AI
Why NV Center Diamonds for Hacking
Quantum Village co-founders Mark Carney and Victoria Kumaran could not get hands on quantum hardware. So they built their own. The target: nitrogen-vacancy (NV) center diamond magnetometry. NV centers in diamond form stable “virtual atoms” without cooling. Mark explained that the diamond lattice is so rigid the quantum defect cannot vibrate. That means room-temperature operation. The physics: a green LED at 525 nm excites the defect, which emits red light at 620 nm. Microwaves at 2.87 GHz modulate that red light. A magnetic field splits the signal. Measure the split, measure the field.
Building a $160 Sensor with Off-the-Shelf Parts
The team replaced expensive lasers with super-bright green LEDs. No phase term in the Hamiltonian means coherence does not matter. For microwaves they used an ADF4351 chip generating from 35 MHz to over 4 GHz. Two monolithic amplifiers boosted the signal. A BPW34 photodiode detected red light. Instead of a $50 dichroic mirror, they used red filter gel from Amazon at 80% of the performance. The microcontroller is an ESP32 costing $4. They wrote the firmware in Arduino for portability. A transimpedance amplifier built from a dual op-amp and voltage divider saved $10. Total bill of materials: roughly $160.
From Noise to Signal: First Magnetocardiography Results
To verify the sensor worked, the team drove to the University of Leeds and enlisted Professor Ben Varcoe. Victoria held electrodes for a reference ECG. The sensor’s output went through $30,000 of filtering equipment. The resulting yellow line — a magnetocardiogram — aligned exactly with the electrical heartbeat. In a second demo, Mark shook a diamond on a Post-it note next to a $5,000 reference magnetometer. The sensor’s yellow line tracked the reference. He also hit the sensor with a neodymium magnet inside a paper‑roll isolation chamber. The signal split clearly. “It works,” Mark said.
The Uncut Gem Badge: Open Source and Hackable
The finished design became the Uncut Gem badge for Defcon 33. The PCB includes a prototyping area, broken-out SPI and I²C pins, and USB‑C. Mark noted it is meant to be hacked — add an accelerometer, barometer, or your own microcontroller. All schematics, PCB files, and firmware are released open source. Someone in Italy, David Deessa, already built his own copy. The team wants contributions: better filtering, a custom antenna, Wi‑Fi connectivity. “This is the community that gave us the space to do this,” Victoria said.
Notable Quotes
we managed to get in touch with Debeers uh because that’s a sentence I have in my life now Mark Carney · ▶ 27:03
a total hack a total cheat but it saves like $10 on the bomb Mark Carney · ▶ 24:14
Holy c A. Actually, I might have been humoring you both a little bit when you were coming all this way. Victoria Kumaran quoting Professor Ben Varcoe · ▶ 41:30
the diamond has seen far far hotter temperatures. it’ll just go “Ah, fine.” Mark Carney · ▶ 32:23
Key Takeaways
- An NV center diamond quantum sensor can be built for under $160 using LEDs and Arduino firmware.
- The sensor performed magnetocardiography, detecting a human heartbeat without contact.
- The design is released as a full open-source Defcon badge for further hacking.
About the Speaker(s)
Mark “LargeCardinal” Carney is a mathematician and Quantum Hacker. Working at the bleeding edge of technology for two decades, he has presented on quantum information, machine learning, cryptography, and cybersecurity data science. His work was recently nominated for Innovation of the Year at the SANS Difference Makers Awards. He co-founded Quantum Village.
Victoria “V__Wave” Kumaran has been hacking tech since age 8. With a background in product design, finance, and machine learning for cybersecurity, she was an Entrepreneurial Lead on the NSF I-Corps Program. She studied art and design at Central Saint Martins and co-founded Quantum Village.