Is anyone into quantum technologies and quantum metrology? - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: May 02, 2024, 07:16:56 pm
content: Good evening,I wonder if anyone is into quantum technologies and metrology, beside JVS? So something like vapour cells, NV-centers, ... Even if just one a research level, I would be interested to hear what you are working on and what you have achieved as of now.-branadic-

author: KE5FX
author_rank: Super Contributor
timestamp: May 02, 2024, 07:44:50 pm
content: I've wanted to build an Rb MOT ever since I saw one demonstrated at a NIST seminar, but just haven't gotten a round tuit (or a spare $15K or so to buy one off the shelf from ColdQuanta^WInfleqtion.) Does that count?

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: May 02, 2024, 09:34:15 pm
content: Thermometry is my thing, so I am interested in quantum dots as optical temperature sensors e.g.https://link.springer.com/article/10.1007/s11051-019-4629-8No achievements. Unfortunately I have several projects lined up ahead of that one, including oneon temperature-sensitive Ruby fluorescence. So lessons learned there might carry over to QDs.

author: dietert1
author_rank: Super Contributor
timestamp: May 05, 2024, 06:18:31 am
content: Any physicist doing precision measurements can dream of discovering previously unknown effects. Of course it depends on his/her resources, but also it may be luck. Technology is a statistical precondition for new discoveries and patents.Regards, Dieter

author: zrq
author_rank: Frequent Contributor
timestamp: May 05, 2024, 09:56:42 pm
content: After working for around 2 years for a cold atoms/atom vapour magnetometry research group, I would not make that as a hobby, simply too expensive and time consuming...

author: KE5FX
author_rank: Super Contributor
timestamp: May 05, 2024, 10:22:37 pm
content: Well, that's kind of the idea behind a hobby, now, isn't it?

author: coppercone2
author_rank: Super Contributor
timestamp: May 05, 2024, 10:38:58 pm
content: i feel like its really hard to get that equipment and also the whole idea of maintaining a stock pile of coolant is really lame for a hobby

author: KE5FX
author_rank: Super Contributor
timestamp: May 05, 2024, 11:16:19 pm
content: Quote from: coppercone2 on May 05, 2024, 10:38:58 pmThat's, uh,not how it works.

author: nimish
author_rank: Regular Contributor
timestamp: May 05, 2024, 11:19:08 pm
content: Quote from: branadic on May 02, 2024, 07:16:56 pmNIST will sell you a Josephson junction array on a chip for ~$300k. Perfect voltage standard as of 2019.

author: coppercone2
author_rank: Super Contributor
timestamp: May 05, 2024, 11:25:59 pm
content: Quote from: KE5FX on May 05, 2024, 11:16:19 pmmost quantum technologies require a shit load of cryogenic coolant.

author: zrq
author_rank: Frequent Contributor
timestamp: May 06, 2024, 10:11:43 am
content: Well, not necessary true. For many cold atom experiments one don't need cryogenics, but in fact a heated oven to generate a beam of atom to be Zeeman slowed and loaded to a MOT.... For the projects using warm vapor it's more obvious.

author: coppercone2
author_rank: Super Contributor
timestamp: May 06, 2024, 08:35:17 pm
content: that is nice to know I thought liquid helium was a requirement for 95% of quantum physics.someone should make a list of quantum apparatus that can be used without LH

author: branadic
author_rank: Super Contributor
timestamp: May 06, 2024, 08:58:06 pm
content: Interesting to note that only a handful of people are into the quantum field.I recently started with NV centers in diamand, a quantum system working at room temperature. We breadboarded the very first quantum magnetometer last week and are currently working on an improved version. But that is just the start to develope a gut feeling and to further improve the setup. I have one or the other idea what is yet to come.-branadic-

author: iMo
author_rank: Super Contributor
timestamp: May 07, 2024, 05:03:39 pm
content: Afaik all today's semiconductor lasers for optical networks are based on QD.Would be interesting to have such a laser handy, run it at a low power, at a "constant" temperature and current and use it as a voltage source (like we do sometimes with an LED).

