Engineering dissipation dilution of strained nanomechanical resonators*

Dissipation dilution by tensile strain enables micro- and nano- mechanical resonators that have quality factors (Q) exceeding those of bulk vibrations in the same material by orders of magnitude. For a long time, uniform beam- and membrane- shape resonators made of high-stress stoichiometric silicon nitride have been the system of choice to attain high Q and low effective mass—key parameters in force sensing and cavity optomechanics. Recently it was discovered that dissipation dilution (and hence Q) can be increased substantially in non-uniform resonators through techniques such as “soft clamping”, engineering local strain and “tapered clamping”. We show that soft clamping combined with strain engineering can be applied to nanobeams to produce record-high quality factors up to 800 million at room temperature and Q × frequency exceeding 10^15 Hz. The complementary tapered clamping approach results in enhanced Q for the fundamental flexural mode, unachievable with soft clamping. Time permitting, we will also present results on dissipation dilution engineering of membranes and cavity optomechanics with engineered resonators.