NEMO

Nanowire electro-mechanical-optical systems

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 Obiettivo del progetto (Objective)

'The aim of this project is the realization of a new class of electrical devices, in which mechanical deformation of a nano-object are used to tune its electronic transport properties. This is done through the use of radiation-pressure actuated optical forces on suspended one-dimensional electronic systems, such as semiconductor nanowires. While research in opto-mechanical systems and electro-mechanical systems is advancing at a rapid pace, the joining of the two fields is still lacking and opto-electro-mechanical devices are scarcely investigated. In these devices spatial deformations control the electronic properties of nano-object; suspended nanowires, for example, can oscillate (guitar string modes) modifying their distance with a back-gate electrode, linking mechanical deformation to an effective gating field which, in properly designed system, can control the flow of single electrons (Coulomb blockade). This proposal considers the realization of on-chip systems in which this dynamic is controlled by the use of optical forces, to obtain a precise and reliable tool to address the nanometric displacement of the object. Exploiting the capability of nanowires to sustain fiber-like optical modes, a coupling of photonic modes between an optical waveguide/microcavity is envisioned. Apart from its interest as a mini-invasive waveguide detector, this will open the route to the investigation of mechanical modes of nanowires coupled with optical waveguides/cavities or in LC resonant circuits, with the achievement of controlling the vibrational state of the object by shining light into the optical system. The final goal is the realization of optically controlled electro-mechanical transistors, both field-effect and single electrons, which could represent an absolutely new kind of device for sensing and a new exciting platform for fundamental physics invetigations.'

Introduzione (Teaser)

An EU-funded project paved the way to developing opto- electro-mechanical systems that could represent a new platform for studying quantum hybrid systems.

Descrizione progetto (Article)

While research into optomechanical and electromechanical systems is progressing by leaps and bounds, joint initiatives in these fields are still scarce. By coupling microwave resonant circuits and optical cavities to the same mechanical resonator, new kind of device functionalities can be envisaged.

The EU-funded project 'Nanowire electro-mechanical-optical systems' (NEMO) addressed the development of such devices. In these cases, the mechanical deformation of a nano-object is used to tune its electromagnetic and transport properties. This can be achieved through radiation pressure on suspended 1D structures such as semiconductor nanowires (NWs). Their versatile optical, electrical and mechanical properties can be controlled, offering the opportunity to add or improve functionalities of nanomechanical devices.

NEMO preliminary tested two cases regarding the modulation of NW electrical properties through the use of gradient gating fields. These included NWs subjected to strong asymmetric or fast oscillating fields and NW heterostructures coupled to far-field antennas. The main results included spin control in NW quantum dots and terahertz radiation detection with hetero-structured NW-based field-effect transistors.

Scientists then explored devices in which optical and electrical cavities are coupled through a common mechanical resonator. This included investigating standard optomechanical systems that can be capacitively coupled to electrical circuits.

Work focused on devising a silicon optomechanical photonic crystal with both large optomechanical and electromechanical couplings The main feature was the realization of nanometric capacitor gaps, resulting in a strong electrical control of the optical properties of the system.

Project activities subsequently led to the production of mechanical silicon nitride NW coupled to superconducting LC resonators. In this platform, which is compatible with optical device fabrication, many remarkable effects have been shown: in particular, coherent phonon emission, field-enhanced strong coupling, cooling close to the ground state were observed for a low-frequency mechanical mode.

Realising a device in which a silicon nitride NW is coupled to a resonant microwave circuit paves the way to the realisation of a full opto-electro-mechanical system. The striking feature would be to operate these hybrid opto-electro-mechanical systems in the quantum state, in which single electronic, photonic and phononic excitations can be controlled.

NEMO findings represent a milestone on the path to quantum networks based on hybrid devices. Coupling the optomechanical and electromechanical platforms will allow harnessing the advantages of both systems leading, for example, to quantum repeaters for long-distance qubits telecommunication.