:

[0006] The modulation and demodulation method based on heteronuclear ions includes the following steps:

[0007] Step 1: Prepare the first ion and the second ion to the ground state of Rabi oscillation of the first ion and the ground state of Rabi oscillation of the second ion, respectively;

[0008] Step 2: Divide the total signal to be transmitted into the signal to be transmitted of the first ion and the signal to be transmitted of the second ion. Modulate the AWG waveform generated by the arbitrary waveform generator with the signal to be transmitted of the first ion and the signal to be transmitted of the second ion respectively to obtain the first modulation signal and the second modulation signal respectively, and output them through different output channels respectively.

[0009] Step 3: Modulate the initial laser beam of the first ion and the initial laser beam of the second ion using the first modulation signal and the second modulation signal respectively to obtain the first modulated light and the second modulated light respectively;

[0010] The initial laser for the first ion is a laser that causes the first ion to oscillate in Rabi, and the initial laser for the second ion is a laser that causes the second ion to oscillate in Rabi.

[0011] Step 4: Apply the first modulation light and the second modulation light to the first ion and the second ion in the ground state of Rabi oscillation, respectively. Then, obtain the first Rabi oscillation curve and the second Rabi oscillation curve as time changes, respectively, by state detection, showing the population of the excited state of the first ion and the population of the excited state of the second ion in Rabi oscillation.

[0012] Step 5: Fit the Rabi frequency of the first ion using the first Rabi oscillation curve and the second Rabi oscillation curve, respectively. Rabi frequency of the second ion Then through and The signals to be transmitted for the first ion and the second ion are demodulated separately; finally, the signals to be transmitted for the first ion and the second ion are spliced ​​together to obtain the total signal to be transmitted.

[0013] The first and second ions are heteronuclear ions.

[0014] As described above, step 2 specifically includes the following steps:

[0015] Step 2.1: Determine the Rabi frequency range of the first ion and the Rabi frequency range of the second ion corresponding to the output voltage range of the arbitrary waveform generator based on the following formulas:

[0016] ;

[0017] ;

[0018] In the formula, The output voltage amplitude of an arbitrary waveform generator. denoted as the Rabi driving coefficient of the first ion. is the Rabi driving coefficient of the second ion;

[0019] Step 2.2: Divide the output voltage range of the arbitrary waveform generator, the Rabi frequency range of the first ion corresponding to the output voltage range, and the Rabi frequency range of the second ion corresponding to the output voltage range into 2... n The output voltage range of each segment is determined by defining the Rabi frequency range of the first ion and the Rabi frequency range of the second ion, and the center voltage corresponding to the center Rabi frequency of the first ion and the center voltage corresponding to the center Rabi frequency of the second ion are determined.

[0020] Step 2.3: Divide the signal to be transmitted of the first ion into segments, and edit the AWG waveform into segments according to the signal to be transmitted of the first ion in each segment to obtain the first modulation signal including the signal to be transmitted of the first ion.

[0021] The signal to be transmitted of the second ion is segmented, and the AWG waveform is segmented and edited according to each segment of the signal to be transmitted of the second ion to obtain a second modulation signal including the signal to be transmitted of the second ion.

[0022] In step 2.3, the signal to be transmitted is segmented in the following way, and the AWG waveform of each segment is edited:

[0023] The signal to be transmitted is divided into multiple segments, each segment consisting of n bits of signal to be transmitted, and each segment consisting of 2 n Two signal states, each segment of the signal to be transmitted has 2 n The signal states are respectively related to 2 n The output voltage ranges of each segment correspond one-to-one, resulting in 2. n The output voltage range corresponding to each of the signal states is determined, and then step 2.2 is used to determine the 2 n The Rabi frequency ranges corresponding to the various signal states;

[0024] Finally, the AWG waveform output by the arbitrary waveform generator is divided into the same number of segments. Each AWG waveform corresponds to each segment of the signal to be transmitted. Based on the center voltage corresponding to the signal state of each segment of the signal to be transmitted, the AWG waveform of each segment is modulated to obtain the modulated signal.

[0025] Where n is the number of bits in each AWG waveform segment, and n is a positive integer. The time of one cycle corresponding to the smallest center Rabi frequency is taken as the length of each AWG waveform segment.

[0026] The total signal to be transmitted is divided as described above in the following manner:

[0027] When the total number of bits N of the signal to be transmitted is even, the first N / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the first ion, and the last N / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the second ion; when the total number of bits of the signal to be transmitted is even, the first (N+1) / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the first ion, and the last (N-1) / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the second ion.

[0028] When the number of bits in the signal to be transmitted is not an integer multiple of n, the last segment of the signal to be transmitted is padded with 0s and m-1 ones in sequence to make the last segment of the signal to be transmitted n bits, where m is the difference in the number of bits between the last segment of the signal to be transmitted and n, and the length of the AWG pulse edited from the last segment of the signal to be transmitted is set to half the period time of the period corresponding to the minimum center Rabi frequency.

