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The production of a working quantum computer has become a real possibility, thanks to recent developments in the nanotechnology field, 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. Quantum theory explains the behavior and nature of matter and its energy at the quantum level.
Quantum computers can handle more than just the binary information which conventional computers operate on. Quantum computers can also handle data in between a 0 or 1 bit, which should, in turn, provide new types of simulation and calculations.
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 classical 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 illustrated how the collaborators designed a version of Schrodinger’s cat - which is both dead and alive simultaneously - from silicon; 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, which is 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. This is known as a photon echo and allows for 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 scientists in Sydney in February 2012. This was done through the accurate positioning of a phosphorus atom in a silicon crystal. This nano-device represents a breakthrough in the development of quantum computers. Individual atoms are manipulated with extremely high precision and a scanning tunneling 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 nms apart, and the other set 100 nms apart. The application of a voltage across the electrodes causes it to function like a transistor, which is a device capable of amplifying and switching electronic signals.
Further advances since 2014 show that new technologies which utilize quantum behavior for computing and other applications are closer to being realized. These advancements will help to create highly powerful computers as well as highly sensitive detectors which can be used to probe biological systems.
There are two other significant breakthroughs. The first is the ability to control quantum units of information called quantum bits, or qubits at room temperature. Previously, temperatures close to absolute zero were required, but the creation of new diamond-based material has allowed spin qubits to be operated at room temperature. The imaging of single molecules has therefore been made possible by diamond-based sensors - as demonstrated by Awschalom as well as 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, which enables 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 modeling that can be used for nuclear fallout, oil discovery and environmental monitoring. The modeling capabilities of quantum computing will help to understand the fundamental nature of matter.
Sources and Further Reading
This article was updated on the 3rd September, 2019.