---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '21917'
abstract:
- lang: eng
  text: A defining feature of quantum many-body systems is the exponential scaling
    of the Hilbert space with the number of degrees of freedom. This exponential complexity
    naïvely renders a complete state characterization, for instance via the complete
    set of bipartite Renyi entropies for all disjoint regions, a challenging task.
    Recently, a compact way of storing subregions' purities by encoding them as amplitudes
    of a fictitious quantum wave function, known as entanglement feature, was proposed.
    Notably, the entanglement feature can be a simple object even for highly entangled
    quantum states. However the complexity and practical usage of the entanglement
    feature for general quantum states has not been explored. In this work, we demonstrate
    that the entanglement feature can be efficiently learned using only a polynomial
    amount of samples in the number of degrees of freedom through the so-called tensor
    cross interpolation (TCI) algorithm, assuming it is expressible as a finite bond
    dimension MPS. We benchmark this learning process on Haar and random MPS states,
    confirming analytic expectations. Applying the TCI algorithm to quantum eigenstates
    of various one dimensional quantum systems, we identify cases where eigenstates
    have entanglement feature learnable with TCI. We conclude with possible applications
    of the learned entanglement feature, such as quantifying the distance between
    different entanglement patterns and finding the optimal one-dimensional ordering
    of physical indices in a given state, highlighting the potential utility of the
    proposed purity interpolation method.
acknowledgement: "We acknowledge useful discussions with Richard Küng\r\non the interpolation
  methods and error spreading, Ilia\r\nA. Luchnikov, Margarita Davydova, and, in particular,
  Hiroshi Shinaoka, Marc Ritter, Yuriel Nuñez\r\nfor useful discussions about TCI
  and the various\r\nworkarounds within the TensorCrossInterpolation.jl\r\nlibrary.
  We also acknowledge the comments of anonymous Referee B, that encouraged us to expand
  the\r\nmanuscript with discussion of additional applications\r\nof entanglement
  feature in Section 4.3. M.S. acknowledges discussions with D. V. Savostyanov at
  the 2nd\r\nInternational Quantum Tensor Networks (IQTN) plenary meeting at Flatiron
  Institute’s Center for Computational Quantum Physics (CCQ) for introduction\r\nto
  the TCI approach. D.K and M.S. acknowledge support by the European Research Council
  (ERC) under We acknowledge useful discussions with Richard Küng\r\non the interpolation
  methods and error spreading, Ilia\r\nA. Luchnikov, Margarita Davydova, and, in particular,
  Hiroshi Shinaoka, Marc Ritter, Yuriel Nuñez\r\nfor useful discussions about TCI
  and the various\r\nworkarounds within the TensorCrossInterpolation.jl\r\nlibrary.
  We also acknowledge the comments of anonymous Referee B, that encouraged us to expand
  the\r\nmanuscript with discussion of additional applications\r\nof entanglement
  feature in Section 4.3. M.S. acknowledges discussions with D. V. Savostyanov at
  the 2nd\r\nInternational Quantum Tensor Networks (IQTN) plenary meeting at Flatiron
  Institute’s Center for Computational Quantum Physics (CCQ) for introduction\r\nto
  the TCI approach. D.K and M.S. acknowledge support by the European Research Council
  (ERC) under We acknowledge useful discussions with Richard Küng\r\non the interpolation
  methods and error spreading, Ilia\r\nA. Luchnikov, Margarita Davydova, and, in particular,
  Hiroshi Shinaoka, Marc Ritter, Yuriel Nuñez\r\nfor useful discussions about TCI
  and the various\r\nworkarounds within the TensorCrossInterpolation.jl\r\nlibrary.
  We also acknowledge the comments of anonymous Referee B, that encouraged us to expand
  the\r\nmanuscript with discussion of additional applications\r\nof entanglement
  feature in Section 4.3. M.S. acknowledges discussions with D. V. Savostyanov at
  the 2nd\r\nInternational Quantum Tensor Networks (IQTN) plenary meeting at Flatiron
  Institute’s Center for Computational Quantum Physics (CCQ) for introduction\r\nto
  the TCI approach. D.K and M.S. acknowledge support by the European Research Council
  (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant
  Agreement No. 850899).\r\nR.V. acknowledges partial support from the US Department
  of Energy, Office of Science, Basic Energy\r\nSciences, under award No. DE-SC0023999,
  and the\r\nSwiss National Science Foundation (grant 10008234).\r\nThis research
  was supported in part by grant NSF\r\nPHY-2309135 to the Kavli Institute for Theoretical\r\nPhysics
  (KITP)"
article_number: '2114'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Dmytro
  full_name: Kolisnyk, Dmytro
  id: 530a7320-5355-11ee-ae5a-82a46997aaa7
  last_name: Kolisnyk
  orcid: 0000-0002-8612-8202
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Romain
  full_name: Vasseur, Romain
  last_name: Vasseur
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Kolisnyk D, Medina Ramos RA, Vasseur R, Serbyn M. Tensor cross interpolation
    of purities in quantum many-body systems. <i>Quantum</i>. 2026;10. doi:<a href="https://doi.org/10.22331/q-2026-05-22-2114">10.22331/q-2026-05-22-2114</a>
  apa: Kolisnyk, D., Medina Ramos, R. A., Vasseur, R., &#38; Serbyn, M. (2026). Tensor
    cross interpolation of purities in quantum many-body systems. <i>Quantum</i>.
    Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften.
    <a href="https://doi.org/10.22331/q-2026-05-22-2114">https://doi.org/10.22331/q-2026-05-22-2114</a>
  chicago: Kolisnyk, Dmytro, Raimel A Medina Ramos, Romain Vasseur, and Maksym Serbyn.
    “Tensor Cross Interpolation of Purities in Quantum Many-Body Systems.” <i>Quantum</i>.
    Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften,
    2026. <a href="https://doi.org/10.22331/q-2026-05-22-2114">https://doi.org/10.22331/q-2026-05-22-2114</a>.
  ieee: D. Kolisnyk, R. A. Medina Ramos, R. Vasseur, and M. Serbyn, “Tensor cross
    interpolation of purities in quantum many-body systems,” <i>Quantum</i>, vol.
