Researchers at the University of Basel have developed a new technique that allows them to use only laser light to cool a thin layer of skin to near-zero temperatures. Such supercooled membranes can be used as sophisticated sensors.
Johannes Kepler, a German astronomer, proposed solar sails 400 years ago, which could be used by ships to travel through space. He believed that when light has a substance, there is energy. He was also able to explain why comet tails point away from the sun using this concept.
Today, atoms and other particles are slowed down and cooled using the light energy, among other things. Complex equipment is required to do this.
Using only laser light, a team of researchers at the University of Basel has successfully cooled a tiny device whose temperature is zero, or minus 273.15 °C. The group was led by Dr. Philipp Treutlein and Dr. Patrick Potts. Their findings have recently been published in a scientific journal Physical Review X.
Reviews Without Ratings
What makes our method unique is that we achieve this cooling without making any kind of measurement.
Maryse Ernzer, First Author and PhD Student, University of Basel
The laws of quantum mechanics dictate that measurements, which are often important in feedback loops, cause quantum states to change and cause chaos. In order to avoid this, researchers from Basel have developed a method known as a communication system in which laser light acts as both a sensor and a damper.
He achieved this by cooling and cooling the thermal shock of a silicon nitrate membrane about half a millimeter in size.
The researchers pointed a laser beam at the membrane and fed the light reflected by the membrane into a fiber optic cable for the experiment. The vibration of the membrane caused a small change in the oscillation phase of the reflected light during this time.
The information contained in the oscillation phase of the membrane’s instantaneous movement was used, with a time delay, to apply the appropriate energy to the membrane at the appropriate time using the same laser light.
Ernzer added, “.This is like slowing down the swing by lightly touching the ground with his feet at the right time.“
The researchers used a 30-meter long fiber optic cable to achieve the best latency of about 100 nanoseconds.
Close to Absolute Zero
Professor Potts and his colleagues made a theoretical description of the new method and calculated the values we could expect to achieve at high temperatures; That was confirmed by the experiment.
Dr. Manel Bosch Aguilera, Postdoctoral Researcher, University of Basel
The membrane was stabilized by him and his colleagues at 480 micro-Kelvin or less than a thousand degrees above zero.
The next step will involve refining the experiment until the membrane achieves the quantum mechanical ground state of oscillations, which is the lowest possible temperature. The creation of so-called compressed membrane states should be possible.
Due to their ability to increase the accuracy of measurement, such states are of great interest in sensor construction. Atomic force microscopes, which are used to analyze surfaces with nanometer dimensions, are one of the most important of such sensors.
Journal Reference:
Ernzer, M. and al. (2023) Optical Coherent Feedback Control of a Mechanical Oscillator. Physical Review X. doi:10.1103/PhysRevX.13.021023.
Source: https://www.unibas.ch/en.html
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