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Contact: Alina Hirschmann
ICFO-The Institute of Photonic Sciences

Ultra-sensitive force sensing with a levitating nanoparticle

ICFO scientists have optically levitated nanoparticles in high vacuum conditions and measured the highest Q-factor ever observed in nano- or micromechanical systems

IMAGE: This is a silica nanoparticle trapped by tightly focused laser beams.

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A recent study led by researchers of the Institute of Photonic Sciences (ICFO) achieved the highest force sensitivity ever observed with a nano-mechanical resonator. The scientific results of this study have been published in Nature Physics.

Nano- and micromechanical oscillators with high quality (Q) factors have gained much attention for their potential application in sensing, signal processing and transduction as well as in fundamental research aiming at observing quantum effects in increasingly larger systems. Despite recent advances in the design and fabrication of mechanical resonators, their Q-factor has so far been limited by coupling to the environment through physical contact to a support. To overcome this limitation, the present work proposes to use optically levitated objects in vacuum that do not suffer from clamping losses.

In this recent ICFO study, scientists have optically levitated nanoparticles in high vacuum conditions and measured the highest Q-factor ever observed in nano- or micromechanical systems. The combination of an ultra-high Q-factor together with the tiny mass of the nanoparticles leads to an unprecedented force sensitivity at room temperature. The system is so sensitive that the weak forces arising from collisions between the nanoparticle and the residual air molecules are enough to drive it into the nonlinear regime. For the first time, this study demonstrates that ultra-high Q-factor nano-resonators intrinsically behave nonlinearly. In addition, the researchers show that, when combined with feedback cooling, the levitating nanoparticle can be used as a force-sensor, sufficiently sensitive to detect ultra-weak interactions, such as non-Newtonian gravity-like forces and tiny forces arising from quantum vacuum fluctuations.

Gieseler remarks that "Thermal motion is commonly observed in nano-mechanical systems. However, observing nonlinear features of thermal motion is a true novelty and, thus, challenges our understanding of how these high-Q nano-mechanical systems behave."

The advent of this new class of nano-mechanical oscillators will open new avenues for ultrasensitive force sensing and benefit the experimental investigation of quantum physics.

This discovery has been possible thanks to the collaboration between the Plasmon Nano-optics group led by ICREA Prof. at ICFO Romain Quidant and the Nano-Photonics group led by Prof. Lukas Novotny, from the Photonics Laboratory (ETH Zurich), as well as the support from the Fundació Cellex Barcelona through its Nest program.

Ref: Jan Gieseler, Lukas Novotny & Romain Quidant, Thermal nonlinearities in a nanomechanical oscillator, Nature Physics (2013), doi:10.1038/nphys2798


About ICFO:

ICFO-The Institute of Photonic Sciences was created in 2002 by the government of Catalonia and the Technical University of Catalonia as a center of research excellence devoted to the science and technologies of light with a triple mission: to conduct frontier research, train the next generation of scientists and technologists, and provide knowledge and technology transfer. In recognition of research excellence, ICFO was granted the Severo Ochoa accreditation by the Ministry of Science and Innovation. In addition, ICFO has secured the number one position worldwide among Physics research institutes in the Mapping Excellence study led by the Administrative Headquarters of the Max Planck Society ('Ranking and mapping of universities and research-focused institutions worldwide based on highly-cited papers').

Research at ICFO targets the forefront of science and technology based on light with programs directed at applications in Health, Renewable Energies, Information Technologies, Security and Industrial processes, among others. The center currently hosts 300 professionals including researchers and PhD students, working in 60 laboratories. All research groups and facilities are located in a dedicated 14.000 m2 building situated in the Mediterranean Technology Park in the metropolitan area of Barcelona.

Researchers at ICFO publish in the most prestigious journals and collaborate with a wide range of companies around the world. The Client Liaison Program at ICFO, which includes members of a large number of local and international companies, aims to create synergies between ICFO and the industrial sector. The institute actively promotes the creation of spin-off companies by ICFO researchers. The institute participates in a large number of projects and international networks of excellence. Foundation Cellex finances the NEST program at ICFO which makes possible many ambitious frontier research projects.

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