    10. Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften,
    2026.
  ista: Kolisnyk D, Medina Ramos RA, Vasseur R, Serbyn M. 2026. Tensor cross interpolation
    of purities in quantum many-body systems. Quantum. 10, 2114.
  mla: Kolisnyk, Dmytro, et al. “Tensor Cross Interpolation of Purities in Quantum
    Many-Body Systems.” <i>Quantum</i>, vol. 10, 2114, Verein zur Förderung des Open
    Access Publizierens in den Quantenwissenschaften, 2026, doi:<a href="https://doi.org/10.22331/q-2026-05-22-2114">10.22331/q-2026-05-22-2114</a>.
  short: D. Kolisnyk, R.A. Medina Ramos, R. Vasseur, M. Serbyn, Quantum 10 (2026).
corr_author: '1'
date_created: 2026-05-26T19:39:12Z
date_published: 2026-05-22T00:00:00Z
date_updated: 2026-06-02T09:15:13Z
day: '22'
ddc:
- '530'
department:
- _id: MaSe
- _id: GradSch
doi: 10.22331/q-2026-05-22-2114
ec_funded: 1
external_id:
  arxiv:
  - '2503.17230'
file:
- access_level: open_access
  checksum: f8ce78607ad06120cdf894dc8cef55da
  content_type: application/pdf
  creator: dernst
  date_created: 2026-06-02T09:12:11Z
  date_updated: 2026-06-02T09:12:11Z
  file_id: '21939'
  file_name: 2026_Quantum_Kolisnyk.pdf
  file_size: 3284798
  relation: main_file
  success: 1
file_date_updated: 2026-06-02T09:12:11Z
fulldoi: https://doi.org/10.22331/q-2026-05-22-2114
has_accepted_license: '1'
intvolume: '        10'
language:
- iso: eng
month: '05'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Quantum
publication_identifier:
  eissn:
  - 2521-327X
publication_status: published
publisher: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
quality_controlled: '1'
status: public
title: Tensor cross interpolation of purities in quantum many-body systems
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 10
year: '2026'
...
---
OA_place: repository
OA_type: green
_id: '21272'
abstract:
- lang: eng
  text: Finding the ground state of Ising spin glasses is notoriously difficult due
    to disorder and frustration. Often, this challenge is framed as a combinatorial
    optimization problem, for which a common strategy employs simulated annealing,
    a Monte Carlo (MC)-based algorithm that updates spins one at a time. Yet, these
    localized updates can cause the system to become trapped in local minima. Cluster
    algorithms (CAs) were developed to address this limitation and have demonstrated
    considerable success in studying ferromagnetic systems; however, they tend to
    encounter percolation issues when applied to generic spin glasses. In this work,
    we introduce a novel CA designed to tackle these challenges by leveraging precomputed
    two-point correlations, aiming solve combinatorial optimization problems in the
    form of Max-Cut more efficiently. In our approach, clusters are formed probabilistically
    based on these correlations. Various classical and quantum algorithms can be employed
    to generate correlations that embody information about the energy landscape of
    the problem. By utilizing this information, the algorithm aims to identify groups
    of spins whose simultaneous flipping induces large transitions in configuration
    space with high acceptance probability - even at low energy levels - thereby escaping
    local minima more effectively. Notably, clusters generated using correlations
    from the Quantum Approximate Optimization Algorithm exhibit high acceptance rates
    at low temperatures. These acceptance rates often increase with circuit depth,
    accelerating the algorithm and enabling more efficient exploration of the solution
    space.
acknowledgement: "P.J.E was partially funded by the German BMWK project QCHALLenge
  (Grant No. 01MQ22008B).\r\n"
article_processing_charge: No
arxiv: 1
author:
- first_name: Peter J.
  full_name: Eder, Peter J.
  last_name: Eder
- first_name: Aron
  full_name: Kerschbaumer, Aron
  id: ade85a9c-3200-11ee-973b-91c1eb240410
  last_name: Kerschbaumer
  orcid: 0009-0002-2370-8661
- first_name: Jernej Rudi
  full_name: Finžgar, Jernej Rudi
  last_name: Finžgar
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Martin J. A.
  full_name: Schuetz, Martin J. A.
  last_name: Schuetz
- first_name: Helmut G.
  full_name: Katzgraber, Helmut G.
  last_name: Katzgraber
- first_name: Sarah
  full_name: Braun, Sarah
  last_name: Braun
- first_name: Christian B.
  full_name: Mendl, Christian B.
  last_name: Mendl
citation:
  ama: 'Eder PJ, Kerschbaumer A, Finžgar JR, et al. Quantum-guided cluster algorithms
    for combinatorial optimization. In: <i>2025 IEEE International Conference on Quantum
    Computing and Engineering</i>. IEEE; 2025. doi:<a href="https://doi.org/10.1109/qce65121.2025.00033">10.1109/qce65121.2025.00033</a>'
  apa: 'Eder, P. J., Kerschbaumer, A., Finžgar, J. R., Medina Ramos, R. A., Schuetz,
    M. J. A., Katzgraber, H. G., … Mendl, C. B. (2025). Quantum-guided cluster algorithms
    for combinatorial optimization. In <i>2025 IEEE International Conference on Quantum
    Computing and Engineering</i>. Albuquerque, NM, United States: IEEE. <a href="https://doi.org/10.1109/qce65121.2025.00033">https://doi.org/10.1109/qce65121.2025.00033</a>'
  chicago: Eder, Peter J., Aron Kerschbaumer, Jernej Rudi Finžgar, Raimel A Medina
    Ramos, Martin J. A. Schuetz, Helmut G. Katzgraber, Sarah Braun, and Christian
    B. Mendl. “Quantum-Guided Cluster Algorithms for Combinatorial Optimization.”
    In <i>2025 IEEE International Conference on Quantum Computing and Engineering</i>.
    IEEE, 2025. <a href="https://doi.org/10.1109/qce65121.2025.00033">https://doi.org/10.1109/qce65121.2025.00033</a>.
  ieee: P. J. Eder <i>et al.</i>, “Quantum-guided cluster algorithms for combinatorial
    optimization,” in <i>2025 IEEE International Conference on Quantum Computing and
    Engineering</i>, Albuquerque, NM, United States, 2025.
  ista: 'Eder PJ, Kerschbaumer A, Finžgar JR, Medina Ramos RA, Schuetz MJA, Katzgraber
    HG, Braun S, Mendl CB. 2025. Quantum-guided cluster algorithms for combinatorial
    optimization. 2025 IEEE International Conference on Quantum Computing and Engineering.
    QCE: International Conference on Quantum Computing and Engineering.'
  mla: Eder, Peter J., et al. “Quantum-Guided Cluster Algorithms for Combinatorial
    Optimization.” <i>2025 IEEE International Conference on Quantum Computing and
    Engineering</i>, IEEE, 2025, doi:<a href="https://doi.org/10.1109/qce65121.2025.00033">10.1109/qce65121.2025.00033</a>.
  short: P.J. Eder, A. Kerschbaumer, J.R. Finžgar, R.A. Medina Ramos, M.J.A. Schuetz,
    H.G. Katzgraber, S. Braun, C.B. Mendl, in:, 2025 IEEE International Conference
    on Quantum Computing and Engineering, IEEE, 2025.
conference:
  end_date: 2025-09-05
  location: Albuquerque, NM, United States
  name: 'QCE: International Conference on Quantum Computing and Engineering'
  start_date: 2025-08-30
corr_author: '1'
date_created: 2026-02-17T08:00:17Z
date_published: 2025-09-01T00:00:00Z
date_updated: 2026-02-18T08:45:56Z
day: '01'
department:
- _id: MaSe
doi: 10.1109/qce65121.2025.00033
external_id:
  arxiv:
  - '2508.10656'
fulldoi: https://doi.org/10.1109/qce65121.2025.00033
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.48550/arXiv.2508.10656
month: '09'
oa: 1
oa_version: Preprint
publication: 2025 IEEE International Conference on Quantum Computing and Engineering
publication_identifier:
  eisbn:
  - '9798331557362'
publication_status: published
publisher: IEEE
quality_controlled: '1'
status: public
title: Quantum-guided cluster algorithms for combinatorial optimization
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2025'
...
