All hypothetical superdense carbon allotropes have dissimilar band gaps compared to the others. Among the best-known applications of entanglement are superdense coding and quantum teleportation. In contrast to superdense allotropes, T-carbon would have very low density and hardness. However, a qubit can hold more information, e.g. up to two bits using superdense coding. The composition of the superdense matter in the core remains uncertain. Superdense coding is a form of secure quantum communication. Superdense coding is the underlying principle of secure quantum secret coding.