Dynamic ZZ Interaction Control for Superconducting Qubits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing quantum computing technologies face a trade-off between increasing the exchange coupling strength for faster two-qubit gates and minimizing the spurious ZZ interaction, which leads to idle gate errors and circuit infidelity.
Innovation Solution
A quantum device with a biasing component that dynamically controls ZZ interactions between qubits using continuous wave tones applied via drive lines, adjusting phase and amplitude differences to cancel or mitigate static ZZ interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the exchange coupling strength J is increased to speed up two-qubit gates, then the gate speed is improved, but the spurious ZZ interaction increases causing idle gate errors and circuit infidelity
Solution Approach 1:
The patent applies preliminary anti-action by using continuous wave (CW) tones to preemptively counteract the spurious ZZ interaction before it degrades circuit fidelity. The CW tones are specifically tuned to induce an ac Stark shift that cancels the unwanted ZZ coupling, while allowing the exchange coupling J to remain strong for fast two-qubit gates. This resolves the contradiction by applying a counteracting field that neutralizes the harmful effect without reducing the useful coupling strength.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the frequency, amplitude, and phase of CW drive tones applied to the qubits. By tuning these parameters, the system can induce controlled ac Stark shifts that cancel the spurious ZZ interaction while maintaining the desired exchange coupling strength. This allows independent optimization of gate speed and fidelity through parameter control rather than structural modification.
2Productivity
If the exchange coupling strength J is increased to increase entanglement rates, then the entanglement rate is improved, but the idle gate error increases due to spurious ZZ interaction
Solution Approach 1:
The patent converts the harmful spurious ZZ interaction into a beneficial effect by using CW tones to induce an ac Stark shift. The same coupling mechanism that causes the unwanted ZZ interaction is leveraged to create a controllable energy shift that can be tuned to cancel the harmful ZZ coupling. This transforms the problematic interaction into a useful control mechanism for eliminating idle gate errors while preserving high entanglement rates.
Solution Approach 2:
The system applies preliminary anti-action by continuously applying CW tones that preemptively counteract the spurious ZZ interaction during idle periods. This prevents the accumulation of idle gate errors that would otherwise occur with strong exchange coupling, allowing the system to maintain high entanglement rates without the penalty of increased error rates during non-gate operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the performance of quantum computing devices by reducing idle gate errors and improving circuit fidelity while maintaining strong exchange coupling.
Implementation Method 1
By applying an off-resonant drive to non-computational transitions in a pair of capacitively-coupled fluxoniums a ZZ-interaction due to unequal ac-Stark shifts of the computational levels is induced.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Systems, devices, computer-implemented methods, and/or computer program products that facilitate dynamic control of ZZ interactions for quantum computing devices.In one example, a quantum device can comprise a biasing component that is operatively coupled to first and second qubits via respective first and second drive lines. The biasing component can facilitate dynamic control of ZZ interactions between the first and second qubits using continuous wave (CW) tones applied via the respective first and second drive lines.