BREAKTHROUGH IN QUANTUM COMPUTATION

摘要

Classical Computers, from the humble PC to the laptops, notebooks, iPads to the supercomputers employ digital logic, circuits which deal with two-state logic, BITS 0 and 1. They sped up computation enormously upto 1016 floating point operations per second (10 petaFLOPs) and the fastest is that of Tianhe-2 which boasts 33.86 petaFLOPs (which is about a million billion times the 56 floating point operations per second of IBM 1620 made in 1961). Quantum computer works on a sequence of QUBITS and follows the principle of quantum mechanics which dominates any physical phenomenon in a sub-atomic scale. Quantum computers attempt at speeding up computations using superposition of QUBITS which are linear combination of quantum basis states and exhibit quantum entanglement. A single QUBIT can represent a 1, a 0 or any quantum superposition of these states |1＞ and |0＞. In general a quantum computer with n QUBITS can be in arbitrary superposition of 2~n different states simultaneously whereas a classical computer can only be in one of these 2~n states at any one time. A quantum computer operates by manipulating those QUBITS with a fixed sequence of quantum logic gates determined by the quantum algorithm.