Allow 128 bit indices #35
Description
Hi there,
great work! Could you by any chance allow the use of a custom index type? This makes a lot of sense e.g. for extremely shallow circuits, where the state vector is very sparse throughout but could e.g. be on 100 qubits; BigInt would be awesome, but if that's an issue then maybe at least Int128, as an option? And maybe even allow Int32, for relatively dense sparse matrices -- saves a lot of memory.