A New Portal into Equilibrium Quantum Superpositions and Computing Using Magnets

A New Portal into Equilibrium Quantum Superpositions and Computing Using Magnets - Featured

In a new theoretical study, IFIMAC members Anna-Luisa E. Römling, Alejandro Vivas-Viaña, Carlos Sánchez Muñoz, and Akashdeep Kamra propose a novel measurement protocol to uncover and utilize the intrinsically quantum nature of magnetic ground states. The proposal could inspire future experiments and designs of quantum devices. The IFIMAC collaboration has resulted in the article “Resolving nonclassical magnon composition of a magnetic ground state via a qubit” published in Physical Review Letters.
Magnets have recently been predicted to host squeezed states – quantum states with reduced quantum fluctuations in one observable and harboring entanglement – in equilibrium. The ground state manifests itself as a quantum superposition of states with different number of magnons – the bosonic particles that can exist in the magnet. This intrinsic squeezing of quantum magnets is of high interest for quantum technologies and computing. Its unique equilibrium nature requires new innovative ways of utilizing it. The work by the IFIMAC team presents a first proposal for detecting this robust equilibrium quantum superpositions harbored by ferromagnets. It proposes and employs a new direct dispersive interaction between the magnon mode and a spin qubit which may stem from the exchange interaction between spins. The work predicts that the magnetic ground state reveals itself in qubit spectroscopy as multiple nontrivial peaks, each of which corresponds to a different contribution to the quantum superposition. This first protocol opens doors towards utilizing the entanglement that exists naturally in several quantum materials for carrying out useful applications such as quantum computing or sensing. [Full article]

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