Cooling capability higher than typical
In the experiment, the Innsbruck researchers pair the mechanical things– in their case a vibrating beam– to the superconducting circuit by means of an electromagnetic field. To do this, they attached a magnet to the beam, which is about 100 micrometers long. When the magnet relocations, it alters the magnetic flux through the circuit, the heart of which is a so-called SQUID, a superconducting quantum disturbance device.
Its resonant frequency changes depending on the magnetic flux, which is measured utilizing microwave signals. In this method, the micromechanical oscillator can be cooled to near the quantum mechanical ground state.
David Zöpfl from Gerhard Kirchmairs team describes, “The modification in the resonant frequency of the SQUID circuit as a function of microwave power is not linear. Zöpfl and Kirchmair are confident that this might be the foundation for the search for quantum homes in larger macroscopic items.
Recommendation: “Kerr Enhanced Backaction Cooling in Magnetomechanics” by D. Zoepfl, M. L. Juan, N. Diaz-Naufal, C. M. F. Schneider, L. F. Deeg, A. Sharafiev, A. Metelmann and G. Kirchmair, 17 January 2023, Physical Review Letters.DOI: 10.1103/ PhysRevLett.130.033601.
The research study was funded by the Austrian Science Fund FWF and the European Union, to name a few. Co-authors Christian Schneider and Lukas Deeg are or were members of the FWF Doctoral Program Atoms, Light, and Molecules (DK-ALM).
Superconducting circuit (white) on a silicon substrate repaired in a copper holder. The close-up reveals the SQUID in the center of the circuit and straight above it the micromechanical oscillator with a magnet on its underside. In the experiment, the Innsbruck scientists pair the mechanical item– in their case a vibrating beam– to the superconducting circuit through a magnetic field. When the magnet relocations, it changes the magnetic flux through the circuit, the heart of which is a so-called SQUID, a superconducting quantum interference device.
Superconducting circuit (white) on a silicon substrate fixed in a copper holder. The close-up reveals the SQUID in the center of the circuit and directly above it the micromechanical oscillator with a magnet on its underside.
Enhancing ease of access to the quantum homes of macroscopic objects.
Through optomechanical experiments, researchers intend to delve into the boundaries of the quantum realm and lay the foundation for the creation of highly delicate quantum sensors. In these experiments, daily noticeable objects are combined to superconducting circuits through electro-magnetic fields.
To produce practical superconductors, these experiments are carried out inside cryostats at a temperature of around 100 millikelvins. Nevertheless, this is still far from low adequate to truly go into the quantum world. In order to observe quantum results on massive things, they need to be cooled to almost absolute zero through advanced cooling strategies.
Physicists led by Gerhard Kirchmair from the Department of Experimental Physics at the University of Innsbruck and the Institute of Quantum Optics and Quantum Information (IQOQI) have actually now demonstrated a nonlinear cooling system with which even massive things can be cooled well.