Summary
Qubits, or quantum bits, are the fundamental units of quantum computers and they can be built from a variety of technologies, e.g., neutral atoms, ions, superconducting circuits, photons. Irrespective of the technology used to build them, they are fragile and can retain their coherence (to preserve the stored information) only for a limited time, which typically ranges from microseconds to seconds. Besides, when the qubits are manipulated through external forces to perform useful computation, the application of these forces can also be faulty, leading to many errors in the computational proces
