What Does Quantum Computing Mean?
Quantum Computing is a theoretical computing technique based on quantum mechanical ideas such as superposition, entanglement etc. We all are familiarized with the fact that any computing device used in the present stores data in binary language. The two bits 0 and 1 represent the binary language. This is the basis of all arithmetic and logic operations in any electronic device.
In Quantum Computers, there is an additional state, a state which is a superposition of 0 and 1. When an operation is done on the bit (here qubits), it is actually done on the two values (0 and 1) simultaneously. Thus operations can be done on large number of values using comparatively smaller number of qubits (or memory) at a faster rate.
The superposition indicates that the bit is in two states at the same time. Each state has a probability described by a numerical coefficient. Thus for describing one bit, we require two coefficients. For two, three and four bit quantum computers, we require four, eight and sixteen numbers respectively. For an n-bit quantum computing system, 2^50 (1,12,58,99,90,68,42,624) values are needed. Therefore, the computer’s memory capacity is several times exponentially larger than the actual number of qubits present, which implies that it exhibits a very smaller physical size.
Qubits may be represented by any suitable object with its size in the quantum mechanical scale including atoms and photons. Depending on the object used for representation, other elements used in the processing unit are chosen. For instance, if photon is used, then mirrors and beam splitters are likely to be employed in the processing unit.
One of the greatest challenges involved in the research of quantum computing to keep the computer isolated from the environment. It is due to the following property of quantum mechanics.
“Any attempt to observe or measure a quantum system will disturb it."