Quantum Coherence Control at Temperatures up to 1400 K

Coherent quantum control at high temperatures is important for expanding the quantum world and is useful for applying quantum technologies to realistic environments. Quantum control of spins in diamond has been demonstrated near 1000 K, with the spins polarized and read out at room temperature and controlled at elevated temperatures by rapid heating and cooling. Further increase of the working temperature is challenging due to fast spin relaxation in comparison with the heating and cooling rates. Here we significantly improve the heating and cooling rates by using reduced graphene oxide as the laser absorber and heat drain and hence realize coherent quantum operation at up to 1400 K, which is higher than the Curie temperatures of all known materials. This work facilitates the use of diamond sensors to study a wide range of magnetic effects in the high-temperature regime, such as thermoremanent magnetism and magnetic shape memory effects.