Vertical SQUID Loop Tuning for Low-Noise Strong-Field Operation
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Solution Overview
Problem
Superconducting circuits are sensitive to magnetic fields, and existing shielding methods are inadequate for reducing noise in strong magnetic fields, particularly for devices requiring topological behavior, as they induce additional noise and limit flux tunability.
Innovation Solution
A superconducting quantum interference device (SQUID) with a Josephson junction in a superconductive loop is oriented such that it can be tuned using a magnetic field parallel to the substrate, reducing flux noise by minimizing the effective surface area exposed to perpendicular fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If local shielding is used to reduce flux noise, then noise sensitivity is improved, but the ability to generate strong magnetic fields is lost
Solution Approach 1:
The SQUID loop is reoriented from a planar configuration to a three-dimensional vertical configuration, extending perpendicular to the substrate surface. This dimensional change allows the loop to be tuned by in-plane magnetic fields while remaining insensitive to out-of-plane fields, effectively resolving the contradiction between noise reduction and strong field capability.
2Object-affected harmful factors
If large multilayer shields are used to reduce noise, then flux noise is reduced, but device complexity increases
Solution Approach 1:
The invention extracts the noise rejection function from the magnetic field tuning function by selectively orienting the SQUID loop. This allows the device to inherently reject out-of-plane noise without requiring additional shielding layers, while simultaneously maintaining sensitivity to in-plane fields for tuning purposes.
3Object-affected harmful factors
If the superconductive loop is oriented vertically, then insensitivity to perpendicular magnetic fields is achieved, but the effective surface area exposed to parallel fields must be optimized
Solution Approach 1:
The SQUID loop structure is designed with specific local geometries including vertical extensions and planar segments at different heights. This creates different functional zones within the loop structure, where vertical portions provide perpendicular field rejection and strategically positioned planar segments provide controlled coupling to parallel fields for tuning.
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
This approach significantly reduces flux noise and allows for greater tolerance to strong magnetic fields, enabling more stable operation of superconducting circuits while maintaining flux tunability.
Implementation Method 1
The SQUID comprises a Josephson junction arranged in a superconductive loop
Implementation Method 2
a superconductive loop includes a portion which extends perpendicular to the planar surface
Implementation Method 3
a first magnet configured to apply a first magnetic field parallel to the planar surface
Data Source
AI summary
A system comprises a substrate having a planar surface; a first magnet configured to apply a first magnetic field parallel to the planar surface; a circuit arranged on the planar surface; and a superconducting quantum interference device, SQUID, operably linked to the circuit. The SQUID comprises a Josephson junction arranged in a superconductive loop. The superconductive loop includes a portion which extends perpendicular to the planar surface and is orientated such that the SQUID is tuneable by the first magnet. By allowing the SQUID to be tuned using a magnetic field which is parallel to the planar surface, a reduction in flux noise may be achieved. Also provided are a method of operating a SQUID, and a SQUID.