Quantum Computing
A Step Closer To Quantum Computer

A quantum computer is a computation device that makes use of quantum mechanical phenomena to perform various operations on data and uses quantum properties to represent it.The quantum computers are completely different from digital computers and usually share some theoretical similarities with non-deterministic and probabilistic computers.

These computers can perform many difficult calculations,search huge amounts of data at a very rapid speed than the existing super computer systems.Though quantum computing is still in infancy,continuous experiments are being carried out to produce quantum computers that will be very much useful in different fields.

A conventional computer manipulates the information in the form of bits which can have values of 1 or 0 where as in the quantum physics,a bit in a quantum computer,called ‘qubit’, can have any value between 1 and 0.Assigning each qubit with a well defined value,either 1 or 0 is the first step in building the quantum computer.

A quantum computer with a given number of qubits is different from a classical computer made of the same number of classical bits.

The electrons and atomic nuclei rotate around their own axes with a spin and the spin based qubit makes use of it.They can rotate both clockwise and anticlockwise (equivalent to 1 and 0), and in both directions simultaneously (a mix of 1 and 0) which is a different approach.

imagesInitiating the spin-based qubits requires all the atomic nuclei to spin in the same direction,either up or down. With the most common method of dynamic nuclear polarisation,nuclear spin is polarised.The electron spins influences the nucleus to spin in the same direction.

The process requires strongly spin polarised electrons and works efficiently at lower temperatures.However,at room temperature, the spin orientation in the electrons can easily be lost as it is sensitive to breaking from its surroundings.

Researchers now has a solution for this problem, Professor Weimin Chen and his colleagues at Linkoping University, in cooperation with German and American researchers,have succeeded in both starting and reading nuclear spins at room temperature,relevant to qubits for quantum computers.

Earlier,the research group presented a spin filter that works well at room temperature.This filter lets electrons that have the required spin direction and shuns others.Now,with its help,they have successfully produced a flow of free electrons with a given spin in a material – in this case GaNAs (gallium nitrogen arsenide).

The spin polarisation creates a strong polarisation of the nuclear spin in extra Ga atoms.This is the first time that strong nuclear spin polarisation of a defect atom in a solid is demonstrated at room temperature by spin-polarised conduction electrons. The polarisation happens very quickly i.e.,in less than a nano-second.

We prove experimentally that the measurable magnetic field from the nuclei, as well as the strong polarisation of the nuclear spins in the material at room temperature, comes from the dynamic polarisation of the nuclear spin in the extra added Ga atoms,” says professor Chen,the Division of Functional Electronic Materials at the Department of Physics,LiU.

This method also has the advantage of making use of free electrons and it allows to control the polarisation of the spin in the nucleus electrically through which the information lying in the spin can be noth initiated and read.

Thus,with this new invention,the quantum computers can soon be a reality competing with the existing super computers.

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