Ultra-coherent Nanomechanical Oscillators
Abstract
Mechanical oscillators are ubiquitous in modern information technology, and are used for timekeeping, in MEMS accelerometers and in radio frequency filters in cell-phones. Nevertheless, quantum control of engineered mechanical oscillators remained an outstanding challenge of condensed matter physics and quantum optics. In this proposal, EPFL will engineer improved mechanical oscillators that enable new capabilities for sensing and fundamental research. The quality factor of a mechanical oscillator is defined as the ratio of the energy stored in the oscillator divided by the energy it loses per cycle. It is an important figure of merit for many applications – in particular, it determines the force sensitivity of the oscillator as well as the amount of time the oscillator can store quantum information. Therefore, large improvements to the quality factors of these oscillators can catalyze devices for sensing of force, mass, acceleration, electrical or magnetic fields with exceptional sensitivity. On the fundamental side, improved oscillators can provide impetus to a wide range of applications that already make use of mechanical systems for storing, interconversion or processing of signals and information, for example to build quantum networks and computers. EPFL proposes a program that explores a new way of increasing quality factors of mechanical oscillators, both to realize an untapped potential for extreme mechanical quality factors, and to investigate applications that harness it. A three-pronged approach is envisioned, combining insights from material science, phononic bandgap engineering, and elastic strain engineering. The guiding principle behind this approach is “dissipation dilution,” a mechanism whereby straining a mechanical structure effectively increases its stiffness without altering its internal loss. Dissipation dilution enhances the quality factor of a solid state structure’s vibrational modes, regardless of the intrinsic loss of the substrate material. Currently, the best mechanical oscillators use amorphous materials (Si3N4), which have high intrinsic loss. EPFL will develop new fabrication methods that allow the use of crystalline materials to fabricate nanobeams with much lower intrinsic loss. The nanobeams will have extreme aspect ratios: 20 nanometers thick and up to 10 millimeters long. We will apply recently developed micropatterning techniques to the oscillators that allow increased stress and reduced loss at the clamping points of the nanobeams, which would otherwise be a limiting factor. Following successful development of these ultracoherent nanomechanical oscillators, we will explore applications of the devices; for example sensing and quantum optomechanics.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 05, 2018
- Source ID
- HR00111810003
Entities
People
- Tobias Kippenberg
Organizations
- Defense Advanced Research Projects Agency
- Swiss Federal Institute of Technology in Lausanne