How can HR employees increase the amount of qualified and potentially excellent candidates to apply for a job while avoiding having to sift through those less-excellent applications?

The best possible person a human resource professional can hire is the best person who applies for the job.

If ability and intelligence are normally distributed, more people applying for a job increases the chances of an excellent person in the applicant pool.

How can HR employees increase the amount of qualified and potentially excellent candidates to apply for a job while avoiding having to sift through those less-excellent applications?