Quantum physicists in Oriol Romero-Isart’s research group in Innsbruck show in two current publications that, despite Earnshaw’s theorem, nanomagnets can be stably levitated in an external static magnetic field owing to quantum mechanical principles. The quantum angular momentum of electrons, which also causes magnetism, is accountable for this mechanism.
Already in 1842, British mathematician Samuel Earnshaw proved that there is no stable configuration of levitating permanent magnets. If one magnet is levitated above another, the smallest disturbance will cause the system to crash. The magnetic top, a popular toy, circumvents the Earnshaw theorem: When it is disturbed, the gyrating motion of the top causes a system correction and stability is maintained.
In collaboration with researchers from the Max Planck Institute for Quantum Optics, Munich, physicists in Oriol Romero-Isart’s research group at the Institute for Theoretical Physics, Innsbruck University, and the Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, have now shown that: “In the quantum world, tiny non-gyrating nanoparticles can stably levitate in a magnetic field.”
“Quantum mechanical properties that are not noticeable in the macroscopic world but strongly influence nano objects are accountable for this phenomenon,” says Oriol Romero-Isart.
Stability caused by gyromagnetic effect
Albert Einstein and Dutch physicist Wander Johannes de Haas discovered in 1915 that magnetism is the result of quantum mechanical principles: the quantum angular momentum of electrons, or so-called electron spin. Physicists in Oriol Romero-Isart’s research group have now shown that electron spin allows the stable levitation of a single nanomagnet in a static magnetic field, which should be impossible according to the classic Earnshaw theorem.
The theoretical physicists carried out comprehensive stability analyses depending on the object’s radius and the strength of the external magnetic field. The results showed that, in the absence of dissipation, a state of equilibrium appears. This mechanism relies on the gyromagnetic effect: Upon a change in direction of the magnetic field, an angular momentum occurs because the magnetic moment couples with the spin of the electrons.
“This stabilizes the magnetic levitation of the nanomagnet,” explains first author Cosimo Rusconi. In addition, the researchers showed that the equilibrium state of magnetically levitated nanomagnets exhibits entanglement of its degrees of freedom.
New field of research
Oriol Romero-Isart and his team are optimistic that these levitated nanomagnets can soon be observed experimentally. They have made suggestions on how this could be achieved under realistic conditions. Levitated nanomagnets are a new experimental research field for physicists.
Studies of nanomagnets under unstable condition could lead to the discovery of exotic quantum phenomena. In addition, after coupling several nanomagnets, quantum nano magnetism could be simulated and studied experimentally. Levitated nanomagnets are also of high interest for technical applications, for example for developing high precision sensors.
The research was supported by the Austrian Federal Ministry of Science, Research, and Economy (BMWFW) and the European Research Council (ERC).
o) Quantum Spin Stabilized Magnetic Levitation. Cosimo C. Rusconi, Vera Pöchhacker, Katja Kustura, J. Ignacio Cirac, Oriol Romero-Isart. Phys. Rev. Lett. 119, 167202 DOI: 10.1103/PhysRevLett.119.167202
o) Linear Stability Analysis of a Levitated Nanomagnet in a Static Magnetic Field: Quantum Spin Stabilized Magnetic Levitation. Cosimo C. Rusconi, Vera Pöchhacker, J. Ignacio Cirac, Oriol Romero-Isart. Phys. Rev. B 96, 134419 DOI: 10.1103/PhysRevB.96.134419
Department of Theoretical Physics
University of Innsbruck
phone: +43 512 507 4730
Public Relations Office
University of Innsbruck
phone: +43 512 507 32022
http://dx.doi.org/10.1103/PhysRevLett.119.167202 - Quantum Spin Stabilized Magnetic Levitation. Cosimo C. Rusconi, et.al. Phys. Rev. Lett. 119, 167202
http://dx.doi.org/10.1103/PhysRevB.96.134419 - Linear Stability Analysis of a Levitated Nanomagnet in a Static Magnetic Field: Quantum Spin Stabilized Magnetic Levitation. Cosimo C. Rusconi, et.al. Phys. Rev. B 96, 134419
http://iqoqi.at/en/group-page-romero-isart - Quantum Nanophysics, Optics and Information Group
Dr. Christian Flatz | Universität Innsbruck
APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie
First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences