Adverse effects of laser frequency noise in LMT clock atom interferometers

Clock atom interferometry is an emerging technique in precision measurements, poised to outperform conventional free-space atom optics due to its superior propensity for large momentum transfer (LMT). Momentum separations of several hundreds of photon momenta have already been demonstrated, breaking long-standing records in the field. However, the utility of LMT clock interferometers has recently been under debate due to limitations posed by the frequency noise of the interferometry laser, raising a concern about quadratic scaling of error with the number of pulses. Here we show that the population error of n sequential pulses in an LMT interferometer applied from alternating directions scales with n instead of n^2, as would be the case when probing a two-level system n consecutive times from the same direction. Additionally, we explore incidental contributions to the interferometer signal from parasitic interferometer paths. We find that laser frequency noise is not a fundamental limitation for LMT clock atom interferometers for lasers with an RMS noise amplitude below 10Hz.