Spintronics May Lead to Quantum Microchips

Rashan writes "A Scientific American article which waxes poetic about the possibility of microchips which use the "spin" of an electron to perform their functions." An excellent explanation of a complex subject.

Comments

Re:terminology .. explained

[wass]

Electronics use electrons, so spintronics must use...spintrons?

No, they use Spin-dependent electrons. This is spintronics, in a nutshell.

Up until now, almost all electronic devices have made use only of the electronic charge. Ie, amplifying it, switching on it, transferring it, etc.

Well, in a subtle manner, there is spin dependence in the above, due to Pauli exclusion, but that's buried in the quantum statistics.

Remember the electron is a spin-1/2 fermion, and hence has two possible states for a measure of it's spin in any given direction. Spin is an inherent property of many particles, with no classical analog, but you can think of it roughly as an angular momentum. Spin is quantized, unlike a spinning top. A spinning top is a classical system, which can have any rotational speed from 0 to any positive/negative values. (Negative means opposite direction of spin as a positive value).

Since the electrons are quantized spin-1/2 particles, there are only two measures of the spin angular momentum that are valid. +-(1/2)hbar where hbar is the Planck constant. Thus, an electron can only spin one way or another, there are no intermediate values (including no zero value, so it's ALWAYS spinning). Also note that this spin doesn't really represent the electron spinning about it's own axis, it's an inherently internal concept that's is actually quite involved.

These two values of spin of an electron can now be exploited in new devices. Right now the goal is to make devices that can inject electrons of one value of spin, and make transistors that work only for certain values of spin, or preserve spin parity, etc. Quantum computation would work nicely here too because the two states of spin are a good basis for representing a binary digit.

I haven't read the Scientific American article, so I don't know if I'm just repeating the obvious or not. But I'm a graduate physics student right now, and I hope to eventually work on some applications of spintronics. It is a currently buzzing field with much potential.