Mutually unbiased bases for quantum states defined over p-adic numbers
  We describe sets of mutually unbiased bases (MUBs) for quantum states defined over the p-adic numbers Q_p, i.e. the states that can be described as elements of the (rigged) Hilbert space L2(Q_p). We find that for every prime p>2 there are at least p+1 MUBs, which is in contrast with the situation for quantum states defined over the real line R for which only 3 MUBs are known.   We comment on the possible reason for the difference regarding MUBs between these two infinite dimensional Hilbert spaces. 
Wim van Dam and Alexander Russell
quant-ph