[Homemade Quantum Computer NMRQCP] Handwritten Circuit Diagrams

*Original Japanese version is available here.

 Hello! I'm a KOSEN student taking on the challenge of developing a quantum computer using a homemade Earth's Field NMR (EFNMR) system.

This time, from my development notes "Creating a Circuit Diagram 2", I'll be talking about the "circuit diagram" itself, which serves as the blueprint for the project, and the ideas I added to avoid breaking the delicate circuits!

The Foundation of Everything! Handwritten Circuit Diagrams

First, I'll show you how I usually design my circuits. This is the circuit diagram of the EFNMRQC I'm currently developing.

*I apologize that the handwritten notes in the circuit diagram photos are in Japanese! Please use a translation feature if you'd like to read them.

As you can see in the photos, I handwrite the component placement and wiring in detail on graph paper. Using PC CAD software to draw it neatly is fine, but when it comes to actively jotting down ideas in my head and thinking about the flow of electricity, this analog handwriting style still feels the most natural to me.

A "Two-Stage" Protection Circuit to Save the Amplifier from High Currents

And there is an important new mechanism I added to this circuit diagram.

A temporarily very large current is passed through the sensor coil of the quantum computer to polarize the spins. However, if this massive current flows into the "amplifier circuit"—the heart of the system for picking up extremely weak signals—the parts will instantly be charred black.

To prevent this, I originally used a component called a "fast recovery diode" to stop the high current from flowing from the coil into the amplifier circuit.

However, I thought "I'm still worried about just relying on that," so just to be absolutely sure, I added an even more reliable safety measure to the circuit diagram. That is the "M5 Relay Unit."

A relay is a component that uses electrical signals to physically click a switch open or closed. By adding this, I was able to "physically block" the current to the amplifier circuit exactly at the moment a strong pulse is fired.

Blocking with a diode, and physically disconnecting with a relay. With this, a perfect fail-safe system that only connects the amplifier when it is safe has been completed on the circuit diagram!

• Daily experiment notes and code: Available on my GitHub repository (nmr-qc-project)
  
• Real-time development scenes and oscilloscope waveforms: Posting on X (formerly Twitter)
  

If you are wondering things like "Will it really work?" or "How do you generate waveforms?", please bookmark this blog and follow me on X!