---
OA_place: publisher
_id: '17208'
abstract:
- lang: eng
  text: "Can current quantum computers provide a speedup over their classical counterparts
    for some kinds of problems? In this thesis, with a focus on ground state search/preparation,
    we address some of the challenges that both quantum annealing and variational
    quantum algorithms suffer from, hindering any possible practical speedup in comparison
    to the best classical counterparts. \r\n\r\nIn the first part of the thesis, we
    study the performance of quantum annealing for solving a particular combinatorial
    optimization problem called 3-XOR satisfability (3-XORSAT). The classical problem
    is mapped into a ground state search of a 3-local classical Hamiltonian $H_C$.
    We consider how modifying the initial problem, by adding more interaction terms
    to the corresponding Hamiltonian, leads to the emergence of a first-order phase
    transition during the annealing process. This phenomenon causes the total annealing
    duration, $T$, required to prepare the ground state of $H_C$ with a high probability
    to increase exponentially with the size of the problem. Our findings indicate
    that with the growing complexity of problem instances, the likelihood of encountering
    first-order phase transitions also increases, making quantum annealing an impractical
    solution for these types of combinatorial optimization problems.\r\n\r\nIn the
    second part, we focus on the problem of barren plateaus in generic variational
    quantum algorithms. Barren plateaus correspond to flat regions in the parameter
    space where the gradient of the cost function is zero in expectation, and with
    the variance decaying exponentially with the system size, thus obstructing an
    efficient parameter optimization.  We propose an algorithm to circumvent Barren
    Plateaus by monitoring the entanglement entropy of k-local reduced density matrices,
    alongside a method for estimating entanglement entropy via classical shadow tomography.
    We illustrate the approach with the paradigmatic example of the variational quantum
    eigensolver, and show that our algorithm effectively avoids barren plateaus in
    the initialization as well as during the optimization stage. \r\n\r\nLastly, in
    the last two Chapters of this thesis, we focus on the quantum approximate optimization
    algorithm (QAOA), originally introduced as an algorithm for solving generic combinatorial
    optimization problems in near-term quantum devices. Specifically, we focus on
    how to develop rigorous initialization strategies with guarantee improvement.
    Our motivation for this study lies in that for random initialization, the optimization
    typically leads to local minima with poor performance. Our main result corresponds
    to the analytical construction of index-1 saddle points or transition states,
    stationary points with a single direction of descent, as a tool for systematically
    exploring the QAOA optimization landscape. This leads us to propose a novel greedy
    parameter initialization strategy that guarantees for the energy to decrease with
    an increasing number of circuit layers. Furthermore, with precise estimates for
    the negative Hessian eigenvalue and its eigenvector, we establish a lower bound
    for energy improvement following a QAOA iteration."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
citation:
  ama: Medina Ramos RA. Exploring the optimization landscape of variational quantum
    algorithms. 2024. doi:<a href="https://doi.org/10.15479/at:ista:17208">10.15479/at:ista:17208</a>
  apa: Medina Ramos, R. A. (2024). <i>Exploring the optimization landscape of variational
    quantum algorithms</i>. Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:17208">https://doi.org/10.15479/at:ista:17208</a>
  chicago: Medina Ramos, Raimel A. “Exploring the Optimization Landscape of Variational
    Quantum Algorithms.” Institute of Science and Technology Austria, 2024. <a href="https://doi.org/10.15479/at:ista:17208">https://doi.org/10.15479/at:ista:17208</a>.
  ieee: R. A. Medina Ramos, “Exploring the optimization landscape of variational quantum
    algorithms,” Institute of Science and Technology Austria, 2024.
  ista: Medina Ramos RA. 2024. Exploring the optimization landscape of variational
    quantum algorithms. Institute of Science and Technology Austria.
  mla: Medina Ramos, Raimel A. <i>Exploring the Optimization Landscape of Variational
    Quantum Algorithms</i>. Institute of Science and Technology Austria, 2024, doi:<a
    href="https://doi.org/10.15479/at:ista:17208">10.15479/at:ista:17208</a>.
  short: R.A. Medina Ramos, Exploring the Optimization Landscape of Variational Quantum
    Algorithms, Institute of Science and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-07-09T09:14:24Z
date_published: 2024-07-09T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '09'
ddc:
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaSe
doi: 10.15479/at:ista:17208
ec_funded: 1
file:
- access_level: closed
  checksum: 6f45273d04f4418bc2adc018baed0525
  content_type: application/zip
  creator: rmedinar
  date_created: 2024-07-09T09:21:44Z
  date_updated: 2024-07-10T11:34:09Z
  file_id: '17212'
  file_name: Raimel_Thesis-Final.zip
  file_size: '14218691'
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  checksum: 6724a95bec772dbabc0111b9f08a805e
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  file_id: '17275'
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  success: 1
file_date_updated: 2024-07-17T09:23:24Z
fulldoi: https://doi.org/10.15479/at:ista:17208
has_accepted_license: '1'
keyword:
- Quantum computing
- Variational Quantum Algorithms
- Optimization
language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '133'
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '10545'
    relation: part_of_dissertation
    status: public
  - id: '10067'
    relation: part_of_dissertation
    status: public
  - id: '17222'
    relation: part_of_dissertation
    status: public
  - id: '13125'
    relation: part_of_dissertation
    status: public
  - id: '11471'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
title: Exploring the optimization landscape of variational quantum algorithms
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...
---
OA_place: repository
_id: '17222'
abstract:
- lang: eng
  text: "The quantum approximate optimization algorithm (QAOA) uses a quantum computer\r\nto
    implement a variational method with $2p$ layers of alternating unitary\r\noperators,
    optimized by a classical computer to minimize a cost function. While\r\nrigorous
    performance guarantees exist for the QAOA at small depths $p$, the\r\nbehavior
    at large depths remains less clear, though simulations suggest\r\nexponentially
    fast convergence for certain problems. In this work, we gain\r\ninsights into
    the deep QAOA using an analytic expansion of the cost function\r\naround transition
    states. Transition states are constructed in a recursive\r\nmanner: from the local
    minima of the QAOA with $p$ layers we obtain transition\r\nstates of the QAOA
    with $p+1$ layers, which are stationary points characterized\r\nby a unique direction
    of negative curvature. We construct an analytic estimate\r\nof the negative curvature
    and the corresponding direction in parameter space at\r\neach transition state.
