Conda 4.6 added official support for Python in PowerShell. They also improved support in general for a variety of shells, so it's worth updating conda in any case.
Update to latest conda by from Command Prompt / Terminal:
conda update conda
setup the new shell support (PowerShell, Bash, Command Prompt, etc.) with
conda init --dry-run --verbose
if you're OK with the changes, make them happen for real by:
reopen shell(s) to see new conda environment.
You may get an error upon opening PowerShell like:
Documents\WindowsPowerShell\profile.ps1 cannot be loaded because running scripts is disabled on this system. For more information, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170
If it's OK for your computing environment, consider ExecutionPolicy like:
Set-ExecutionPolicy -ExecutionPolicy RemoteSigned