Method for generating a signal to be provided to a microwave antenna of a quantum computing device, device, system, computer program, and computer-readable storage medium

Abstract

A method for generating a signal to be provided to a microwave antenna of a quantum computing device is specified, the method comprising: - providing (S1) an operating signal component having at least one first frequency and having at least one first amplitude, wherein the at least one first amplitude changes over a first time interval, - determining (S2) an idle signal component having a second frequency different from the first frequency and having a second amplitude dependent on the at least one first amplitude, and - generating (S3) the signal comprising the operating signal component and the idle signal component, wherein a total power (P tot ) of the signal is constant over the first time interval. Further, a device, a system, a computer program, and a computer-readable storage medium are specified.

Description

[0001] P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0002] 1

[0003] Description

[0004] METHOD FOR GENERATING A SIGNAL TO BE PROVIDED TO A MICROWAVE ANTENNA OF A QUANTUM COMPUTING DEVICE, DEVICE, SYSTEM, COMPUTER PROGRAM, AND COMPUTER - READABLE STORAGE MEDIUM

[0005] The present disclosure relates to a method, a device, a system, a computer program, and a computer - readable storage medium for generating a signal to be provided to a microwave antenna of a quantum computing device.

[0006] Typically, robust singe qubit pulses are often shaped in amplitude, such that during the pulses ' evolution, a load caused by a respective signal on a signal chain varies. This varying load generates non- linearities in the signal chain, creating crosstalk, and may introduce thermal drifts.

[0007] An obj ect to be achieved is to provide a method for generating a signal which provides a constant load to a signal chain. Furthermore, a device, a system, a computer program, and a computer - readable storage medium for generating such a signal are to be provided.

[0008] The method for generating a signal to be provided to a microwave antenna of a quantum computing device is described.

[0009] Exemplarily, the quantum computing device comprises a quantum processor, configured to host at least one quantum bit, qubit for short. For example, the quantum processor is an ion trap. Exemplarily, the microwave antenna is configured to provide microwave radiation to the quantum processor, particularly a processing region thereof.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0010] 2

[0011] The ion trap is, for example, configured to host at least one ion, exemplarily a plurality of ions, in the processing region. Exemplarily, at most 100 ions or at most 60 ions are provided in the processing region. Each ion can form a qubit of the quantum processor.

[0012] The ion trap can be a Paul trap, a linear ion trap, a surface ion trap or a multi - layer ion trap. The ion trap comprises, for example, a set of electrodes configured to conf ine and / or manipulate at least one ion at a processing region. For example, a radio frequency, RF, voltage is applied to at least some electrodes of the set of electrodes such that a time-varying electric field is provided in the processing region configured to confine and / or to manipulate the ion. For example, the ion intersects with a trapping axis and / or oscillates around a trapping axis within the processing region.

[0013] For example, the microwave radiation is generated by the microwave antenna dependent on the generated signal. The generated signal is, for example, transmitted to the microwave antenna via the signal chain. Exemplarily, the microwave radiation is applied to at least some ions, in particular by the microwave antenna. The microwave radiation is, for example, configured to induce a transition between energy levels of at least some of the ions. Exemplarily, by applying the microwave radiation, an operation on the quantum states of the ions, such as qubit rotations or state preparations, is performed.

[0014] The microwave radiation is in particular characteristic of electromagnetic radiation with a frequency of at least 0.1P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0015] 3

[0016] GHz and at most 500 GHz, in particular at least 0.3 GHz and at most 300 GHz.

[0017] The ion trap comprises, for example, at least one magnet arrangement configured to establish a magnetic field in the processing region. The at least one magnet arrangement can comprise at least one permanent magnet arrangement and / or at least one coil. The at least one magnet arrangement is, for example, spaced apart from the processing region in lateral directions and / or in a vertical direction. In particular, the at least one magnet arrangement is configured to establish a gradient of magnitudes of the magnetic field in the processing region, e.g. along the trapping axis. Therefore, the magnetic field of the magnet arrangement has, for example, different magnitudes for different positions in the processing region and, in particular, for different positions on the trapping axis.

[0018] Advantageously, if there is a plurality of ions in the processing region, the resonance frequency of each of the ions on which the magnetic field gradient of the magnet arrangement acts, is different, i. e. unique, for each ion in the processing region.

[0019] According to at least one embodiment of the method, an operating signal component is provided, having at least one first frequency and having at least one first amplitude, wherein the at least one first amplitude changes over a first time interval. Exemplarily, the operating signal component is configured to induce the transition between the energy levels of at least some of the ions. In particular, the first frequency is configured to interact with the correspondingP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0020] 4

[0021] ion. For example, the operation on the quantum states of the ions is implemented by the operating signal component.

