Reply to ``Comment on `Ramsey spectroscopy, matter-wave interferometry, and the microwave-lensing frequency shift' ''

Abstract

The Comment by [Jefferts et al. PRA] discusses the microwave lensing frequency shift's possible dependence on the initial wave packet size and two effects of wall interactions, the frequency shifts that they produce and the nature of how dressed states are clipped by apertures. I identify conceptual errors in their criticisms, some of which are related to fundamental problems in their lensing treatment [Ashby et al. Phys. Rev. A 91, 033624 (2015)] for the NIST-F1 and F2 atomic clocks. Aside from typesetting errors that they note, the criticisms in the Comment are shown to be incorrect.

Microwave lensing frequency shift of the PHARAO laser-cooled microgravity atomic clock

“…For fountains, this frequency shift typically ranges from δν/ν = 6 × 10 −17 to 9 × 10 −17 [7][8][9][10] and a majority of fountains that contribute to International Atomic Time correct for this systematic error. Recently, some controversy has arisen as NIST has argued that microwave lensing shifts are significantly smaller than 6 × 10 −17 to 9 × 10 −17 and that they must go to zero in the limit of zero microwave amplitude [10][11][12], in addition to raising other questions [13,14]. One of us has shown that the microwave lensing frequency shift directly corresponds to photon recoil shifts that occur when atomic wave packets span many wavelengths of an electromagnetic field [15].…”