[0029] As mentioned above, the number of bits in each AWG waveform segment is 2. By padding the last bit of the signal to be transmitted in the second ion with zeros, the signals to be transmitted in the first and second ions are made to be integer multiples of 2.

[0030] As described above, step 4 specifically includes the following steps:

[0031] Step 4.1: Apply the first modulation light to the first ion in the ground state of Rabi oscillation. The first ion interacts with the first modulation light to generate Rabi oscillation. The first ion oscillates between the ground state of Rabi oscillation and the excited state of Rabi oscillation. Then, perform state detection on the first ion to obtain the population of the excited state of Rabi oscillation of the first ion.

[0032] The second modulation light is applied to the second ion in the ground state of Rabi oscillation. The second ion interacts with the second modulation light to generate Rabi oscillation, causing the second ion to oscillate between the ground state of Rabi oscillation and the excited state of Rabi oscillation. Then, state detection is performed on the second ion to obtain the population of the excited state of Rabi oscillation of the second ion.

[0033] Step 4.2: Modify the time when the first modulated light acts on the first ion in step 4.1 until the population of the excited state of the Rabi oscillation of the first ion no longer changes with the time of action, and obtain the first Rabi oscillation curve of the population of the excited state of the Rabi oscillation of the first ion changing with time.

[0034] Change the time in step 4.1 when the second modulated light acts on the second ion until the population of the excited state of the Rabi oscillation of the second ion no longer changes with the time of application, and obtain the second Rabi oscillation curve of the population of the excited state of the Rabi oscillation of the second ion changing with time.

[0035] As described above, step 5 specifically includes the following steps:

[0036] Step 5.1: Divide the first Rabi oscillation curve into segments according to the length of each AWG waveform segment, and fit the Rabi frequency of each segment of the first Rabi oscillation curve.

[0037] According to step 2.3, the first ion 2 nThe Rabi frequency range of the first ion corresponding to each of the signal states is determined. Each segment of the Rabi frequency of the first ion is demodulated into the corresponding signal state. Finally, the signal states corresponding to each segment of the Rabi frequency of the first ion are arranged in chronological order to obtain the signal to be transmitted of the first ion.

[0038] Step 5.2: Divide the Rabi oscillation curve of the second ion into segments according to the length of each AWG waveform segment, and fit the Rabi frequency of the Rabi oscillation curve of the second ion in each segment.

[0039] According to the second ion obtained in step 2.4, 2 n The Rabi frequency range of the second ion corresponding to each of the signal states is determined. Each Rabi frequency segment of the second ion is demodulated into a corresponding signal state. Finally, the signal states corresponding to each Rabi frequency segment of the second ion are arranged in chronological order to obtain the signal to be transmitted from the second ion.

[0040] Step 5.3: The signal to be transmitted of the first ion and the signal to be transmitted of the second ion are spliced ​​together to obtain the total signal to be transmitted.

[0041] An ion trap system includes an ion trap and a laser module, and further includes an arbitrary waveform generator and an acousto-optic modulator module;

[0042] The ion trap is used to trap a first ion and a second ion, which are heteronuclear ions.

[0043] The laser module is used to generate an initial laser that excites the Rabi oscillations of the first and second ions, and outputs the laser to the acousto-optic modulator module for modulation.

[0044] The arbitrary waveform generator is used to obtain a first modulation signal and a second modulation signal based on the transmission signal of the first ion and the transmission signal of the second ion, respectively, and outputs the first modulation signal and the second modulation signal to the acousto-optic modulator module through different output channels;

[0045] The acousto-optic modulator module is used to modulate the initial laser of the first ion according to the first modulation signal to obtain the first modulated light; and to modulate the initial laser of the second ion according to the second modulation signal to obtain the second modulated light; the first modulated light is used to excite the Rabi oscillation of the first ion, and the second modulated light is used to excite the Rabi oscillation of the second ion.

[0046] It also includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, it implements the heteronuclear ion-based modulation and demodulation method as described above.

[0047] A quantum computer comprising the ion trap system described above.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) The method of the present invention modulates and demodulates information through Rabi oscillation of heteronuclear ions. When the signal is intercepted, the interceptor will only get a laser with power changing within the microsecond scale. Existing power detection equipment is difficult to accurately respond to power changes at the microsecond level, making decryption difficult and ensuring the accuracy and security of information transmission.

[0050] (2) Compared with the traditional single probe modulation and demodulation method, the present invention is more efficient in quantum channels, has a higher quantum resource utilization rate, and improves the information transmission rate.

[0051] (3) The optical path of the present invention is less difficult to build than that of homonuclear ion optical path, and the crosstalk rate of the laser of heteronuclear ion interacting with the ion is lower than that of homonuclear ion interacting with the ion through the addressing optical path. Attached Figure Description

[0052] Figure 1 This is a flowchart of the method of the present invention;

[0053] Figure 2 As in Embodiment 1 of the present invention 40 Ca + The AWG waveform of the first modulation signal, where the horizontal axis represents time and the vertical axis represents voltage;

[0054] Figure 3 As in Embodiment 1 of the present invention 40 Ca + The first Rabi oscillation curve is plotted, where the horizontal axis represents time (µs) and the vertical axis represents population.

