what does it mean that a particle is a pure eigenstate?
could someone explain this to me simply ?
You'll have to give some context as to where you read that.
I have tried and tried to simply explain it failing every time.
Here is the answer.
States are positive operators of unit trace. States of the form |u><u| are called pure. States of the form ∑ pi |ui><ui| are called mixed. It can be shown all states are pure or mixed. If that is gibberish then sorry its the best I can do - explaining linear algebra in English is impossible.
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