Room-temperature ultrasensitive mass spectrometer via dynamical decoupling

We propose an ultrasensitive mass spectrometer based on a coupled quantum-bit-oscillator system. Under dynamical decoupling control of the quantum bit (qubit), the qubit coherence exhibits a comb structure in the time domain. The time-comb structure enables high-precision measurements of oscillator frequency, which can be used as an ultrasensitive mass spectrometer. We show that, in the ideal case, the sensitivity. of the proposed mass spectrometer has better performance at higher temperature and scales with the temperature T as eta similar to T-1/2. While taking into account qubit and oscillator decay, the optimal sensitivity reaches a universal value independent of environmental temperature T. The measurement sensitivity eta also shows an improved dependence on the control-pulse number N as eta similar to N-3/2, in comparison with the N-1/2 scaling in previous magnetometry studies. With the present technology on solid-state spin qubit and high-quality optomechanical system, our proposal is feasible to realize an ultrasensitive room-temperature mass spectrometer.