[0022] For example, the first amplitude changes as a function of time within the first time interval. This means, for example, that the operating signal component is a modulated signal component having a time- variable first amplitude. This means that the operating signal component implements an amplitude -shaped operating pulse.

[0023] If the operating signal component comprises more than one first frequency, each first frequency is assigned to one of the ions. In particular, each first frequency corresponds to the respective resonance frequency of the respective ion to be addressed. If the operating signal component comprises more than one first frequency, the operating signal can comprise more than one first amplitude. In particular, each first frequency can have a corresponding first amplitude, wherein the first amplitude changes over time.

[0024] According to at least one embodiment of the method, an idle signal component is determined, having a second frequency different from the first frequency and having a second amplitude dependent on the at least one first amplitude.

[0025] Exemplarily, the idle signal component is not configured to induce the transition between the energy levels of at least some of the ions. In particular, the second frequency is not configured to interact with the corresponding ion.

[0026] For example, the at least one second amplitude changes over the first time interval. In particular, the second amplitude changes as a function of time within the first time interval. This means, for example, that the idle signal component is aP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0027] 5

[0028] further modulated signal component having a time- variable second amplitude.

[0029] If the operating signal component comprises more than one first frequency and / or more than one first amplitude, the idle signal component comprises one second frequency and one second amplitude. In particular, the second amplitude is determined dependent on the operating signal component, particularly the first amplitudes thereof.

[0030] According to at least one embodiment of the method, the signal is generated, comprising the operating signal component and the idle signal component, wherein a total power of the signal is constant over the first time interval. In particular, the second amplitude of the idle signal component is determined dependent on the first amplitude, particularly dependent on all first amplitudes, such that the total power of the signal is constant over the first time interval. This means that the total power of the signal does not vary over the first time interval, at least within the generation limits of a generator device generating the signal.

[0031] For example, the first amplitude and the second amplitude, particularly the second amplitude, of the components can be determined such that the total power is kept constant while the second amplitude of the resonant tone can follow an arbitrary traj ectory, particularly dependent on the first amplitude. This means that the idle signal component implements an amplitude - shaped idle pulse.

[0032] Exemplarily, the total power of the signal having the first frequency and the second frequency being different from oneP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0033] 6

[0034] another is proportional to the sum of the squared f irst amplitude as a function of time and the squared second amplitude as a function of time.

[0035] In particular, constant over time means that the total power of the signal is constant, e.g. equal, for every point in time within the first time interval.

[0036] It is an idea of the present disclosure, inter alia, that for qubits that can be addressed in frequency space, e. g. trapped ions in a magnetic gradient field, it is possible to provide a constant signal comprising the operating signal component and the idle signal component, wherein the idle signal component is advantageously detuned from the qubits ' resonances, and does neither change the state of the qubit that is being addressed nor the state of other qubits within the processing region, e.g. being a quantum register. Such an additional idle signal component, together with the actual operating signal component used to manipulate a qubit' s state, provides a constant load on the signal chain.

[0037] Advantageously, using such a generated signal eliminates a fluctuating thermal load on the ion trap. Furthermore, this advantageously mitigates non- linearities in an amplification characteristic of the signal chain, reducing crosstalk effects between multiple qubit driving fields and therefore reduces infidelities of the implemented quantum algorithm.

[0038] According to at least one embodiment of the method, the at least one first frequency is resonant or near - resonant to at least one qubit of the quantum computing device. In particular, the generated signal comprises the first frequency being resonant or near - resonant with respect to theP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0039] 7

[0040] qubit, such that the resulting microwave radiation is, for example, configured to induce a transition between energy levels of the qubit.

[0041] According to at least one embodiment of the method, the second frequency is off - resonant to the at least one qubit. Exemplarily, the second frequency is off - resonant to all the qubits within the processing region. In particular, the generated signal comprises the second frequency being off -resonant with respect to the qubit, such that the resulting microwave radiation is, for example, not configured to induce the transition between the energy levels of the qubit.

[0042] If the second frequency is of f - resonant, the second frequency does not match the respective transition, such that the interaction efficiency is approximately zero.

[0043] According to at least one embodiment of the method, the signal is generated by an arbitrary waveform generator. In particular, the arbitrary waveform generator is configured to generate, e.g. to synthesize, both the operating signal component and the idle signal component to the signal.

[0044] For example, a classical computing device is configured to determine the idle signal component based on the provided operating signal component. Both components are provided, for example, to the arbitrary waveform generator, where the signal is generated based on the two components.

[0045] Alternatively, the arbitrary waveform generator is configured to determine the idle signal component based on the provided operating signal component and subsequently generate the signal based on both of the components.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0046] According to at least one embodiment of the method, the signal is generated by a field-programmable gate array with a numerical generator.