author: zrq
author_rank: Frequent Contributor
timestamp: May 07, 2024, 06:59:48 pm
content: I think VCSELs are prevalent for the lowest end 850nm transceivers, and most O-band and C-band high-end devices are usually InP quantum well lasers, still quantum but not dots. QD lasers are mostly still in R&D.

author: Harfner
author_rank: Contributor
timestamp: May 08, 2024, 03:40:24 am
content: Quote from: iMo on May 07, 2024, 05:03:39 pmYou mean, like an LED is sometimes used as sort-of-zener diode? Would a quantum dot laser have good voltage stability if used that way?

author: iMo
author_rank: Super Contributor
timestamp: May 08, 2024, 07:05:44 am
content: Quote from: zrq on May 07, 2024, 06:59:48 pmIt could be.. QDots, QWells, QLayers, QWires - those are today's buzzwords..Quote from: Harfner on May 08, 2024, 03:40:24 amYes, no idea..

author: coppercone2
author_rank: Super Contributor
timestamp: May 08, 2024, 07:36:28 am
content: the most interesting thing about quantum dots is is that its just fine powder. I think the name is super marketing. Because really, its a fine powder, treated with basically anti caking coatings, much like table salt.how about semiconductor meal. and angel hair wire.I felt a little cheated when I found out what quantum dots actually were.

author: vonB
author_rank: Newbie
timestamp: May 08, 2024, 07:24:44 pm
content: Hello guys.Im currently working in quantum technologies as eeSomething about quantum computers and quantum key distribution

author: iMo
author_rank: Super Contributor
timestamp: May 13, 2024, 08:07:14 pm
content: Quantum Dots.. a lot of them..https://www.samsungdisplay.com/eng/tech/quantum-dot.jsp

author: branadic
author_rank: Super Contributor
timestamp: September 26, 2024, 05:02:51 pm
content: After building first NV-based setups with microdiamonds to demonstrate Quenching we went forward and build our first ODMR/Zeeman splitting setup using a discrete build Omega resonantor based on some SMA posts that were soldered together with 1 pF Mica capacitor and a magnet wire loop in between. After some tweaking of the lenght of the magnet wire we achived a nice 2.87 GHz resonance frequency.I now wanted to go a step further using planar Omega resonators. There are quite a few publications out there addressing this topic, which would be a good starting point for simulation, replication and adjusting to individual needs, such as:Antenna for microwave manipulation of NV colour centresAs my pocket is not that deep I tried simulating the geometry from the aforementioned paper using Sonnet Lite. I think I have setup everything properly. Unfortunately, the simulation is far of from what I expected (see images attached). Is anyone into RF simulation and can help?Is there any other free tool for such tasks?-branadic-

author: RoGeorge
author_rank: Super Contributor
timestamp: September 26, 2024, 06:54:43 pm
content: Quote from: vonB on May 08, 2024, 07:24:44 pmIs that about using quantum encryption with classical computers, or does it includes hardware quantum computers, too?I am curious about the hardware implementation of quantum computing in general, and about how are they built in practice (depending on which type of quantum phenomena they are based on).

author: KE5FX
author_rank: Super Contributor
timestamp: September 26, 2024, 10:27:57 pm
content: Quote from: branadic on September 26, 2024, 05:02:51 pmPost the Sonnet Lite file?

author: branadic
author_rank: Super Contributor
timestamp: September 27, 2024, 07:33:53 am
content: I have attached the file to the former post.-branadic-

author: moerm
author_rank: Regular Contributor
timestamp: September 28, 2024, 08:21:09 am
content: I looked around but found no provider for "quantum technologies in the cloud", so my answer is 'No'. After all, everything and anything must be done in the cloud nowadays or else it's not really modern and high-tech.(Side note: I actually studied Physics but never got interested in quantum-. Please take the above as tongue in cheek ...)

