Hi everyone! I’m a KOSEN student building a DIY EFNMR Quantum Computer.

In this log, I want to share the 7 hardware upgrades and noise reduction strategies we are planning to implement next in order to clean up our FID signal.

1. Sealing the Aluminum Shielding Enclosure

Currently, because we have cables running in and out of the aluminum case, we can't close the lid completely. Environmental noise is leaking through this gap. The best solution is to drill small, exact-sized holes in the enclosure for the cables to pass through. Drilling is a bit of a last resort because it's difficult, but it's the most effective way. Another option is sealing the gap with aluminum tape, but peeling it off every time we need to tweak the circuit would be a nightmare.

2. Migrating the Amp from Breadboard to Perfboard

Right now, our ultra-low noise amplifier circuit is built on a breadboard. However, the breadboard itself acts as a giant antenna, picking up noise and feeding it straight into the op-amp. To fix this, we will permanently solder the amp circuit onto a universal PCB (perfboard).

3. Adding an Analog High-Pass Filter (HPF)

We plan to physically filter out low-frequency environmental noise before it even reaches the ADC. We will build an analog High-Pass Filter (HPF) using film capacitors and resistors directly into the amplifier circuit.

4. Coaxial Shielding for the Coil-to-Amp Connection

We are currently using standard jumper wires to transmit the microscopic signal from the sensor coil to the amplifier. We will replace these jumpers with shielded coaxial cables to block electromagnetic interference (EMI) during signal transmission.

5. Twisting the Polarization Battery Cables

The thick cables running from the 12V lead-acid battery to the polarizing coil are currently just bundled together. When a massive current flows, they generate their own magnetic field, causing internal noise. We will twist the positive and negative cables together (creating a twisted pair) to cancel out the emitted magnetic fields.

6. Adding a Relay to the Polarization Circuit

Currently, the high-current polarization circuit is controlled solely by a MOSFET. By integrating a mechanical relay into the circuit, we will be able to physically isolate and disconnect the polarization circuit from the amplifier during the highly sensitive receiving phase.

7. Changing the Measurement Location (Going Outdoors!)

For our recent successful FID observation, we measured in a room with relatively stable magnetic fields. However, a room is still inside a building—surrounded by rebar concrete and electronic devices emitting noise. To eliminate these sources entirely, we plan to pack up the system and run the experiment outdoors in a wide-open park!

Personal Note: The Real Fun Begins!

Now that we’ve entered the noise-reduction phase, this project feels more like real quantum computing than ever! Noise is one of the biggest hurdles in cutting-edge quantum computer development right now. This is where the real struggle—and the real fun—lies. To achieve my dream of becoming a quantum hardware developer, I am going to grind through these noise countermeasures and level up my engineering skills!

Follow Our Journey!

• Real-time updates on X (Twitter): https://x.com/nmrqcproject
• Detailed development logs and source code on GitHub: https://github.com/nmrqcproject/nmr-qc-project/blob/main/README.md
• Detailed development logs in Japanese / 日本語での詳しい開発記録 (Zenn): https://zenn.dev/nmrqcp