bmnmasdas

4 ms·

1. 1.▲
   by bmnmasdas 12y ago

   The density matrix is as real as the wave function when it comes to describing the corresponding subsystem. In the situation I was sketching, there is no measurement, no collapse, and the "measurement problem" does not play a role
2. 2.▲
   by bmnmasdas 12y ago

   I'm not the OP, but here is an example: The statement "It's not possible to measure the position and momentum of a particle simultaneously." can be interpreted as that it is not possible to acquire any joint information
3. 3.▲
   by bmnmasdas 12y ago

   > (And if you're referring to a direct tensor product of two single particle states, I'm still considering that an entangled state since it can unitarily evolve out of that configuration into one that can't be written as a
4. 4.▲
   by bmnmasdas 12y ago

   The point is that entanglement always refers to an a priori choice of subsystems (say, Alice and Bob). This is the part that makes the phenomenon non-trivial. If there are other systems around (say, Eve the environment) then the joint state
5. 5.▲
   by bmnmasdas 12y ago

   I guess I was being generous when interpreting your statement that "all components of a quantum system are always entangled". For pure states, such a statement is trivially true in the sense any kind of interaction in the Hamilton
6. 6.▲
   by bmnmasdas 12y ago

   I would argue that using the term "entanglement" to refer to the situation where "the entanglement of the system is much more apparent" or "tensor products are not a good approximation anymore" is completely re