Quantum Bayesian Networks

September 12, 2011

Is Building a Quantum Computer Now Within the Reach of Hobbyists?

Filed under: Uncategorized — rrtucci @ 5:40 pm

The legions of science & technology “geek” hobbyists who built early automobiles, aeroplanes, radios, model rockets, homebrewed computers, Linux operating system … (more recently even genetic engineering)—these amateur scientists have a long and glorious history. In most cases, their main goal was not to build a device that worked as well as an off-the-shelf one, but rather to try to build a working device from scratch, so as to be intimately familiar with every nut and bolt in it. To do this as cheaply as possible. To learn a lot and have a lot of fun in the process.

It’s inevitable that some hobbyists will eventually try to build their own quantum computer. Recent NIST work, about which I wrote a previous blog post, may soon make this possible. The new NIST contraption avoids many of the expensive lasers and cooling systems used in their earlier devices. Sci-Tech hobbyists have tried stranger things before. For instance, check out this article about a “fusioneer” named Taylor Wilson (now 17 years old) who built his first nuclear reactor at the tender Mouseketeer age of 14. Now, at first glance, one would think that building a quantum computer would be cheaper and no doubt safer than building a nuclear reactor, don’t you think?

I recently sent the following email to Dr. Christian Ospelkaus, a member of the team that built the new NIST device.

According to your recent paper
 “Microwave quantum logic gates for trapped ions”

your ion trap operates at room temperature.
Does that mean that your device does not require any cooling at all? 
Would cooling make it work better by reducing decoherence effects?
How expensive and/or difficult would it be for a hobbyist to reproduce your device?

Thank you in advance for your answers.

He was kind enough to respond immediately to my email. Here is his reply, which he has kindly agreed to let me post here:

Hi Robert,

thanks for your email. The trap does indeed operate at room temperature. In one of our other experiments (Brown et al., Nature 471, 196 (2011), attached), we had used a cryogenic ion trap (4 Kelvin electrode temperature). That can be done to avoid certain motional decoherence effects which were not an issue in the experiment in the paper you were referring to.

If you’d like to look into the cooling issue, you can look at Deslauriers et al. (attached) and Labaziewicz et al. (attached).

As far as reproducing the results goes, it depends on the budget 🙂 The laser system for ionization, optical pumping and pre-cooling is probably around 200k in total, the vacuum apparatus 10k, the control system maybe 25k, the CCD camera 20k, the imaging system 20k, plus a little bit of this and that. Plus you would have to make the chip, which is being produced in a multi-million dollar cleanroom facility at NIST. What helps you in a big place like NIST is that most of these things are already there, if you want to try out a new idea, like these microwave gates.

The corresponding experiment, with lasers used to do the quantum gates, would be much more expensive, an additional 300k for lasers easily.

I don’t know what your background is, but the simplest ion trapping you can do operates at air and traps spores and stuff like that. Here is a funny video by Theodor Hänsch that shows some of these traps:

You can’t do any quantum stuff with that, but it does look pretty. Watch out with the high voltage!

Best regards,



Deslauriers et al. – 2006 – Scaling and Suppression of Anomalous Heating in Io.pdf (480 KB) Download

Brown et al. – 2011 – Coupled quantized mechanical oscillators.pdf (842 KB) Download

Labaziewicz et al. – 2008 – Suppression of Heating Rates in Cryogenic Surface-.pdf (1.9 MB) Download


1 Comment »

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