Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Quantum-limited Measurement Method for Nanosensors

A team of scientists at the Max Planck Institute of Quantum Optics succeeds in applying a novel optical method to nanomechanical oscillators

New fabrication techniques have enabled the development of on-chip mechanical elements whose dimensions are on the nanometre (one millionth mm) scale. Their application, however, has been limited by the lack of sufficiently sensitive techniques for measuring the motion of these tiny devices.

Schematic of the experiment: The nanostrings (yellow) interact with the optical near-field that leaks out of the toroid glass-resonator (violet). When a single string is approached into the optical near-field, the optical resonance frequency of the microresonator gets exponentially reduced. MPQ

A team of scientists around Prof. Tobias Kippenberg (Leader of the Independent Junior Research Group "Laboratory of Photonics and Quantum Measurements" at the Max Planck Institute of Quantum Optics in Garching and Tenure Track Assistant Professor at the EPFL Lausanne) and Prof. Jörg Kotthaus (Professor at LMU Munich) has now successfully developed a novel method at MPQ (Nature Physics, Advance Online Publication, DOI: 10.1038/NPHYS1425).

On-chip glass cylinders with diameters around 50 microns which are capable of storing light played a key role in the study. The scientists could show that the optical near-field, that is the light-field that is leaking out of the glass cylinders, can be used as actuator and sensitive probe for nanomechanical oscillators. This enables measurements that are only limited by the fundamental quantum fluctuations of light.

Thereby, the novel technique for the first time allows measurement sensitivities at the level of the quantum mechanical zero-point fluctuations of the nano-oscillators which is of great interest for fundamental research. But also applications such as single-atom or single-charge detection by atomic or magnetic force microscopy may benefit from the extremely low-noise method with a noise background at the level of the standard quantum-limit.

Nanomechanical oscillators are ideal candidates for studying quantum limits of mechanical motion in an experimental setting. Moreover, they are the basis for a variety of precision measurements. Significant attention has been devoted to developing sensitive readout techniques for motion over the past decade. Optical methods have thereby achieved the best results. However, these have been limited to objects which are larger than the wavelength. Techniques based on electron flow which are applicable to nanoscale objects have so far reached only limited precision.

The MPQ and LMU physicists have now for the first time successfully applied optical methods to nanoscale mechanical oscillators. This is fundamentally challenging as diffraction losses occur as soon as sub-wavelength objects are being looked at. In the present experiment this problem is bypassed by using optical near-fields. A key element is a cylindrical resonator made out of glass with a diameter of approximately 50 microns. The microtoroid can store light if it exhibits the right wavelength, that is if the toroid's optical circumference is an integer multiple of the wavelength. A small portion of the stored light, however, the so-called optical near-field, leaks out of the resonator and can be used as a probe for the nanomechanical oscillators (see Figure). These are strained silicon nitride strings which have typical cross-sections of 100 times 500 nanometres and are 15-40 microns long (nanostrings and microtoroids were fabricated in the clean rooms of Prof. Kotthaus at LMU and at EPFL Lausanne).

If the nanostrings are brought in close proximity to the toroid, that is into its near-field which extends a few hundred nanometres from its surface, both can interact with each other. Thereby the nanostrings act as a dielectric and locally change the refractive index seen by the light field. This leads to a change of the toroid's optical circumference and thus of the toroid's resonance frequency.

The optical resonance frequency shift caused by a single nanostring is so large that even its Brownian motion has a strong and easily measureable influence. This allows highly-sensitive measurements of the strings' motion. The sensitivity to changes in the distance between string and toroid is thereby as small as the quantum-mechanical zero-point fluctuations of the nanostring which are expected at absolute zero temperature and equal the standard quantum-limit.

Besides the high sensitivity to the motion of nanoscale objects there is another important aspect of the work, Georg Anetsberger, PhD student Prof. Kippenberg's group, emphasizes. Equally important is the first experimental demonstration that also nanoscale objects can directly be manipulated by radiation pressure, e.g. cooled down or driven into oscillation. "We can observe that the dipole force of the optical near-field leads to dynamical backaction which can drive the nanostrings into coherent, laser-like oscillations."

The employed method can in principle be applied to all dielectric nanomechanical oscillators which could further foster their use as ultra-sensitive sensors. Once more, Prof. Kippenberg says, the versatility of microtoroids which have been the focus of his research for a few years now becomes evident. "We have developed an experimental platform which could greatly broaden the possible applications of nanomechanical oscillators. Moreover it constitutes an interface which allows the interaction of photons and phonons in such a way that quantum-mechanical effects could become measureable even at room temperature."

[Georg Anetsberger/Olivia Meyer-Streng]

Original publication:
G. Anetsberger, O. Arcizet, Q. P. Unterreithmeier, R. Rivière, A. Schliesser, E. M.Weig, J. P. Kotthaus and T. J. Kippenberg
Near-field cavity optomechanics with nanomechanical oscillators
Nature Physics, Advance Online Publication, DOI: 10.1038/NPHYS1425
Prof. Dr. Tobias Kippenberg
Max Planck Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching
Phone: +49 - 89 / 32905 727
Fax: +49 - 89 / 32905 200
Georg Anetsberger
Max Planck Institute of Quantum Optics
Phone.: +49 - 89 / 32905 334
Fax: +49 - 89 / 32905 200
Dr. Olivia Meyer-Streng
Max Planck Institute of Quantum Optics
Press & Public Relations
Tel.: +49 - 89 / 32905 213
Fax: +49 - 89 / 32905 200

Dr. Olivia Meyer-Streng | Max-Planck-Gesellschaft
Further information:

More articles from Physics and Astronomy:

nachricht Subnano lead particles show peculiar decay behavior
25.04.2018 | Ernst-Moritz-Arndt-Universität Greifswald

nachricht Getting electrons to move in a semiconductor
25.04.2018 | American Institute of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

Science & Research
Overview of more VideoLinks >>>