Join two un-related tables using JPA EntityManager

I need to join two JPA entities on a property when there is no FK/PK relation between the two. I am using Hibernate and can use HQL query like this

 select foo, bar from FooEntity as foo, BarEntity as bar
 where  foo.someothercol = 'foo' and foo.somecol = bar.somecol

However, I want to avoid dependency on Hibernate and use EntityManager instead. Please help.