Silencing a quantum drum

HOT developed a small mechanical drum almost unaffected by thermal fluctuations but sensitive to quantum disturbance that can be mitigated by a technique similar to noise-cancelling earphones.

Our present-day precise measurement and signal processing applications are now operating at their physical limits. A FET-Proactive H2020 project called Hybrid Optomechanical Technology (HOT), will be developing quantum technologies that surpass this limit based on the idea of light interacting with moving objects. A small mechanical drum has to be installed for these technologies to work. HOT consortium partner from the University of Copenhagen found a way to design this drum that is ultra-precise as it follows the laws of quantum physics.


Mechanical drums must have a mechanical motion controlled at the level of quantum fluctuations – these are much smaller than the random movements observed by any objects at any temperature. In addition, any measurement of the motion at a quantum level will inevitably disturb it. The main challenge then is to create a tiny drum sensitive enough to discern the microscopic quantum motion and to remove any form of disturbance.


Researchers from the Niels Bohr Institute at the University of Copenhagen have recently demonstrated in a paper a solution to this challenge. They first designed and fabricated a small mechanical drum which can complete many oscillations unaffected by external influences, including thermal fluctuations. Secondly, they employed feedback techniques, similar to those employed in noise-cancelling earphones, in order to counteract the strong quantum-level motion disturbances induced by precise measurements.


Video demonstration on silencing the quantum drum – Credits: HOT


The synergy between engineering techniques and quantum physics will play a crucial role in upcoming technologies for quantum information processing as well as ultra-precise sensing. These technologies will find applications in medical imaging, and accurate navigation deep underground.


For more information:

Measurement-based quantum control of mechanical motion

M. Rossi, D. Mason, J. Chen, Y. Tsaturyan, A. Schliesser

Nature 563, 53 (2018)

DOI: 10.1038/s41586-018-0643-8