Cryogenic Cooling Using Only Electrons

 

Scientists at the UT Arlington have produced the world’s first electronic device that can cool electrons to -228 degrees Celsius without using any other external device to do so!

This is done by investigating into the fascinating world of quantum physics, utilizing a synthetic quantum well which is then integrated into the chip allowing it to be cooled to the cryogenic temperature range.This is very exciting indeed, as heating is the most common and largest problem of computational devices. Heat can not only cause systems to degrade faster, but offer a multitude of problems when processing data as you will see on the video below, not having a medium to extract the heat can be devastating to microprocessors:

 

 

But why do computers get hot within the first place?Computer_case_coolingair_flow

 

This is a large question with quite detailed answers, but to keep it short and simple we can break it down to pieces to better understand why heat is such a problem for electronic devices.

Computers are modular devices, which means that their parts can be interchanged for others. This  is usually done to improve performance of the system for the users needs, below is a short list of the main parts of a PC:

  • CPU – Central Processing Unit
  • RAM – Random Access Memory
  • GPU – Graphics Processing Unit
  • HDD – Hard Disk Drive
  • Motherboard
  • PSU – Power Supply Unit

 

pc-parts

 

Each unit above serves a critical purpose within the machine, however the CPU can be associated to the human brain in terms of what it does. As this part of the PC processes and manages all the data. Quite literally every piece of data is fed into the CPU to be given instructions or processed.

Now to be able to cope with the masses of data that the other parts of the computer send to it, the CPU’s of today such as the i7 4790k (for example) have around 1.4 billion transistors! With each transistor being at different electrical states which we can say are either a 1 or 0 . These transistors are switching between these states at around 4GHz (that 4 billion times a second). The video below gives a brief description of what a transistor is and how it works!

Assuming you have watched the video you can begin to comprehend just how hot a CPU can get without cooling, that is why it is so critical that the BTU (British Thermal Unit) count needs to be kept as low as possible in order to keep the machine as efficient as possible.

 

At this current time you can cool your pc utilizing liquid or air as a medium to carry the heat generated away, thus keeping the CPU cool. But this takes up power too, and overall it may not be much for one PC but when you consider that there are around 2,802,478,934 people connected to the internet in December 2013 as a latest figure (taken from http://www.internetworldstats.com/stats.htm) and you multiply this by the power 1 fan takes (going on the assumption that everyone only uses 1 fan to cool their pc) which is around a 4 watt average, that gives us a staging figure of:

2,802,478,934 * 4 = 11,209,915,736

That’s eleven billion, two hundred nine million, nine hundred fifteen thousand, seven hundred thirty-six watts (11.2 giga watt)  for everyone who has a pc with at least one 4 watt fan! ( most tower pc’s have around 4+ fans)

 

aerial photograph by www.webbaviation.co.uk

Aerial photo of London

So this is big deal!

 

So how does it work?

 

It utilizes an aspect of the quantum world called a quantum well. A quantum well is a very small and narrow gap between two semiconducting devices. As the electrons meet the well only those with a low energy potential can cross the gap. While other higher energy electrons cannot cross until their potential energy is reduced. The well is created by thin bandgap semiconductor material between two semiconductors , the pictures below show this is  in more detail:

A diagram illustrating the layout of UTA’s Quantum Well

 uta-quantum-well-design-640x506

The stream of electrons passing though the Quantum Well loose even more potential energy . This effectively leaves the electrons which reach the other side (cold electrons) of the well with less energy, thus wasting less whilst still allowing (in this case) the transistor to switch states. (more information regarding this process can be found within the research paper link located below)

To prove that they had cracked this the researchers produced Single Electron Transistors (SET) which are extremely sensitive to thermal excitation, usually this type of transistor has to be cooled using liquid helium. The SET’s ran at perfectly at room temperature utilizing this configuration maintaining a temperature of around 45 kelvin,  -228 degrees with no external input needed from the researchers.

(The picture of the “gold” type chip which is the title picture of this page shows the real SET chip with quantum wells.)

The hard part now is to implement these quantum wells into ordinary electronic goods, as the findings from this experiment showed that this could reduce the energy consumption of most micro-electronic devices by a factor of 10 times. This 10 time reduced power factor consumption can have dramatic effects of the, proceeding power, size and weight of the device including a massive boost to the battery life of future devices with this architecture!

To read more about this experiment in detail please go to the link below:

[Research paper: doi:10.1038/ncomms5745 – “Energy-filtered cold electron transport at room temperature”]

 

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