Quantum physicists just proved that stabilized nanomagnet levitation is possible.
Almost two centuries ago, British mathematician Samuel Earnshaw demonstrated that permanent magnets could not sustain levitation. But, things might change now that modern researchers were able to provide evidence it is possible to stabilize nanomagnet levitation through the application of quantum mechanical principles.
In a paper presented by Earnshaw to the Cambridge Philosophical Society in 1839, he explained that it is not possible to place a collection of bodies, subject only to electrostatic forces, in a way that they will stay in stable equilibrium configuration. Known as the Earnshaw Theorem, it is also said to be applicable to magnetic forces.
However, quantum physicists in Oriol Romero-Isart‘s research group in Innsbruck, Austria recently published two studies that counter the Earnshaw Theorem. Apparently, despite Earnshaw’s findings, nanomagnets can sustain levitation in an external static magnetic field.Scientists just discovered that nanomagnet #levitation is possible! #QuantumClick To Tweet
In collaboration with researchers from the Max Planck Institute for Quantum Optics in Munich, Germany, the physicists from Oriol Romero-Isart’s research group at the Institute for Theoretical Physics in Innsbruck University, and the Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences were able to circumvent the Earnshaw Theorem with quantum mechanical properties.
“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,” the researchers explained.
The scientists conducted comprehensive stability analyses based on the object’s radius and the strength of the external magnetic field. The results of the study showed that state of equilibrium appears in the absence of dissipation.
The mechanism was reported to be reliant on gyromagnetic effect which states that an angular momentum occurs when there’s a change in the direction of magnetic field due to the coupling of magnetic moment and the spin of the electrons. And, according to Cosimo Rusconi, the first author of the study, this stabilizes the magnetic levitation of the nanomagnet.
“We theoretically show that, despite Earnshaw’s theorem, a nonrotating single magnetic domain nanoparticle can be stably levitated in an external static magnetic field. The stabilization relies on the quantum spin origin of magnetization, namely, the gyromagnetic effect.
We predict the existence of two stable phases related to the Einstein–de Haas effect and the Larmor precession. At a stable point, we derive a quadratic Hamiltonian that describes the quantum fluctuations of the degrees of freedom of the system. We show that, in the absence of thermal fluctuations, the quantum state of the nanomagnet at the equilibrium point contains entanglement and squeezing.”
Romero-Isart is positive that the nanomagnet levitation could soon be observed experimentally. The study of levitated nanomagnets is a new experimental field for physicists. Studying the phenomenon under unstable condition could potentially lead to the discovery of rare quantum events. Aside from this, nanomagnet levitation is also being studied for its many possible applications, for instance in the development of high precision sensors.