9

If Alice and Bob have an entangled pair of qubits and Alice locally measures her qubit, it does not affect local state of the Bob's qubit in any way. Mathematically, if Alice measures but does not look at the measurement outcome, density matrix of the Bob's qubit does not change. The sole fact of Alice's measurement does not affect the Bob's qubit in any way....


7

It is certainly true that, within the mathematical description of qubits, operations on one qubit can require the whole description to be updated. This therefore affects the description of every qubit. Those who take a 'epistemic' view of this mathematical description might say that we are just updating our knowledge about the other qubits, and that it ...


5

What is non-classicality? I'm not sure if there's a universally accepted definition, but the way that I'd define it is: if all possible outcomes of experiments on a particular quantum system can be described by a probability distribution, then the system is classical. Otherwise, it is non-classical. In alternative terminology, for a classical system, people ...


3

I don't think I can answer this question precisely, but I would like to say some things. Since this question was asked, much has changed in the field. We have the following known sources that may interest any reader passing by (since probably by now the OP is an expert in the subject, I hope this answer can be useful): Two very broad reviews on the notion ...


3

Is this just bad phrasing (or a typo) on Wikipedia's side, or am I missing something? It does sound like bad phrasing. The idea here is that our set of observables is not necessarily mutually (pairwise) commuting. If you have three observables $A$, $B$ and $C$, and $[A,B]=0$ and $[B,C]=0$, then you're right that the measurement of $A$ will have no effect on ...


2

The commuting model only differs from the spatial (tensor-product) model when one considers infinite-dimensional Hilbert spaces, so one would have to start with considering circuits with an infinite number of degrees of freedom. That being said, such a model has been considered in this paper and is called the $C^*$-circuit model.


1

The Quantum Reality group at the Centre for Quantum Technologies (National University of Singapore) https://qreality.quantumlah.org/


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