[0055] Figure 4 As in Embodiment 1 of the present invention 43 Ca + The AWG waveform of the second modulation signal, where the horizontal axis represents time and the vertical axis represents voltage;

[0056] Figure 5 As in Embodiment 1 of the present invention 43 Ca + The second Rabi oscillation curve is plotted, where the horizontal axis represents time (µs) and the vertical axis represents population.

[0057] Figure 6 This is a structural diagram of the ion trap system of Embodiment 2 of the present invention;

[0058] Figure reference numerals and corresponding component names:

[0059] 1-First 729nm laser; 2-Second 729nm laser; 3-First arbitrary waveform generator; 4-First acousto-optic modulator; 5-Second acousto-optic modulator; 6-First vacuum cavity. Detailed Implementation

[0060] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. The embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0061] Example 1:

[0062] Modulation and demodulation methods based on heteronuclear ions, such as Figure 1 This includes the following steps:

[0063] The pair of heteronuclear ions used in this embodiment are 40 Ca + and 43 Ca + These are respectively used as the first ion and the second ion in this embodiment.

[0064] Step 1, 40 Ca + and 43 Ca + Prepared separately to 40 Ca + The ground state of Rabi oscillations and 43 Ca + The ground state of the Rabi oscillation is specifically: 40 Ca + and 43 Ca + They were cooled to their vibrational ground state by lasers, and then the vibrational ground state was... 40 Ca + Prepared from state ground state, obtain ground state 40 Ca + ; the vibrational ground state 43 Ca + Prepared from state ground state, obtain ground state 43 Ca + .

[0065] in, Total electronic angular momentum The magnetic quantum number, Total angular momentum (total electron angular momentum) (and the vector sum of nuclear spin I). Total angular momentum (magnetic quantum number).

[0066] It should be noted that this embodiment is based on... 40 Ca + and 43 Ca + Prepared separately to and For example, the method of the present invention is not limited to the above two sub-levels in this step, but can also be applied to any of the other sub-levels of the ground state.

[0067] Step 2: Divide the total signal to be transmitted into two segments, and use them as... 40 Ca + The signal to be transmitted and 43 Ca + The signal to be transmitted is controlled, in order to 40 Ca + The signal to be transmitted will be generated by an arbitrary waveform generator (AWG, in this embodiment the arbitrary waveform generator is AWG4100). 40 Ca + The AWG waveform is modulated to obtain the first modulation signal, and then... 43 Ca + The signal to be transmitted is generated by an arbitrary waveform generator. 43 Ca + The AWG waveform is modulated to obtain a second modulated signal. The arbitrary waveform generator outputs the first modulated signal and the second modulated signal through different output channels, respectively. Figure 2 for 40 Ca + The AWG waveform of the first modulation signal. Figure 4 for 43 Ca + The AWG waveform of the second modulation signal; specifically including the following steps:

[0068] Step 2.1: Determine the output voltage range corresponding to the arbitrary waveform generator (AWG). 40 Ca + Rabi frequency range and 43 Ca + The Rabi frequency range is calculated based on the following formula:

[0069] (1);

[0070] (2);

[0071] In the formula, The output voltage amplitude of an arbitrary waveform generator. for 40Ca + Rabi driving coefficients, for 43 Ca + Rabi driving coefficients, for 40 Ca + Rabi frequency, for 43 Ca + Rabi frequency;

[0072] by 40 Ca + For example, in this embodiment, the output voltage range of the arbitrary waveform generator AWG4100 is -0.5 V to 0.5 V, then the corresponding... 40 Ca + The Rabi frequency range is 0 to 200 kHz × 2 .

[0073] Rabi driving coefficient (This embodiment is) and The size of the excited ion energy level is related to the laser power, laser polarization, laser spot size, laser direction, and the two energy levels excited by the laser. In this embodiment, the laser power is 35mW; the laser polarization is linear, with the polarization direction making a 90° angle with the direction of the main magnetic field; the main magnetic field is the magnetic field that causes Zeeman splitting of the ion energy level; the size of the 729 nm laser spot irradiating the ion is 80 micrometers; the laser incident direction is along the direction of the cap electrode of the ion trap; the excited ion energy levels are the ground state and excited state in this embodiment. .

[0074] Step 2.2: Set the output voltage range of the arbitrary waveform generator and the corresponding output voltage range... 40 Ca + The Rabi frequency range and the corresponding output voltage range 43 Ca + The Rabi frequency range is divided into 2 n Segment, determine the output voltage range corresponding to each segment 40 Ca + Rabi frequency range and 43 Ca + The Rabi frequency range, and determine each segment 40 Ca + The center voltage corresponding to the center Rabi frequency in the Rabi frequency range and each segment 43 Ca + The center voltage corresponding to the center Rabi frequency of the Rabi frequency range, where n is the number of bits encoded in each AWG waveform segment, and n is a positive integer.

