Spintronics, Superposition, Qubits – Definition, Applications and The Potential For Quantum Computers

Download PDF Copy

Aug 8 2006

Topics Covered

Background

Spintronics is a relatively new term derived from “spin based electronics”. Spintronics uses the spin of electrons and charge together, rather than charge alone to represent binary data values. The advantage of spintronics is that it requires much less power than conventional technologies whilst operating at much higher speeds. Applications for spintronics include computer memory, sensors and disk drives.

Superposition

Spintronics theory is based in the quantum mechanical idea of superposition – that an object can simultaneously possess two or more values for the same quantity or state at any given time. In 1935 Erwin Schrodinger outlined his idea that a cat placed in a sealed box with a deadly device is then not known to be either dead, nor alive. Applying quantum physics, the cat therefore takes on the superposition state of being both alive and dead simultaneously. It is only if we open the box to look inside that the cat is observed to be one or the other and then the superposition state is removed.

Considering an electron spinning through one axis only. This electron can be said to spin either up or down. These spins can represent the binary values of 0 or 1. The problem is that the act of observing or measuring the spin actually changes the value so we still don’t know what the value was. Like Schrodinger’s Cat, if the act of opening the box kills the cat, we still don’t know if the cat was alive while in the box.

Qubits

Superposition of states allows us to assume the electron is spinning a little bit up and little bit down at the same time – in other words the electron represents both the bit values 0 and 1 simultaneously. This is called a Quantum Bit or Qubit.

Spintronics

In conventional electronics charges are simply moved around a circuit and the spin of electrons is ignored. This means that eight bits are required to represent numbers between 0 and 255 and only one number can only give given at any particular moment in time. Spintronics uses qubits, so the "spin up" and "spin down" superposition states of 0 or 1 allow 8 qubits to represent every number between 0 and 255 simultaneously.

The result is that spintronics can be used to hold and carry much more information than conventional electronics. Power consumption is also dramatically reduced.

Applications

Short term applications for spintronics include ultra-high capacity disk drives and super fast computer memories. Spintronics are already being used in computer hard drive disk heads. Disk head transducers use a “spin valve” that consists of layered magnetic materials with high sensitivity to magnetic fields. In the presence of a magnetic field the spin valve allows all electrons through, but when a magnetic field is absent, it only lets electrons with some spins through.

Some scientists believe that with further development, spintronics holds the key to quantum computers.

Source: AZoNano

For more information on this source please visit AZoNano