Dissipation-Based Quantum Sensing of Magnons with a Superconducting Qubit

Area of Science:

• Quantum physics
• Condensed matter physics
• Quantum sensing

Background:

• Hybrid quantum systems integrate diverse quantum phenomena for advanced applications.
• Quantum sensing offers high precision measurements by leveraging quantum properties.
• Magnons, as quantized spin waves, are crucial for understanding magnetic phenomena.

Purpose of the Study:

• To experimentally demonstrate quantum sensing of a steady-state magnon population.
• To utilize hybrid quantum devices for detecting magnons in ferrimagnetic crystals.
• To achieve high-sensitivity magnon detection using superconducting qubits.

Main Methods:

• Fabrication of hybrid quantum devices integrating superconducting qubits and ferrimagnetic crystals.
• Dispersive coupling of a magnetostatic magnon mode to a superconducting qubit.
• Utilizing Ramsey interferometry to detect magnon-induced qubit dephasing.
• Probing the relationship between magnon population and qubit coherence time.

Main Results:

• Successful quantum sensing of a steady-state magnon population.
• Achieved a magnon detection sensitivity of approximately 10^{-3} magnons/sqrt[Hz].
• Demonstrated that qubit coherence time is reduced proportionally to the magnon population due to dissipation-induced dephasing.

Conclusions:

• Hybrid quantum devices provide a powerful platform for sensitive magnon detection.
• The demonstrated protocol enables precise measurement of magnon populations in magnetic materials.
• This work advances quantum sensing capabilities for condensed matter and quantum device applications.