Not sure what you think a quantum computer would have to do with a physical QD taggant ? If that taggant is registered in the blockhain it will be verified if not it will be deemed counterfeit.A quantum computer isnt doing anything to change that fact.It was mentioned the qdots when produced have a date stamp nevermind billions of posible combinations that could not be duplicated by a counterfeit.They would first have to have a reactor..then be able to date stamp and then create a duplicate signature of an original product code that was registered on the block chain.Quantum computers don't create physical qdots that's where the idea ends that they are a threat.Bitcoin different story all together.