Current-Biased Tunable Qubit Layout for Low-Noise Frequency Control
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Solution Overview
Problem
Current frequency tunable qubit devices based on superconducting quantum interference devices (SQUIDs) suffer from universal flux noise, magnetic crosstalk, and require high current levels for operation, making them inefficient and sensitive to noise.
Innovation Solution
A current biased frequency tunable qubit design incorporating a first Josephson junction and two additional Josephson junctions in series, along with a high kinetic inductance wire, allows for frequency control using current instead of magnetic fields, reducing noise sensitivity and current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SQUID-based frequency tunable qubit devices are used, then frequency tuning capability is achieved, but universal flux noise and magnetic crosstalk increase
Solution Approach 1:
The SQUID loop is segmented into two separate Josephson junctions located in different current paths, eliminating the shared loop structure that causes flux noise. This segmentation allows frequency tuning through current application to individual junctions without the magnetic crosstalk inherent in traditional SQUID configurations.
Solution Approach 2:
A high kinetic inductance wire is introduced as an intermediary element in the current path to enable precise frequency tuning with lower current levels. The high kinetic inductance provides enhanced current-to-frequency conversion efficiency, reducing the need for high current operation that would otherwise generate magnetic crosstalk.
2Adaptability or versatility
If traditional SQUID-based qubit devices are used, then frequency tuning is achieved, but high current levels are required for operation
Solution Approach 1:
A high kinetic inductance wire is introduced as an intermediary element in the current path to enable precise frequency tuning with lower current levels. The high kinetic inductance provides enhanced current-to-frequency conversion efficiency, reducing the need for high current operation that would otherwise generate magnetic crosstalk.
Solution Approach 2:
The kinetic inductance parameter of the wire is specifically optimized to high values, fundamentally changing the electrical characteristics of the current path. This parameter change enables the system to achieve the same frequency tuning range with significantly reduced current levels compared to traditional SQUID designs.
3Adaptability or versatility
If SQUID-based qubit devices are used, then frequency tunability is achieved, but noise sensitivity increases
Solution Approach 1:
The SQUID loop is segmented into two separate Josephson junctions located in different current paths, eliminating the shared loop structure that causes flux noise. This segmentation allows frequency tuning through current application to individual junctions without the magnetic crosstalk inherent in traditional SQUID configurations.
Solution Approach 2:
The shared magnetic flux loop structure is extracted and removed from the design. By eliminating the common loop area that threads magnetic flux, the system removes the source of universal flux noise while retaining frequency tuning capability through independent control of the two Josephson junctions.
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 efficient frequency tuning with lower current consumption, reduced noise sensitivity, and improved coherence, enabling more compact and robust quantum computing architectures.
Implementation Method 1
a first Josephson junction located along a first current path of the device. The device also can comprise a second Josephson junction and a third Josephson junction coupled in series along a second current path
Implementation Method 2
a high kinetic inductance wire located along a first current path of the device, wherein the high kinetic inductance wire has a kinetic inductance level that satisfies a defined threshold kinetic inductance level
Data Source
AI summary
Techniques for designing, creating, and utilizing a current biased tunable qubit are presented. A qubit device can comprise a first Josephson junction (JJ) located along a first current path of the device, and a second JJ and third JJ coupled in series along a second current path in parallel with the first current path, wherein the second and third JJs facilitate controlling frequency of the device. The first JJ can be larger in area than each of the second and third JJs, wherein a current splitting ratio between the first current path and second current path can be increased thereby. The device can comprise a capacitor with a first terminal associated with the second and third JJs, and a second terminal associated with ground. Alternatively, a high kinetic inductance wire can be used in the first current path, instead of the JJ.