author: nctnico
author_rank: Super Contributor
timestamp: September 28, 2024, 08:46:56 pm
content: Quote from: branadic on May 02, 2024, 07:16:56 pmNot really into doing quatum stuff myself but as I'm deeply entangled into high-precission (tens of picoseconds) time transfer over long distance, I am and have been involved with quite a few research projects around quantum technology to allow measuring quantum related effects spanning great distances. Interesting stuff but it takes some reading to understand what the projects are actually about. The scientist are typically so deeply submerged in their research that they have a hard time explaining their project in a way somebody not involved with it can understand what they are on about.Very interesting to have a front row seat though.

author: branadic
author_rank: Super Contributor
timestamp: February 21, 2025, 09:43:59 pm
content: Here is a sneak preview of what we are working on in our projectQOOOL Sensing, its a quantum based magnetometer for educational purpose.You can see the first signs of live of a very cheap mostly 3D printed setup reading the spin of electrons of NV centers in a 150 µm HPHT microdiamond. The Zeeman splitting at zero magnetic field (lower dip ms=-1, upper dip ms=+1) is most likely the result of strain in the diamond used. The setup is rather simple and no optics are involved.The measurement shown in the scope capture is a continuous frequency sweep from 2.67 to 3.07 GHz in steps of 1 MHz, which currently takes about 30 s. No expensive microwave generator involved and no averaging just yet. The fluorescence dip occures at around 2.87 GHz.-branadic-

author: branadic
author_rank: Super Contributor
timestamp: April 13, 2025, 08:33:41 am
content: QuoteNo, but I am willing to send the file up on request though.However, I've meanwhile found out that the reason the resonator does not behave as expected is due to the way Sonnet simulates. The board is sitting inside a conductive box tied to ground, so in order to get reasonable results you have to stay away from the walls of this box on all sides. Once you follow that rule, results are matching reallity better.To answer my question myselfQuoteopenEMS seems to be a very powerful tool that I've totally missed so far. However, getting into it isn't easy.Another sidenote, none of the microwave structures I've built and measured so far performed nearly as good as my discrete resonator described above. It eventually led to the following results for different diamonds and light sources:https://qoool-sensing.org/en/news/19-Diamond-Test-en-branadic-

author: coppercone2
author_rank: Super Contributor
timestamp: April 13, 2025, 10:27:26 am
content: like moonrakerhttps://jamesbond.fandom.com/wiki/Moonraker_Laser_Riflebtw if lecroy wanted to be useful they would put a part # for the SA instead of some BS slogan and their name. god thats distracting lol that they put their slogan in scope pics. I am just imagining having that show up in my reports. I feel like its completely mental.Teledyne Lecroy : Spam everywhere you lookTeledyne Lecroy : make your report look like you pulled random pictures from a sales brochureTeledyne Lecroy : distract the document reviewer with useless bullshit (and crash your probe into the sun)Teledyne Lecroy : we spray it like a wild cat

author: joeqsmith
author_rank: Super Contributor
timestamp: April 13, 2025, 12:32:42 pm
content: Quote from: coppercone2 on April 13, 2025, 10:27:26 amJust doing a quick Google image, Hantek, Tek, Siglent, OWON, RIGOL, KEYSIGHT TECHNOLOGIES all place their logos in their screen captures. Seems like a stupid post, or I missed something.

author: coppercone2
author_rank: Super Contributor
timestamp: April 13, 2025, 04:42:46 pm
content: I have yet to run into the 'slogan'. Normal companies might put hardware rev and hardware type.what are they doing trying to win the election?

