(Press-News.org) When a mirror reflects light, it experiences a slight push. This radiation pressure can be increased considerably with the help of a small superconducting island. This was revealed by the joint research done in the Aalto University and the Universities of Jyväskylä and Oulu. The finding paves a way for the studies of mechanical oscillations at the level of a single photon, the quantum of light. The results of the research were published in Nature Communications in April.
In our everyday lives, the effects of the radiation pressure of light can be neglected. Your furniture is not moved over even though the light, or more generally the electromagnetic radiation, emitted by your lamps bounces off from its surfaces thus creating a radiation pressure force. An ordinary 100 Watt light-bulb causes a radiation pressure that is only a trillionth (one part to 1000000000000) of the normal atmospheric pressure. Nevertheless, in space the relevance of the phenomenon becomes apparent: because of the radiation pressure the tails of comets typically point away from the Sun. Radiation pressure has also been proposed as the propulsion for the solar sails.
In the recent years, the radiation pressure has been harnessed also in the field of laser physics. It can be used to couple the electromagnetic laser field to, for example, the movement of the small mechanical oscillators that can be found inside ordinary watches. Due to the weakness of the interaction, one typically needs substantially strong laser fields.
- Radiation pressure physics in these systems have become measurable only when the oscillator is hit by millions of photons, explains theorist Jani Tuorila from the University of Oulu.
In the work reported here, the researchers combine their knowledge on experimental and theoretical physics, and show how the strength of the radiation pressure coupling can be considerably increased. They placed a superconducting island in between the electromagnetic field and the oscillator to mediate the interaction.
- In the measurements, we exploited the Josephson coupling of the superconducting junctions, especially its nonlinear character, explains Juha Pirkkalainen from Aalto University, the post-doctoral researcher who conducted the measurements.
The researchers were able to alter the radiation pressure coupling significantly.
- With the superconducting island, the radiation pressure increased a millionfold the value we had previously achieved, reports the supervisor of the experimental group, professor Mika Sillanpää from Aalto University.
Because of the increased radiation pressure coupling, the oscillator observes the electromagnetic field with the precision of a single photon. Correspondingly, the oscillators reveal themselves to the field with the resolution of a single quantum of oscillations, a phonon.
- Such strong coupling allows, in principle, the measurement of quantum information from an oscillator nearly visible to the naked eye, explains professor Tero Heikkilä from the University of Jyväskylä who was in charge of the theoretical studies.
The research enables the observation of quantum phenomena in larger structures than before. Thus, it allows studying the validity of the quantum mechanical laws in large structures. - Some claim that the theory holds only with very small particles. Nevertheless, the existence of an upper limit for the validity region has not been found - yet.
INFORMATION:
The research was conducted within the Academy of Finland Center of Excellence on Low Temperature Quantum Phenomena and Devices and it got also support by the European Research Council.
Link to the article: http://www.nature.com/ncomms/2015/150427/ncomms7981/abs/ncomms7981.html
Reference: J.-M. Pirkkalainen, S.U. Cho, F. Massel, J. Tuorila, T.T. Heikkilä, P.J. Hakonen, and M.A. Sillanpää, Cavity optomechanics mediated by a quantum two-level system, Nature Communications 6, 27 April 2015.
Additional information:
Prof. Tero Heikkilä, tero.t.heikkila@jyu.fi; +358 40 805 4804
Department of Physics and Nanoscience Center, University of Jyväskylä
Prof. Mika Sillanpää, mika.sillanpaa@aalto.fi; +358 50 344 7330
Department of Applied Physics, Aalto University
Dr. Jani Tuorila, jani.tuorila@oulu.fi; +358 2 9448 1881
Research Centre for Molecular Materials/theoretical physics, University of Oulu
Physicists have shown how heat can be exploited for controlling magnetic properties of matter. The finding helps in the development of more efficient mass memories. The result was published yesterday in Physical Review Letters. The international research group behind the breakthrough included Finnish researchers from the University of Jyväskylä and Aalto University.
The ability to control the huge amount of information within the Internet is largely based on the ability to use the magnetic properties of electrons for reading memory devices. The phenomenon is ...
