Experimental perspectives on the interplay between quantum and gravity physics

There is a rich history of experimental effort that has been aimed at exploring the effects of gravitational fields on the elementary building blocks of matter: atoms, nuclei and subatomic particles, including the photon and neutrino. Much of this work was originally empirically motivated, with many of the investigations driven simply by curiosity over how the gravitational field might affect either various attributes of the quantized states of matter or the behavior of fundamental particles. More recently, searches for novel or anomalous aspects of gravity (torsion, screening effects, etc.) have employed "exotic" matter (eg., spin-polarized substances, superconductors, etc.) the properties of which can be understood only in terms of quantum mechanics. Substantial theoretical developments have often either preceded or accompanied that class of experiments. All of this reflects the desire of experimental physics to contribute insight into the problem of the inter-play between quantum and gravity physics. An overview of this broad class of experimental studies is presented here, with some emphasis on searches for (1) new gravitational effects on single particles and particle beams, (2) certain types of potential violation of the weak equivalence principle, and (3) gravitomagnetic anomalies.