star-topology molecule, 2-propanol, solved in acetone-d6 and the magnetic field is simulated by rotational pulse sequences acting on the sensor. The environment surrounding them can be engineered by adding Fe(III) impurity in the solvent and by selectively decoupling H spins in the 2-propanol molecule. We demonstrated the entanglement-enhanced phase sensitivity and discussed its enhancement mechanism. We also showed that the magnetic field sensing was affected by noise. Importantly, we demonstrate that, when the noise is time-inhomogeneous, the effect of the noise can be suppressed by a dynamical decoupling technique during the entanglement enhanced magnetic field sensing. Our results would provide a useful test bench to assess the practicality of quantum sensors under the effect of various types of noise.

Acknowledgments {#acknowledgments .unnumbered}
===============

This work was supported by CREST(JPMJCR1774), JST. This work is also supported by Leading Initiative for Excellent Young Researchers MEXT Japan and MEXT KAKENHI (Grant No. 15H05870).

In the preceding work [@Binho2019], we systematically studied the three cases when the environments consisted of 1, 3, and 12 spins $+$ Markovian environment generated by magnetic impurities. We add another case study here, 6 spins $+$ Markovian environment by using 2-propanol solved in acetone d6.

The longitudinal relaxation times, 