Research Group Meetings on Quantum Technologies

February 19, 2026

São Paulo, Brazil

Instituto Principia, Rua Pamplona 145
Auditório Boulevard (Centro de Ciências)

Zoom ID: 898 7538 9477
Password: 933604

Home

Quantum technologies are emerging as a new frontier of science and engineering, with potential applications in various fields such as communication, computation, metrology, and sensing. The development of quantum technologies requires the convergence of leading experiments and theoretical research, as well as the collaboration and exchange of ideas among different communities and regions.

ICTP-SAIFR is promoting one-day meetings (to be run every 2 months) of the São Paulo community working in the related areas of quantum technologies, quantum information, and quantum computing. The idea is to have a light schedule, with a couple of talks and plenty of time for discussion. The main purpose is to explore the synergies between different groups and between experimental and theoretical researchers.

Main organizer:

  • Gustavo Wiederhecker (Unicamp)

Co-organizers: 

  • Marcos Cesar de Oliveira (Unicamp) & Dario Rosa (ICTP-SAIFR/IFT-UNESP)  – Quantum Processing
  • Sergio Muniz (IFSC-USP) & Raul Celistrino (UFSCar) – Quantum Sensing
  • Barbara Amaral (USP) & Marcelo Martinelli (USP)  – Quantum Communications
  • Rodrigo Capaz (UFRJ) & Gustavo Wiederhecker (Unicamp) – Critical Infrastructure for building Quantum Devices
  • Eduardo Miranda (Unicamp) & Victor Quito (IFSC-USP)  – Emergent Quantum Phenomena in Condensed Matter Physics

 

If you wish to present a poster, please register using the provided link. All presentations are pre-approved; however, the organizers may contact you via email if they require additional information or adjustments to your work. If you do not wish to present a poster, you are still welcome to participate in the meeting without registration.

Announcement:

Register HERE

If you want to receive mailings about the meetings, click HERE.

Meeting at February 19

 

Program for Thursday – February 19:

Morning:

9:00 – 9:40 – Hermann Freire (UFG) – Altermagnets, pair-density waves and the superconducting diode effect – Video

9:40 – 10:20 – Krissia de Zawadski (IFSC-USP) – VQE approach to optimize a $N$-qubit heat engine fuelled by entanglement

10:20 – 10:40 – Coffee Break

10:40 – 11:20 – Willian Natori (Unicamp) – Fractionalization in Fractal Dimensions: Chiral Kitaev Spin Liquids and Majorana Metals on a Sierpinski Gasket – Video

11:20 – 12:00 – Dario Rosa (IFT) – Krylov and Chords Somewhere Over the Rainbow – Video

Afternoon:

14:00 – 14:40 – Walber Hugo de Brito (IFUSP-USP) – Orbital Selective Electronic Correlations and Topological Superconductivity of Iron Chalcogenide: a DMFT perspective – Video

14:40 – 14:45 – Gabriela Lemos (UFRJ) – Neurofísica e a Iniciativa Ciência Pioneira – Video

14:45 – 17:00: Poster Session and Coffee Break 

Participants


Posters

  • Barboza, Pedro Loureiro (Instituto de Física da Universidade de São Paulo, Brazil): Remarkable states in spin chains

We study how signatures of classical chaos appear in a quantum many-body system and how they relate to thermalization and non-ergodic structures. We analyze a one-dimensional Ising chain with longitudinal and transverse fields in both the classical limit and the quantum regime. In the classical model, we show that two initial conditions generate unstable periodic orbits that become chaotic under small perturbations. In the quantum model, level statistics confirms non-integrability and eigenstate properties are consistent with the Eigenstate Thermalization Hypothesis. Nevertheless, we find a weak but systematic concentration of eigenstate weight in the phase space along those unstable classical periodic orbits, providing evidence for genuine quantum scars. These results show that classical chaotic structures can leave observable imprints in non-integrable quantum systems that nevertheless thermalize.

  • Bonança, Marcus (Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP), Brazil): Landauer bound for information erasure in classical rotor lattices

It will be shown that cyclic processes performed on classical rotor lattices that have a critical point lead to information erasure and hence to Landauer’s bound for the energetic cost of it.

