Quantum Superpositions of Mechanical Oscillators

More than a 100 years after the discovery of Quantum Mechanics, the emergence of classical behaviour in a world that is believed to be described by Quantum Theory is still not well understood. There is therefore still a debate on whether Quantum Theory should also be valid on the macroscopic length and mass scales of our everyday life or whether it is expected to break down for objects above a certain size or weight. To resolve this question, researcher aim for conducting experiments that show (or do not show) quantum behaviour for ever large and heavier objects. Recently, mechanical oscillators such as vibrating cantilevers or thin beams have been successfully cooled to their ground states, where all thermal noise has been removed to the largest possible degree. These devices are thus very promising candidates for exploring quantum behaviour at mesoscopic or even macroscopic scales. Yet for purely harmonic oscillators, such ground states do not show any non-classical features. In this project we plan to develop an approach for bringing a thin beam that is clamped at both ends into a quantum state formed by a superposition of the beam being deflected in one direction and being deflected in the opposite direction. This can for example be achieved by pressing the beam on both ends along its axes. From a critical pressure on, the beam will buckle in one or the other direction. To ensure that not one or the other deflection is realised but their quantum superposition, the motion of the beam needs to be cooled. To this end we want to explore a combination of means to make the beam buckle and cooling techniques for such beams. Experimentally feasible ways to do this, could be a combination of applied electrostatic fields (rather than mechanical pressure) for the buckling and optical light fields for the cooling. 

Please send inquiry emails to Dr. Michael Hartmann at M.Hartmann@hw.ac.uk