Molecular Transistor – A Revolutionary Step Towards Quantum Computer
Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks. Quantum computers have the potential to perform certain calculations significantly faster than any silicon-based computer.
Scientists have already built basic quantum computers that can perform certain calculations; but a practical quantum computer is still years away.
Scientists have now made a transistor composed of a single phosphorus atom, surpassing the limits of Moore's law. According to a report published in Nature Nanotechnology, the scientists have etched the atom into a silicon bed. It has been given 'gates' that control electrical flow and metallic contacts to apply voltage.
Image: Electric field emanating from the charged red atom causes energy level shifts in the molecule allowing current to flow. (Courtesy of the National Research Council of Canada)
According to a TOI report, the researchers said that it is first of such devices that use a repeatable technology and will lead to the creation of quantum computer. Due to this technology, the computer will be significantly smaller and faster as compared to the existing technology.
A single atom on a silicon surface can be controllably charged, while all surrounding atoms remain neutral. A molecule placed adjacent to that charged allows electrical current to flow through the molecule from one electrode to another. The current flowing through the molecule can be switched on and off by changing the charge state of the adjacent atom. The results are promising and are considered to be a scientific breakthrough.
Quantum computers could one day replace silicon chips, just like the transistor once replaced the vacuum tube. But for now, the technology required to develop such a quantum computer is beyond our reach. Most research in quantum computing is still very theoretical.
During the 1930's key figures such as Alan Turing developed the classical theories of computing. These theories describe the limitations of machine-executable algorithms and are still in use today. It is interesting to note that most of these theories predate the modern computer which only came into existence as we know it during the 1950's. The modern computer has developed rapidly since then, from valve technology through to VLSI integrated circuits. We have already reached the stage where the design features of modern processors are so small that they are being affected by the strange rules of quantum mechanics.
Whilst these effects represent a limit to the size reduction that has been one of the key methods of increasing processor performance, a school of thought has developed believing that maybe these effects can be used to our advantage in some kind of new computer, a quantum computer.
Richard Feynman led the way by producing an abstract model of how, in principle, a quantum system could be used to perform computations. Then, in 1985, David Deutsch published a ground breaking theoretical paper describing how any physical process could be modeled perfectly (in theory) using a quantum computing system. Such a computer, he argued, would be able to perform tasks like true random number generation that no classical computer can achieve. The most powerful feature of a quantum computer would be its ability to use the phenomenon of 'quantum parallelism' to perform certain types of calculations in a fraction of the time taken by a classical computer
In the classical model of a computer the most fundamental building block, the bit, can only exist in one of two distinct states, a '0' or a '1'. In a quantum computer the rules are changed. Not only can a 'quantum bit', usually referred to as a 'qubit', exist in the classical '0' and '1' states, but it can also be in a superposition of both! In this coherent state, the bit exists as a '0' and a '1' in a manner which may at first seem hard to accept. Let's consider a register of three classical bits: it would be possible to use this register to represent any one of the numbers from 0 to 7 at any one time. If we then consider a register of three qubits, we can see that if each bit is in the superposition or coherent state, the register can represent all the numbers from 0 to 7 simultaneously!
A processor that can use registers of qubits will in effect be able to perform calculations using all the possible values of the input registers simultaneously. This phenomenon is called quantum parallelism, and is the motivating force behind the research being carried out in quantum computing.
Although the future of quantum computing looks promising, we have only just taken our first steps to actually realising a quantum computer. There are many hurdles which need to be overcome before we can begin to appreciate the benefits they may deliver. Researchers around the world are racing to be the first to achieve a practical system, a task which some scientists think is futile. David Deutsch - one of the ground breaking scientists in the world of quantum computing - said himself that perhaps 'their most profound effect may prove to be theoretical'.
In comparison the progress in quantum communications has been somewhat more fruitful. Companies like BT have actually achieved working systems that are able to use quantum effects to detect eavesdropping on a channel. Whether or not such systems will prove practical remains to be seen.
Can we really build a useful quantum computer?
