Interferometric gravitational wave detectors are poised to launch a new era of gravitational wave astronomy and unprecedented tests of general relativity. These detectors also provide opportunities for studying quantum phenomena on unprecedented scales. The sensitivity of a new generation interferometric gravitational wave detectors, currently being constructed, is expected to be almost entirely limited by quantum mechanics. I will explore the quantum limit and describe experimental progress toward circumventing it. These experiments will lay the foundations for higher sensitivity in gravitational wave detectors, and also provide unexpected opportunities to study quantum behavior of human scale objects.