Four-Qubit Coupler Layout for Low-Capacitance Quantum Circuits
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Solution Overview
Problem
Current superconducting quantum circuits lack a practical implementation of four-body interaction couplers, which are essential for improving noise resilience and enabling efficient quantum computations.
Innovation Solution
A superconducting quantum circuit with a four-body interaction coupler is designed, featuring first to fourth qubits and a coupler with a planar circuit configuration, including electrodes and a nonlinear element with a Josephson junction, optimized to reduce floating capacitance and enhance coupling strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a four-body interaction coupler is implemented using conventional superconducting quantum circuit designs, then quantum computation capability is improved, but floating capacitance increases causing noise sensitivity
Solution Approach 1:
The coupler is divided into multiple independent electrodes (first electrode with first and second opposing portions, second electrode with third and fourth opposing portions) that can be independently configured and optimized. This segmentation allows each electrode to be designed with specific gap widths to minimize floating capacitance while maintaining the four-body interaction functionality.
Solution Approach 2:
Different regions of the circuit are given different properties: the gaps between electrodes and ground plane are designed with specific width characteristics in certain regions to reduce floating capacitance, while other regions maintain standard configurations for quantum computation functionality. The nonlinear element is positioned at specific locations to optimize local coupling strength.
2Strength
If electrode size is increased to improve coupling strength, then interaction strength is improved, but floating capacitance with ground plane increases
Solution Approach 1:
The coupler incorporates a nonlinear element (Josephson junction or SQUID) that enables dynamic control of the coupling strength. By applying magnetic flux to the SQUID loop or adjusting the Josephson junction parameters, the coupling strength can be varied in real-time without changing the physical electrode dimensions, thus avoiding increased floating capacitance.
Solution Approach 2:
The coupling strength is controlled by changing parameters of the nonlinear element rather than physical dimensions. The critical current of the Josephson junction or the magnetic flux through the SQUID loop is adjusted to modulate the coupling, allowing strong interactions without increasing electrode size or floating capacitance.
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 proposed design enhances noise resilience and enables practical implementation of four-body interaction couplers, improving the strength and stability of quantum interactions in superconducting quantum circuits.
Implementation Method 1
the nonlinear element includes a Josephson junction
Implementation Method 2
a magnitude of coupling can be variably controlled by applying a magnetic flux to a SQUID loop in which two Josephson junctions are provided
Implementation Method 3
first and second electrodes spaced apart from a ground plane disposed surrounding peripheries of the first and second electrodes, respectively, arranged opposing to each other
Data Source
AI summary
A coupler includes first and second electrodes and a nonlinear element including a Josephson junction. The first and second electrodes are spaced apart from a ground plane surrounding peripheries thereof and arranged opposed to each other. The first/second electrode includes two opposing portions extended toward first and second qubits/third and fourth qubits. At least either one of a gap between the first electrode and the ground plane facing the first electrode and a gap between the second electrode and the ground plane facing the second electrode, includes a gap width of at least a value of a same extent as or a fraction of a size of the first electrode or the second electrode.