Best possible test which differentiates qubits

[Dragonfall]

What is the best possible test for differentiating qubits? Assuming we have only ONE copy of each. What if a few (but still small number of) copies were allowed?

 

[f95toli]

The Divinchenzo Criteria?
Or do you mean something more specific, like T1 and T2?

 

[Dragonfall]

Something specific, like the swap-test.

http://en.wikipedia.org/wiki/Quantu..._the_same_for_every_recipient_.28Swap_Test.29

I worded the question wrong. I meant the best KNOWN test.

 

[Dragonfall]

What is this T1 and T2?