Is There an Operator for the Existence of an Object in Quantum Mechanics?

[rar0308]

Before a measurement we don't have any information about a object. So we don't know about a existence of the object. But we are trying to measure something of the object. Is there operator of existence of a object? All operators commute with this?

 

[Niles]

Before a measurement we don't have any information about a object. So we don't know about a existence of the object. But we are trying to measure something of the object. Is there operator of existence of a object? All operators commute with this?

I wouldn't say I agree with the bolded part. For example in some quantum optics experiments, we get a signal when the thing we want to perform measurements on (photons) is detected, I am talking about http://arxiv.org/ftp/quant-ph/papers/0611/0611112.pdf" . Actually I can't think of an example where we don't know about the existence of the object we want to measure on. Maybe someone more experienced can contribute here.