[0047] According to at least one embodiment of the method, the operating signal component is provided by a first signal generator, and the idle signal component is provided by a second signal generator, which is different from the first signal generator.

[0048] According to at least one embodiment of the method, the signal is provided by a signal chain to the microwave antenna for producing a microwave signal. Exemplarily, the signal chain comprises all elements arranged between a generator, where the signal is generated, and the microwave antenna, wherein the signal chain also includes the microwave antenna. The signal chain comprises, for example, the microwave antenna and at least two of the following elements: at least one wire, at least one attenuator, at least one amplifier, at least one filter, at least one mixer, at least one coupler.

[0049] For example, the microwave antenna and / or the quantum processor of the quantum computing device are located, at least partially, particularly completely, in a vacuum chamber and / or a cryogenic chamber. Further, the signal chain connected to the microwave antenna can be arranged at least partially in the vacuum chamber and / or the cryogenic chamber.

[0050] According to at least one embodiment of the method, a load applied to the signal chain, when providing the signal to the microwave antenna, is constant. In particular, when the signal is applied to the signal chain, the resulting load isP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0051] 9

[0052] approximately constant across all elements of the signal chain as the total power of the signal is constant.

[0053] Approximately constant means, for example, that the resulting load does not deviate by more than 5% from a mean value of the resulting load.

[0054] Exemplarily, for mitigation of the deviation, the off resonance signal is within good transmission frequency band of the signal chain reasonably close in frequency to the resonance signal.

[0055] According to at least one embodiment of the method, the signal only comprises the idle signal component in a second time interval between two operating signal components, and the total power of the signal is constant over the first time interval and the second time interval. In particular, constant over time means that the total power of the signal is constant, e.g. equal, for every point in time within the first time interval and the second time interval.

[0056] For example, the signal comprises a plurality of operating signal blocks. Each operating signal block is characteristic of an operating signal component and an idle signal component, as provided and determined as described herein above. The operating signal blocks are provided successively in time, particularly one after the other, in the signal. Each operating single block corresponds to a respective time interval, particularly characteristic of the first time interval.

[0057] Exemplarily, the signal comprises a first operating signal block in the first time interval, comprising a first operating signal component and a first idle signal component.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0058] 10

[0059] For example, the signal comprises a second operating signal block in a further first time interval, comprising a second operating signal component and a second idle signal component.

[0060] For example, at least some of the operating signal blocks are spaced apart from one another by an idle signal block. The idle signal block only comprises the idle signal component. Each idle signal block corresponds to a respective time interval, particularly characteristic of the second time interval.

[0061] Exemplarily, the signal comprises a first idle signal block in the second time interval, comprising only an idle signal component. The first idle signal block is, in particular, arranged between the first operating signal block and the second operating signal block. The first idle signal block spaces the first operating signal block and the second operating signal block apart in time.

[0062] Thus, also for time intervals where no operation is to be performed on the qubit, the total power being constant is advantageously applied to the signal chain.

[0063] Furthermore, a device for generating a signal to be provided to a microwave antenna of a quantum computing device is described. The device is configured to perform the method described herein. Therefore, all features and embodiments disclosed in connection with the method are also disclosed in connection with the device and vice versa. In particular, the device is part of or is the quantum computer device.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0064] 11

[0065] Furthermore, a system is described, wherein the system can comprise or comprises the device for generating the signal as described herein. Therefore, all features and embodiments disclosed in connection with the device are also disclosed in connection with the system and vice versa.

[0066] According to at least one embodiment, the system comprises the device described herein before.

[0067] According to at least one embodiment, the system further comprises the quantum computing device with the microwave antenna, as described herein before. For example, the quantum computing device further comprises the quantum processor.

[0068] According to at least one embodiment, the device provides the signal to the microwave antenna.

[0069] In addition, a computer program is specified, comprising instructions which, when the computer program is executed by a computer, cause the computer program to execute the method described herein.

[0070] Further, a computer - readable storage medium is specified, on which the computer program described herein is stored.

[0071] In the following, the method and the system are explained in more detail with reference to exemplary embodiments and the associated Figures.

[0072] Figure 1 shows a flowchart of the method according to an exemplary embodiment.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0073] 12

[0074] Figures 2 and 3 each exemplarily show a diagram of a signal being generated by the method according to an exemplary embodiment.

[0075] In method stage SI according to Figure 1, an operating signal component is provided, wherein the operating signal component has at least one first frequency and at least one f irst amplitude. The at least one first amplitude changes over a first time interval. This means that the operating signal component is a modulated signal component having a time-variable first amplitude over the first time interval. The operating signal component is, for example, shown in connection with the diagrams of Figures 2 and 3.