author: branadic
author_rank: Super Contributor
timestamp: June 25, 2025, 09:11:19 am
content: We currently present our CW-ODMR setup, QOOOL Kit Magneto based on our π-Mk1 platform, live on the World of Quantum fair in Munich.-branadic-

author: branadic
author_rank: Super Contributor
timestamp: August 01, 2025, 12:41:59 pm
content: If anyone is interested, our first paper on quantum sensing is publicly accessable:https://www.mdpi.com/2673-8724/5/3/18(for the time being until it is available viahttps://doi.org/10.3390/magnetism5030018)-branadic-

author: RoGeorge
author_rank: Super Contributor
timestamp: August 01, 2025, 01:38:54 pm
content: The link doesn't work for me, I get a page from doi.org saying:Quote

author: KE5FX
author_rank: Super Contributor
timestamp: August 01, 2025, 04:47:08 pm
content: Same here, but the mdpi.org link worked.Very cool stuff! The homebrew resonator is a neat idea, but I can see it being tricky to set up for schools without access to a VNA. Good incentive to buy your kit! Of course a NanoVNA would be usable, even without being locked to a GPSDO.It could provide the stimulus signal for that matter. (I don't suppose there's any sign of return-loss variation with the LED on versus off, is there?)How would the responses achieved with the LEDs compare to what you'd get from a green laser pointer? Or do you need to rely on the broad spectrum coming from the LED?Also, any comparisons of HPHT diamonds with the pricier CVD ones?

author: branadic
author_rank: Super Contributor
timestamp: August 01, 2025, 05:12:26 pm
content: Thank youThe homebrew resonators performs better than any other resonator I have had in my hands up to this stage. But I do agree, it is not too easy to tune it perfectly to 2.87 GHz without a VNA. However, if you use a tooth pick and wind the copper wire around it and form an Ω with a distance of 1 - 2 mm between the wire ends, you are almost there.Nonetheless, we will present an even better and cheaper resonator in an upcoming paper, that doesn't require any tuning.No, there is no return loss variation with/without the diamond inside the resonator or the LED turned on/off.I don't think there is a huge improvement with a laser, because the fluorescence of the diamond is already pretty strong. On the other hand, lasers have a limited temperature of operation and require way more attention, while at the same time they suffer from speckle noise. Fluorescence collection efficiency is key and we will show dramatically improved ODMR signals in the upcoming papers.CVD diamonds with different NV concentration are already here and will be saved and prepared for another paper, so stay tuned.-branadic-

author: KE5FX
author_rank: Super Contributor
timestamp: August 01, 2025, 06:26:45 pm
content: I ordered some of the MDNV150umHi30mg crystals, we'll see if I can build the world's worst atomic clock with them.I've actually wanted to set up an NV fluorescence demo for some time, but until your paper came out, I hadn't seen any references to economical NV diamonds. ThorLabs charges $4K for their Element Six CVD crystals, which is a bit steep for weekend-scale goofball experiments.

author: branadic
author_rank: Super Contributor
timestamp: August 01, 2025, 07:21:44 pm
content: Meanwhile, we have quite a variety of diamonds including HPHT and there MDNV700850um50mg, which are way easier to handle. But they were not available during the work of this paper. But on the other hand, that leaves a lot of opportunities for more work to be published.When it comes to atomic clocks based on NV centers, there are at least two papers you want to look at, that is DOI: 10.1103/PhysRevA.87.032118 and DOI:10.1038/s41598-018-31984-4 so whatever you built, it's at least not the worlds first NV based atomic clock-branadic-

author: RoGeorge
author_rank: Super Contributor
timestamp: August 01, 2025, 07:33:40 pm
content: The link from mdpi.com was OK, thank you.Have read the paper, nice work!In case anybody is curious how Zeeman line-splitting was possible to observe experimentally long before LEDs, MCUs, VNAsand fabricated diamonds with Nitrogen vacancies, here's a one minute video (read the video description for any explanations):Zeeman Effect, Effektxofunkox-scientific experimentshttps://youtube.com/watch?v=iyBjPiRlxzgAnd this other 10 minutes video from a different channel (same experiment but with spoken explanations):Zeeman Effect - Control light with magnetic fieldsApplied Sciencehttps://youtube.com/watch?v=OzkcB1lkgGU