[0075] In this embodiment, n=2, meaning each small segment of the AWG waveform transmits two bits of information. The AWG output is divided into four segments: 0-0.125 V, 0.125 V-0.25 V, 0.25 V-0.375 V, and 0.375 V-0.5 V, corresponding to... 40 Ca + Rabi frequency - , - , - , - ;by 40 Ca + For example, when the signal to be transmitted is 00, the amplitude of the AWG output signal is set to 0.0625V, corresponding to... When the signal to be transmitted is 01, the amplitude of the AWG output signal is set to 0.1875V, corresponding to... When the signal to be transmitted is 10, the amplitude of the AWG output signal is set to 0.3125V, corresponding to... When the signal to be transmitted is 11, the amplitude of the AWG output signal is set to 0.4375V, corresponding to... .

[0076] Step 2.3, according to 40 Ca + Edit the AWG waveform of the information to be transmitted: 40 Ca + The signal to be transmitted is divided into multiple segments, each segment 40 Ca + The signal to be transmitted consists of n bits of signal to be transmitted, each segment 40 Ca + The signal to be transmitted includes 2 n Each signal state will be a segment 40 Ca + 2 of the signals to be transmitted n The states are respectively related to 2 n The output voltage ranges of each segment correspond one-to-one, thus obtaining... 40 Ca + 2 n The output voltage range corresponding to each signal state is determined according to step 2.2. 40 Ca + 2 n The Rabi frequency ranges corresponding to the various signal states.

[0077] Finally, the output of the arbitrary waveform generator... 40 Ca +The AWG waveform is divided into the same number of segments, each segment 40 Ca + The AWG waveform and each segment 40 Ca + The signals to be transmitted correspond one-to-one, according to each segment 40 Ca + The center voltage corresponding to the signal state of the signal to be transmitted is used as the modulation amplitude for each segment. 40 Ca + The AWG waveform is modulated to obtain the first modulated signal.

[0078] Step 2.4, according to 43 Ca + Edit the AWG waveform of the information to be transmitted: 43 Ca + The signal to be transmitted is divided into multiple segments, each segment 43 Ca + The signal to be transmitted consists of n bits of signal to be transmitted, each segment 43 Ca + The transmitted signal includes 2 n Each signal state will be a segment 43 Ca + 2 of the signals to be transmitted n The states are respectively related to 2 n The output voltage ranges of each segment correspond one-to-one, thus obtaining... 43 Ca + 2 n The output voltage range corresponding to each signal state is determined according to step 2.2. 43 Ca + 2 n The Rabi frequency ranges corresponding to the various signal states.

[0079] Finally, the output of the arbitrary waveform generator... 43 Ca + The AWG waveform is divided into the same number of segments, each segment 43 Ca + The AWG waveform and each segment 43 Ca + The signals to be transmitted correspond one-to-one, according to each segment 43 Ca + The center voltage corresponding to the signal state of the signal to be transmitted is used as the modulation amplitude for each segment. 43 Ca + The AWG waveform is modulated to obtain the second modulated signal.

[0080] The time of one cycle corresponding to the minimum center Rabi frequency is taken as the length of each AWG waveform segment. In this embodiment, the minimum center Rabi frequency (i.e. The corresponding period is 40us, ensuring that the signals corresponding to 00, 01, 10, and 11 can all oscillate for at least one cycle within 40us.

[0081] The total signal to be transmitted is divided as follows: when the total number of bits in the signal to be transmitted is even, the first N / 2 bits are taken as... 40 Ca + The signal to be transmitted, and the last N / 2 bits of the signal to be transmitted as 43 Ca + The signal to be transmitted; when the total number of bits of the signal to be transmitted is even, the first (N+1) / 2 bits of the signal to be transmitted are taken as... 40 Ca + The signal to be transmitted, the last (N-1) / 2 bits of the signal to be transmitted are taken as 43 Ca + The signal to be transmitted.

[0082] When the number of bits in the signal to be transmitted is not an integer multiple of n, the last segment of the signal to be transmitted is padded with 0s and m-1 ones in sequence to make the last segment of the signal to be transmitted n bits, where m is the difference in the number of bits between the last segment of the signal to be transmitted and n, and the length of the AWG pulse edited from the last segment of the signal to be transmitted is set to half the period time of the period corresponding to the minimum center Rabi frequency.

[0083] In this embodiment, n is 2, and zeros are padded at the end of the signal to be transmitted to make n = 2. 40 Ca + and 43 Ca + The signal to be transmitted is an integer multiple of 2.

[0084] Taking 001001110 as an example, if the last bit of the signal to be transmitted is padded with 0 to become 0010011100, and it is divided into 00, 10, 01, 11 and 00, then the amplitude from 0 to 40 μs is 0.0625 V, from 40 to 80 μs is 0.3125 V, from 80 to 120 μs is 0.1875 V, from 120 to 160 μs is 0.4375 V, from 160 to 180 μs is 0.0625 V, and from 180 to 200 μs is 0 V.

