Room-temperature quantum devices based on pentacene’s photo-excited triplet state in p-terphenyl

Abstract

Developing quantum technology has inspired scientists and engineers to exploit it in the real- world applications which are challenging to be realized by conventional approaches. Of these applications, quantum devices are indispensable parts, which can play significant and various roles, such as single-photon sources, sensors, transducers, or simulators. Inside quantum devices, functioning material systems are always the crucial components that determine the performance and applicability. Therefore, investigating materials with robust quantum behaviors has become a stringent task for the development of practical quantum devices. Herein, pentacene doped p-terphenyl has been proven to be such a material in which the lowest photo-excited triplet state of pentacene reveals intriguing quantum properties - strong and persistent spin polarization at room temperature and in the terrestrial magnetic field. Employing a home-built zero-field transient electron paramagnetic resonance (ZF-trEPR) spectrometer, the complete zero-field spin dynamics of the pentacene’s lowest triplet state has been determined directly at room temperature. With the understandings of the fundamental spin dynamics, the pentacene-based room-temperature maser device has been improved in terms of the threshold, pumping strategy, and operational duration. Moreover, the same system has also been exploited as a bench-top spin refrigerator which enables an electromagnetic mode of a microwave cavity to be cooled to 10 K while the cavity’s walls remain at room temperature. Besides the room-temperature masers and refrigerators presented here, pentacene-based organic systems revealing rich quantum properties may find more timely applications in quantum technology with proper designs (e.g. miniaturization) and modifications (e.g. change of hosts). On the other hand, this kind of material system can be a promising platform for verifying or exploring novel quantum theories.