Quantum properties of macroscopic objects are currently a hotly debated research topic. A team led by Innsbruck physicist Gerhard Kirchmair has demonstrated in the laboratory a new way to make the quantum properties of macroscopic objects more accessible than ever before. This method allowed the researcher to improve the efficiency of established cooling methods by an order of magnitude.
Optomechanical experiments are allowing scientists to explore the limits of the quantum world and lay the groundwork for the development of highly sensitive quantum sensors. In these experiments, macroscopic objects are coupled into superconducting circuits via electromagnetic fields. To obtain working superconductors, such experiments are performed in a cryostat at temperatures around 100 millikelvins. However, this is still not enough to dive into the quantum world.In order to observe quantum effects on macroscopic objects, sophisticated cooling methods must be used to cool them to near absolute zero. Physicists led by Gerhard Kirchmair from the Department of Experimental Physics at the University of Innsbruck and the Institute for Quantum Optics and Quantum Information (IQOQI) have demonstrated a nonlinear cooling mechanism that can sufficiently cool even large objects.
Cooling capacity higher than usual
In experiments, the Innsbruck researchers couple a mechanical object (a vibrating beam in their case) to a superconducting circuit via a magnetic field. To do this, they attached magnets to a beam about 100 micrometers long. As the magnet moves, the magnetic flux through the circuit changes. At its heart is his so-called SQUID, a superconducting quantum interference device. Its resonant frequency changes according to the magnetic flux, which is measured using a microwave signal. In this way the micromechanical oscillator can be cooled to near the quantum mechanical ground state. Furthermore, his David Zöpfl from Gerhard Kirchmair’s team explains: power. “This new and simple method is of particular interest for cooling larger mechanical objects. Zöpfl and Kirchmair say that this could be the basis for the search for quantum properties of larger macroscopic objects. I’m confident.
The work was carried out in collaboration with Canadian and German scientists and is currently physical review letterThis research was financially supported by the Austrian Science Fund FWF and the European Union, among others. Co-authors Christian Schneider and Lukas Deeg are or were members of the FWF Doctoral Program Atoms, Light and Molecules (DK-ALM).
