Surface dissipation in nanoelectromechanical systems: Unified description with the standard tunneling model and effects of metallic electrodes

Seoanez, Cesar; Guinea, F.; Neto, A. H. Castro

doi:10.1103/physrevb.77.125107

Cited by 83 publications

(96 citation statements)

References 59 publications

(111 reference statements)

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“…We have attempted to explain the low-temperature increase in Q based on the standard tunnelling model 32,34 . For this purpose, we have fit the millikelvin data to a power law as…”

Section: Resultsmentioning

confidence: 99%

Single-crystal diamond nanomechanical resonators with quality factors exceeding one million

et al. 2014

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Diamond has gained a reputation as a uniquely versatile material, yet one that is intricate to grow and process. Resonating nanostructures made of single-crystal diamond are expected to possess excellent mechanical properties, including high-quality factors and low dissipation. Here we demonstrate batch fabrication and mechanical measurements of single-crystal diamond cantilevers with thickness down to 85 nm, thickness uniformity better than 20 nm and lateral dimensions up to 240 mm. Quality factors exceeding one million are found at room temperature, surpassing those of state-of-the-art single-crystal silicon cantilevers of similar dimensions by roughly an order of magnitude. The corresponding thermal force noise for the best cantilevers is B5 Á 10 À 19 N Hz À 1/2 at millikelvin temperatures. Single-crystal diamond could thus directly improve existing force and mass sensors by a simple substitution of resonator material. Presented methods are easily adapted for fabrication of nanoelectromechanical systems, optomechanical resonators or nanophotonic devices that may lead to new applications in classical and quantum science.

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“…We have attempted to explain the low-temperature increase in Q based on the standard tunnelling model 32,34 . For this purpose, we have fit the millikelvin data to a power law as…”

Section: Resultsmentioning

confidence: 99%

Single-crystal diamond nanomechanical resonators with quality factors exceeding one million

et al. 2014

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“…In the same context, the influence of strain on TLSs has been probed recently [29]. However, in the OM setting, TLS ensembles have mainly been studied as a source of decoherence [30][31][32]. In this letter, we demonstrate theoretically that the coupling of an individual TLS to a localized phonon mode of an OM system can be large enough to exceed the mechanical and TLS dissipation rates, and hence it provides a route to cavity QED-like experiments with single phonons.…”

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confidence: 99%

Nonlinear Quantum Optomechanics via Individual Intrinsic Two-Level Defects

et al. 2013

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We propose to use the intrinsic two-level system (TLS) defect states found naturally in integrated optomechanical devices for exploring cavity QED-like phenomena with localized phonons. The Jaynes-Cummings-type interaction between TLS and mechanics can reach the strong coupling regime for existing nano-optomechanical systems, observable via clear signatures in the optomechanical output spectrum. These signatures persist even at finite temperature, and we derive an explicit expression for the temperature at which they vanish. Further, the ability to drive the defect with a microwave field allows for realization of phonon blockade, and the available controls are sufficient to deterministically prepare non-classical states of the mechanical resonator.Introduction.-Cavity optomechanics [1-3] has enabled the preparation of mechanical resonators in states of low phonon occupation via optomechanical (OM) sideband cooling [4][5][6][7][8][9], and to observe their quantum coherent interaction with light [9]. Further, OM systems have enabled displacement detection at or even below the standard quantum limit [10][11][12], thereby complementing other mechanics-based sensing applications [13,14]. They have also been proposed for creating macroscopic quantum superpositions [15] as well as for applications in quantum information [16,17]. However, in experiments carried out so far, the interaction between mechanical oscillator and cavity field is effectively linear, while one of the major challenges in the field is to realize non-linearities at the single phonon level. For example, the intrinsic OM radiation pressure non-linearity is predicted to enable the generation of non-classical states of light and mechanics [18,19], provided that the singlephoton coupling rate exceeds the mechanical frequency and the cavity decay rate. In multi-mode OM systems, the same non-linearity can be exploited more easily and it has been proposed to use it for enhanced readout [20] and quantum information processing [21].Here we propose an alternative route to render the dynamics of the mechanical oscillator nonlinear at the single quantum level: using its natural coupling to intrinsic structural two-level system (TLS) defects and thereby alleviating the need to functionalize the system [see Fig. 1(a)]. Ensembles of TLS defects were first studied in the context of the anomalous and universal low temperature properties of glasses [22][23][24][25][26], where they arise from frustration. In experiments involving Josephson junctions, individual TLSs with transition energies distributed well into the GHz regime were observed and studied for their role in decoherence [27]. Nevertheless, their comparatively long coherence times, and their ability to strongly couple to Josephson junctions via the electric dipole moment have enabled a TLS quantum memory [28]. In the same context, the influence of strain on TLSs has been probed recently [29]. However, in the OM setting, TLS ensembles have mainly been studied

