Table I.

Key parameters and figures of merit of the E-mode in the best (a = 320 µm, h = 35 nm) sample at room temperature, where all measurements were performed, and extrapolated to liquid helium, and dilution refrigerator temperatures.

Temperature T	300	4.2	0.014	K
Frequency f	777			kHz
Effective mass meff	16			ng
Quality factor Q	214	535	2070	106
fQ-product f × Q	166	416	1610	THz
Decoherence rate γ/2π	33,000	175	0.15	Hz
Coherence time τ = 1/γ	0.005	0.91	1060	ms
Number of coh. osc. 2πfτ	23	4400	5.1M	1
Thermal force noise $\sqrt{S_{FF}}$	55	4.1	0.12	$\text{aN}/\sqrt{\text{Hz}}$