Physicists at the University of Basel have developed a new cooling technique for mechanical quantum systems. Using an ultracold atomic gas, the vibrations of a membrane were cooled down to less than 1 degree above absolute zero. This technique may enable novel studies of quantum physics and precision measurement devices, as the researchers report in the journal Nature Nanotechnology.
Ultracold atomic gases are among the coldest objects in existence. Laser beams can be used to trap atoms inside a vacuum chamber and slow down their motion to a crawl, reaching temperatures of less than 1 millionth of a degree above absolute zero – the temperature at which all motion stops.
At such low temperatures, atoms obey the laws of quantum physics: they move around like small wave packets and can be in a superposition of being in several places at once. These features are harnessed in technologies such as atomic clocks and other precision measurement devices.
An ultracold atomic fridge
Can these ultracold gases also be used as refrigerants, to cool other objects to very low temperatures? This would open up many possibilities for the investigation of quantum physics in new and potentially larger systems.
The problem is that the atoms are microscopically small and even the largest clouds produced thus far, which consist of several billion ultracold atoms, still contain far fewer particles than something as small as a grain of sand. As a result, the cooling power of the atoms is limited.
A team of University of Basel researchers led by Professor Philipp Treutlein has now succeeded in using ultracold atoms to cool the vibrations of a millimeter-sized membrane. The membrane, a silicon nitride film of 50 nm thickness, oscillates up and down like a small square drumhead.
Such mechanical oscillators are never fully at rest but show thermal vibrations that depend on their temperature. Although the membrane contains about a billion times more particles than the atomic cloud, a strong cooling effect was observed, which cooled the membrane vibrations to less than 1 degree above absolute zero.
“The trick here is to concentrate the entire cooling power of the atoms on the desired vibrational mode of the membrane,” explains Dr. Andreas Jöckel, a member of the project team. The interaction between atoms and membrane is generated by a laser beam.
As the physicist explains: “The laser light exerts forces on the membrane and atoms. Vibration of the membrane changes the light force on the atoms and vice versa.” The laser transmits the cooling effect over distances of several meters, so the atomic cloud does not have to be in direct contact with the membrane. The coupling is amplified by an optical resonator consisting of two mirrors, between which the membrane is sandwiched.
The first experiment of its kind worldwide
Systems that use light to couple ultracold atoms and mechanical oscillators have already been proposed theoretically. The experiment at the University of Basel is the first worldwide to realize such a system and use it to cool the oscillator. Further technical improvements should make it possible to cool the membrane vibrations to the quantum-mechanical ground state.
For the researchers, cooling the membrane with the atoms is only the first step: “The well-controlled quantum nature of the atoms combined with the light-induced interaction is opening up new possibilities for quantum control of the membrane,” says Treutlein.
This may enable fundamental quantum physics experiments with a relatively macroscopic mechanical system, visible to the naked eye. It may also be possible to generate what are known as entangled states between atoms and membrane. These would allow measurement of membrane vibrations with unprecedented precision, which in turn could enable the development of new kinds of sensors for small forces and masses.
The experiments at the University of Basel were co-funded by the European Union and are part of the National Center of Competence in Research in Quantum Science and Technology (NCCR QSIT) and the Swiss Nanoscience Institute (SNI).
Andreas Jöckel, Aline Faber, Tobias Kampschulte, Maria Korppi, Matthew T. Rakher, and Philipp Treutlein
Sympathetic cooling of a membrane oscillator in a hybrid mechanical-atomic system
Nature Nanotechnology, advance online publication (2014).
Publication date: 24 November 2014
Prof. Dr. Philipp Treutlein, University of Basel, Department of Physics, Tel: +41 (0)61 267 37 66, Email: email@example.com
Olivia Poisson | Universität Basel
When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
Thermal Radiation from Tiny Particles
22.06.2018 | Universität Greifswald
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Materials Sciences
22.06.2018 | Earth Sciences
22.06.2018 | Life Sciences