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“…In this limit, the dominant modes are no longer 3D phonon modes [32] and can contribute a linear temperature dependence [25,30]. This mechanism thus could dominate relaxational damping in our high-frequency resonators.…”

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confidence: 99%

Strong Gate Coupling of High-Q Nanomechanical Resonators

et al. 2010

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The detection of mechanical vibrations near the quantum limit is a formidable challenge since the displacement becomes vanishingly small when the number of phonon quanta tends towards zero. An interesting setup for on-chip nanomechanical resonators is that of coupling them to electrical microwave cavities for detection and manipulation. Here we show how to achieve a large cavity coupling energy of up to (2π) 1 MHz/nm for metallic beam resonators at tens of MHz. We used focused ion beam (FIB) cutting to produce uniform slits down to 10 nm, separating patterned resonators from their gate electrodes, in suspended aluminum films. We measured the thermomechanical vibrations down to a temperature of 25 mK, and we obtained a low number of about twenty phonons at the equilibrium bath temperature. The mechanical properties of Al were excellent after FIB cutting and we recorded a quality factor of Q ∼ 3 × 10 5 for a 67 MHz resonator at a temperature of 25 mK. Between 0.2K and 2K we find that the dissipation is linearly proportional to the temperature. Keywords nanomechanics, NEMS, quantum limit, detection, dissipationThe measurement of small-amplitude vibrations in mechanical systems is becoming an increasingly interesting problem [1,2]. From the point of view of basic science, the study of mechanical systems close to the quantum limit has attracted a lot of interest recently [3,4]. The endeavor towards the ground state of the harmonic phonon oscillations has been going on in various physical systems such as in optomechanics [5][6][7], or in electrically coupled beam resonators which have been measured using single-electron transistors [4,8], or lately, with on-chip microwave cavities [9][10][11][12].The quantum challenge is posed by several issues, including the relatively low frequency (f 0 ∼ 10 MHz), of the lowest modes in suspended beams. The quantum limit implies stringent requirements on temperature, since hf 0 needs to be small in comparison to k B T . On the other hand, at higher frequencies, the coupling to measuring systems diminishes rapidly. Third, the zero-point vibration amplitudes x ZP = /2mω 0 , where m is the effective mass and ω 0 = 2πf 0 is the angular frequency, are vanishingly small even at the atomic scale. Very recently, O'Connell et al.[13] demonstrated a piezoelectric mechanical mode at the quantum ground state by using a coupling to a superconducting qubit. However, bringing a purely mechanical mode to the quantum limit remains an ongoing quest, with the goal becoming a reality probably in the near future.Micromechanical resonators are also used in applications as detectors. The best devices take advantage of the trend to smaller size and higher frequencies, and will soon approach sensing at the atomic mass unit level [14,15]. They could also be operated as sensors of position, force, or high-frequency electromagnetic fields.For conductive resonators, capacitive coupling to an electrical measuring apparatus is useful for readout. In contrast to magnetomotive or optical detection, one can obtain v...

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Surface dissipation in nanoelectromechanical systems: Unified description with the standard tunneling model and effects of metallic electrodes

Cited by 83 publications

References 59 publications

Single-crystal diamond nanomechanical resonators with quality factors exceeding one million

Single-crystal diamond nanomechanical resonators with quality factors exceeding one million

Nonlinear Quantum Optomechanics via Individual Intrinsic Two-Level Defects

Strong Gate Coupling of High-Q Nanomechanical Resonators

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