    The expansion of the QAOA cost function along the\r\nnegative direction to the
    quartic order gives a lower bound of the QAOA cost\r\nfunction improvement. We
    provide physical intuition behind the analytic\r\nexpressions for the local curvature
    and quartic expansion coefficient. Our\r\nnumerical study confirms the accuracy
    of our approximations and reveals that\r\nthe obtained bound and the true value
    of the QAOA cost function gain have a\r\ncharacteristic exponential decrease with
    the number of layers $p$, with the\r\nbound decreasing more rapidly. Our study
    establishes an analytical method for\r\nrecursively studying the QAOA that is
    applicable in the regime of high circuit\r\ndepth."
article_number: '2405.10125'
article_processing_charge: No
arxiv: 1
author:
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Medina Ramos RA, Serbyn M. A recursive lower bound on the energy improvement
    of the quantum approximate optimization algorithm. <i>arXiv</i>. doi:<a href="https://doi.org/10.48550/arXiv.2405.10125">10.48550/arXiv.2405.10125</a>
  apa: Medina Ramos, R. A., &#38; Serbyn, M. (n.d.). A recursive lower bound on the
    energy improvement of the quantum approximate optimization algorithm. <i>arXiv</i>.
    <a href="https://doi.org/10.48550/arXiv.2405.10125">https://doi.org/10.48550/arXiv.2405.10125</a>
  chicago: Medina Ramos, Raimel A, and Maksym Serbyn. “A Recursive Lower Bound on
    the Energy Improvement of the Quantum Approximate Optimization Algorithm.” <i>ArXiv</i>,
    n.d. <a href="https://doi.org/10.48550/arXiv.2405.10125">https://doi.org/10.48550/arXiv.2405.10125</a>.
  ieee: R. A. Medina Ramos and M. Serbyn, “A recursive lower bound on the energy improvement
    of the quantum approximate optimization algorithm,” <i>arXiv</i>. .
  ista: Medina Ramos RA, Serbyn M. A recursive lower bound on the energy improvement
    of the quantum approximate optimization algorithm. arXiv, 2405.10125.
  mla: Medina Ramos, Raimel A., and Maksym Serbyn. “A Recursive Lower Bound on the
    Energy Improvement of the Quantum Approximate Optimization Algorithm.” <i>ArXiv</i>,
    2405.10125, doi:<a href="https://doi.org/10.48550/arXiv.2405.10125">10.48550/arXiv.2405.10125</a>.
  short: R.A. Medina Ramos, M. Serbyn, ArXiv (n.d.).
corr_author: '1'
date_created: 2024-07-10T13:12:09Z
date_published: 2024-05-16T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '16'
department:
- _id: MaSe
doi: 10.48550/arXiv.2405.10125
external_id:
  arxiv:
  - '2405.10125'
fulldoi: https://doi.org/10.48550/arXiv.2405.10125
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.48550/arXiv.2405.10125
month: '05'
oa: 1
oa_version: Preprint
publication: arXiv
publication_status: draft
related_material:
  record:
  - id: '17208'
    relation: dissertation_contains
    status: public
status: public
title: A recursive lower bound on the energy improvement of the quantum approximate
  optimization algorithm
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2024'
...
---
_id: '13125'
abstract:
- lang: eng
  text: 'The quantum approximate optimization algorithm (QAOA) is a variational quantum
    algorithm, where a quantum computer implements a variational ansatz consisting
    of p layers of alternating unitary operators and a classical computer is used
    to optimize the variational parameters. For a random initialization, the optimization
    typically leads to local minima with poor performance, motivating the search for
    initialization strategies of QAOA variational parameters. Although numerous heuristic
    initializations exist, an analytical understanding and performance guarantees
    for large p remain evasive.We introduce a greedy initialization of QAOA which
    guarantees improving performance with an increasing number of layers. Our main
    result is an analytic construction of 2p + 1 transition states—saddle points with
    a unique negative curvature direction—for QAOA with p + 1 layers that use the
    local minimum of QAOA with p layers. Transition states connect to new local minima,
    which are guaranteed to lower the energy compared to the minimum found for p layers.
    We use the GREEDY procedure to navigate the exponentially increasing with p number
    of local minima resulting from the recursive application of our analytic construction.
    The performance of the GREEDY procedure matches available initialization strategies
    while providing a guarantee for the minimal energy to decrease with an increasing
    number of layers p. '
acknowledgement: 'We thank V. Verteletskyi for a joint collaboration on numerical
  studies of the QAOA during his internship at ISTA that inspired analytic results
  on TS reported in this work. We acknowledge A. A. Mele and M. Brooks for discussions
  and D. Egger, P. Love, and D. Wierichs for valuable feedback on the manuscript.
  S.H.S., R.A.M., and M.S. acknowledge support by the European Research Council (ERC)
  under the European Union’s Horizon 2020 research and innovation program (Grant Agreement
  No. 850899). R.K. is supported by the SFB BeyondC (Grant No. F7107-N38) and the
  project QuantumReady (FFG 896217). '
article_number: '062404'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Stefan
  full_name: Sack, Stefan
  id: dd622248-f6e0-11ea-865d-ce382a1c81a5
  last_name: Sack
  orcid: 0000-0001-5400-8508
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Richard
  full_name: Kueng, Richard
  last_name: Kueng
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Sack S, Medina Ramos RA, Kueng R, Serbyn M. Recursive greedy initialization
    of the quantum approximate optimization algorithm with guaranteed improvement.
    <i>Physical Review A</i>. 2023;107(6). doi:<a href="https://doi.org/10.1103/physreva.107.062404">10.1103/physreva.107.062404</a>
  apa: Sack, S., Medina Ramos, R. A., Kueng, R., &#38; Serbyn, M. (2023). Recursive
    greedy initialization of the quantum approximate optimization algorithm with guaranteed
    improvement. <i>Physical Review A</i>. American Physical Society. <a href="https://doi.org/10.1103/physreva.107.062404">https://doi.org/10.1103/physreva.107.062404</a>
  chicago: Sack, Stefan, Raimel A Medina Ramos, Richard Kueng, and Maksym Serbyn.
    “Recursive Greedy Initialization of the Quantum Approximate Optimization Algorithm
    with Guaranteed Improvement.” <i>Physical Review A</i>. American Physical Society,
    2023. <a href="https://doi.org/10.1103/physreva.107.062404">https://doi.org/10.1103/physreva.107.062404</a>.
  ieee: S. Sack, R. A. Medina Ramos, R. Kueng, and M. Serbyn, “Recursive greedy initialization
    of the quantum approximate optimization algorithm with guaranteed improvement,”
    <i>Physical Review A</i>, vol. 107, no. 6. American Physical Society, 2023.
  ista: Sack S, Medina Ramos RA, Kueng R, Serbyn M. 2023. Recursive greedy initialization
    of the quantum approximate optimization algorithm with guaranteed improvement.
