Josephson LC Coupler for Tunable Qubit Coupling and Resonance
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Solution Overview
Problem
Existing calculating devices with multiple nonlinear resonators face challenges in achieving controllability, particularly in controlling coupling strength and resonant frequencies, which affects the efficiency and speed of two-qubit gate operations.
Innovation Solution
Incorporating LC circuits with capacitors and inductors in the coupler design, allowing for modulation of magnetic flux to control coupling strength and resonant frequencies, enabling stable and high-speed two-qubit gate operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional coupler designs are used in calculating devices with multiple nonlinear resonators, then the device structure is simpler, but the controllability of coupling strength and resonant frequencies is poor
Solution Approach 1:
The coupler incorporates LC circuits with variable inductors that can dynamically adjust their inductance values, enabling real-time control of coupling strength and resonant frequencies. This dynamic adjustment capability transforms the static coupler into an adaptable component that can be tuned to different operating conditions, directly resolving the controllability issue while maintaining manageable structural complexity through systematic design.
Solution Approach 2:
The invention changes the electrical parameters (inductance and capacitance) of the coupler by incorporating variable inductors and fixed capacitors in LC circuit configurations. By adjusting the inductance values of the variable inductors, the coupling strength and resonant frequencies can be precisely controlled without fundamentally altering the coupler's structural architecture, thus improving adaptability while keeping device complexity acceptable.
2Speed
If coupling strength is increased for faster gate operations, then operation speed improves, but controllability and stability may be compromised
Solution Approach 1:
The variable inductors in the LC circuits enable dynamic control of coupling strength, allowing the system to optimize the balance between gate operation speed and stability. By adjusting the inductance values in real-time, the coupler can achieve high coupling strength for fast operations when needed, while maintaining controllability through systematic parameter adjustment, thus resolving the contradiction between speed and adaptability.
3Productivity
If resonant frequencies are reduced for better performance, then gate operation efficiency improves, but coupling strength control becomes more difficult
Solution Approach 1:
The LC circuit configuration with variable inductors and fixed capacitors provides independent control over resonant frequency and coupling strength through parameter adjustment. By changing the inductance values, the system can reduce resonant frequencies for improved gate operation efficiency while simultaneously maintaining ease of coupling strength control through the same variable inductor mechanisms, thus resolving the contradiction between productivity and ease of operation.
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 design achieves improved controllability by allowing for zero coupling, high coupling strength, and efficient switching, reducing resonant frequencies, and enabling fast two-qubit gate operations.
Implementation Method 1
a first Josephson junction including a first Josephson junction end portion and a first Josephson junction other-end portion
Implementation Method 2
In a calculating device that utilizes multiple nonlinear resonators, a coupler including LC circuits
Data Source
AI summary
According to one embodiment, a coupler includes first to fourth capacitors, first and second inductors, and a first Josephson junction. The first capacitor includes a first capacitor end portion and a first capacitor other-end portion. The first inductor includes a first inductor end portion, and a first inductor other-end portion. The second inductor includes a second inductor end portion, and a second inductor other-end portion. The first Josephson junction includes a first Josephson junction end portion, and a first Josephson junction other-end portion. A space is surrounded with the first inductor, the second inductor, and the first Josephson junction. The third capacitor includes a third capacitor end portion, and a third capacitor other-end portion. The fourth capacitor includes a fourth capacitor end portion, and a fourth capacitor other-end portion.