  • De Cerqueira Leite Pimentel, Marcos (Instituto de Física da Universidade de São Paulo, Brazil): Topological Heavy Fermion models for MATBG
  • Farinas, Pedro Sanchez (IFSC, USP, Brazil): Disorder and Dissipation in the Nematic Phase Transition of the J1-J2 Model

We investigate the effects of disorder and dissipation on the nematic phase transition of the J1-J2 model. Random interactions generate both random-mass and random-field terms that couple to the nematic order parameter. In the J1 < 2J2 regime, the nematic physics can be mapped onto an effective Hamiltonian resembling a random transverse-field Ising model with additional random longitudinal fields. Dissipation is incorporated by coupling each effective Ising variable to its own bath of harmonic oscillators. We aim to extend the strong-disorder renormalization group (SDRG) method to analyze this effective model.

  • Galdino, João Armando Sandron (Universidade de São Paulo (USP), Brazil): Dynamical quantum phase transitions for extreme quenches in disordered Q-state Potts chains

In this work, we investigate the behavior of dynamical quantum phase transitions (DQPTs) in disordered Q-state Potts spin chains subject to extreme quenches. Using an exact formulation based on transfer matrices, we calculate the rate function of the Loschmidt echo for both discrete and continuous coupling distributions. For the uniform case, we confirm the presence of first-order DQPTs for Q=2 and Q=3, and identify a second-order transition for Q=4, while for Q>4 dynamical singularities are absent. In the disordered scenario, we focus our analysis on continuous bond distributions governed by a power law. Our results demonstrate that disorder competes with the formation of dynamical singularities, revealing the existence of a critical disorder intensity above which DQPTs are entirely suppressed. This phenomenon occurs even when the quench protocol crosses the equilibrium quantum phase transition, thus providing yet another counter-example to the conjecture that such crossings guarantee the occurrence of DQPTs.

  • Gonçalves Moraes, Paulo Henrique (University of São Paulo, Brazil): Bipartite entanglement in the one-dimensional ANNNI model with transverse field

Entanglement has played a significant role in the description of phases in condensed matter physics by exploring the characteristics of purely quantum correlations. Near quantum critical points, it can exhibit scaling behavior, making it a strong candidate for mapping phase transitions [1]. In this work, quantum phase transitions in the one-dimensional Axial Next-Nearest Neighbor Ising (ANNNI) model with transverse field were investigated, with emphasis on the role of bipartite entanglement as a critical indicator. The sensitivity of von Neumann entropy to phase changes was analyzed, and how different choices of bipartitions influence its response in the transition was evaluated. We applied the Lanczos method to numerically determine the ground state of finite chains. The quantum critical points were estimated using finite-size scaling (FSS) techniques. The results reinforce that von Neumann entropy, in addition to adequately identifying the transition between commensurate phases, is sensitive to spatial modulations derived from the competition between interactions in the model. The results are in good agreement with those obtained from the phenomenological scaling of the energy gap [2]. [1] Osterloh, A., Amico, L., Falci, G. et al. Scaling of entanglement close to a quantum phase transition. Nature 416, 608–610 (2002). [2] M. Beccaria, M. Campostrini, and A. Feo. Density-matrix renormalization-group study of the disorder line in the quantum axial next-nearest-neighbor Ising model. Phys. Rev. B 73, 052402 (2006).

  • Leandro, Julia Perretto (IFGW-UNICAMP, Brazil): Classical Phase Diagram of a Frustrated Antiferromagnet

Magnetic frustration gives rise to exotic phases of matter, expanding the way that we can use and explore magnetism and quantum materials. In this study, our goal is to determine the classical phase diagram of a frustrated antiferromagnetic Heisenberg model on a hexagonal lattice, in particular, the one that includes J1 and J2 exchange interactions, along with an anisotropic Dzyaloshinskii-Moriya (DM) term. Using the Luttinger-Tisza method, we determine the ground-state energy and the corresponding spin configurations of the ordered phases. Our investigation provides insights into the competition between exchange interactions and anisotropy, estabilising the first step to extend this model to its quantum counterpart.

