Quantum Register in Quantum Computing
A quantum register is composed of several qubits. The size of the register is determined by the number of qubits. For example, a quantum register of size 4 can store individual numbers from 0 to 15. At any particular time, the 4-qubits can be in any one of 16 possible configurations:
0000, 0001, 0010, … … … … … 1111
Thus, a 4-qubit register can be represented in a superposition of the above 16 states:
|Ψ>=c0 |0000> + c1 | 0001 > + c2 |0010>, … … … + c14 |1110> + c15 |1111>
Where the numbers c0, c1, c2, … …, c15 are complex coefficients such that
A unique advantage of the quantum system is that a linear increase in the number of qubits in a register leads to exponential growth in the state space of the register. The state of a quantum register with m qubits can be represented as 2m-dimensional vector in complex vector space. Since all the states of a quantum register can be in all of its states at the same time. This allows parallel processing capability to solve certain problems in a time that is may-fold faster than that is possible in classical computers.