Much like the early days of semiconductors or classical computers, multiple teams are working on a variety of different approaches to implement quantum computing and it is still too early to tell which one will win out.
The different approaches can be classified in terms of both physical implementation approaches as well as architectural. It is interesting to note that some of the key principles used in quantum computing, like superposition and entanglement, can be valid for a wide variety of mediums such as photons, electrons, circulating current, etc.
For the physical implementation, the leading contenders are:
For architectural major architectural approaches include:
In addition, implementations can differ on whether they require error correction or can achieve satisfactory results without using error correction.