    Physical Review A. 107(6), 062404.
  mla: Sack, Stefan, et al. “Recursive Greedy Initialization of the Quantum Approximate
    Optimization Algorithm with Guaranteed Improvement.” <i>Physical Review A</i>,
    vol. 107, no. 6, 062404, American Physical Society, 2023, doi:<a href="https://doi.org/10.1103/physreva.107.062404">10.1103/physreva.107.062404</a>.
  short: S. Sack, R.A. Medina Ramos, R. Kueng, M. Serbyn, Physical Review A 107 (2023).
corr_author: '1'
date_created: 2023-06-07T06:57:32Z
date_published: 2023-06-02T00:00:00Z
date_updated: 2026-09-11T22:31:10Z
day: '02'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/physreva.107.062404
ec_funded: 1
external_id:
  arxiv:
  - '2209.01159'
  isi:
  - '001016927100012'
file:
- access_level: open_access
  checksum: 0d71423888eeccaa60d8f41197f26306
  content_type: application/pdf
  creator: dernst
  date_created: 2023-06-13T07:28:36Z
  date_updated: 2023-06-13T07:28:36Z
  file_id: '13131'
  file_name: 2023_PhysRevA_Sack.pdf
  file_size: 2524611
  relation: main_file
  success: 1
file_date_updated: 2023-06-13T07:28:36Z
fulldoi: https://doi.org/10.1103/physreva.107.062404
has_accepted_license: '1'
intvolume: '       107'
isi: 1
issue: '6'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review A
publication_identifier:
  eissn:
  - 2469-9934
  issn:
  - 2469-9926
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '17208'
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    status: public
  - id: '14622'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: Recursive greedy initialization of the quantum approximate optimization algorithm
  with guaranteed improvement
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 107
year: '2023'
...
---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '10769'
abstract:
- lang: eng
  text: studiamos aspectos de Teoría Cuántica de Campos a densidad finita usando técnicas
    y conceptos de información cuántica. Nos enfocamos en fermiones de Dirac masivos
    con potencial químico en 1+1 dimensiones espacio-temporales. Usando la entropía
    de entrelazamiento en un intervalo, construimos la función c entrópica que es
    finita. Esta función c no es monótona, e incorpora el entrelazamiento de largo
    alcance proveniente de la superficie de Fermi. Motivados por trabajos previos
    de modelos en la red, calculamos numéricamente las entropías de Renyi y encontramos
    oscilaciones de Friedel. Seguidamente, analizamos la información mutua como una
    medida de correlación entre diferentes regiones. Usando una expansión de distancia
    grande desarrollada por Cardy, argumentamos que la información mutua detecta las
    correlaciones inducidas por la superficie de Fermi todavía al orden dominante
    en la expansión. Finalmente, analizamos la entropía relativa y sus generalizaciones
    de Renyi para distinguir estados con diferente carga. Encontramos que estados
    en diferentes sectores de superselección dan origen a un comportamiento super-extensivo
    en la entropía relativa.
acknowledgement: "Se agradece a Horacio Casini por distintas discusiones y comentarios
  a lo largo del trabajo. LD cuenta con el apoyo de CNEA y UNCuyo, Inst. GT cuenta
  con el apoyo de CONICET,\r\nANPCyT, CNEA, y UNCuyo, Inst. Balseiro. RM cuenta con
  el apoyo de IST Austria. MS cuenta con el apoyode CONICET y UNCuyo, Inst. Balseiro.
  También se agradece a la Asociación Argentina de Física por la posibilidad de presentar
  este artículo en el marco de una Mención Especial por el Premio Luis Másperi 2020."
article_processing_charge: No
article_type: original
author:
- first_name: L.
  full_name: Daguerre, L.
  last_name: Daguerre
- first_name: G.
  full_name: Torroba, G.
  last_name: Torroba
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: M.
  full_name: Solís, M.
  last_name: Solís
citation:
  ama: 'Daguerre L, Torroba G, Medina Ramos RA, Solís M. Non relativistic quantum
    field theory: Dynamics and irreversibility. <i>Anales de la Asociacion Fisica
    Argentina</i>. 2022;32(4):93-98. doi:<a href="https://doi.org/10.31527/analesafa.2021.32.4.93">10.31527/analesafa.2021.32.4.93</a>'
  apa: 'Daguerre, L., Torroba, G., Medina Ramos, R. A., &#38; Solís, M. (2022). Non
    relativistic quantum field theory: Dynamics and irreversibility. <i>Anales de
    la Asociacion Fisica Argentina</i>. Asociación Física Argentina. <a href="https://doi.org/10.31527/analesafa.2021.32.4.93">https://doi.org/10.31527/analesafa.2021.32.4.93</a>'
  chicago: 'Daguerre, L., G. Torroba, Raimel A Medina Ramos, and M. Solís. “Non relativistic
    quantum field theory: Dynamics and irreversibility.” <i>Anales de la Asociacion
    Fisica Argentina</i>. Asociación Física Argentina, 2022. <a href="https://doi.org/10.31527/analesafa.2021.32.4.93">https://doi.org/10.31527/analesafa.2021.32.4.93</a>.'
  ieee: 'L. Daguerre, G. Torroba, R. A. Medina Ramos, and M. Solís, “Non relativistic
    quantum field theory: Dynamics and irreversibility,” <i>Anales de la Asociacion
    Fisica Argentina</i>, vol. 32, no. 4. Asociación Física Argentina, pp. 93–98,
    2022.'
  ista: 'Daguerre L, Torroba G, Medina Ramos RA, Solís M. 2022. Non relativistic quantum
    field theory: Dynamics and irreversibility. Anales de la Asociacion Fisica Argentina.
    32(4), 93–98.'
  mla: 'Daguerre, L., et al. “Non relativistic quantum field theory: Dynamics and
    irreversibility.” <i>Anales de la Asociacion Fisica Argentina</i>, vol. 32, no.
