Question

When is an operator called a 'field operator'?

Answer 1

I am slightly confused of the conditions under which a general operator A^A^ is called a 'field operator'. It was originally my conception that the condition would be that A^A^either creates or destroys a particle at a given spatial location. But suggests in the general case this is not true. 

Answer 2

 I am slightly confused of the conditions under which a general operator is called a 'field operator'. It was originally my conception that the condition would be that either creates or destroys a particle at a given spatial location.