Nav: Home

New device could help answer fundamental questions about quantum physics

December 13, 2018

WASHINGTON -- Researchers have developed a new device that can measure and control a nanoparticle trapped in a laser beam with unprecedented sensitivity. The new technology could help scientists study a macroscopic particle's motion with subatomic resolution, a scale governed by the rules of quantum mechanics rather than classical physics.

The researchers from the University of Vienna in Austria and the Delft University of Technology in the Netherlands report their new device in Optica, The Optical Society's journal for high impact research. Although the approach has been used with trapped atoms, the team is the first to use it to precisely measure the motion of an optically trapped nanoparticle made of billions of atoms.

"In the long term, this type of device could help us understand nanoscale materials and their interactions with the environment on a fundamental level," said research team leader Markus Aspelmeyer from the University of Vienna. "This could lead to new ways of tailoring materials by exploiting their nanoscale features.

"We are working to improve the device to increase our current sensitivity by four orders of magnitude," Aspelmeyer continued. "This would allow us to use the interaction of the cavity with the particle to probe or even control the quantum state of the particle, which is our ultimate goal."

Making tiny measurements

The new method uses a light-guiding nanoscale device called a photonic crystal cavity to monitor the position of a nanoparticle levitating in a traditional optical trap. Optical trapping uses a focused laser beam to exert a force on an object to hold it in place. The technique was recognized by the award of the 2018 Nobel Prize in Physics to pioneer, Arthur Ashkin.

"We know that the laws of quantum physics apply on the scale of atoms and the scale of molecules, but we don't know how large an object can be and still exhibit quantum physics phenomena," said Aspelmeyer. "By trapping a nanoparticle and coupling it to a photonic crystal cavity, we can isolate an object that is larger than atoms or molecules and study its quantum behaviors."

The new device accomplishes a high level of sensitivity by using a long photonic crystal cavity that is narrower than the wavelength of the light. This means that when light enters and travels down the nanoscale cavity, some of it leaks out and forms what is called an evanescent field. The evanescent field changes when an object is placed close to the photonic crystal, which in turn changes how the light propagates through the photonic crystal in a measurable way.

"By examining how light in the photonic crystal changes in response to the nanoparticle, we can deduce the position of the nanoparticle over time with very high resolution," said Lorenzo Magrini, first author of the paper.

Collecting every photon

The new device detects almost every photon that interacts with the trapped nanoparticle. This not only helps it achieve extremely high sensitivity but also means that the new approach uses much less optical power compared to other methods in which most of the photons are lost.

Under vacuum conditions, the researchers demonstrated, for each detected photon, a sensitivity two orders of magnitude higher than conventional methods for measuring nanoparticle displacement in an optical trap. They also report that the strength of the interaction between the particle and evanescent field of the cavity was three orders of magnitude higher than what has been reported previously. Stronger interaction means that the photonic cavity can detect more information about the particle's movement.

Similar to several other research groups around the world, the researchers are working toward achieving quantum measurements. They are now improving their setup and working to substantially boost the device's sensitivity. This would allow measurements to be performed under stronger vacuum conditions that increase a particle's isolation from the environment. In addition to studying quantum mechanics, the new device could be used to precisely measure acceleration and other forces that might arise in microscopic length scales.
-end-
Paper:

L. Magrini, R. A. Norte, R. Riedinger, I. Marinkovi?, D. Grass, U. Deli?, S. Gröblacher, S. Hong, M. Aspelmeyer. "Near-field coupling of a levitated nanoparticle to a photonic crystal cavity," Optica, 5, 12, 1597-1602 (2018).

DOI: https://doi.org/10.1364/OPTICA.5.001597

About Optica

Optica is an open-access, online-only journal dedicated to the rapid dissemination of high-impact peer-reviewed research across the entire spectrum of optics and photonics. Published monthly by The Optical Society (OSA), Optica provides a forum for pioneering research to be swiftly accessed by the international community, whether that research is theoretical or experimental, fundamental or applied. Optica maintains a distinguished editorial board of more than 50 associate editors from around the world and is overseen by Editor-in-Chief Alex Gaeta, Columbia University, USA. For more information, visit Optica.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.

Media Contact:

mediarelations@osa.org

The Optical Society

Related Quantum Mechanics Articles:

A new quantum data classification protocol brings us nearer to a future 'quantum internet'
A new protocol created by researchers at the Universitat Autònoma de Barcelona sorts and classifies quantum data by the state in which they were prepared, with more efficiency than the equivalent classical algorithm.
Bridge between quantum mechanics and general relativity still possible
An international team of researchers developed a unified framework that would account for this apparent break down between classical and quantum physics, and they put it to the test using a quantum satellite called Micius.
'Poor man's qubit' can solve quantum problems without going quantum
Researchers have built and demonstrated the first hardware for a probabilistic computer, a possible way to bridge the gap between classical and quantum computing.
Cracking a decades-old test, researchers bolster case for quantum mechanics
At upcoming FiO + LS conference, researchers will discuss creative tactics to get rid of loopholes that have long confounded tests of quantum mechanics.
Quantum computers to clarify the connection between the quantum and classical worlds
Los Alamos National Laboratory scientists have developed a new quantum computing algorithm that offers a clearer understanding of the quantum-to-classical transition, which could help model systems on the cusp of quantum and classical worlds, such as biological proteins, and also resolve questions about how quantum mechanics applies to large-scale objects.
Imaging of exotic quantum particles as building blocks for quantum computing
Researchers have imaged an exotic quantum particle -- called a Majorana fermion -- that can be used as a building block for future qubits and eventually the realization of quantum computers.
NUS scientists discover how to 'lock' heat in place using quantum mechanics
In a global first, NUS scientists have demonstrated that heat energy can be manipulated by utilising the quantum mechanical principle of anti-parity-time symmetry.
New research explores the mechanics of how birds flock
Wildlife researchers have long tried to understand why birds fly in flocks and how different types of flocks work.
Quantum rebar: Quantum dots enhance stability of solar-harvesting perovskite crystals
Engineering researchers have combined two emerging technologies for next-generation solar power -- and discovered that each one helps stabilize the other.
In the blink of an eye: Team uses quantum of light to create new quantum simulator
Imagine being stuck inside a maze and wanting to find your way out.
More Quantum Mechanics News and Quantum Mechanics Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.