    4, Asociación Física Argentina, 2022, pp. 93–98, doi:<a href="https://doi.org/10.31527/analesafa.2021.32.4.93">10.31527/analesafa.2021.32.4.93</a>.'
  short: L. Daguerre, G. Torroba, R.A. Medina Ramos, M. Solís, Anales de la Asociacion
    Fisica Argentina 32 (2022) 93–98.
date_created: 2022-02-20T23:01:32Z
date_published: 2022-01-13T00:00:00Z
date_updated: 2026-04-02T12:30:12Z
day: '13'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.31527/analesafa.2021.32.4.93
file:
- access_level: open_access
  checksum: ca66a3017205677c5b4d22b3bb74fb0b
  content_type: application/pdf
  creator: dernst
  date_created: 2022-02-21T09:32:44Z
  date_updated: 2022-02-21T09:32:44Z
  file_id: '10782'
  file_name: 2022_AnalesAFA_Daguerre.pdf
  file_size: 4505751
  relation: main_file
  success: 1
file_date_updated: 2022-02-21T09:32:44Z
fulldoi: https://doi.org/10.31527/analesafa.2021.32.4.93
has_accepted_license: '1'
intvolume: '        32'
issue: '4'
language:
- iso: spa
month: '01'
oa: 1
oa_version: Published Version
page: 93-98
publication: Anales de la Asociacion Fisica Argentina
publication_identifier:
  eissn:
  - 1850-1168
publication_status: published
publisher: Asociación Física Argentina
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Non relativistic quantum field theory: Dynamics and irreversibility'
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
volume: 32
year: '2022'
...
---
_id: '11471'
abstract:
- lang: eng
  text: 'Variational quantum algorithms are promising algorithms for achieving quantum
    advantage on nearterm devices. The quantum hardware is used to implement a variational
    wave function and measure observables, whereas the classical computer is used
    to store and update the variational parameters. The optimization landscape of
    expressive variational ansätze is however dominated by large regions in parameter
    space, known as barren plateaus, with vanishing gradients, which prevents efficient
    optimization. In this work we propose a general algorithm to avoid barren plateaus
    in the initialization and throughout the optimization. To this end we define a
    notion of weak barren plateaus (WBPs) based on the entropies of local reduced
    density matrices. The presence of WBPs can be efficiently quantified using recently
    introduced shadow tomography of the quantum state with a classical computer. We
    demonstrate that avoidance of WBPs suffices to ensure sizable gradients in the
    initialization. In addition, we demonstrate that decreasing the gradient step
    size, guided by the entropies allows WBPs to be avoided during the optimization
    process. This paves the way for efficient barren plateau-free optimization on
    near-term devices. '
acknowledgement: "We thank Marco Cerezo, Zoe Holmes, and Nicholas Hunter-Jones for
  fruitful discussion and valuable feedback. We also acknowledge Adam Smith, Johannes
  Jakob Meyer, and Victor V. Albert for comments on the paper. The simulations were
  performed in the Julia programming\r\nlanguage [65] using the Yao module [66]. S.H.S.,
  R.A.M., A.A.M. and M.S. acknowledge support by the European Research Council (ERC)
  under the European Union’s Horizon 2020 research and innovation program (Grant Agreement
  No. 850899)."
article_number: '020365'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Stefan
  full_name: Sack, Stefan
  id: dd622248-f6e0-11ea-865d-ce382a1c81a5
  last_name: Sack
  orcid: 0000-0001-5400-8508
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Alexios
  full_name: Michailidis, Alexios
  id: 36EBAD38-F248-11E8-B48F-1D18A9856A87
  last_name: Michailidis
  orcid: 0000-0002-8443-1064
- first_name: Richard
  full_name: Kueng, Richard
  last_name: Kueng
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. Avoiding barren
    plateaus using classical shadows. <i>PRX Quantum</i>. 2022;3(2). doi:<a href="https://doi.org/10.1103/prxquantum.3.020365">10.1103/prxquantum.3.020365</a>
  apa: Sack, S., Medina Ramos, R. A., Michailidis, A., Kueng, R., &#38; Serbyn, M.
    (2022). Avoiding barren plateaus using classical shadows. <i>PRX Quantum</i>.
    American Physical Society. <a href="https://doi.org/10.1103/prxquantum.3.020365">https://doi.org/10.1103/prxquantum.3.020365</a>
  chicago: Sack, Stefan, Raimel A Medina Ramos, Alexios Michailidis, Richard Kueng,
    and Maksym Serbyn. “Avoiding Barren Plateaus Using Classical Shadows.” <i>PRX
    Quantum</i>. American Physical Society, 2022. <a href="https://doi.org/10.1103/prxquantum.3.020365">https://doi.org/10.1103/prxquantum.3.020365</a>.
  ieee: S. Sack, R. A. Medina Ramos, A. Michailidis, R. Kueng, and M. Serbyn, “Avoiding
    barren plateaus using classical shadows,” <i>PRX Quantum</i>, vol. 3, no. 2. American
    Physical Society, 2022.
  ista: Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. 2022. Avoiding
    barren plateaus using classical shadows. PRX Quantum. 3(2), 020365.
  mla: Sack, Stefan, et al. “Avoiding Barren Plateaus Using Classical Shadows.” <i>PRX
    Quantum</i>, vol. 3, no. 2, 020365, American Physical Society, 2022, doi:<a href="https://doi.org/10.1103/prxquantum.3.020365">10.1103/prxquantum.3.020365</a>.
  short: S. Sack, R.A. Medina Ramos, A. Michailidis, R. Kueng, M. Serbyn, PRX Quantum
    3 (2022).
corr_author: '1'
date_created: 2022-06-29T20:21:32Z
date_published: 2022-06-29T00:00:00Z
date_updated: 2026-09-11T22:31:10Z
day: '29'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/prxquantum.3.020365
ec_funded: 1
external_id:
  arxiv:
  - '2201.08194'
  isi:
  - '000822564300001'
file:
- access_level: open_access
  checksum: a7706b28d24a0e32a55ea04b82a2df43
  content_type: application/pdf
  creator: dernst
  date_created: 2022-06-30T07:14:48Z
  date_updated: 2022-06-30T07:14:48Z
  file_id: '11472'
  file_name: 2022_PRXQuantum_Sack.pdf
  file_size: 4231591
  relation: main_file
  success: 1
file_date_updated: 2022-06-30T07:14:48Z
fulldoi: https://doi.org/10.1103/prxquantum.3.020365
has_accepted_license: '1'
intvolume: '         3'
isi: 1
issue: '2'
keyword:
- General Medicine
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: PRX Quantum
publication_identifier:
  issn:
  - 2691-3399
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
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  - id: '17208'
    relation: dissertation_contains
    status: public
  - id: '14622'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: Avoiding barren plateaus using classical shadows
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 3
year: '2022'
...
---
_id: '15269'
abstract:
- lang: eng
  text: We study different aspects of quantum field theory at finite density using
    methods from quantum information theory. For simplicity we focus on massive Dirac
    fermions with nonzero chemical potential, and work in 1 + 1 space-time dimensions.
