Quantum sensing of control errors in three-level systems by coherent control techniques

The quantum coherent control of a quantum system with high fidelity is rather important in quantum computation and quantum information processing. Many control techniques are used to reach these targets, such as resonant excitation, adiabatic passages, shortcuts to adiabaticity, and composite pulses. However, for a single pulse to realize population transfer, a tiny external error has a slight influence on the final population. The repeated application of the same pulse will greatly amplify the error effect, making it easy to be detected. Here, we propose to measure small control errors in three-level quantum systems through a coherent amplification of their effects using several coherent control techniques. For the two types of Hamiltonian with an SU(2) dynamic symmetry, we analyze how the fidelity of the population transfer is affected by the Rabi frequency error and static detuning deviation based on the pulse sequence with alternating and same phases, respectively. The results show that the sensitivity of detecting these errors can be effectively amplified by control pulse sequences. Furthermore, we discuss the efficiency of sensing the two errors with the control techniques by comparing the full width at half maximum of the population profiles. The results provide an accurate and reliable way for detecting the weak error in three-level quantum systems by repeatedly applying the coherent control pulse.