[0076] In method stage S2, an idle signal component is determined, wherein the idle signal component has a second frequency different from the first frequency and a second amplitude dependent on the at least one first amplitude. The second amplitude changes over a first time interval. This means that the idle signal component is a further modulated signal component having a time- variable second amplitude over the first time interval. The idle signal component is, for example, shown in connection with the diagrams of Figures 2 and 3.

[0077] Subsequently to method stages SI and S2, the signal is generated in method stage S3, wherein the signal comprises the operating signal component and the idle signal component, such that a total power Ptotof the signal is constant over the first time interval. In particular, in method stage S3, the operating signal component and the idle signal component are synthesized to the signal, which can be subsequentlyP2024, 0777 WO N / E2024, 0116 December 17, 2025

[0078] 13

[0079] provided to a microwave antenna of a quantum computing device.

[0080] In particular, the second amplitude of the idle signal component is determined in method stage S2 dependent on the first amplitude, such that the total power Ptotof the signal is constant over the first time interval.

[0081] In the diagram of Figure 2, a time t is provided the x axis and a power P is provided on the y axis. The region in Figure 2 which is not dotted is characteristic of an amplitude shape of a resonant component of the signal generated according to the method of Figure 1, particularly to implement a quantum gate via the microwave antenna. This means that the region which is not dotted corresponds to the operating signal component. The region in Figure 2 which is dotted is characteristic of an amplitude shape of an off - resonant component of the signal generated according to the method of Figure 1, particularly to implement an off - resonant field via the microwave antenna. This means that the region which is dotted corresponds to the idle signal component.

[0082] The total power Ptot of the signal comprising both components is advantageously constant over time.

[0083] In the diagram of Figure 3, a time t is provided on the x axis and a power P is provided on the y axis. The diagram of Figure 3 comprises a first shaped curve SCI corresponding to the operating signal component and a second shaped curve SC2 corresponding to the idle signal component. The signal is generated based on both components according to the method of Figure 1.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0084] 14

[0085] The invention is not limited to the exemplary embodiments by the description based on the latter. Rather, the invention encompasses any new feature as well as any combination of features, which in particular includes any combination of features in the claims, even if this feature or combination itself is not explicitly indicated in the claims or exemplary embodiments.P2024, 0777 WO N / E2024, 0116 December 17, 2025

[0086] 15

[0087] Reference signs

[0088] SI.. S3 method stages

[0089] R1 not dotted

[0090] R2 dotted

[0091] SC1 first shaped curveSC2 second shaped curve

[0092] P power

[0093] Ptot total power

[0094] t time

Claims

P2024, 0777 WO N / E2024, 0116 December 17, 202516Claims1. Method for generating a signal to be provided to a microwave antenna of a quantum computing device, the method comprising:- providing (SI) an operating signal component having at least one first frequency and having at least one f irst amplitude, wherein the at least one first amplitude changes over a first time interval,- determining (S2) an idle signal component having a second frequency different from the first frequency and having a second amplitude dependent on the at least one first amplitude, and- generating (S3 ) the signal comprising the operating signal component and the idle signal component, wherein a total power (Ptot) of the signal is constant over the first time interval.

2. Method according to claim 1, wherein- the at least one first frequency is resonant or near-resonant to at least one qubit of the quantum computing device, and- the second frequency is off - resonant to the at least one qub i t.

3. Method according to claim 1 or 2, wherein- the signal is generated by an arbitrary waveform generator.

4. Method according to claim 1 or 2, wherein- the signal is generated by a field -programmable gate array with a numerical generator.

5. Method according to claim 1 or 2, whereinP2024, 0777 WO N / E2024, 0116 December 17, 202517- the operating signal component is provided by a f irst signal generator, and- the idle signal component is provided by a second signal generator, which is different from the first signal generator.

6. Method according to any one of claims 1 to 5, wherein - the signal is provided by a signal chain to the microwave antenna for producing a microwave signal, and- a load applied to the signal chain, when providing the signal to the microwave antenna, is constant.

7. Method according to any one of claims 1 to 6, wherein - the signal only comprises the idle signal component in a second time interval between two operating signal components, and- the total power (Ptot) of the signal is constant over the first time interval and the second time interval.

8. Device for generating a signal to be provided to a microwave antenna of a quantum computing device, wherein the device being configured to perform the method according to one of the preceding claims.

9. System comprising- the device according to claim 8, and- a quantum computing device with a microwave antenna, wherein- the device provides the signal to the microwave antenna.

10. Computer program comprising instructions which, when the computer program is executed by a computer, cause theP2024, 0777 WO N / E2024, 0116 December 17, 2025- 18 -computer program to execute the method according to one of claims 1 to 7.

11. Computer - readable storage medium on which the computer program according to claim 10 is stored.

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