Quantum Computers

introduction

A quantum computer is one which exploits quantum-mechanical interactions in order to function; this behavior, found in nature, possesses incredible potential to manipulate data in ways unattainable by machines today. The harnessing and organization of this power, however, poses no small difficulty to those who quest after it.

Subsequently, the concept of quantum computing, birthed in the early 80's by physicist Richard Feynman, has existed largely in the realm of theory. Miraculous algorithms which potentially would take a billionth of the time required for classical computers to perform certain mathematical feats, and are implementable only on quantum computers, as such have not yet been realized. A two-bit quantum system, recently developed by a coalition of researchers, constitutes the sole concrete manifestation of the idea.

The intent of these pages is provide a rudimentary understanding of the roots and progress of quantum computing, in order that one may realize the presence and growing significance of this fusion of quantum theory and computation.

overview

The bit, most basic unit of information within a computer, is the building block for all data residing within. An alphanumeric character, for example, usually consumes 1 byte, or 8 bits, of memory. A 2-byte, unsigned integer would be allowed to range from 00000000 00000000 to 11111111 1111111 in binary, or 0-65535 in decimal notation (0-216).

The “bit” of a quantum computer, referred to as qubit (short for quantum bit), might be represented as an atom. Qubits, however, possess an intrinsic and most significant quality: they may simultaneously be assigned 0 or 1, the probability of each expressed as a numerical coefficient. This ability allows quantum computers to exist in multiple states at once, called superposition by those knowledgeable of such things. Subsequently, actions may be carried out in all states simultaneously, allowing parallel operations to be performed with one processing unit. A phenomenon dubbed “entanglement” joins qubits together in a quantum system.

Superpositioning opens the way for several fascinating and potentially problematic uses for quantum computers. Factoring numbers of several hundred digits, a tactic needed to crack some encryption schemes currently in use, would take billions of years on the fastest supercomputers. Theoretically, this might take a year on quantum computers.