Transmon_cross.py

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Introduction

Qiskit Metal is a powerful tool for designing and simulating superconducting circuits. However, like any complex software, it can sometimes exhibit unexpected behavior. In this article, we will explore a specific issue with the TransmonCross design in Qiskit Metal, where the connection pins at 0 and 180 degrees shift when trying to change the claw width for the Xmon. We will also discuss the expected behavior and provide a suggested solution.

What is the Current Behavior?

When trying to change the claw width for the Xmon in Qiskit Metal, the connection pins at 0 and 180 degrees shift. This can be observed when trying to connect a resonator, as the claw and the resonator line do not overlap in the vertical direction, creating a mismatch. This issue can be particularly frustrating when trying to design complex superconducting circuits.

Steps to Reproduce the Problem

To reproduce the problem, follow these steps:

  1. Open Qiskit Metal and create a new design.
  2. Create an Xmon with the following settings:
Q1 = TransmonCrossFL(design, 'Q1', options = dict(
    pos_x = '0mm',
    pos_y='0mm',
    cross_width = '24um',
    cross_length = '156um',
    cross_gap = '12um',
    make_fl = False,
    connection_pads = dict(
        readout = dict(
            connector_location = '180',
            claw_length ='92um',
            claw_width='24um'),
        drive = dict(
            connector_location = '0',
            claw_cpw_length = '0um',
            claw_width = '10um',
            ground_spacing = '30um',
            connector_type = '1'))))
  1. Add a flux line by adding fl_options = dict() and changing make_fl = True.
  2. Rebuild the GUI using gui.rebuild() and autoscale using gui.autoscale().

What is the Expected Behavior?

The expected behavior is that the connection pin should be exactly centered on the cross. This is a critical aspect of designing superconducting circuits, as any misalignment can lead to errors in the circuit's behavior.

Suggested Solutions

One possible solution to this issue is to modify the TransmonCross design to correctly calculate the position of the connection pins. Specifically, the line port_line = draw.LineString([(-c_c_l - c_w, -c_c_w / 2), should be changed to port_line = draw.LineString([(-c_c_l - c_w, -c_w / 2),. This change should fix the issue and ensure that the connection pins are correctly centered on the cross.

Conclusion

In conclusion, the TransmonCross design in Qiskit Metal can exhibit unexpected behavior when trying to change the claw width for the Xmon. However, by modifying the design to correctly calculate the position of the connection pins, we can fix this issue and ensure that the circuit is designed correctly. We hope that this article has been helpful in understanding this issue and providing a solution.

Additional Information

  • Qiskit Metal version: 0.1.5
  • Python version: 3.12.9
  • Operating system: Windows 11 Pro

Related Issues

Code

import qiskit_metal as qt
from qiskit_metal.queuing.layout import TransmonCrossFL

# Create a new design
design = qt.QiskitQIR()

# Create an Xmon with the following settings
Q1 = TransmonCrossFL(design, 'Q1', options = dict(
    pos_x = '0mm',
    pos_y='0mm',
    cross_width = '24um',
    cross_length = '156um',
    cross_gap = '12um',
    make_fl = False,
    connection_pads = dict(
        readout = dict(
            connector_location = '180',
            claw_length ='92um',
            claw_width='24um'),
        drive = dict(
            connector_location = '0',
            claw_cpw_length = '0um',
            claw_width = '10um',
            ground_spacing = '30um',
            connector_type = '1'))))

# Add a flux line
fl_options = dict()
Q1.options['make_fl'] = True
Q1.options['fl_options'] = fl_options

# Rebuild the GUI
gui = qt.QiskitMetalGUI(design)
gui.rebuild()

# Autoscale the GUI
gui.autoscale()
```<br/>
**Q&A: Transmon Cross Design Issue in Qiskit Metal**
=====================================================

**Q: What is the Transmon Cross design issue in Qiskit Metal?**
---------------------------------------------------------

A: The Transmon Cross design issue in Qiskit Metal is a problem where the connection pins at 0 and 180 degrees shift when trying to change the claw width for the Xmon. This can cause the claw and the resonator line to not overlap in the vertical direction, creating a mismatch.

**Q: What are the steps to reproduce the problem?**
------------------------------------------------

A: To reproduce the problem, follow these steps:

1. Open Qiskit Metal and create a new design.
2. Create an Xmon with the following settings:

```python
Q1 = TransmonCrossFL(design, 'Q1', options = dict(
    pos_x = '0mm',
    pos_y='0mm',
    cross_width = '24um',
    cross_length = '156um',
    cross_gap = '12um',
    make_fl = False,
    connection_pads = dict(
        readout = dict(
            connector_location = '180',
            claw_length ='92um',
            claw_width='24um'),
        drive = dict(
            connector_location = '0',
            claw_cpw_length = '0um',
            claw_width = '10um',
            ground_spacing = '30um',
            connector_type = '1'))))
  1. Add a flux line by adding fl_options = dict() and changing make_fl = True.
  2. Rebuild the GUI using gui.rebuild() and autoscale using gui.autoscale().

Q: What is the expected behavior?

A: The expected behavior is that the connection pin should be exactly centered on the cross. This is a critical aspect of designing superconducting circuits, as any misalignment can lead to errors in the circuit's behavior.

Q: How can I fix the issue?

A: One possible solution to this issue is to modify the TransmonCross design to correctly calculate the position of the connection pins. Specifically, the line port_line = draw.LineString([(-c_c_l - c_w, -c_c_w / 2), should be changed to port_line = draw.LineString([(-c_c_l - c_w, -c_w / 2),. This change should fix the issue and ensure that the connection pins are correctly centered on the cross.

Q: What are some related issues in Qiskit Metal?

A: Some related issues in Qiskit Metal include:

Q: What are the system requirements for Qiskit Metal?

A: The system requirements for Qiskit Metal are:

  • Qiskit Metal version: 0.1.5
  • Python version: 3.12.9
  • Operating system: Windows 11 Pro

Q: Can I get more information about Qiskit Metal?

A: Yes, you can get more information about Qiskit Metal by visiting the Qiskit Metal documentation.

Q: How can I contribute to Qiskit Metal?

A: You can contribute to Qiskit Metal by submitting issues, pull requests, or participating in the Qiskit Metal community. You can find more information about contributing to Qiskit Metal by visiting the Qiskit Metal contribution guide.

Q: Where can I find more resources about Qiskit Metal?

A: You can find more resources about Qiskit Metal by visiting the Qiskit Metal resources page.