Optimal control and glassiness in quantum sensing

Qubits are known for being extremely responsive to their external environment, which has proven very beneficial in the domain of quantum sensing. These quantum sensors are very sensitive to small target fields; however, their sensitivity makes them highly prone to being disrupted by external noise. We simulate the use of quantum optimal control to control the qubits for sensing protocols. This allows us to maximize the effects of the target field on the qubit, while minimizing the effects of noise. Our work extends the pioneering results of Poggiali et al [PRX 8, 021059 (2018)] by allowing the use of non-$\pi$ pulses. We find that this refinement results in both improved sensitivity as well as qualitative modifications of the control landscape. In particular, we investigate the ways in which the rough control landscape behaves as an analogue to a (classical) spin glass and comment on how this spin glass behavior can be applied to improve quantum sensing more broadly.