    Using the entanglement entropy on an interval, we construct an entropic <jats:italic>c</jats:italic>-function
    that is finite. Unlike what happens in Lorentz-invariant theories, this <jats:italic>c</jats:italic>-function
    exhibits a strong violation of monotonicity; it also encodes the creation of long-range
    entanglement from the Fermi surface. Motivated by previous works on lattice models,
    we next calculate numerically the Renyi entropies and find Friedel-type oscillations;
    these are understood in terms of a defect operator product expansion. Furthermore,
    we consider the mutual information as a measure of correlation functions between
    different regions. Using a long-distance expansion previously developed by Cardy,
    we argue that the mutual information detects Fermi surface correlations already
    at leading order in the expansion. We also analyze the relative entropy and its
    Renyi generalizations in order to distinguish states with different charge and/or
    mass. In particular, we show that states in different superselection sectors give
    rise to a super-extensive behavior in the relative entropy. Finally, we discuss
    possible extensions to interacting theories, and argue for the relevance of some
    of these measures for probing non-Fermi liquids.
acknowledgement: "We thank H. Casini for many interesting discussions and comments
  on the manuscript.\r\nLD is supported by CNEA and UNCuyo, Inst. Balseiro. RM is
  supported by IST Austria.\r\nMS is supported by CONICET and UNCuyo, Inst. Balseiro.
  GT is supported by CONICET\r\n(PIP grant 11220150100299), ANPCyT (PICT 2018-2517),
  CNEA, and UNCuyo,\r\nInst. Balseiro."
article_number: '79'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Lucas
  full_name: Daguerre, Lucas
  last_name: Daguerre
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Mario
  full_name: Solís, Mario
  last_name: Solís
- first_name: Gonzalo
  full_name: Torroba, Gonzalo
  last_name: Torroba
citation:
  ama: Daguerre L, Medina Ramos RA, Solís M, Torroba G. Aspects of quantum information
    in finite density field theory. <i>Journal of High Energy Physics</i>. 2021;2021(3).
    doi:<a href="https://doi.org/10.1007/jhep03(2021)079">10.1007/jhep03(2021)079</a>
  apa: Daguerre, L., Medina Ramos, R. A., Solís, M., &#38; Torroba, G. (2021). Aspects
    of quantum information in finite density field theory. <i>Journal of High Energy
    Physics</i>. Springer Nature. <a href="https://doi.org/10.1007/jhep03(2021)079">https://doi.org/10.1007/jhep03(2021)079</a>
  chicago: Daguerre, Lucas, Raimel A Medina Ramos, Mario Solís, and Gonzalo Torroba.
    “Aspects of Quantum Information in Finite Density Field Theory.” <i>Journal of
    High Energy Physics</i>. Springer Nature, 2021. <a href="https://doi.org/10.1007/jhep03(2021)079">https://doi.org/10.1007/jhep03(2021)079</a>.
  ieee: L. Daguerre, R. A. Medina Ramos, M. Solís, and G. Torroba, “Aspects of quantum
    information in finite density field theory,” <i>Journal of High Energy Physics</i>,
    vol. 2021, no. 3. Springer Nature, 2021.
  ista: Daguerre L, Medina Ramos RA, Solís M, Torroba G. 2021. Aspects of quantum
    information in finite density field theory. Journal of High Energy Physics. 2021(3),
    79.
  mla: Daguerre, Lucas, et al. “Aspects of Quantum Information in Finite Density Field
    Theory.” <i>Journal of High Energy Physics</i>, vol. 2021, no. 3, 79, Springer
    Nature, 2021, doi:<a href="https://doi.org/10.1007/jhep03(2021)079">10.1007/jhep03(2021)079</a>.
  short: L. Daguerre, R.A. Medina Ramos, M. Solís, G. Torroba, Journal of High Energy
    Physics 2021 (2021).
corr_author: '1'
date_created: 2024-04-03T07:51:06Z
date_published: 2021-03-08T00:00:00Z
date_updated: 2025-09-10T10:15:02Z
day: '08'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1007/jhep03(2021)079
external_id:
  arxiv:
  - '2011.01252'
  isi:
  - '000627376600004'
file:
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fulldoi: https://doi.org/10.1007/jhep03(2021)079
has_accepted_license: '1'
intvolume: '      2021'
isi: 1
issue: '3'
keyword:
- Nuclear and High Energy Physics
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
publication: Journal of High Energy Physics
publication_identifier:
  issn:
  - 1029-8479
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Aspects of quantum information in finite density field theory
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 2021
year: '2021'
...
---
_id: '10067'
abstract:
- lang: eng
  text: The search for novel entangled phases of matter has lead to the recent discovery
    of a new class of “entanglement transitions,” exemplified by random tensor networks
    and monitored quantum circuits. Most known examples can be understood as some
    classical ordering transitions in an underlying statistical mechanics model, where
    entanglement maps onto the free-energy cost of inserting a domain wall. In this
    paper we study the possibility of entanglement transitions driven by physics beyond
    such statistical mechanics mappings. Motivated by recent applications of neural-network-inspired
    variational Ansätze, we investigate under what conditions on the variational parameters
    these Ansätze can capture an entanglement transition. We study the entanglement
    scaling of short-range restricted Boltzmann machine (RBM) quantum states with
    random phases. For uncorrelated random phases, we analytically demonstrate the
    absence of an entanglement transition and reveal subtle finite-size effects in
    finite-size numerical simulations. Introducing phases with correlations decaying
    as 1/r^α in real space, we observe three regions with a different scaling of entanglement
    entropy depending on the exponent α. We study the nature of the transition between
    these regions, finding numerical evidence for critical behavior. Our work establishes
    the presence of long-range correlated phases in RBM-based wave functions as a
    required ingredient for entanglement transitions.
acknowledgement: We would like to thank S. De Nicola, P. Brighi, and V. Karle for
  fruitful discussions and valuable feedback on the manuscript. R.M. and M.S. acknowledge
  support by the European Research Council (ERC) under the European Union's Horizon
  2020 research and innovation program (Grant Agreement No. 850899). R.V. acknowledges
  support from the US Department of Energy, Office of Science, Basic Energy Sciences,
  under Early Career Award No. DE-SC0019168, and the Alfred P. Sloan Foundation through
  a Sloan Research Fellowship.
article_number: '104205'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Romain
  full_name: Vasseur, Romain
  last_name: Vasseur
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Medina Ramos RA, Vasseur R, Serbyn M. Entanglement transitions from restricted
    Boltzmann machines. <i>Physical Review B</i>. 2021;104(10). doi:<a href="https://doi.org/10.1103/physrevb.104.104205">10.1103/physrevb.104.104205</a>
  apa: Medina Ramos, R. A., Vasseur, R., &#38; Serbyn, M. (2021). Entanglement transitions
    from restricted Boltzmann machines. <i>Physical Review B</i>. American Physical
    Society. <a href="https://doi.org/10.1103/physrevb.104.104205">https://doi.org/10.1103/physrevb.104.104205</a>
  chicago: Medina Ramos, Raimel A, Romain Vasseur, and Maksym Serbyn. “Entanglement
    Transitions from Restricted Boltzmann Machines.” <i>Physical Review B</i>. American
    Physical Society, 2021. <a href="https://doi.org/10.1103/physrevb.104.104205">https://doi.org/10.1103/physrevb.104.104205</a>.
