SciPost Submission Page
Boundary Time Crystals as AC sensors: enhancements and constraints
by Dominic Gribben, Anna Sanpera, Rosario Fazio, Jamir Marino, Fernando Iemini
Submission summary
| Authors (as registered SciPost users): | Dominic Gribben |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2406.06273v3 (pdf) |
| Date accepted: | 2025-02-27 |
| Date submitted: | 2025-02-18 15:39 |
| Submitted by: | Gribben, Dominic |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
We investigate the use of a boundary time crystals (BTCs) as quantum sensors of AC fields. Boundary time crystals are non-equilibrium phases of matter in contact to an environment, for which a macroscopic fraction of the many-body system breaks the time translation symmetry. We find an enhanced sensitivity of the BTC when its spins are resonant with the applied AC field, as quantified by the quantum Fisher information (QFI). The QFI dynamics in this regime is shown to be captured by a relatively simple ansatz consisting of an initial power-law growth and late-time exponential decay. We study the scaling of the ansatz parameters with resources (encoding time and number of spins) and identify a moderate quantum enhancement in the sensor performance through comparison with classical QFI bounds. Investigating the precise source of this performance, we find that despite of its long coherence time and multipartite correlations (advantageous properties for quantum metrology), the entropic cost of the BTC (which grows indefinitely in the thermodynamic limit) hinders an optimal decoding of the AC field information. This result has implications for future candidates of quantum sensors in open system and we hope it will encourage future study into the role of entropy in quantum metrology.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Author comments upon resubmission
Please find attached the revised manuscript titled ``\textit{Boundary Time Crystals as AC sensors: enhancements and constraints}'' We are grateful to the reviewers for their time and insightful comments. We have carefully considered all the feedback and detailed our responses below. We hope with these changes, the article is now ready for publication.
Yours Sincerely,
Dr. Dominic Gribben - on behalf of the Authors
List of changes
1. Expanded the discussion following Equation (1) in order to clarify the nature and terminology of boundary time crystals. Additional references have also been included to provide a broader theoretical context.
See paragraph ``Specifically this is known as... supporting a time crystal phase.''.
2. To improve coherence, we have expanded the discussion in Section 3 regarding the expected scaling of the QFI and its implications.
See paragraphs ``The QFI bounds the uncertainty in estimating the value of $g$... decode the information about $g$'' and ``A few bounds of the QFI ... Heisenberg limit with $F=N^2 t^2$.'' Additionally, we agree that the operator $\hat L_g$ was not used directly in obtaining our results, and therefore we have removed it.
3. We have ensured consistency in figure normalizations. Now, all figures with QFI data use a uniform normalization of $F/N$ for clarity and comparability.
4. We have now included a discussion on our choice of z-direction for the external field, along with references to related studies. See paragraph ``Our observations indicate that...a greater precision in its estimation.''
5. We have included the following statement in the manuscript: ``The data and codes of this manuscript are available from the corresponding author upon reasonable request.''
6. We have removed the usage of S as total spin length, adding explictly its value when needed.
Current status:
Editorial decision:
For Journal SciPost Physics: Publish
(status: Editorial decision fixed and (if required) accepted by authors)
Reports on this Submission
Report
The Authors have addressed all my previous remarks and adequately incorporated my suggestions. The manuscript in its present form is fit for publication as is.
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)