Nonlinear damping and dephasing in nanomechanical systems

Atalaya, Juan; Kenny, Thomas W.; Roukes, M. L.; Dykman, M. I.

doi:10.1103/physrevb.94.195440

Cited by 35 publications

(37 citation statements)

References 63 publications

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“…As such, the understanding of the sources of frequency fluctuations in nano-mechanical devices becomes an essential technical topic [1,[19][20][21][22][23]. But in the first place, it is also a fundamental research goal: the measured frequency noise in actual devices is much larger than all expectations [22,[24][25][26], demonstrating even non-linear features for carbon-based systems [27,28]. Thus, attempts have been made to model noise sources [29,30], or to create model experiments experimentally demonstrating the underlying mechanisms [19,31,33,34].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear frequency transduction of nanomechanical Brownian motion

et al. 2017

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We report on experiments addressing the non-linear interaction between a nano-mechanical mode and position fluctuations. The Duffing non-linearity transduces the Brownian motion of the mode, and of other non-linearly coupled ones, into frequency noise. This mechanism, ubiquitous to all weaklynonlinear resonators thermalized to a bath, results in a phase diffusion process altering the motion: two limit behaviors appear, analogous to motional narrowing and inhomogeneous broadening in NMR. Their crossover is found to depend non-trivially on the ratio of the frequency noise correlation time to its magnitude. Our measurements obtained over an unprecedented range covering the two limits match the theory of Y. Zhang and M. I. Dykman, Phys. Rev. B 92, 165419 (2015), with no free parameters. We finally discuss the fundamental bound on frequency resolution set by this mechanism, which is not marginal for bottom-up nanostructures.arXiv:1704.06119v2 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Nonlinear frequency transduction of nanomechanical Brownian motion

et al. 2017

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“…The nonlinear dephasing/damping has been proposed to originate in nonlinear phononic interactions between the low frequency mechanical modes and thermal phonons. 18 Finally, a common speculation reported in the literature is that frequency noise is related to defects, 6,11,19 which can be either extrinsic or constitutive of the material (like in a glass). The presence of these so-called Two-Level Systems (TLS) is also proposed to explain damping mechanisms in NEMS, 21,22 and have been shown recently to lead to peculiar features (especially in the noise) for mesoscopic systems such as quantum bits and NEMS.…”

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confidence: 99%

Measuring Frequency Fluctuations in Nonlinear Nanomechanical Resonators

et al. 2018

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Advances in nanomechanics within recent years have demonstrated an always expanding range of devices, from top-down structures to appealing bottom-up MoS and graphene membranes, used for both sensing and component-oriented applications. One of the main concerns in all of these devices is frequency noise, which ultimately limits their applicability. This issue has attracted a lot of attention recently, and the origin of this noise remains elusive to date. In this article we present a very simple technique to measure frequency noise in nonlinear mechanical devices, based on the presence of bistability. It is illustrated on silicon-nitride high-stress doubly clamped beams, in a cryogenic environment. We report on the same T/ f dependence of the frequency noise power spectra as reported in the literature. But we also find unexpected damping fluctuations, amplified in the vicinity of the bifurcation points; this effect is clearly distinct from already reported nonlinear dephasing and poses a fundamental limit on the measurement of bifurcation frequencies. The technique is further applied to the measurement of frequency noise as a function of mode number, within the same device. The relative frequency noise for the fundamental flexure δ f/ f lies in the range 0.5-0.01 ppm (consistent with the literature for cryogenic MHz devices) and decreases with mode number in the range studied. The technique can be applied to any type of nanomechanical structure, enabling progress toward the understanding of intrinsic sources of noise in these devices.

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“…In contrast, positive nonlinear friction originates from the decay that involves two vibrational quanta of the mode [14]. For nonlinear friction of nanomechanical modes and cavity modes, the excitations of the reservoir can be, respectively, phonons [15,16] or propagating photons [11], see Fig. 1a.…”

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Strong negative nonlinear friction from induced two-phonon processes in vibrational systems

Dong¹,

Dykman²,

Chan³

2018

Nat Commun

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Self-sustained vibrations in systems ranging from lasers to clocks to biological systems are often associated with the coefficient of linear friction, which relates the friction force to the velocity, becoming negative. The runaway of the vibration amplitude is prevented by positive nonlinear friction that increases rapidly with the amplitude. Here we use a modulated electromechanical resonator to show that nonlinear friction can be made negative and sufficiently strong to overcome positive linear friction at large vibration amplitudes. The experiment involves applying a drive that simultaneously excites two phonons of the studied mode and a phonon of a faster decaying high-frequency mode. We study generic features of the oscillator dynamics with negative nonlinear friction. Remarkably, self-sustained vibrations of the oscillator require activation in this case. When, in addition, a resonant force is applied, a branch of large-amplitude forced vibrations can emerge, isolated from the branch of the ordinary small-amplitude response.

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Nonlinear damping and dephasing in nanomechanical systems

Cited by 35 publications

References 63 publications

Nonlinear frequency transduction of nanomechanical Brownian motion

Nonlinear frequency transduction of nanomechanical Brownian motion

Measuring Frequency Fluctuations in Nonlinear Nanomechanical Resonators

Strong negative nonlinear friction from induced two-phonon processes in vibrational systems

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