Wider research context:

Microwave quantum technology has drawbacks that need a hybrid solution. Magnons (magnetization waves in magnets) are the ideal complement as they have similar frequencies, much smaller wavelengths, and exotic properties such as tunable dispersion and nonlinearity, stemming from their complexity as solid-state excitations. The field of magnonics has used these properties in the classical domain in advanced information processing nanodevices. Bringing this technology to the quantum regime would enable magnon-microwave hybrid quantum devices with new functionalities based on exploiting exclusively magnonic properties that are absent for photons. However, no experiment has proven quantum behavior in magnonic nanodevices. A pressing challenge is the lack of a theoretical formalism to describe quantum magnon dynamics in nanostructures, determine the value and lower bounds to their decoherence rate, and reach such bounds via nanoengineering.

Objectives:

InspireQMag1 will solve this challenge via nanophotonics-inspired quantum magnonics. This multidisciplinar approach has three goals: (1) develop a quantitative theoretical description of quantum magnon propagation in nanostructures, e.g. a quantum master equation and software to solve it (2) provide expressions for the magnon decoherence rate and routes to suppress it by nanostructure or bath engineering (3) propose feasible short-term experiments to certify quantum magnonic behavior in nanostructures.

Approach:

As magnons are more complex than photons, nanophotonics methods cannot be extended directly and a new theoretical formalism will be built. Using classical magnonics, condensed matter theory, and open quantum systems theory, InspireQMag1 will derive and optimize quantum dynamical equations describing the evolution of quantum magnonic states in nanostructures. This method will provide analytical expressions for the dynamical rates, e.g. decoherence rates, and thus pave the way to control them via nanostructure engineering. InspireQMag1 will also propose experiments to certify quantum magnonic behavior in nanodevices (e.g. coherence-preserving photon-magnon-photon transduction), based on quantum optics protocols. These goals need my multidisciplinar expertise (quantum nanophotonics, open quantum systems, magnonics) and close contact with experimental collaborators.

Level of innovation:

InspireQMag1’s nanophotonics-inspired approach is new to quantum magnonics. It will unlock the exploration of the quantum regime of magnonic nanodevices, allowing the magnonics community to join the hybrid quantum technology endeavor. Here, harnessing the unconventional magnon properties could provide quantum platforms/protocols with new capabilities. InspireQMag1's will bridge the gap between classical nanomagnonics and microwave quantum technology and facilitate their common goal of devising next-generation quantum devices.