SciPost Submission Page
Generalized Gibbs ensembles in weakly interacting dissipative systems and digital quantum computers
by Iris Ulčakar, Zala Lenarčič
Submission summary
| Authors (as registered SciPost users): | Iris Ulcakar |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202408_00014v1 (pdf) |
| Date submitted: | 2024-08-12 17:28 |
| Submitted by: | Ulcakar, Iris |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Identifying use cases with superconducting circuits not critically affected by the inherent noise is a pertinent challenge. Here, we propose using a digital quantum computer to showcase the activation of integrable effects in weakly dissipative integrable systems. Dissipation is realized by coupling the system's qubits to ancillary ones that are periodically reset. We compare the digital reset protocol to the usual Lindblad continuous evolution by considering non-interacting integrable systems dynamics, which can be analyzed using scattering between the Bogoliubov quasiparticles caused by the dissipation. The inherent noise would cause extra scattering but would not critically change the physics. A corresponding quantum computer implementation would illuminate the possibilities of stabilizing exotic states in nearly integrable quantum materials.
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
Current status:
Reports on this Submission
Strengths
1- Well written paper containing exciting results on a timely topic.
2- Combination of analytical and numerical results.
Report
The authors compare different methods for non-interacting, integrable many-body systems that are weakly coupled to baths and explore their potential implementation on digital quantum computers, including platforms like superconducting circuits and trapped ions. The dissipation is realized by coupling the system to ancillas that are periodically reset, and it is demonstrated that highly non-thermal generalized Gibbs ensembles can be stabilized.
Given the interest of the work to the realization on actual NISQ devices, it might be interesting to show some data for small and noisy systems to get an idea about how challenging it would be to observe the non-thermal on actual devices (e.g., using the Qiskit or Cirq simulator that allows including noise models).
The manuscript is well written, and the main results are presented clearly. In summary, this work contains novel and exciting results, and thus I recommend publication in SciPost Physics.
Requested changes
1- Potentially include simulation data on a small and noisy systems.
2- Maybe add a legend to Fig. 1a and Fig. 3 to see the time scales it takes to reach the steady state.
Recommendation
Publish (easily meets expectations and criteria for this Journal; among top 50%)
Strengths
- interesting application of GGE and dissipation
- could be relevant for digital quantum experiments
Weaknesses
- too much overlap with https://arxiv.org/abs/2404.12175
- no numerical confirmations of the main claims
Report
The authors consider a slight generalisation of the circuit implemented in the recent experiments Science 383(6689), 1332 (2024), where a many body system is cooled to low temperature using interaction with a spin ancilla bath that is constantly resetted to its ground state. Here the authors want to show that this cooling if the many-body system is integrable can lead to a GGE and not to a simple low-temperature state. Their approach uses the fact that if the interaction with the ancilla is weak, then one can write a kinetic equation for the quasiparticle of the many-body model (mappable to free fermions).
The calculations seem all correct and the idea is interesting, but it has a large overlap with another publication that came a few months before their work - https://arxiv.org/abs/2404.12175.
Moreover, most of their claims are never substantiated by numerical simulations. Given that the authors want to say that their work is relevant for experiments, they should be able to do a simple numerical simulation other with exact dynamics or MPS for 10 or 20 sites and show the approach to a GGE instead of a GE. Without this, there are too many assumptions (namely that quasiparticles remain stable on the scale where the cooling is done) that make the main results not fully trustable.
Requested changes
- provide numerical simulations to benchmark at least qualitatively the claims
- comment more on the relations with https://arxiv.org/abs/2404.12175
Recommendation
Publish (meets expectations and criteria for this Journal)