Two-Mode Quantum Coupler for ZZ Interaction Cancellation
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Solution Overview
Problem
Existing quantum computing technologies face challenges in suppressing ZZ interactions between qubits, which can inhibit the fidelity of quantum operations and are not effectively addressed by current methods such as two-junction qubits or flux-tunable couplers.
Innovation Solution
A quantum coupler device operating in two oscillating modes with equal exchange coupling between superconducting qubits, utilizing symmetric and antisymmetric excitations of Josephson Junctions to suppress ZZ interactions and improve quantum gate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If qubits are coupled via a bus, then quantum operations can be performed, but residual ZZ interactions occur that reduce fidelity
Solution Approach 1:
The patent introduces a coupler device as an intermediary between qubits that mediates their interaction. The coupler operates in two distinct oscillating modes that enable controlled coupling while suppressing unwanted ZZ interactions, effectively acting as a mediator that filters harmful interactions while permitting necessary quantum operations.
Solution Approach 2:
The coupler device utilizes dynamic oscillating modes that can be tuned and controlled. By operating in specific oscillating modes, the system dynamically adjusts the coupling characteristics to enable quantum operations while suppressing ZZ interactions, transforming a static coupling problem into a dynamically controllable system.
2Adaptability or versatility
If flux-tunable couplers are used, then coupling can be adjusted, but only flux-tunable transmon qubits can be utilized
Solution Approach 1:
The coupler device is designed with universal functionality that can interface with different types of qubits. By providing a standardized coupling mechanism that operates independently of specific qubit types, the system achieves multi-functionality and versatility, allowing various qubit implementations to be used without being restricted to a single qubit type.
3Device complexity
If two-junction qubits are used, then multiple qubits can be encoded in a single circuit, but they do not function as fixed-frequency couplers between transmon qubits
Solution Approach 1:
The system segments the quantum circuit into distinct functional components: qubits and a separate coupler device. This segmentation allows the coupler to be independently optimized for its specific function of mediating interactions between qubits, while maintaining the ability to encode multiple qubits in the circuit. The two-junction structure is assigned to the coupler rather than the qubits, giving the coupler the desired fixed-frequency characteristics.
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
The solution reduces quantum gate errors, increases gate speed, and enhances the fidelity and accuracy of quantum processors by effectively canceling ZZ interactions over a defined range of qubit frequencies.
Implementation Method 1
utilizing symmetric and antisymmetric excitations of Josephson Junctions to suppress ZZ interactions
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
Devices and/or computer-implemented methods to facilitate ZZ cancellation between qubits are provided. According to an embodiment, a device can comprise a coupler device that operates in a first oscillating mode and a second oscillating mode. The device can further comprise a first superconducting qubit coupled to the coupler device based on a first oscillating mode structure corresponding to the first oscillating mode and based on a second oscillating mode structure corresponding to the second oscillating mode. The device can further comprise a second superconducting qubit coupled to the coupler device based on the first oscillating mode structure and the second oscillating mode structure.