Sample Holder Cavity and Through-Hole Resonance Suppression
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Solution Overview
Problem
Existing sample holders for superconducting quantum circuits do not effectively increase the resonance frequency of the chip mode, leading to decoherence issues when a signal of a specific frequency is input to the chip.
Innovation Solution
A sample holder design featuring a base with a cavity below the chip and a PCB with a through hole that supports the chip, where the PCB includes a dielectric, front-surface and back-surface grounds, and a conductor connecting these grounds, effectively increasing the resonance frequency of the chip mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chip is mounted on a PCB placed on a metal base with the back surface of the chip in contact with the metal base, then the chip is securely supported and electrically connected, but resonance occurs at specific frequencies causing decoherence of the superconducting quantum circuit
Solution Approach 1:
The patent extracts the harmful resonant cavity by introducing a through-hole that penetrates the metal base, removing the enclosed space that causes chip mode resonance. This allows the electromagnetic field to leak out and prevents the formation of resonant standing waves, thereby eliminating the decoherence issue while maintaining secure chip support and electrical connection.
Solution Approach 2:
The patent introduces an intermediary structure (the through-hole with conductive material) that mediates between the chip and the metal base. This intermediary provides an alternative path for electromagnetic field dissipation and electrical connection, preventing the direct formation of resonant modes between the chip back surface and the metal base while maintaining necessary electrical connectivity.
2Device complexity
If the back surface of the chip contacts the metal base directly, then electrical connection and mechanical support are simplified, but the resonance frequency of the chip mode remains low causing decoherence
Solution Approach 1:
The patent extracts the problematic enclosed cavity space by creating a through-hole in the metal base. This removes the resonant chamber that limits the chip mode resonance frequency, allowing the system to maintain structural simplicity while achieving higher coherence by eliminating the harmful resonant environment.
Solution Approach 2:
The patent changes the geometric parameter of the mounting structure by introducing a through-hole that penetrates the metal base. This parameter change transforms the enclosed cavity into an open structure, fundamentally altering the resonance characteristics and raising the chip mode resonance frequency above the operational band, thereby improving quantum circuit coherence.
3Reliability
If a cavity is formed below the chip in the metal base to increase resonance frequency, then chip mode resonance is suppressed, but the mounting structure becomes more complex
Solution Approach 1:
Instead of adding a complex cavity structure below the chip, the patent extracts the problem by creating a through-hole that removes the enclosed cavity space. This approach achieves the same goal of suppressing chip mode resonance but with a simpler implementation that integrates seamlessly with the existing metal base structure.
Solution Approach 2:
Rather than adding structure below the chip to create a controlled cavity environment, the patent inverts the approach by removing material to create a through-hole. This inversion transforms the problem from managing an enclosed resonant cavity to allowing open-space field dissipation, achieving decoherence reduction with reduced structural complexity.
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 sample holder design significantly increases the resonance frequency of the chip mode, reducing decoherence and enhancing the performance of superconducting quantum circuits.
Implementation Method 1
a conductor that electrically connects the front-surface ground and the back-surface ground. The conductor is disposed on an end face of the through hole
Implementation Method 2
At least a part of the base below the through hole has a cavity... in order to suppress the influence of the chip mode, a cavity is formed immediately below the chip by hollowing out a part of the metal base immediately below the chip
Data Source
AI summary
A sample holder includes a base comprising a support structure and a printed circuit board (PCB) in contact with the base. The PCB includes: a dielectric; a front-surface ground (GND) formed on a front surface of the dielectric; a back-surface GND formed on a back surface of the dielectric; a through hole penetrating from the front-surface GND to the back-surface GND, the through hole in which a chip is disposed, and a conductor that electrically connects the front-surface GND and the back-surface GND on an end face of the through hole. At least a part of the base below the through hole has a cavity. The support structure that supports a surface of the chip and is electrically connected to the base. The support structure is disposed in the cavity.