This is a million dollar question, which our future generation will solve!
Acknowledgement ----
(The entire material above are collected from internet resources and various scientific sites)
Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks. Quantum computers have the potential to perform certain calculations significantly faster than any silicon-based computer.
Scientists have already built basic quantum computers that can perform certain calculations; but a practical quantum computer is still years away.
Scientists have now made a transistor composed of a single phosphorus atom, surpassing the limits of Moore's law. According to a report published in Nature Nanotechnology, the scientists have etched the atom into a silicon bed. It has been given 'gates' that control electrical flow and metallic contacts to apply voltage.
According to a TOI report, the researchers said that it is first of such devices that use a repeatable technology and will lead to the creation of quantum computer. Due to this technology, the computer will be significantly smaller and faster as compared to the existing technology.
A single atom on a silicon surface can be controllably charged, while all surrounding atoms remain neutral. A molecule placed adjacent to that charged allows electrical current to flow through the molecule from one electrode to another. The current flowing through the molecule can be switched on and off by changing the charge state of the adjacent atom. The results are promising and are considered to be a scientific breakthrough.
Quantum computers could one day replace silicon chips, just like the transistor once replaced the vacuum tube. But for now, the technology required to develop such a quantum computer is beyond our reach. Most research in quantum computing is still very theoretical.
During the 1930's key figures such as Alan Turing developed the classical theories of computing. These theories describe the limitations of machine-executable algorithms and are still in use today. It is interesting to note that most of these theories predate the modern computer which only came into existence as we know it during the 1950's. The modern computer has developed rapidly since then, from valve technology through to VLSI integrated circuits. We have already reached the stage where the design features of modern processors are so small that they are being affected by the strange rules of quantum mechanics.
Whilst these effects represent a limit to the size reduction that has been one of the key methods of increasing processor performance, a school of thought has developed believing that maybe these effects can be used to our advantage in some kind of new computer, a quantum computer.
Richard Feynman led the way by producing an abstract model of how, in principle, a quantum system could be used to perform computations. Then, in 1985, David Deutsch published a ground breaking theoretical paper describing how any physical process could be modeled perfectly (in theory) using a quantum computing system. Such a computer, he argued, would be able to perform tasks like true random number generation that no classical computer can achieve. The most powerful feature of a quantum computer would be its ability to use the phenomenon of 'quantum parallelism' to perform certain types of calculations in a fraction of the time taken by a classical computer
In the classical model of a computer the most fundamental building block, the bit, can only exist in one of two distinct states, a '0' or a '1'. In a quantum computer the rules are changed. Not only can a 'quantum bit', usually referred to as a 'qubit', exist in the classical '0' and '1' states, but it can also be in a superposition of both! In this coherent state, the bit exists as a '0' and a '1' in a manner which may at first seem hard to accept. Let's consider a register of three classical bits: it would be possible to use this register to represent any one of the numbers from 0 to 7 at any one time. If we then consider a register of three qubits, we can see that if each bit is in the superposition or coherent state, the register can represent all the numbers from 0 to 7 simultaneously!
A processor that can use registers of qubits will in effect be able to perform calculations using all the possible values of the input registers simultaneously. This phenomenon is called quantum parallelism, and is the motivating force behind the research being carried out in quantum computing.
Although the future of quantum computing looks promising, we have only just taken our first steps to actually realising a quantum computer. There are many hurdles which need to be overcome before we can begin to appreciate the benefits they may deliver. Researchers around the world are racing to be the first to achieve a practical system, a task which some scientists think is futile. David Deutsch - one of the ground breaking scientists in the world of quantum computing - said himself that perhaps 'their most profound effect may prove to be theoretical'.
In comparison the progress in quantum communications has been somewhat more fruitful. Companies like BT have actually achieved working systems that are able to use quantum effects to detect eavesdropping on a channel. Whether or not such systems will prove practical remains to be seen.
Can we really build a useful quantum computer?
This is a million dollar question, which our future generation will solve!
Acknowledgement ----
(The entire material above are collected from internet resources and various scientific sites)
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