Gigantic Quantum Superpositions for Dark Matter Searches and Gravitational Wave Detection

In everyday life, we are intuitively accustomed to thinking of massive objects as existing in a definite position in space. However, quantum mechanics remarkably predicts that massive particles such as atoms can exist in a quantum superposition of two places at the same time. Atom interferometers make use of this counterintuitive phenomenon to make very precise measurements of small forces. Here, I propose to dramatically enhance the sensitivity of these measurements by developing a new type of atom interferometer in which levitated atoms are separated over tens of meters for tens of seconds. These gigantic quantum superpositions, orders of magnitude larger the state-of-the-art, will enable new approaches to search for the mysterious dark matter that makes up most of the mass of our universe and will pave the way for gravitational wave detection in a part of the spectrum that is not addressed by the LIGO detector or the LISA satellite detector.