  • Rabelo, Lucas Gabriel (Instituto de Física da Universidade de São Paulo, Brazil): Kondo screening and random-singlet formation in highly disordered systems

In this work, we introduce the two-impurity Kondo problem as a minimal model to capture the anomalous low-temperature thermodynamics of doped semiconductors, such as Si:P, across the metal-insulator transition (MIT). In particular, we consider pairs of local magnetic moments coupled to a highly disordered, non-interacting electronic bath that undergoes a MIT as a function of doping. Using a large-N variational mean-field approach, we capture both the inhomogeneous local Fermi-liquid and the insulating random-singlet phase and find that the local moment susceptibility exhibits a robust power-law behavior, χ(T) ∝ T^(-α), where the exponent $\alpha$ evolves smoothly with doping and saturates in the metallic regime, in close agreement with experimental observations. Our results highlight the competition between Kondo screening and random singlet formation as the minimal ingredients required for a microscopic description of the anomalous low-temperature behavior of strongly disordered, interacting systems.

  • Soares, João Pedro (IFSC – USP, Brazil): Engenharia de Floquet e dinâmica exata de sistemas quânticos de poucos níveis

Este Trabalho disserta sobre as técnicas que englobam a Engenharia de Floquet, permitindo a resolução de problemas quânticos perturbados por potenciais periódicos. Tais potenciais alteram as características do sistema, modificando suas simetrias e introduzindo novos parâmetros, que impactam as energias e são, caracteristicamente, mais controláveis experimentalmente. A maioria dos problemas analisados envolve o acoplamento entre spin e um campo magnético externo. Diversas foram as técnicas de resolução empregadas: solução analítica exata, expansão para altas frequências e simulações numéricas, por exemplo. Nos regimes adequados, todos os resultados foram concordantes. Ademais, o trabalho adentrou o tópico da evolução temporal sobre a ótica de Floquet, que introduz o conceito de operadores estroboscópicos, H_F[t0], que descrevem como o sistema sai do ponto t = t_0 e como ele chega em t = t_0 +T – um período T à frente. Sua obtenção continua relacionada à adoção de técnicas aproximativas, válidas sob determinados regimes. O tratamento numérico, com auxílio da decomposição de Trotter-Suzuki, permite descrever como o sistema evolui em todos os pontos temporais; em particular, os múltiplos do período. Os resultados mostram que, para frequências altas, qualquer método adotado concorda com os valores obtidos. Por fim, discutiu-se, sob a ótica dos métodos aplicados anteriormente, um modelo baseado na literatura científica. O hamiltoniano em questão não descreve mais um acoplamento magnético, mas sim um supercondutor topológico de segunda ordem, que tem suas características alteradas a partir da introdução de um potencial periódico cossenoidal. Esta discussão particularmente interessa, pois, apesar do modelo ser naturalmente mais complexo que os outros analisados neste Trabalho, as mesmas técnicas de resolução são aplicáveis, o que revela a força do formalismo introduzido.

  • Tavares, Lucas Góis (Universidade de São Paulo, Brazil): A powerful method to evaluate the mass gap of an aperiodic XX model.

We present a numerical method for evaluating the mass gap of quantum chains with aperiodic couplings. Building upon techniques previously applied to free-fermionic systems, our approach is extended to the XX model whose couplings follow inflation rules. The method relies on the computation of the largest root of a characteristic polynomial, providing efficient estimates of the mass gap and its finite-size scaling behavior. We demonstrate that the Laguerre bound, used as an initial guess for the largest root, yields accurate approximations that capture the leading critical properties of the system. This framework allows us to explore the interplay between aperiodicity and quantum criticality, including the emergence of nontrivial dynamical exponents. Our results highlight the relevance of this method as a versatile tool for studying the XX model with deterministic aperiodic structures.

 

Previous Meetings

 

November 28, 2025

Organizers:

  • Rodrigo Capaz (UFRJ)
  • Gustavo Wiederhecker (Unicamp)

Invited Speakers:

  • Gustavo Wiederhecker (Unicamp): Intro – Video
  • Rodrigo Capaz (UFRJ): Microfab – Video
  • Felix Hernandez (USP): Cryogenics – Video
  • Newton Frateschi (Unicamp): Device testbed – Video
  • Eduardo Mobilon (CPQD): Cybersecurity in the Quantum Domaisn and the CPQD Testbed – Video
  • Paulo Nussenzveig (USP): Quantum networks – Role of Institutions – Video
  • Marcelo Nalim (Unesp – Instituto de Química): FAPESP EMU Program – Video
  • Cecilia Silva (MackGraphe), Edison Puig (ITA), Claudemir Coral (Instituto de Pesquisas ELDORADO), Thiago Alegre (Unicamp): Round table 1 – Discussion on Fab and Testbed – Video
  • Felix Hernandez (USP), Odilon Couto (Unicamp), Francisco Rouxinol (Unicamp): Round table 2 – Discussion on Cryogenics – Video

