# Helium!!!

There’s a new club night in Birmingham called ‘Helium’:

The DJs sport names such as ‘Diesel’, ‘Vermin’ and ‘Yumbolt’. Now if I were spinnin’ choonz at this club I would have called myself DJ Supersolid, but then again maybe they haven’t been keeping up to date with the latest developments in condensed matter physics.

The club has an ‘elements’ theme in general, with an Oxygen room, a Nitrogen room and a Carbon room. Cute. No Niobium room though, booo…

# These things are scaling pretty quickly…

Via Michael Nielsen:

Quantum Computers

From the website:

“Maybe you’ve never heard of Quantum Computers before and are partial to purchasing from another company that might have advertising everywhere you look.”

Ah, shucks… so that’s where I was going wrong.

# Fridge surgery

Take a look at this picture:

Yes I am hacksawing a dilution refrigerator….

One of the entry ports to the IVC has been hardsoldered with a stainless steel placeholder bush. We need to replace this with our custom made copper bush with feedthroughs for coaxes and DC lines. It is virtually impossible to remove this part given the small space around it, and we decided that we don’t want to put power tools nearby, lest we accidentally buzz through the dilution unit. Which would be a bit like putting a scalpel through the jugular.

So hacksaw it is.

I wonder how many low temperature physicists have wanted to saw their dilution fridges in half before. Today I got to indulge in that pleasure. The results weren’t pretty at times:

Although half way through I started thinking ‘I hope that this is the right part I’m sawing…’

# It’s just too cool to be a scientist these days.

Via Pharyngula:

I was thinking after the LHC rap that a QC rap video would be cool to do, but I don’t think anything I could do could possibly match the standards set by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO):

I also now want a giant gold medallion with a $\Psi$ on it…

# Man climbs building with vacuum gloves

Very cool! 🙂 We have a building at the University with that same kind of metal cladding. I guess it would work on glass too, although the building would probably have to be clean and shiny.

# It’s not cake but it’s close!

Here are some pictures of our Liquid Nitrogen Ice cream endeavours… mmm. Disclaimer: Don’t try this at home unless you have had training in handling cryogenic liquids 🙂

Ingredients: Cream, milk or that strange stuff we don’t have over here, sugar, crushed fruit, and liquid nitrogen. Recipe: Stir the sugar into the cream until it dissolves, then beat it with a whisk until it is light and fluffy. Then add the fruit, mix it in, and then add the LN2, stirring continously until it has hardened. It takes about 5 minutes, as opposed to waiting for it to cool in the freezer for hours. You can use chocolate chips too but for some reason the fruit one seemed to come out better.

Because you have to keep stirring it, it tends to come out in fluffy bits rather than scoopable ice cream, but you can still pack it into a bowl or cone the same way 🙂

Rather tasty too. You have to be careful when you eat it, sometimes you get a REALLY cold bit in the middle and a rather bad Ice Cream Headache
To keep it from melting on a hot summer’s day, just add more LN2 topping:

# Quantum computing fail…again.

Courtesy of Quantum Bayesian Networks, an article entitled “The Quantum Leap of Quantum Computing” on Penny Sleuth. It’s great to see a wider business and market audience becoming interested in QC.

However, this is slightly irritating:

“This means computers would become exponentially more powerful because each “quantum bit” (qubit) could store a much greater range of numbers than the two that binary math restricts us to. Imagine a laptop with the computing power of the world’s 10 most powerful supercomputers. Then you begin to grasp the potential of quantum computing.”

In the spirit of a very popular television program:

Let me explain for any readers who are slightly confused at this point: Quantum computers will be very good at solving certain types of hard problems somewhat faster than classical computers. This should become some sort of mantra. (If anyone can think of a catchy version that would be cool).

They won’t be general purpose machines. The best way to think of a QC is more like a co-processor (say like a hardware graphics accelerator).

The types of problems that they will be good at solving are exciting and interesting in themselves. Quantum computers are cool enough without the overhype 🙂

# Lab tasks which make me wish I was a theorist

It’s not all fun and games in the lab. Here is a list of the top 10 (in my opinion) most boring tasks that need doing in a Low Temperature device laboratory:

10.) Chiselling ice off the cold traps
You have to do this otherwise you can’t get them out. Some cold traps are better than others, the ones I have on my fridge aren’t very good, they get iced up quite often.

9.) Adding exchange gas to the IVC.
I use Hydrogen exchange gas, which allows the innards of the vacuum can to cool by conduction and convection, before the temperature gets low enough to freeze out the Hydrogen (at which point it becomes a pretty good vacuum). However, adding it to the IVC is slightly irritating as you need to connect up a vacuum pump, balloon of Hydrogen, etc.

8.) Calibrating thermometers
Thermometry is a pain. Alas, it is also one of the most important parts of the apparatus, as temperature is a rather important variable in most experiments. Writing software calibrations, entering long tables of values, using generic calibrations if you’ve lost the long tables of values….

7.) Making leak-tight He-4 to vacuum feedthroughs.
Stycast is your friend 🙂 They have to be tested by being dipped into a dewar of helium, via a hollow feedthrough rod to which they are soldered in place at one end, whilst the other end is simultaneously connected to a leak detector.

6.) Winding magnets / making superconducting persistent mode magnets
Spot welding superconducting joints for heat switches and winding/potting/quench training magnets – argh!

5.) Making custom filters
Commercial kit just doesn’t work at low temperatures. I’ve had commercial filters fail a few times, and it’s not an easy bug to fix, especially when they only stop working at liquid helium temperatures…