Balanced SQUID Coupler Layout for Cross-Talk Cancellation
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Solution Overview
Problem
Existing superconducting quantum interference device (SQUID) tunable couplers face challenges in efficiently coupling input currents to signal lines while minimizing unwanted control currents that cause cross-talk.
Innovation Solution
A balanced SQUID tunable coupler system is introduced, featuring two SQUIDs inductively coupled to both the input and signal lines, with a single control line modulating the coupling strength. This arrangement cancels out control currents induced in both the input and signal lines, eliminating the need for complex calibration procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single SQUID is used as a tunable coupler, then the device structure is simple, but control currents induce cross-talk between input and signal lines
Solution Approach 1:
The single SQUID is divided into two separate SQUIDs (first SQUID and second SQUID), each handling different coupling functions. This segmentation allows the control currents to be distributed and canceled between the two devices, reducing cross-talk while maintaining structural manageability
Solution Approach 2:
The patent employs counterbalancing by arranging the first and second SQUIDs such that their control currents produce equal and opposite magnetic effects on the input and signal lines. This counterweight approach cancels the harmful cross-talk effects while preserving the desired coupling functionality
2Object-generated harmful factors
If SQUIDs with larger inductance are used, then cross-talk is reduced, but the dynamic range decreases and device size increases
Solution Approach 1:
By splitting the coupling function across two SQUIDs with smaller individual inductances, the system achieves the cross-talk cancellation effect without requiring large inductance values in each device, thereby preserving dynamic range
Solution Approach 2:
The patent combines the effects of two SQUIDs with smaller inductances to achieve the same overall coupling performance as a single large-inductance SQUID, while simultaneously canceling cross-talk through proper arrangement and control
3Measurement precision
If complex calibration procedures are implemented, then coupling precision is improved, but testing time and costs increase
Solution Approach 1:
The balanced SQUID configuration provides self-cancellation of control currents through its symmetric structure, automatically eliminating cross-talk without requiring external calibration procedures. This self-service mechanism maintains coupling precision while dramatically reducing testing time and 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 balanced SQUID tunable coupler system reduces testing time and costs by eliminating the need for complex calibration, allows for the use of SQUIDs with smaller inductance, and provides better dynamic range by utilizing larger Josephson Junctions.
Implementation Method 1
a first superconducting quantum interference device (SQUID) inductively coupled to the input line and the signal line, and a second SQUID inductively coupled to the input line and the signal line
Implementation Method 2
a control line inductively coupled to the first SQUID and the second SQUID
Data Source
AI summary
A tunable coupler system includes an input line configured to receive an input current and a signal line configured to provide a signal line current. The tunable coupler system further includes a first superconducting quantum interference device (SQUID) inductively coupled to the input line and the signal line, and a second SQUID inductively coupled to the input line and the signal line. In addition, the tunable coupler system includes a control line inductively coupled to the first SQUID and the second SQUID. The first SQUID and the second SQUID are configured to couple the input current in the input line to the signal line to form the signal line current. A coupling strength between the input line and the signal line is determined based on a control current in the control line.