[0085] The value of n depends on the stability of the system. The more stable the system, the smaller the error between the experimentally fitted Rabi frequency and the theoretical Rabi frequency, and the larger the value of n can be.

[0086] Step 3: Pair the signal with the first modulation signal. 40 Ca + The 729nm laser is modulated to obtain the first modulated light; the second modulation signal is then used to modulate the light. 43Ca + The 729nm laser is modulated to obtain the second modulated light.

[0087] Step 4: Apply the first modulated light to ground state 40 Ca + Above, the laser interacts with the surface to generate Rabi oscillations, which are then obtained through state detection. 40 Ca + excited state The first Rabi oscillation curve showing population change over time; applying the second modulated light to... ground state 43 Ca + Above, the laser interacts with the surface to generate Rabi oscillations, which are then obtained through state detection. 43 Ca + excited state The second Rabi oscillation curve of population changing with time, Figure 3 for 40 Ca + The first Rabi oscillation curve. Figure 5 for 43 Ca + The second Rabi oscillation curve plot specifically includes the following steps:

[0088] Step 4.1: Apply the first modulated light to ground state 40 Ca + superior, 40 Ca + The interaction with the first modulated light produces Rabi oscillations. 40 Ca + exist ground state and excited state Oscillate between, then on 40 Ca + Perform state detection to obtain 40 Ca + excited state The people of Buju.

[0089] Apply the second modulated light to ground state 43 Ca + superior, 43 Ca + The interaction with the second modulated light produces Rabi oscillations, making 43 Ca + exist ground state and excited state Oscillate between, then on 43 Ca + Perform state detection to obtain43 Ca + excited state The people of Buju.

[0090] Step 4.2: Modify the first modulated light in step 4.1 to act on... 40 Ca + The time on, until 40 Ca + The population of the excited state no longer changes with time, thus obtaining 40 Ca + excited state The first Rabi oscillation curve showing the population change over time.

[0091] Change the second modulated light in step 4.1 to act on 43 Ca + Time t on, until 43 Ca + The population of the excited state no longer changes with time, thus obtaining 43 Ca + excited state The second Rabi oscillation curve showing the population change over time.

[0092] Step 5: Fit the first Rabi oscillation curve to obtain... 40 Ca + Rabi frequency Fitting the second Rabi oscillation curve 43 Ca + Rabi frequency Finally passed and Demodulate each 40 Ca + The signal to be transmitted and 43 Ca + The signal to be transmitted will finally be 40 Ca + The signal to be transmitted and 43 Ca + The total signal to be transmitted is obtained by splicing the signals to be transmitted, specifically including the following steps:

[0093] Step 5.1: Divide the first Rabi oscillation curve into segments of 40µs, according to... Fitting 40 Ca + Each Rabi frequency segment, where, for 40 Ca + Population of excited states The first modulated light in step 4.2 acts on 40 Ca+ The time spent on it.

[0094] According to step 2.3 40 Ca + 2 n The signal states correspond to the following: 40 Ca + The Rabi frequency range will 40 Ca + Each Rabi frequency segment is demodulated into its corresponding signal state, and finally... 40 Ca + The signal states corresponding to each Rabi frequency segment are arranged in chronological order to obtain... 40 Ca + The signal to be transmitted.

[0095] Step 5.2: Divide the second Rabi oscillation curve into segments of 40µs, according to... Fitting 43 Ca + Each Rabi frequency segment, where, for 43 Ca + Population of excited states The second modulated light in step 4.2 acts on 43 Ca + The time spent on it.

[0096] According to step 2.4 43 Ca + 2 n The signal states correspond to the following: 43 Ca + The Rabi frequency range will 43 Ca + Each Rabi frequency segment is demodulated into its corresponding signal state, and finally... 43 Ca + The signal states corresponding to each Rabi frequency segment are arranged in chronological order to obtain... 43 Ca + The signal to be transmitted.

[0097] Step 5.3, 40 Ca + The signal to be transmitted and 43 Ca + The signals to be transmitted are spliced ​​together to obtain the total signal to be transmitted.

[0098] by 40 Ca + For example, the fitting frequency is in When the frequency is between 0 and 0, the demodulation information is 00, and the fitting frequency is between 0 and Between these values, the demodulation information is 0 and 1, and the fitting frequency is between Between these values, the demodulation information is 10, and the fitted frequency is in the range of 10. Between these points, the demodulation information is 11; for the last segment, the fitting frequency is... When Rabi oscillations occur between and within 40 µs, the demodulation information is 00, and the fitting frequency is within... When Rabi oscillations occur only within the first 20 µs of a 40 µs interval, the demodulation information is 0, and the fitting frequency is within... When Rabi oscillations occur between and within 40 µs, the demodulation information is 10, and the fitting frequency is within... When Rabi oscillations occur only in the first 20 µs within a 40 µs interval, the demodulation information is 1.

