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The production of a working quantum computer has become a real possibility thanks to recent developments in the field nanotechnology but there is still a long way to go.
What is a Quantum Computer?
The field of quantum computing focuses on the development of computer technologies based on the principles of quantum theory which explains the behaviour and nature of matter and energy at the quantum level.
Quantum computers can handle more than just binary information, which conventional computers operate on. Quantum computers can also handle data in between a 0 or 1 bit, implying that new types of simulation and calculations can be performed.
In quantum computations the spin direction, which is either up or down, serves as the basic information unit which is similar to the 0 or 1 bit in a classic computing system. Electron spin can assume both 0 and 1 simultaneously, as a result of quantum entanglement, which greatly enhances the ability to perform complex computations.
Silicon-Based Quantum Computer
A lot of work in the field of quantum computing is still in the theoretical stages as there are still a lot of obstacles to overcome. In 2010, a team of researchers from the University of Surrey, UCL, the FOM Institute for Plasma Physics and the Heriot-Watt University in Edinburgh made a crucial step towards the production of an economical quantum computer.
The team published a paper in Nature which shows how they designed a version of Schrodinger’s cat, which is both dead and alive simultaneously from silicon, which is the same material used to produce ordinary computer chips. The team used a high intensity, short pulse from the Dutch FELIX laser in order to place an electron orbiting in silicon into two states at the same time, also known as a quantum superposition state.
The superposition state can be controlled so that electrons emit light at a specific time after superposition is created, which is known as a photon echo and enables complete control over the atoms. This work shows that the same quantum engineering used by atomic physicists in advanced instruments known as cold metal traps, can also be applied to the silicon chip which can be used to create the common transistor. As a result, the development of a silicon-based quantum computer may be just over the horizon.
The world’s smallest transistor was built by Sydney scientists in February 2012 by accurately positioning of a phosphorus atom in a silicon crystal. This nano device is a breakthrough in the development of quantum computers. Individual atoms were manipulated with extremely high precision and a scanning tunnelling microscope was used to substitute a single silicon atom from a group of six atoms with a single phosphorus atom to an accuracy of just 0.5 nanometres.
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The single atom was placed between two electrode pairs, with one 20 nanometres apart and the other 100 nanometres apart. The application of a voltage across the electrodes caused it to function like a transistor, which is a device capable of amplifying and switching electronic signals.
Recent advancements show that new technologies utilising quantum behaviour for computing and other applications are closer to being realised. These advancements will help to create highly powerful computers as well as highly sensitive detectors which can be used to probe biological systems.
These advancements include two significant breakthroughs. One is the ability to control quantum units of information called quantum bits, or qubits, at room temperature. Until recently, temperatures close to absolute zero were required but the creation of new diamond-based materials has allowed spin qubits to be operated at room temperature. Imaging of single molecules has been made recently possible by diamond-based sensors as shown by Awschalom and researchers at Stanford University and IBM Research.
The second breakthrough is the ability to control these quantum bits for several seconds before they behave normally. Highly pure forms of silicon have helped researchers control a quantum mechanical property called spin. At Princeton, a team of researchers showed spin could be controlled in billions of electrons for several seconds using highly pure silicon-28.
Quantum computing may find applications in cryptography, enabling the secure communication of information and decryption by someone using a powerful quantum computer. They can also be used for astronomical and physics complex calculations as well as simulation and modelling that can be used for nuclear fallout, oil discovery and environmental monitoring. The modelling capabilities of quantum computing will help to understand the fundamental nature of matter.
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