Superconducting Chip Package with Pillar-Based Magnetic Shielding
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Solution Overview
Problem
The existing packaging solutions for superconducting chips, such as qubit chips, suffer from magnetic shielding deficiencies due to gaps between shielding components, leading to magnetic field leakage and reduced coherence times, especially as the number of qubits increases, necessitating improved magnetic field attenuation.
Innovation Solution
A package design featuring a metal plate and carrier substrate sandwiched between planar magnetic shield structures, with hollow cylindrical pillars made of high magnetic permeability material clamped between the shield structures to create a low reluctance path and enhance magnetic field attenuation, significantly reducing magnetic field leakage at cryogenic temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional cylindrical magnetic shields are used to shield superconducting chips, then magnetic field attenuation is provided, but the shields are bulky and consume much of the limited experimental space in dilution refrigerators
Solution Approach 1:
The magnetic shielding function is segmented into multiple planar shield structures positioned at different locations around the superconducting chip, rather than using a single bulky cylindrical shield. This allows distributed magnetic field attenuation with reduced overall volume
Solution Approach 2:
The shielding approach transitions from a three-dimensional cylindrical shield to two-dimensional planar shield structures. This dimensional reduction significantly decreases the volume occupied by the shielding system while maintaining effective magnetic field attenuation through strategic positioning of multiple planes
2Productivity
If the number of qubits on chip is increased, then quantum processing capability is improved, but the number of connectors and cables required increases, creating a bottleneck with cylindrical shields
Solution Approach 1:
The shielding system is segmented into multiple planar structures that can be positioned to accommodate numerous connectors and cables without requiring them to pass through a single cylindrical barrier, thus reducing routing complexity
Solution Approach 2:
By transitioning from cylindrical to planar shielding, the system allows connectors and cables to be routed in multiple planes and directions, significantly increasing the density and number of connections that can be accommodated without increasing overall system complexity
3Device complexity
If planar magnetic shield structures are used with gaps between shields, then device complexity is reduced, but magnetic field leakage increases due to the gaps
Solution Approach 1:
Magnetic bridging elements are introduced as intermediary components between the planar shield structures. These elements act as magnetic conduits that bridge the gaps between shields, preventing magnetic field leakage while maintaining the simplicity of the planar shield configuration
Solution Approach 2:
The shielding system combines planar magnetic shield structures with magnetic bridging elements to create a composite shielding solution. This composite approach maintains the low complexity of planar structures while eliminating their primary weakness (gaps) through the addition of magnetic bridging material
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 use of high magnetic permeability pillars increases magnetic field attenuation by up to 200 times compared to previous designs, effectively addressing the shielding deficiencies and improving the coherence times of superconducting chips.
Implementation Method 1
the unavoidable gap between the shields due to the thickness of the copper mounting plate significantly degrades the shielding properties due to magnetic field leakage
Implementation Method 2
pillsars formed of a magnetic shielding material which are clamped between the planar portions of the shield structures, wherein said one or more pillars are penetrating the carrier substrate and the metal support plate
Implementation Method 3
a metal support plate having a front and back surface, with the carrier substrate mounted on the front surface of said metal support plate, the metal support plate being configured to be coupled to a low temperature stage of a refrigerating apparatus
Implementation Method 4
superconducting chips mounted on the carrier substrate... a semiconductor chip comprising electrically conductive materials which are suitable for exhibiting superconductivity at a given temperature range, which may be a cryogenic temperature range
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
A package (21) according to the invention comprises a metal plate (1) and a carrier substrate (2) mounted on the top surface thereof, comprising one or more superconducting chips (6) mounted on the carrier substrate or configured to receive said one or more chips mounted thereon. The carrier substrate (2) and the plate (1) are sandwiched between the planar portions (7a,9:7a,11a) of a first and second magnetic shield structure (7,9;7,11), at least the first structure comprising a planar portion (7a) and a receptacle-shaped shell portion (7b) arranged above and around the chip location. The package comprises one or more pillars (15) formed of a magnetic shielding material which are clamped between the planar portions of the shield structures, wherein said one or more pillars (15) are penetrating the carrier substrate (2) and the metal support plate (1) and wherein the one or more pillars are in physical contact with both of said planar portions (7a,9:7a,11a). According to a preferred embodiment, the pillars are hollow cylinders (15) arranged around the screws of screw connections (8) realizing a clamping force between the planar portions of the first and second shield structure (7,9;7,11).