Have you ever seen a bit?

Look at a bit (three of them actually!).Magnetic microscope image of three nanomagnetic computer bits. Each bit is a tiny bar magnet only 90 nanometers long. The image hows a bright spot at the “North” end and a dark spot at the “South” end of the magnet. The “H” arrow shows the direction of magnetic field applied to switch the direction of the magnets. Credit: Jeongmin Hong et al./Science Advances

The Moore's law has run out of steam, however the Moore's law means many things. Sure, the continuous decrease in price of the transistor is now over, and the increase in density (smaller and smaller transistors) is reaching the end of the line.

Hence, packing more and more number crunching performance in a single chip is getting more and more difficult.

However, there are still areas where progress can occur, like new architectures that foster better processing for specific kinds of applications (like the IBM Synapse chip) or new material that can improve the energy efficiency (like graphene and other single layer structures).

A team of researchers at UC Berkeley and at Lawrence Berkeley National Laboratory have presented in a paper the result of their work on using magnetic chips for processing. 

In physics one of the basic tenets is that there is not such a thing as a free lunch. In order to get something done you need to accept an increase in the entropy and this in turns involves the generation of heat. Heat is, in a way, the amount of energy that is not used to do what you want to do  (yes, it also applies to cooking: even if you are using heat to cook your spaghetti, part of the chemical transformation that makes a difference between a raw and a cooked spaghetti generates heat and this is "wasted").

This general rules applies to "bits" as well. If you manipulate bits, to create an information, you have to accept that part of the energy used is converted to heat (and it is wasted... from your point of view).

There is a low physical limit to the energy that need to be used to manipulate a bit, and it was pointed out in 1961 by a physicist, Rolf Landauer, working at IBM. In 2012 it was proved that indeed this limit exists (the Landauer limit) and now the researchers at Berkely have been able to show that using magnetic "bits" they can approach this limit, in other words make chips much more effective from an energy standpoint.

What also interested me, and this is the reason for the title of this post, is that they found a way to show each bit, and its value, by highlighting the magnetic polarity. First time that I see such an approach.

Author - Roberto Saracco

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