I defend an unorthodox interpretation of quantum states of many particles of the same type, according to which individuation of the components of a composite system of identical particles is done not with the help of unphysical labels (indices) but physically meaningful projections operators. This unorthodox conception requires a modification of the standard notion of entanglement, in order to exclude states whose non-factorizability comes entirely from the (anti-)symmetrization of a product state. I will report several facts regarding the connections of the new concept of entanglement with the issue of discernibility. I will also discuss recent experiments involving measurement-induced entanglement, and I will point out that they do not threaten the cogency of the new concept of entanglement applied to identical particles. I will argue that the non-local correlations observed in these experiments are explainable not by the entanglement of the initial state but by the creation of a new, genuinely entangled state by means of a pre-measurement selection.
Philosophy of Physics Seminar Convenor for TT22: Simon Saunders | Philosophy of Physics Group Website