  ieee: R. A. Medina Ramos, R. Vasseur, and M. Serbyn, “Entanglement transitions from
    restricted Boltzmann machines,” <i>Physical Review B</i>, vol. 104, no. 10. American
    Physical Society, 2021.
  ista: Medina Ramos RA, Vasseur R, Serbyn M. 2021. Entanglement transitions from
    restricted Boltzmann machines. Physical Review B. 104(10), 104205.
  mla: Medina Ramos, Raimel A., et al. “Entanglement Transitions from Restricted Boltzmann
    Machines.” <i>Physical Review B</i>, vol. 104, no. 10, 104205, American Physical
    Society, 2021, doi:<a href="https://doi.org/10.1103/physrevb.104.104205">10.1103/physrevb.104.104205</a>.
  short: R.A. Medina Ramos, R. Vasseur, M. Serbyn, Physical Review B 104 (2021).
corr_author: '1'
date_created: 2021-10-02T09:03:42Z
date_published: 2021-09-30T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '30'
department:
- _id: MaSe
doi: 10.1103/physrevb.104.104205
ec_funded: 1
external_id:
  arxiv:
  - '2107.05735'
  isi:
  - '000704414400002'
fulldoi: https://doi.org/10.1103/physrevb.104.104205
intvolume: '       104'
isi: 1
issue: '10'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2107.05735
month: '09'
oa: 1
oa_version: Preprint
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review B
publication_identifier:
  eissn:
  - 2469-9969
  issn:
  - 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '17208'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: Entanglement transitions from restricted Boltzmann machines
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 104
year: '2021'
...
---
_id: '10545'
abstract:
- lang: eng
  text: Classical models with complex energy landscapes represent a perspective avenue
    for the near-term application of quantum simulators. Until now, many theoretical
    works studied the performance of quantum algorithms for models with a unique ground
    state. However, when the classical problem is in a so-called clustering phase,
    the ground state manifold is highly degenerate. As an example, we consider a 3-XORSAT
    model defined on simple hypergraphs. The degeneracy of classical ground state
    manifold translates into the emergence of an extensive number of Z2 symmetries,
    which remain intact even in the presence of a quantum transverse magnetic field.
    We establish a general duality approach that restricts the quantum problem to
    a given sector of conserved Z2 charges and use it to study how the outcome of
    the quantum adiabatic algorithm depends on the hypergraph geometry. We show that
    the tree hypergraph which corresponds to a classically solvable instance of the
    3-XORSAT problem features a constant gap, whereas the closed hypergraph encounters
    a second-order phase transition with a gap vanishing as a power-law in the problem
    size. The duality developed in this work provides a practical tool for studies
    of quantum models with classically degenerate energy manifold and reveals potential
    connections between glasses and gauge theories.
acknowledgement: We would like to thank S. De Nicola, A. Michaidilis, T. Gulden, Y.
  Nez-Fernndez, P. Brighi, and S. Sack for fruitful discussions and valuable feedback
  on the manuscript. M.S. acknowledges useful discussions with E. Altman, L. Cugliandolo,
  and C. Laumann. We acknowledge support from the European Research Council (ERC)
  under the European Union's Horizon 2020 Research and Innovation Programme Grant
  Agreement No. 850899.
article_number: '062423'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Raimel A
  full_name: Medina Ramos, Raimel A
  id: CE680B90-D85A-11E9-B684-C920E6697425
  last_name: Medina Ramos
  orcid: 0000-0002-5383-2869
- first_name: Maksym
  full_name: Serbyn, Maksym
  id: 47809E7E-F248-11E8-B48F-1D18A9856A87
  last_name: Serbyn
  orcid: 0000-0002-2399-5827
citation:
  ama: Medina Ramos RA, Serbyn M. Duality approach to quantum annealing of the 3-variable
    exclusive-or satisfiability problem (3-XORSAT). <i>Physical Review A</i>. 2021;104(6).
    doi:<a href="https://doi.org/10.1103/physreva.104.062423">10.1103/physreva.104.062423</a>
  apa: Medina Ramos, R. A., &#38; Serbyn, M. (2021). Duality approach to quantum annealing
    of the 3-variable exclusive-or satisfiability problem (3-XORSAT). <i>Physical
    Review A</i>. American Physical Society. <a href="https://doi.org/10.1103/physreva.104.062423">https://doi.org/10.1103/physreva.104.062423</a>
  chicago: Medina Ramos, Raimel A, and Maksym Serbyn. “Duality Approach to Quantum
    Annealing of the 3-Variable Exclusive-or Satisfiability Problem (3-XORSAT).” <i>Physical
    Review A</i>. American Physical Society, 2021. <a href="https://doi.org/10.1103/physreva.104.062423">https://doi.org/10.1103/physreva.104.062423</a>.
  ieee: R. A. Medina Ramos and M. Serbyn, “Duality approach to quantum annealing of
    the 3-variable exclusive-or satisfiability problem (3-XORSAT),” <i>Physical Review
    A</i>, vol. 104, no. 6. American Physical Society, 2021.
  ista: Medina Ramos RA, Serbyn M. 2021. Duality approach to quantum annealing of
    the 3-variable exclusive-or satisfiability problem (3-XORSAT). Physical Review
    A. 104(6), 062423.
  mla: Medina Ramos, Raimel A., and Maksym Serbyn. “Duality Approach to Quantum Annealing
    of the 3-Variable Exclusive-or Satisfiability Problem (3-XORSAT).” <i>Physical
    Review A</i>, vol. 104, no. 6, 062423, American Physical Society, 2021, doi:<a
    href="https://doi.org/10.1103/physreva.104.062423">10.1103/physreva.104.062423</a>.
  short: R.A. Medina Ramos, M. Serbyn, Physical Review A 104 (2021).
date_created: 2021-12-14T20:46:07Z
date_published: 2021-12-14T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '14'
department:
- _id: MaSe
doi: 10.1103/physreva.104.062423
ec_funded: 1
external_id:
  arxiv:
  - '2106.06344'
  isi:
  - '000753659200004'
fulldoi: https://doi.org/10.1103/physreva.104.062423
intvolume: '       104'
isi: 1
issue: '6'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2106.06344
month: '12'
oa: 1
oa_version: Preprint
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
  call_identifier: H2020
  grant_number: '850899'
  name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review A
publication_identifier:
  eissn:
  - 2469-9934
  issn:
  - 2469-9926
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '17208'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: Duality approach to quantum annealing of the 3-variable exclusive-or satisfiability
  problem (3-XORSAT)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 104
year: '2021'
...
