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, here are some additional conferences:
Rigetti Computing hosted a Quantum Computing Hackathon on April 6-7, 2018 at their headquarters in Berkeley, California. Participants developed quantum programming projects that run on either Rigetti’s simulator or their real 19 qubit chip and had their projects judged with a winner announced at the end. The event has now passed, but you can view a summary of the Hackathon winners and their projects on the Rigetti blog page here.
The 2018 Adiabatic Quantum Computing Conference will be held on June 25-28, 2018 at the NASA Ames Research Center in Mountain View, California. Details can be found at: https://ti.arc.nasa.gov/events/aqc-18/.
CEA-Leti will host the 2nd Grenoble Quantum Engineering Day in Grenoble, France on July 6, 2018. Details will be available on their web site at http://www.leti-innovation-days.com/Pages/Workshops/2nd-Quantum-Workshop.aspx.
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.