# Are superdense coding and teleportation just a prototype or the 'only' type?

I am interested to know if models in quantum mechanics and techniques like superdense coding teleportation are just single cases where they were found to work. Or rather just a prototype of many other examples of similar things.

What I mean is, the Deutsch oracle is just a single algorithm that was found or they found many examples similar to this and it is just a prototype?

Superdense works only if you follow the exact protocol of applying $$\Bbb I$$, $$X$$, $$Z$$, $$ZX$$? Only two qubits? Or rather it's just an example of many other known things? It seems unreasonable that this is a single example. Aren't there other 3, 4 qubits with same techniques performed by applying other matrices?

Same for teleportation.

As for superdense coding, you can design different schemes for $$n, m$$ qubits, but they are not giving any advantage over a simple scheme $$1 \text{qubit} + 1 \text{ebit} \rightarrow 2 \text{cbits}$$. In general, if Alice has access to $$n$$ qubits and Bob has access to $$m$$ qubits and all $$n+m$$ qubits are entangled, then Alice can't transmit more than $$n+\text{min}(n,m)$$ classical bits by sending her qubits to Bob.