[0099] When the signal to be transmitted is 001001110 40 Ca + The Rabi oscillation of the excited state, the Rabi frequency fitted from 0-40 μs is Based on the above correspondence between Rabi frequency and information, the corresponding demodulated information is 00, and the Rabi frequency fitted from 40-80 us is... The corresponding demodulation information is 10, and the Rabi frequency fitted from 80-120 us is... The corresponding demodulation information is 01, and the Rabi frequency fitted from 120-160 us is... The corresponding demodulation information is 11, and the Rabi frequency fitted from 160-200 us is... Furthermore, Rabi oscillations only occur within the 160-180 µs range, with no oscillations within the 180-200 µs range, corresponding to a demodulation information of 0. Therefore, the total demodulation information is 001001110, due to the excitation... 40 Ca + 729 nm laser and excitation for transitions between ground and excited states 43 Ca + The frequency difference of the 729 nm laser light used for the transition between the ground and excited states is 4.8 GHz, which is consistent with... 40 Ca + The 729 nm laser that causes resonance between the ground and excited states will not excite 43 Ca + The transition between the ground state and the excited state, and 43 Ca + The 729 nm laser, which causes resonance between the ground and excited states, will not excite the ground and excited states. 40 Ca + The transition between the ground state and the excited state is used for 43 Ca + The frequencies of the two 397 nm laser beams used for state detection are the same as those used for... 40Ca + The frequency differences of the 397 nm laser used for state detection were 1.9 GHz and 1.3 GHz, respectively, for use in... 40 Ca + The 397 nm laser for state detection will not excite 43 Ca + The transition between the S-state and the P-state is used for 43 Ca + The 397 nm laser for state detection will not excite 40 Ca + The transition between the S state and the P state, therefore 40 Ca + and 43 Ca + It can simultaneously modulate and demodulate two different signals without interfering with each other.

[0100] The method of the present invention is not limited to 40 Ca + and 43 Ca + It is also applicable to other ions ( 9 Be + 、 24 Mg + , 25 Mg + , 40 Ca + , 43 Ca + , 86 Sr + , 88 Sr + , 137 Ba + , 138 Ba + and 171 Yb + The method of this invention can be implemented by any pairwise combination of the above ions, such as... 9 Be + - 25 Mg + , 9 Be + - 40 Ca + , 40 Ca + - 88 Sr + , 171 Yb + - 138 Ba + .

[0101] Example 2:

[0102] The total signal to be transmitted in this embodiment is 00100111000011010, with 001001110 as the base. 40 Ca + The AOM signal is modulated to 00011010. 43 Ca + The AOM signal was modulated. A 729 nm laser was then applied to the interaction, resulting in... 40 Ca + and 43 Ca + The Rabi oscillation curve, 40 Ca + The demodulation information is 001001110, and the Rabi frequency fitted from 0-40 µs is... The corresponding demodulation information is 00, and the Rabi frequency fitted from 40-80 us is... The corresponding demodulation information is 01, and the Rabi frequency fitted from 80-120 us is... The corresponding demodulation information is 10, and the Rabi frequency fitted from 120-160 us is... The corresponding demodulation information is 10. There is no Rabi oscillation in the 160-200 µs range, therefore no demodulation information is available. 43 Ca + The demodulation information is 00011010. 40 Ca + and 43 Ca + The overall demodulation information is 00100111000011010.

[0103] Example 3:

[0104] An ion trap system includes a laser module, a first arbitrary waveform generator 3, an acousto-optic modulator module, and an ion trap. Figure 6 This is a structural diagram of an ion trap system.

[0105] Ion traps are used to trap organisms. 40 Ca + and 43 Ca + The ion trap is located in the first vacuum chamber 6;

[0106] The laser module is used to generate excitation. 40 Ca + and 43 Ca +The initial laser is generated by Rabi oscillation and output to the acousto-optic modulator module for modulation. In this embodiment, two 729nm lasers are used, namely a first 729nm laser 1 and a second 729nm laser 2. The 729nm laser generated by the first 729nm laser 1 is used to excite the initial laser. 40 Ca + Rabi oscillation, the 729nm laser generated by the second 729nm laser 2 is used for excitation 43 Ca + Rabi oscillations;

[0107] The first arbitrary waveform generator 3 is used to... 40 Ca + The signal to be transmitted and 43 Ca + The signal to be transmitted is respectively obtained as a first modulation signal and a second modulation signal, and the first modulation signal and the second modulation signal are respectively output to the acousto-optic modulator module through different output channels;

[0108] The acousto-optic modulator module is used to adjust the acousto-optic modulator according to the first modulation signal. 40 Ca + The initial 729nm laser light is modulated to obtain the first modulated light; the second modulation signal is then used to modulate the light. 43 Ca + The initial 729nm laser light is modulated to obtain a second modulated light; the first modulated light is used to modulate the second modulated light. 40 Ca + Interaction, stimulation 40 Ca + Rabi oscillation, the second modulated light is used with 43 Ca + Interaction, stimulation 43 Ca + Rabi oscillation; in this embodiment, two acousto-optic modulators (i.e., the first acousto-optic modulator 4 and the second acousto-optic modulator 5) are used to respectively... 40 Ca + and 43 Ca + The initial 729nm laser is modulated. The optical path setup of this invention is less difficult than that of homonuclear ion optical path setup. Furthermore, the crosstalk rate when heteronuclear ion 729nm laser interacts with ions is lower than the crosstalk rate when homonuclear ions interact with ions through an addressing optical path.

