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Quantum Computers
As classical computers are reaching their limit of performance, quantum computers are
merely taking form. Richard Feynman presented the first ideas of quantum computing
20 years ago. Ideas that have been continuosly developed since then. Lots of thick
books on quantum information processing have been written. Even though noone has been
able to build a quantum computer and sinceneraly noone is even close.
So what is a quantum computer and how is it different from a normal computer?
Information in a normal computer is stored in bits, either 1 or 0. A register of
n-bits can then store one of 2$^n$ possible configurations. Information in a quantum computer is stored in qubits. The qubit is choosen to be a quantum system that
consists of two states. Usually denoted $\ket{0}$ and $\ket{1}$. A quantum system
can be in a superposition. Meaning that it can be in the $\ket{0}$ and the $\ket{1}$
state at the same time. A register of n-qubits can then store all 2$^n$ configurations
at the same time. This register can be used as one single input for a function. This
is called quantum parallellism. A normal computer would have to do 2$^{n}$ computations
or have 2$^{n}$ processors working in parallell.
Two qubits can also be in a so called entangled state. Meaning that whatever happen
to one qubit will affect the other. Even if they do not interact with each other at
the moment.
Superposition and entanglement are what make a quantum cmputer and a classical computer fundamentally different from each other. These almost magical properties of a quantum computer seem to offer an enormous gain. However if you measure the content of a register you will only get one answer. Since the quantum system is said to collapse.
But there is a few proposed algorithms that would amke use of the quantum parallellism.
I won't go through them. But I think the most interesting application will be its
ability to simulate other quantum systems, which is not feasible on a normal computer.
But just for you data nerd punks I'll explain two algorithms. The first is an algorithm
that Shor has presented. With that algorithm you would be able to crack RSA. Another
algorithm has been presented by Grover. With that algorithm you will be able to crack DSA.
As classical computers are reaching their limit of performance, quantum computers are
merely taking form. Richard Feynman presented the first ideas of quantum computing
20 years ago. Ideas that have been continuosly developed since then. Lots of thick
books on quantum information processing have been written. Even though noone has been
able to build a quantum computer and sinceneraly noone is even close.
So what is a quantum computer and how is it different from a normal computer?
Information in a normal computer is stored in bits, either 1 or 0. A register of
n-bits can then store one of 2$^n$ possible configurations. Information in a quantum computer is stored in qubits. The qubit is choosen to be a quantum system that
consists of two states. Usually denoted $\ket{0}$ and $\ket{1}$. A quantum system
can be in a superposition. Meaning that it can be in the $\ket{0}$ and the $\ket{1}$
state at the same time. A register of n-qubits can then store all 2$^n$ configurations
at the same time. This register can be used as one single input for a function. This
is called quantum parallellism. A normal computer would have to do 2$^{n}$ computations
or have 2$^{n}$ processors working in parallell.
Two qubits can also be in a so called entangled state. Meaning that whatever happen
to one qubit will affect the other. Even if they do not interact with each other at
the moment.
Superposition and entanglement are what make a quantum cmputer and a classical computer fundamentally different from each other. These almost magical properties of a quantum computer seem to offer an enormous gain. However if you measure the content of a register you will only get one answer. Since the quantum system is said to collapse.
But there is a few proposed algorithms that would amke use of the quantum parallellism.
I won't go through them. But I think the most interesting application will be its
ability to simulate other quantum systems, which is not feasible on a normal computer.
But just for you data nerd punks I'll explain two algorithms. The first is an algorithm
that Shor has presented. With that algorithm you would be able to crack RSA. Another
algorithm has been presented by Grover. With that algorithm you will be able to crack DSA.
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