Posted in experimental insights, feeling dumb, humour, physics fail on December 8, 2009 | 2 Comments »
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 [...]
Posted in experimental insights, research blogging on October 28, 2009 | 2 Comments »
Drafting out ideas for where everything goes:
The fridge in question will be used for several different ‘interchangeable’ experiments, which always makes it tricky to wire. The majority of the lines need to be coaxial, as they will be used for either microwave transmission or fast pulse control of qubits.
Posted in RSFQ, experimental insights, learnin' stuff, quantum computing, research blogging on October 21, 2009 | 3 Comments »
It’s hard work being the only postdoc in the village. One day I’m fixing wiring on the fridge, the next I’m analysing the effect of spin-flip scattering on my superconductor-ferromagnet data. Today I’m being the local RSFQ/SQUID layout afficionado.
I’m designing some qubit circuits. Process design rules are a pain, there are about 10 layers in [...]
Posted in experimental insights, fun and games on September 11, 2009 | 1 Comment »
We were having problems lowering the Heliox insert into the storage dewar, the vacuum can would touch the top of the liquid Helium before the seal could be made, resulting in a rapid and somewhat violent boil-off of Liquid Helium. Frozen fingers ensued, as did cursing at the wastage of gas. Unfortunately I don’t have [...]
Posted in experimental insights, expt vs theory showdown on August 25, 2009 | 2 Comments »
So my dilution refrigerator is nicknamed Frosty. In addition to being a neat acronym (FRidge Of Substantially Tempramental Yield) the name is somewhat more grounded in one of his physical attributes, i.e. that of being rather inefficient at keeping the cold where it should be It’s really important to remember not to touch [...]
Posted in experimental insights, expt vs theory showdown on August 3, 2009 | 4 Comments »
Low temperature experiments are very expensive to run. That’s why we need such large grants to do research for a 2-3 year project. Just considering Liquid Helium alone:
I run the fridge about 2 times a month, and I use about 150L of LHe4 each time. Liquid Helium costs about £5 a litre. I also run [...]
Posted in artsey, experimental insights, expt vs theory showdown, lifelogging on July 27, 2009 | 5 Comments »
Should I digitise my lab books?
The answer to this is almost definitely yes. Other than it taking a long time, there aren’t really any disadvantages to doing so. It would mean I had access to all my experimental settings in digital form, and I would have a built in cross-reference of the plots that are [...]
Posted in cake, experimental insights, quantum computing, research blogging on July 7, 2009 | 2 Comments »
Here is a picture of the new experimental setup:
In this picture we are testing that the apparatus cools down OK. This type of fridge is an Oxford Instruments Heliox, which is a He-3 based cooling system. The principle of operation is that you cool a ‘plate’ of metal to 1.5K by pumping a small amount [...]
Posted in artsey, experimental insights on June 29, 2009 | 2 Comments »
So how do you actually make electrical contact to tiny microchips? Wirebonding is the standard industrial technique. For large chips (e.g. complex processors) fabricated in foundries, the process is fully automated. However in small research labs, a manual wirebonder is used, as each chip tends to be different.
I was rather enamoured by various artsey and [...]
Posted in experimental insights, superconductors on June 9, 2009 | 2 Comments »
The CF cryostat is a lovely piece of kit for quickly measuring samples down to 4.2K. Here is a picture:
The dewar containing the liquid Helium can be seen on the left. The setup is rather simple, you have a gas pump, a thin transfer tube (the silver tube joining the dewar to the cryostat) and [...]