[0109] It also includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the modulation and demodulation method based on heteronuclear ions as described in Example 1.

[0110] A quantum computer, including an ion trap system.

[0111] It should be noted that the embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A modulation and demodulation method based on heteronuclear ions, characterized in that, Includes the following steps: Step 1: Prepare the first ion and the second ion to the ground state of Rabi oscillation of the first ion and the ground state of Rabi oscillation of the second ion, respectively; Step 2: Divide the total signal to be transmitted into the signal to be transmitted of the first ion and the signal to be transmitted of the second ion. Modulate the AWG waveform generated by the arbitrary waveform generator with the signal to be transmitted of the first ion and the signal to be transmitted of the second ion respectively to obtain the first modulation signal and the second modulation signal respectively, and output them through different output channels respectively. Step 3: Modulate the initial laser beam of the first ion and the initial laser beam of the second ion using the first modulation signal and the second modulation signal respectively to obtain the first modulated light and the second modulated light respectively; The initial laser for the first ion is a laser that causes the first ion to oscillate in Rabi, and the initial laser for the second ion is a laser that causes the second ion to oscillate in Rabi. Step 4: Apply the first modulation light and the second modulation light to the first ion and the second ion in the ground state of Rabi oscillation, respectively. Then, obtain the first Rabi oscillation curve and the second Rabi oscillation curve as time changes, respectively, by state detection, showing the population of the excited state of the first ion and the population of the excited state of the second ion in Rabi oscillation. Step 5: Fit the Rabi frequency of the first ion using the first Rabi oscillation curve and the second Rabi oscillation curve, respectively. Rabi frequency of the second ion Then through and The signals to be transmitted for the first ion and the second ion are demodulated separately; finally, the signals to be transmitted for the first ion and the second ion are spliced ​​together to obtain the total signal to be transmitted. The first and second ions are heteronuclear ions.

2. The modulation and demodulation method based on heteronuclear ions according to claim 1, characterized in that, Step 2 specifically includes the following steps: Step 2.1: Determine the Rabi frequency range of the first ion and the Rabi frequency range of the second ion corresponding to the output voltage range of the arbitrary waveform generator based on the following formulas: ； ； In the formula, The output voltage amplitude of an arbitrary waveform generator. denoted as the Rabi driving coefficient of the first ion. is the Rabi driving coefficient of the second ion; Step 2.2: Divide the output voltage range of the arbitrary waveform generator, the Rabi frequency range of the first ion corresponding to the output voltage range, and the Rabi frequency range of the second ion corresponding to the output voltage range into 2... n The output voltage range of each segment is determined by defining the Rabi frequency range of the first ion and the Rabi frequency range of the second ion, and the center voltage corresponding to the center Rabi frequency of the first ion and the center voltage corresponding to the center Rabi frequency of the second ion are determined. Step 2.3: Divide the signal to be transmitted of the first ion into segments, and edit the AWG waveform into segments according to the signal to be transmitted of the first ion in each segment to obtain the first modulation signal including the signal to be transmitted of the first ion. The signal to be transmitted of the second ion is segmented, and the AWG waveform is segmented and edited according to each segment of the signal to be transmitted of the second ion to obtain a second modulation signal including the signal to be transmitted of the second ion.

3. The modulation and demodulation method based on heteronuclear ions according to claim 2, characterized in that, In step 2.3, the signal to be transmitted is segmented in the following way, and the AWG waveform of each segment is edited: The signal to be transmitted is divided into multiple segments, each segment consisting of n bits of signal to be transmitted, and each segment consisting of 2 n Two signal states, each segment of the signal to be transmitted has 2 n The signal states are respectively related to 2 n The output voltage ranges of each segment correspond one-to-one, resulting in 2. n The output voltage range corresponding to each of the signal states is determined, and then step 2.2 is used to determine the 2 n The Rabi frequency ranges corresponding to the various signal states; Finally, the AWG waveform output by the arbitrary waveform generator is divided into the same number of segments. Each AWG waveform corresponds to each segment of the signal to be transmitted. Based on the center voltage corresponding to the signal state of each segment of the signal to be transmitted, the AWG waveform of each segment is modulated to obtain the modulated signal. Where n is the number of bits in each AWG waveform segment, and n is a positive integer. The time of one cycle corresponding to the smallest center Rabi frequency is taken as the length of each AWG waveform segment.

