Scalar Aharonov–Bohm Phase in Ramsey Atom Interferometry under Time-Varying Potential

Round  1

Reviewer 1 Report

This paper is based around an examination of the effect of perturbative fields on a Ramsey atom interferometer - driven by two photon transitions.  It is a logical extension of the authors previous work published in PRA [].

While I find the research to be a competent and thorough examination of this particular effect, the motivation and need for this study are sorely missing from the manuscript. Invoking an interesting name for a commonly observed interferometric phase shift is not enough - the authors really need to show why this is an important/useful study.  This is particularly the case as a time standard the authors refer to - a cs atomic clock based on Ramseys technique, uses RF transitions *precisely* to avoid the effect the authors study. The authors say this themselves as well: 

line 236 “However, in a conventional Cs atomic fountain clock [6], the ac Stark shift is too small to detect.”

Maybe I’m missing a critical piece of the authors argument, as to why the time dependent shift is important and applicable to the Cs frequency standard?

Thus my conclusion is that the work is scientifically sound, but seriously lacking on the motivational aspects that put it in context.  The work is suitable for publication upon a revision of the introductory material, taking this into account.   Specifically, all the authors need to do is state very very clearly why the large shifts present in an optically driven Ramsey interferometer are important when these shifts do not significantly contribute to the error budget of the RF driven Ramsey clocks that constitute or time standards.  

I would also appreciate it if the authors concluded with some forward looking comments about how time dependent shifts may impact future time standards based on single photon optical transitions, such as ion and lattice clocks. 

Author Response

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper by A. Morinaga et al., entitled “Scalar Aharonov-Bohm Phase in Ramsey Atom Interferometry under Time-Varying Potential” presents an experimental analysis on phase shift due to magnetic fields in Ramsey interferometer. The interferometer is made with cold atoms interacting with Raman interaction in a co-propagating configuration. They study the contribution due to a change in the detuning for the 1st and the 2nd pulse and a contribution due to the propagation of the two coherent hyperfine states between the two pulses. The former effect is analysed as an analogue to the Aharonov-Bohm effect. They demonstrate that the measured phase shift is in agreement with an elementary theory of the Ramsey interrogation.

The paper presents experiments that will interest a large community, in particular because of it connection to frequency standard measurements. In conclusion, I recommend this paper for publication if the comments below are considered.

1-                  Strictly, the Scalar Aharonov-Bohm (SAB) effect is related to charged particles and an interest for this effect is related to the observable phase shift even in the absence of electromagnetic fields. This effect illustrates the importance of electromagnetic potentials or asks the question of non-locality in quantum physics. In this paper the SAB is mimicked with a constant magnetic field. If the authors want to keep this terminology they should clarify this analogy and in particular they have to show the limits of the analogy: field instead of potential, gauge invariance, no-forces acting on the atom …

2-                  Omega3 is used for the detuning with the intermediate state. This notation is confusing, I would prefer Delta

3-                  f in the envelope function without potential and f’ is the envelope function with the potential ON. This writing is confusing; I would prefer another letter than f for the envelope function with the potential ON.

4-                  The authors should explain how the selection in Zeeman sub-level is made: is it only the resonance condition with the Raman laser?

5-                  How Teff is define and how the authors explain the figure 3(b)?

6-                  Line 148 Teff = 1011µs instead of 1011 ms?

7-                  In section 4.3 : I don’t understand Stark shift formula proportional to T. If this effect is due to the interaction with the Raman pulses I would not expect to have an effect which scales with the time between the pulses but with tau or Omegaeff.

Author Response

Author Response File: Author Response.pdf

Reviewer 3 Report

P { margin-bottom: 0.08in; }

In this paper, the authors investigate the phase shift caused by the scalar Aharonov-Bohm (AB) effect onto Ramsey fringes. The AB effect arises from a time-dependent scalar potential.

However, very similar measurements were reported in a previous paper written by some ot the authors, which is cited in the present manuscript as Ref.[10]: K. Shinoara, T. Aoki, and A. Morinaga. In Ref.[10] the authors also measure a phase-shift due to the scalar Aharanov-Bohm effect in a Ramsey atom interferometer using sodium atoms.

Therefore, from my present understanding of the manuscript, I see no clear novelty with respect to Ref.[10] which would – with my current understanding - justify this publication. In Ref.[10] the scalar AB effect was investigated with a sodium interferometer.

If the results presented in this manuscript are really different, then they authors should point out clearly why in the introduction and show the differences/similarities with respect to Ref.[10]. Also, the authors claim that they have proposed a method enabling to evaluate the uncertainty of a primary atomic clock induced by the scalar AB effect. In Ref.[12], some ot the authors of the present papers also measured the influence of the scalar AB phase on an atomic clock. How is the present work related to that of Ref.[12]? What is the point that they address here that was not address in Ref.[12]?

Last, even if it less important, the authors claim in introduction that they derive an “experimental” formula. What do they mean with that?

The authors must carefully address these points justifying the novelty of this work with respect to the results presented in the previous publications [10,12].

In the present form, and until these points are carefully addressed, I cannot recommend the manuscript for publication.

Author Response

Author Response File: Author Response.pdf

Round  2

Reviewer 1 Report

The revised manuscript is suitable for publication

Author Response

Dear the first Reviewer,

 Thank you for your  second review of our manuscript. We are pleased to know that you will accept our the revised manuscript. Furthermore, according to the editors recomendation, the English langauge of introduction, the last part of discussions and conclusions was corrected by a native speaker. We hope the English langugage will be fine.

Yours Sincerely

Atsuo Morinaga

Reviewer 2 Report

The reviseded version is fine to me.

Author Response

Dear the second Reviewer,

 Thank you for your  second review of our manuscript. We are pleased to know that you will accept our  revised manuscript. Furthermore, according to the editors recomendation, the English langauge of introduction, the last part of discussions and conclusions was corrected by a native speaker. We hope the English langugage will be fine.

Yours Sincerely

Atsuo Morinaga