SciPost Submission Page
Energy exchange and fluctuations between a dissipative qubit and a monitor under continuous measurement and feedback
by Tsuyoshi Yamamoto, Yasuhiro Tokura
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Tsuyoshi Yamamoto |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202412_00043v1 (pdf) |
| Data repository: | https://zenodo.org/records/14252485 |
| Date accepted: | 2025-01-21 |
| Date submitted: | 2024-12-23 03:11 |
| Submitted by: | Yamamoto, Tsuyoshi |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Continuous quantum measurement and feedback induce energy exchange between a dissipative qubit and a monitor even in the steady state, as a measurement backaction. Using the Lindblad equation, we identified the maximum and minimum values of the steady-state energy flow as the measurement and feedback states vary, and we demonstrate the qubit cooling induced by these processes. Turning our attention to quantum trajectories under continuous measurement and feedback, we observe that the energy flow fluctuates around the steady-state values. We reveal that the fluctuations are strongly influenced by the measurement backaction, distinguishing them from the standard Poisson noise typically observed in electronic circuits. Our results offer potential application in the development of quantum refrigerators controlled by continuous measurement and feedback, and provide deep insight into quantum thermodynamics from the perspective of fluctuation.
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
We have attached the revised version of our manuscript in PDF format to this correspondence. The revisions in the resubmitted manuscript are highlighted in blue for clarity.
List of changes
- First paragraph on page 2: We have improved the sentence about the dissipation effects in continuous measurement.
- Second paragraph on page 2: We have revised the explanation of the Poisson noise for the electronic current.
- Eq. (5) and below on page 4: We have added a comment to clarify that our setup is valid for multiple heat baths.
- Below Eq. (7) on page 5: we have included an explanation of θ_m and θ_n.
- End of page 5: We have modified the sentence about the effective coupling strength and the effective temperature.
- Caption of Fig. 2 on page 5: We have added values for the effective coupling strength and the effective temperature.
- Beginning of page 6: We have added a discussion about the bounds of the heat current in the transient region.
- Page 7: We have introduced a new Section 3.4 about quantum measurement cooling, along with new figures as Fig. 3.
- Eq. (16) on page 8: We have added the definition of the conditional heat current.
- Below Eq. (21) on page 10: We have revised the explanation of the Poisson noise for the electronic current.
- End of Section 4.1 on page 10: We have improved the discussion on the comparison with the electronic current.
- Below Eq. (28) on page 12: We have added a discussion about sub-Poisson statistics.
- End of Section 5 on page 14: We have included a comment about the possibility of experimental detection.
- End of Section 5 on page 14: We have provided information on Zenodo, where we have uploaded our numerical data.
- We have replaced “heat current” with “energy exchange” or “energy flow”.
- We have avoided using the term “bound” to prevent ambiguity.
Published as SciPost Phys. Core 8, 016 (2025)
Reports on this Submission
Report #2 by Anonymous (Referee 1) on 2025-1-11 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202412_00043v1, delivered 2025-01-11, doi: 10.21468/SciPost.Report.10478
Strengths
- Targets a timely topic in quantum thermodynamics.
Weaknesses
- A novel link between different research areas is not elaborated convincingly enough.
Report
I thank the authors for the effort they put in improving the manuscript, following the suggestions by all referees. In particular, referring to my previous comments:
- the statements about electronic noise are now more precise;
- the addition of the COP analysis is useful and provides a starting point to compare the performance of the proposed setup with further quantifiers, such as the thermodynamic uncertainty relation;
- I greatly appreciate the publication of the data on the quantum trajectory analysis.
Despite these improvements, I stand by the assessment in my previous report that the acceptance criterium mentioned by the authors is not quite met. As I previously mentioned, I do not think that the analysis of the noise and Fano factor qualifies as a novel and synergetic link between different research areas. Indeed, the authors consider a quantity (the current noise) which is also standardly investigated in electronic transport, explaining why in their setup it can show both sub- and super-Poissonian features. However, it is not clear to me how the insights from their analysis are beneficial for electronic transport settings and viceversa.
I would also like to point out that the importance of analysing the fluctuations is well recognised in several works in quantum thermodynamics. While I acknowledge that this analysis is novel for the specific model investigated by the authors, I still fail to see that the authors' work provides the claimed novel and synergetic link.
In conclusion, I think this manuscript is a valuable contribution to the quantum thermodynamics community, but I believe it is more appropriate to recommend publication in SciPost Physics Core, whose acceptance criteria are met.
Recommendation
Accept in alternative Journal (see Report)
Strengths
1- Clearly written
2- Interesting topic
Report
The authors have taken into account the criticism presented by the three Referees to improve the manuscript. I can recommend the present version for publication.
Recommendation
Publish (meets expectations and criteria for this Journal)