4. The modulation and demodulation method based on heteronuclear ions according to claim 3, characterized in that, The total signal to be transmitted is divided in the following way: When the total number of bits N of the signal to be transmitted is even, the first N / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the first ion, and the last N / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the second ion; when the total number of bits of the signal to be transmitted is even, the first (N+1) / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the first ion, and the last (N-1) / 2 bits of the signal to be transmitted are used as the signal to be transmitted for the second ion. When the number of bits in the signal to be transmitted is not an integer multiple of n, the last segment of the signal to be transmitted is padded with 0s and m-1 ones in sequence to make the last segment of the signal to be transmitted n bits, where m is the difference in the number of bits between the last segment of the signal to be transmitted and n, and the length of the AWG pulse edited from the last segment of the signal to be transmitted is set to half the period time of the period corresponding to the minimum center Rabi frequency.

5. The modulation and demodulation method based on heteronuclear ions according to claim 4, characterized in that, The number of bits in each AWG waveform segment is 2. By padding the last bit of the signal to be transmitted in the second ion with zeros, the signals to be transmitted in the first and second ions are made to be integer multiples of 2.

6. The modulation and demodulation method based on heteronuclear ions according to claim 1, characterized in that, Step 4 specifically includes the following steps: Step 4.1: Apply the first modulation light to the first ion in the ground state of Rabi oscillation. The first ion interacts with the first modulation light to generate Rabi oscillation. The first ion oscillates between the ground state of Rabi oscillation and the excited state of Rabi oscillation. Then, perform state detection on the first ion to obtain the population of the excited state of Rabi oscillation of the first ion. The second modulation light is applied to the second ion in the ground state of Rabi oscillation. The second ion interacts with the second modulation light to generate Rabi oscillation, causing the second ion to oscillate between the ground state of Rabi oscillation and the excited state of Rabi oscillation. Then, state detection is performed on the second ion to obtain the population of the excited state of Rabi oscillation of the second ion. Step 4.2: Modify the time when the first modulated light acts on the first ion in step 4.1 until the population of the excited state of the Rabi oscillation of the first ion no longer changes with the time of action, and obtain the first Rabi oscillation curve of the population of the excited state of the Rabi oscillation of the first ion changing with time. Change the time in step 4.1 when the second modulated light acts on the second ion until the population of the excited state of the Rabi oscillation of the second ion no longer changes with the time of application, and obtain the second Rabi oscillation curve of the population of the excited state of the Rabi oscillation of the second ion changing with time.

7. The modulation and demodulation method based on heteronuclear ions according to claim 4, characterized in that, Step 5 specifically includes the following steps: Step 5.1: Divide the first Rabi oscillation curve into segments according to the length of each AWG waveform segment, and fit the Rabi frequency of each segment of the first Rabi oscillation curve. According to step 2.3, the first ion 2 n The Rabi frequency range of the first ion corresponding to each of the signal states is determined. Each segment of the Rabi frequency of the first ion is demodulated into the corresponding signal state. Finally, the signal states corresponding to each segment of the Rabi frequency of the first ion are arranged in chronological order to obtain the signal to be transmitted of the first ion. Step 5.2: Divide the Rabi oscillation curve of the second ion into segments according to the length of each AWG waveform segment, and fit the Rabi frequency of the Rabi oscillation curve of the second ion in each segment. According to the second ion obtained in step 2.4, 2 n The Rabi frequency range of the second ion corresponding to each of the signal states is determined. Each Rabi frequency segment of the second ion is demodulated into a corresponding signal state. Finally, the signal states corresponding to each Rabi frequency segment of the second ion are arranged in chronological order to obtain the signal to be transmitted from the second ion. Step 5.3: The signal to be transmitted of the first ion and the signal to be transmitted of the second ion are spliced ​​together to obtain the total signal to be transmitted.

8. An ion trap system, comprising an ion trap and a laser module, characterized in that, It also includes arbitrary waveform generator and acousto-optic modulator modules; The ion trap is used to trap a first ion and a second ion, which are heteronuclear ions. The laser module is used to generate an initial laser that excites the Rabi oscillation of the first and second ions, and outputs the laser to the acousto-optic modulator module for modulation. The arbitrary waveform generator is used to obtain a first modulation signal and a second modulation signal based on the transmission signal of the first ion and the transmission signal of the second ion, respectively, and outputs the first modulation signal and the second modulation signal to the acousto-optic modulator module through different output channels; The acousto-optic modulator module is used to modulate the initial laser of the first ion according to the first modulation signal to obtain the first modulated light; and to modulate the initial laser of the second ion according to the second modulation signal to obtain the second modulated light; the first modulated light acts on the first ion in the Rabi oscillation ground state and interacts with the first modulated light to generate Rabi oscillation, causing the first ion to oscillate between the ground state and the excited state; the second modulated light acts on the second ion in the Rabi oscillation ground state and interacts with the second modulated light to generate Rabi oscillation, causing the second ion to oscillate between the ground state and the excited state.

9. An ion trap system according to claim 8, characterized in that, It also includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, it implements the modulation and demodulation method based on heteronuclear ions as described in any one of claims 1-7.

10. A quantum computer, characterized in that, Includes the ion trap system as described in claim 9.

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