Robust AC Vector Sensing at Zero Magnetic Field with Pentacene

Area of Science:

• Quantum sensing
• Molecular spintronics
• Microwave field detection

Background:

• Electronic spins in solid-state systems are effective for probing microwave fields.
• Molecular crystals offer advantages like high spin density and chemical tunability for spin-based sensors.
• Existing methods often require cryogenic temperatures or external magnetic fields.

Purpose of the Study:

• To demonstrate microwave vector magnetometry using molecular spins at room temperature and zero magnetic field.
• To achieve full three-dimensional microwave field reconstruction.
• To enhance sensitivity and spatial resolution for quantum sensing applications.

Main Methods:

• Utilized the photoexcited spin triplet of deuterated pentacene molecules in naphthalene crystals.
• Detected Rabi frequencies of anisotropic spin-triplet transitions for two crystallographic orientations.
• Implemented a phase alternated protocol to extend rotating-frame coherence time.

Main Results:

• Achieved full 3D microwave field reconstruction at room temperature and zero external magnetic field.
• Demonstrated sensitivities of $1\mu T/\sqrt{Hz}$ with sub-micrometer spatial resolution.
• Extended rotating-frame coherence time by an order of magnitude using a phase alternated protocol.

Conclusions:

• Pentacene-based molecular spins represent a practical and high-performance platform for microwave quantum sensing.
• The developed control techniques are broadly applicable to other molecular and solid-state spin systems.
• This work paves the way for advanced microwave field detection under ambient conditions.