We’re probably all familiar with the Hall Effect, at least to the extent that it can be used to make solid-state sensors for magnetic fields. It’s a cool bit of applied physics, but there are other ways to sense magnetic fields, including leveraging the weird world of quantum physics with this diamond, laser, and microwave open-source sensor.
Having never heard of quantum sensors before, we took the plunge and read up on the topic using some of the material provided by [Mark C] and his colleagues at Quantum Village. The gist of it seems to be that certain lab-grown diamonds can be manufactured with impurities such as nitrogen, which disrupt the normally very orderly lattice of carbon atoms and create a “nitrogen vacancy,” small pockets within the diamond with extra electrons. Shining a green laser on N-V diamonds can stimulate those electrons to jump up to higher energy states, releasing red light when they return to the ground state. Turning this into a sensor involves sweeping the N-V diamond with microwave energy in the presence of a magnetic field, which modifies which spin states of the electrons and hence how much red light is emitted.
Building a practical version of this quantum sensor isn’t as difficult as it sounds. The trickiest part seems to be building the diamond assembly, which has the N-V diamond — about the size of a grain of sand and actually not that expensive — potted in clear epoxy along with a loop of copper wire for the microwave antenna, a photodiode, and a small fleck of red filter material. The electronics primarily consist of an ADF4531 phase-locked loop RF signal generator and a 40-dB RF amplifier to generate the microwave signals, a green laser diode module, and an ESP32 dev board.
All the design files and firmware have been open-sourced, and everything about the build seems quite approachable. The write-up emphasizes Quantum Village’s desire to make this quantum technology’s “Apple II moment,” which we heartily endorse. We’ve seen N-V sensors detailed before, but this project might make it easier to play with quantum physics at home.
Is this similar action to a tunnel diode?
This project really makes quantum tech feel accessible. Love how everything is open-sourced, so anyone can dive into exploring it at home. Amazing dear.
NV diamond is not accessible. How can I make this at home without the diamond? I have never even heard of anyone selling NV diamond for less than 100 GBP, let alone the miraculous 10 GBP reported in the table. Please reply with a link if people are selling that cheap NV diamond.
I think NV based magnetometer have many real world applications, and this could be good startup idea, if anyone interested let me know. I have few NV grade wafers in spare. Looking for expert in photonics and heterodyne frequencies to improve the sensitivity.
I’m really interested in at least one Nv diamonds for hobbyistic research – i heard for 2 years about it, contacted also a provider of nv diamonds in the hope to get a offer to buy one but i get no answer from the company.I’m no expert in photonics and heterodyne frequencys, but i would be really happy if i can get a nv doped diamond, for replicating the experiment and also for some own tests.
Simply write to some of the research groups and they would happily help.
If you bring down the price of a good quality magnetometer by an order of magnitude, please write a hackaday article to tell us :D
I’m usually not that whiny, but be careful with green DPSS lasers, especially if you don’t know if there is an IR blocking filter to remove any 1064 nm radiation from the diode pumping the NLO/KTP crystal that does photon upconversion to 532 nm. Besides the point is moot anyway, many green LASERs damage the retina no matter before the eyelid reflex may trigger. But it in a box or behind those orange safety filters.
I know a guy with permanent blind spots due to such an accident, luckily not me, no less I feel sorry for him.
This makes me feel like a real use for AR headsets would be letting you work with your eyes completely protected.
Equip them with swappable camera modules, perhaps remove 99% of the AR to keep latency down and you’d have something good for working with any laser.
(Written 1 min after waking up so if it’s nuts forgive me)
Not nuts at all. Glasses can only do so much. My biggest argument against a laser cutter is eye damage to me and my family if they happen into the work area.
Maybe an AR headset that has the frequency filters on the camera to detect stray out of band (for our visual senses) laser emissions to at least show where invisible leaks exist. Lasers are cool, and mighty scary.
Peril sensitive sunglasses?
You’re right, they miss a “Don’t look into the laser with your remaining eye” sign.
We should probably update the writeup to encourage LED exploration, as I don’t think the laser is required.
Not sure if this is a DPSS laser. The NV effect works on 520nm, which is available as a ‘direct’ diode.
What can this do that a Hall sensor can’t?
I’m sure I am overlooking this, but does it anywhere say what the resolution or noise floor of the magnetic field is?
I’m curious how it compares the K and Rb optically pumped magnetometers
Atomic magnetometers are likely more sensitive than this without specific and quite heavy filtering/processing for the specific kind of output you’re looking for. That said, NVC diamonds are easier to procure, transport, and use for those who are relatively uninitiated.
Even if the electronics is very simple, I think the major problem is to find a fluorescent diamond containing NV centers. The 10$ estimate seems unrealistic.
Agreed.
Very similar projects: https://hackaday.io/project/202795-building-an-eternity-quantum-computing-with-yb
It may be worth exploring a hybrid approach that combines the advantages of both methods—our ytterbium-based quantum processor and NV-center diamond sensors—to create an even more versatile and high-precision quantum magnetic sensor.
https://hackaday.io/project/202795-building-an-eternity-quantum-computing-with-yb
While nitrogen-vacancy centers in diamond offer excellent sensitivity at room temperature and mature optical readout techniques, ytterbium ions allow for tunable magnetic resonance transitions and deeper integration into spin-based quantum logic systems.
By combining these architectures—optically driven NV systems for surface-level detection and ytterbium-ion-based spin lattices for deeper-field or more programmable measurements—we could develop a next-generation quantum sensing platform that is not only sensitive but also modular, reconfigurable, and scalable.