author: KE5FX
author_rank: Super Contributor
timestamp: August 01, 2025, 07:52:27 pm
content: Quote from: branadic on August 01, 2025, 07:21:44 pmThanks, the Hodges paper from 2013 looks really interesting. It would be very cool to see two-pulse spectroscopy happening, but I was just going to send some wideband PM with the signal generator and lock to it in the usual way. I imagine the T2 time will be much too short with the HPHT diamonds to do the two-pulse thing. Probably be lucky to get ADEVs near 1E-6 given how wide the line width is.

author: tggzzz
author_rank: Super Contributor
timestamp: August 01, 2025, 08:41:22 pm
content: New paper about quantum computers is available..."Similarly, quantum factorisation is performed using sleight-of-hand numbers that have been selected to make them very easy to factorise using a physics experiment and, by extension, a VIC-20, an abacus, and a dog."https://www.schneier.com/blog/archives/2025/07/cheating-on-quantum-computing-benchmarks.htmland the original paperhttps://eprint.iacr.org/2025/1237.pdf

author: soyouzka
author_rank: Newbie
timestamp: August 03, 2025, 09:37:23 pm
content: yeah, i work on optical atomic clockstheres a cool leaderboard style graph of optical atomic clock performance you can find here:https://www.adelaide.edu.au/ipas/research-groups/precision-measurement-group/portable-atomic-clocks/precision-timing-plot

author: KE5FX
author_rank: Super Contributor
timestamp: August 03, 2025, 11:36:49 pm
content: Quote from: soyouzka on August 03, 2025, 09:37:23 pmVery nice visualization. I took the liberty of adding another Rb standard to it.(5065A with Corby Dawson's optical BPF mod)

author: KE5FX
author_rank: Super Contributor
timestamp: August 12, 2025, 01:14:11 am
content: Quote from: branadic on August 01, 2025, 07:21:44 pmThe 150um diamonds aren't too hard to work with, given a microscope. They fluoresce nicely when hit with a laser pointer:I couldn't see any dips when sweeping the RF through the 2.6 - 3.0 GHz range, though. Are you normally able to perceive the brightness fluctuations visually in your setup? I didn't have time to rig up a photodiode and TIA, but that's next.

author: KE5FX
author_rank: Super Contributor
timestamp: August 12, 2025, 02:42:22 am
content: Another homebrew-friendlyNV project, announced atDEFCON.

author: branadic
author_rank: Super Contributor
timestamp: August 12, 2025, 06:31:43 am
content: I know this project, but am honestly not too excited about it.It is a good idea to place the diamond in the center of the loop and form a nice circular loop to begin with, as you want a homogenious microwave field.But to answer your question, I have never checked, if the fluorescence drop is visible in our builds with the naked eye. However, if you switch between two frequencies, say on resonance and off resonance, you should see the diamond blinking. But first you have to ensure that you get the expected ODMR spectrum.-branadic-

author: soyouzka
author_rank: Newbie
timestamp: August 28, 2025, 04:30:40 am
content: There is a well-hidden addendum here I just found out about:https://a1120960.github.io/PAC-SWaP

author: branadic
author_rank: Super Contributor
timestamp: October 03, 2025, 09:11:56 am
content: Next week @ the Quantum Effects 2025 in Stuttgart we will, beside the final QOOOL Kit Fluoro for the senseBox and many other physics experiments, present our QOOOL Kit Magneto prototype, a fully USB-powered NV-Magnetometer, controlled by GNU Octave.https://qoool-sensing.org/en/news/39-Quantum-Effects-2025-enIt's still larger than it needs to be, but is assembled with prototype boards, that can be miniaturized further in the future. In case you are nearby, you might want to visit us and play with the quantum sensor yourself.-branadic-