To meet the demands of 2020, the 5G research has attracted global attention and made remarkable progress. 5G will be the first meaningful unified wideband mobile communication system. A recent research has systematically overviewed the latest progress on the 5G research and highlighted the network architecture and several promising techniques which could be employed in the future 5G systems. The research also foresees potential research keypoints and directions.
The related research paper "Key techniques for 5G wireless communications: network architecture, physical layer, ...
Researchers from the University of Liverpool have used mathematical equations to shed new light on how flowing fluid hinders the movement of bacteria in their search for food.
Many bacteria are mobile and inhabit a variety of dynamic fluid environments: from turbulent oceans to medical devices such as catheters.
Mathematicians from the Universities of Liverpool and Manchester developed a new set of equations to study how flowing fluid affected the movement of bacteria and how the swimming behaviour of the bacteria themselves affected their travel.
Bacteria can ...
New research has indicated that obesity in children has quite different causes at different ages. The research, led by the University of Exeter Medical School and part of the internationally respected EarlyBird Study, could have far-reaching implications for attempts to reduce the global epidemic of childhood obesity, as it indicates that very different approaches may be needed at various stages of development.
In a study published today (Monday April 27) in the International Journal of Obesity, scientists compared data on contemporary children with those of the 1980's. ...
Quantum particles behave in strange ways and are often difficult to study experimentally. Using mathematical methods drawn from game theory, physicists of Ludwig-Maximilias-Universitaet (LMU) in Munich have shown how bosons, which like to enter the same state, can form multiple groups.
When scientists explore the mysterious behavior of quantum particles, they soon reach the limits of present-day experimental research. From there on, progress is only possible with the aid of theoretical ideas. NIM investigator Professor Dr. Erwin Frey and his team at the Dept. of Statistical ...
Silicon (Si) is the second most abundant element of the earth`s crust after oxygen. It has long been neglected by ecologists, as it is not considered an essential nutrient for plants. However, research of recent years showed that it is beneficial for the growth of many plants, including important crops such as rice, wheat and barley.
For instance, Si enhanced the resistance against pests, pathogens and abiotic stresses such as salts, drought and storms. Silicon might, thus, play a crucial role in the development of `sustainable` rice production systems with lower or ...
Emory scientists have adapted an antiviral enzyme from bacteria called Cas9 into an instrument for inhibiting hepatitis C virus in human cells.
The results were published Monday April 27, 2015 in Proceedings of the National Academy of Sciences.
Cas9 is part of the CRISPR genetic defense system in bacteria, which scientists have been harnessing to edit DNA in animals, plants and even human cells. In this case, Emory researchers are using Cas9 to put a clamp on RNA, which hepatitis C virus uses for its genetic material, rather than change cells' DNA.
Although several ...
Many experimental and clinical data have demonstrated that antibiotic-resistance pathogens, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), may play a vital role in priming chronic inflammation. There is thus a great need to develop novel antibacterial materials, and particularly those that are less likely to lead to bacterial resistance.
Now, in a paper appearing recently in Science Bulletin, a team of scientists at the National Center for Nanoscience and Technology, China, led by Guangjun Nie and Yuliang Zhao, has designed and synthesized biocompatible ...
The autonomous locomotion for a macroscopic machine remains an intriguing issue for the researchers to explore. Recently, Professor LIU Jing and his group from Tsinghua University demonstrated that as a versatile material, the liquid metal could be self-actuated when fueled with aluminum (Al) flake, and the motion thus enabled would persist for more than an hour at a quite high velocity.
Based on the previous study, the present work proposed to realize a much larger liquid metal machine, which could autonomously move and accelerate with the increase of temperature. More ...
Stark disparities by race, education and literacy
Slower medication refills and access to lab results
Harder to keep doctors informed about chronic conditions
CHICAGO -- Online sites that offer secure access to one's medical record, often referred to as patient portals, are increasingly important for doctor and patient communication and routine access to health care information. But patient portals could widen the gap in health disparities among the most vulnerable patients, according to a new Northwestern Medicine study.
Patients with low health literacy, less ...