 

April 23, 2025

Organizers:

  • Barbara Amaral (USP)
  • Marcelo Martinelli (USP)

 

Invited Speakers:

  • Rafael Chaves Souto Araújo (IIF/UFRN): Beyond Thought Experiments: Turning Quantum Foundations into Quantum Technology
  • Valeria Loureiro da Silva (Senai/Cimatec/BA): QuIIN – Estimulando a Inovação em Tecnologias Quânticas /QuIIN – Fostering Innovation in Quantum Technologies
  • Antônio Zelaquett Khoury (IF/UFF): Rio Quantum Network: a metropolitan quantum communication network in Rio de Janeiro
  • Filippo Ghiglieno (UFSCAR): Recentes avanços na implementação da rede de comunicação quântica em São Carlos
  • Daniel Felinto Pires Barbosa (DF/UFPE): Perspectivas para implantação de uma internet quântica em Recife
  • Rafael Ferreira Pinto do Rego Barros (IFUSP): QneSP – distributing entanglement across the state of São Paulo

 

Videos: 

2025-04-23
Close

asdasdasd

{abstract}

Photos: Here

Participant list: Here

February 20, 2025

Organizers:

  • Raul Celistrino (UFSCar)
  • Sergio Muniz (IFSC-USP)

Invited Speakers:

  • Daniel Varela Magalhães (USP): Quantum sensing with atoms
  • Carmem Maia Gilardoni (CBPF):  Quantum sensing with defects in solids
  • José Inácio da Costa Filho (Harvard Medical School):  Quantum-inspired super-resolution microscopy

Invited panelists (round-table):

  • João Paulo Sinnecker (CBPF) – Superconducting devices
  • Luís Gustavo Marcassa (USP) – Quantum sensors with Rydberg atoms
  • Philippe Courteille (USP) – Matter-wave gravimetry
  • Thiago Alegre (Unicamp): Optomechanical devices
  • Hans M. Florez (UFABC): Atomic vapor-cell magnetometers

Videos: 

2025-02-20
Close

asdasdasd

{abstract}

Participant list: Here

Photos: Here

December 3, 2024

Organizers:

  • Marcos Cesar de Oliveira (Unicamp)
  • Dario Rosa (ICTP-SAIFR & IFT-Unesp)

Invited Speakers:

 

Videos: 

  2024-12-03

Close

asdasdasd

{abstract}

Posters:

  • Eduardo Sell Gonçalves (Instituto de Física “Gleb Wataghin”, UNICAMP): Tunable Degenerate Optical Parametric Oscillation in Photonic Molecules
  • Gustavo Moreto (Unicamp): Fabrication and Characterization of a Superconducting Qubit
  • José Rodrigo Blanco Peleteiro (Unicamp): Towards Direct Entangled Generation on Thin Film Lithium Niobate
  • Maria Carolina Volpato (Unicamp): Estimating the electrical energy cost of performing arbitrary state preparation using qubits and qudits in integrated photonic circuits
  • Gregory Alexandre Ferreira (UNICAMP): Towards Deterministic Single Photon Sources in a Photonic Chip via Temporal Multiplexin
  • Lucas Alexandre Marques Rattighieri (Universidade Estadual Paulista “Júlio de Mesquita Filho”): A Hybrid Classical-Quantum Approach for Detecting Abrupt Changes in Meteorological Time Series
  • Guilherme Eduardo Lopes Pexe (Unesp): Using a Feedback-Based Quantum Algorithm to Analyze the Critical Properties of the ANNNI Model Without Classical Optimization
  • Poliana Ferreira (Unicamp): Machine Learning for Synthesis and Optimization of Operations in Quantum Computing 

Abstracts: Here

Photos

Research Group Meetings on Quantum Technologies

Additional Information

 

Poster presentation: Participants who are presenting a poster MUST BRING A PRINTED BANNER . The banner size should be at most 1 m (width) x 1,5 m (length). We do not accept A4 or A3 paper.