Beyond linear coupling in microwave optomechanics

Abstract

We explore the nonlinear dynamics of a cavity optomechanical system. Our realization consisting of a drumhead nanoelectromechanical resonator (NEMS) coupled to a microwave cavity allows for a nearly ideal platform to study the nonlinearities arising purely due to radiation-pressure physics. Experiments are performed under a strong microwave Stokes pumping which triggers mechanical self-sustained oscillations. We analyze the results in the framework of an extended nonlinear optomechanical theory and demonstrate that quadratic and cubic coupling terms in the opto-mechanical Hamiltonian have to be considered. Quantitative agreement with the measurements is obtained considering only genuine geometrical nonlinearities: no thermo-optical instabilities are observed, in contrast with laser-driven systems. Based on these results, we describe a method to quantify nonlinear properties of microwave optomechanical devices. Such a technique, now available in the quantum electromechanics toolbox, but completely generic, is mandatory for the development of schemes where higher-order coupling terms are proposed as a resource, like quantum nondemolition measurements or in the search for new fundamental quantum signatures, like quantum gravity. We also find that the motion imprints a wide comb of extremely narrow peaks in the microwave output field, which could also be exploited in specific microwave-based measurements, potentially limited only by the quantum noise of the optical and the mechanical fields for a ground-state-cooled NEMS device.

A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

“…Measurements are performed at the lowest possible powers (n cav ∝ P in ~300-600 drive photons confined in the cavity) in order to limit the impact of damping/amplifying. However, driving the system up to the blue-detuned instability (when the damping vanishes), we can show that the mechanical mode exhibits self-sustained motion in the nanometre range 32 , which means that these devices are potentially very well adapted for exploring CSL physics. Furthermore, no physical heating of the device can be detected in this range of injected powers, down to 500 μK, which is remarkable.…”

Resonant nonlinear response of a nanomechanical system with broken symmetry

“…The red curve in this figure, on the other hand, shows the response for this voltage calculated using the above value of γ (V) eff . Equation (1) does not fit the data, indicating that the Duffing model no longer applies for V d = 40 mV.…”

“…The RWA is often applied also to a vibrational system with additional cubic nonlinearity β. In this approximation the response to the resonant field is mapped onto that of the Duffing model (1) with the renormalized nonlinearity parameter γ eff replacing the bare Duffing parameter γ [14]…”

“…Refs. [1][2][3][4][5][6] for recent examples. An important advantageous feature of such systems is a small decay rate, with the ratio Q of the vibration eigenfrequency ω 0 to the decay rate 2Γ reaching 5 × 10 10 [6] for localized acoustic modes and 8×10 8 for flexural modes [7].…”

Unconditional measurement-based quantum computation with optomechanical continuous variables

“…These requirements may be realized in current and near-future experiments. In fact, there are many platforms that can be used to implement our scheme, including membrane-in-the-middle configurations [80,86,88,89,95,[134][135][136], ultracold atoms inside a cavity [85], photonic crystals [93,94,98,101], circuit QED [96], electromechanical systems [74,[81][82][83]103,104], microdisks [87,[90][91][92], and optically levitated particles [97,99,105,[137][138][139]. In particular, very large quadratic couplings are within reach of current experiments [87,94,98,140,141].…”