A quantum computer is based on the amazing properties of quantum systems. In these a quantum bit, also known as a qubit, exists in two states at the same time and the information from two qubits is entangled in a way that has no equivalent whatsoever in the normal world.
David Deutsch, Oxford University theoretical physicist, is credited with being the father of quantum computing.
Deutsch invented the idea of the quantum computer in the 1970s as a way to experimentally test the "Many Universes Theory" of quantum physics -- the idea that when a particle changes, it changes into all possible forms, across multiple universes.
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.
Quantum computers have superior qualities in comparison to the type of computers currently in use. If they are realised, then quantum computers will be able to carry out tasks that are beyond the abilities of all normal computers.
It is highly likely that workable quantum computers will need to be produced using existing manufacturing techniques from the chip industry. Working on this basis, scientists at Delft University of Technology are currently studying two types of qubits: one type makes use of tiny superconducting rings, and the other makes use of 'quantum dots'.
Now for the first time a 'controlled-NOT' calculation with two qubits has been realised with the superconducting rings. This is important because it allows any given quantum calculation to be realised.
The result was achieved by the PhD student Jelle Plantenberg in the team led by Kees Harmans and Hans Mooij. The research took place within the FOM (Dutch Foundation for Fundamental Research on Matter) concentration group for Solid State Quantum Information Processing.
Quantum computers hold the possibility of solving what computer science calls "NP-complete" problems, the problems that are impossible or nearly impossible to calculate on a classical computer. Picking out a single pattern from a collection of patterns, such as your mother from a photo of people, is easy for you, but beyond the reach of your PC.
Despite many common concepts with classical computer science, quantum computing is still widely considered as a special discipline within the broad field of theoretical physics. One reason for the slow adoption of QC by the computer science community is the confusing variety of formalisms (Dirac notation, matrices, gates, operators, etc.), none of which has any similarity with classical programming languages, as well as the rather ``physical'' terminology in most of the available literature.
QCL (Quantum Computation Language) tries to fill this gap: QCL is a high level, architecture independent programming language for quantum computers, with a syntax derived from classical procedural languages like C or Pascal. This allows for the complete implementation and simulation of quantum algorithms (including classical components) in one consistent formalism.
David Deutsch, Oxford University theoretical physicist, is credited with being the father of quantum computing.
Deutsch invented the idea of the quantum computer in the 1970s as a way to experimentally test the "Many Universes Theory" of quantum physics -- the idea that when a particle changes, it changes into all possible forms, across multiple universes.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.
Quantum computers have superior qualities in comparison to the type of computers currently in use. If they are realised, then quantum computers will be able to carry out tasks that are beyond the abilities of all normal computers.
It is highly likely that workable quantum computers will need to be produced using existing manufacturing techniques from the chip industry. Working on this basis, scientists at Delft University of Technology are currently studying two types of qubits: one type makes use of tiny superconducting rings, and the other makes use of 'quantum dots'.
Now for the first time a 'controlled-NOT' calculation with two qubits has been realised with the superconducting rings. This is important because it allows any given quantum calculation to be realised.
The result was achieved by the PhD student Jelle Plantenberg in the team led by Kees Harmans and Hans Mooij. The research took place within the FOM (Dutch Foundation for Fundamental Research on Matter) concentration group for Solid State Quantum Information Processing.
Quantum computers hold the possibility of solving what computer science calls "NP-complete" problems, the problems that are impossible or nearly impossible to calculate on a classical computer. Picking out a single pattern from a collection of patterns, such as your mother from a photo of people, is easy for you, but beyond the reach of your PC.
Despite many common concepts with classical computer science, quantum computing is still widely considered as a special discipline within the broad field of theoretical physics. One reason for the slow adoption of QC by the computer science community is the confusing variety of formalisms (Dirac notation, matrices, gates, operators, etc.), none of which has any similarity with classical programming languages, as well as the rather ``physical'' terminology in most of the available literature.
QCL (Quantum Computation Language) tries to fill this gap: QCL is a high level, architecture independent programming language for quantum computers, with a syntax derived from classical procedural languages like C or Pascal. This allows for the complete implementation and simulation of quantum algorithms (including classical components) in one consistent formalism.
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