Andrew White from the quantum technology laboratory at the University of Queensland, Australia, maintains an excellent web page listing conferences related to quantum technology around the world. You can find his most recent listing for 2018 conferences here.
In addition to the conferences shown on the list mentioned above, the 2018 Adiabatic Quantum Computing Conference will be held on June 25-28, 2018 at the NASA Ames Research Center in Mountain View, California.
Also, the 3rd International Conference on Quantum Optics and Quantum Communications will be held on September 10-11, 2018 in London, UK. Click here for details.