{"id":946,"date":"2025-12-04T09:56:51","date_gmt":"2025-12-04T08:56:51","guid":{"rendered":"https:\/\/www.qst.unina.it\/?page_id=946"},"modified":"2026-05-11T10:18:08","modified_gmt":"2026-05-11T08:18:08","slug":"academic-year-2025-2026","status":"publish","type":"page","link":"https:\/\/www.qst.unina.it\/index.php\/academic-year-2025-2026\/","title":{"rendered":"Academic year 2025\/2026"},"content":{"rendered":"\t\t
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14\/05\/2026<\/h3>

h 16:00 Room 0M03- Physics Department\u00a0<\/p>

Online:\u00a0Online participation via MS Teams\u00a0link<\/a><\/p>

In case your access is denied, log out from your institutional account and open MS Teams in your web browser.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Speaker: Fabrizio Minganti (Alice & Bob, Paris)<\/strong><\/h3>

Cats, chaos, dissipation<\/span><\/h3>

Abstract
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Abstract: Cat states are a promising platform for realizing quantum computers with a low hardware footprint and intrinsic error correction [1]. In this talk, I will describe how engineered dissipation [2] and parametric processes can confine the state of the system and stabilize cat states. I will discuss recent advances in the control and calibration of these states [3\u20134], and their potential to enable fault-tolerant quantum computation.<\/p>

Beyond their role as quantum hardware, these superconducting devices also provide an ideal platform for investigating many-body quantum phenomena in dissipative systems. In particular, I will discuss how the concepts of quantum error correction and phase transitions are connected. Building on a formal framework for analyzing chaos in strongly dissipative quantum systems [5], I will examine the emergence of chaos in these systems and its connection to the degradation of cat-state performance [6].<\/p>

[1] Mirrahimi et al., New J. Phys. 16, 045014 (2014)<\/p>

[2] Leghtas et al., Science (2015), Vol. 347, No. 6224<\/p>

[3] Melo et at., arXiv (2025)<\/p>

[4] A cat qubit that jumps every hour (blogpost: https:\/\/alice-bob.com\/blog\/just-out-of-the-lab-a-cat-qubit-that-jumps-every-hour\/<\/a>)<\/p>

[5] Ferrari et al, Phys. Rev. Res. (2025)<\/p>

[6] Ferrari et al., in preparation<\/p>

Short Bio: Graduated in \u00c9cole Normale Sup\u00e9rieure, Paris (2015); PhD in Universit\u00e9 Paris Cit\u00e9 under the supervision of Cristiano Ciuti (2018). JSPS Fellow at RIKEN, Japan, with Franco Nori (2019-2021). Research Scientist at EPFL in the group of Vincenzo Savona (2021-2024). Staff Quantum physicist at Alice & Bob since July 2024. <\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Past seminars<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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20\/03\/2026<\/h3>

h 11:30 Room 0M03 – Physics Department\u00a0<\/p>

Online:\u00a0Online participation via MS Teams\u00a0link<\/a><\/p>

In case your access is denied, log out from your institutional account and open MS Teams in your web browser.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Speaker: Niccol\u00f2 Traverso Ziani<\/span> (Universita` di Genova)<\/strong><\/h3>

Quantum critical quantum batteries<\/span><\/h3>

Abstract
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Qualitatively speaking, quantum batteries are quantum systems engineered to store and release energy on demand [1]. One\u2011dimensional arrays of qubits are particularly insightful in this context because they map naturally onto quantum spin chains out of equilibrium. This connection allows one to analyze their charging dynamics using concepts developed for quantum quenches [2] in a context where the quantum battery is naturally many-body.
In this talk, I will discuss how quantum phase transitions and integrability shape the performance of spin\u2011chain quantum batteries. I will show that in (Jordan-Wigner) integrable systems the quantum phase diagram strongly affects the stored energy at long charging times [3,4]. In contrast, when integrability is broken, even the charging power displays clear signatures of quantum criticality, exhibiting a strong enhancement around the phase transition [5].<\/p>

[1] F. Campaioli, S. Gherardini, J. Q. Quach, M. Polini, and G. M. Andolina, Colloquium: Quantum batteries, Rev. Mod. Phys. 96, 031001 (2024).
[2] A. Mitra, Quantum Quench Dynamics, Annual Review of Condensed Matter Physics, Vol. 9:245-259 (2018).
[3] R. Grazi, D. Sacco Shaikh, M. Sassetti, N. Traverso Ziani, and D. Ferraro, Controlling energy storage crossing quantum phase transitions in an integrable spin quantum battery, Phys. Rev. Lett. 133, 197001 (2024).
[4] R. Grazi, F. Cavaliere, M. Sassetti, D. Ferraro, and N. T. Ziani, Charging free fermion quantum batteries, Chaos, Solitons & Fractals 196, 116383 (2025).
[5] D. Farina, M. Sassetti, V. Cataudella, D. Ferraro, and N. Traverso Ziani,\u00a0 Charging power enhancement at the phase transition of a non-integrable quantum battery, arXiv:2603.02819.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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9\/12\/2025<\/h3>

h 14:00 Room 0M03 – Physics Department\u00a0<\/p>

Online:\u00a0Online participation via MS Teams\u00a0link<\/a><\/p>

In case your access is denied, log out from your institutional account and open MS Teams in your web browser.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Speaker: Olivier Buisson (CNRS, Neel Institute, Grenoble, France)<\/strong><\/h3>

High fiedlity and suppression of measurement-induced state transitions in cos\u03c6-coupling transmon readout<\/span><\/h3>

Abstract
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The field of superconducting qubits is constantly evolving with \u00a0\u00a0\u00a0\u00a0\u00a0 new types of circuit and designs but, when it comes to qubit \u00a0\u00a0\u00a0\u00a0\u00a0 readout, the use of simple transverse linear coupling is \u00a0\u00a0\u00a0\u00a0\u00a0 overwhelmingly prevalent. This type of coupling intrinsically \u00a0\u00a0\u00a0\u00a0\u00a0 limits the readout mode\u2019s dispersive shift and is known to cause \u00a0\u00a0\u00a0\u00a0\u00a0 Purcell effect. We propose here to overcome these limitations by \u00a0\u00a0\u00a0\u00a0\u00a0 engineering a non-linear cos\u03d5-coupling between the transmon qubit \u00a0\u00a0\u00a0\u00a0\u00a0 and a dedicated readout mode. This is based upon previous \u00a0\u00a0\u00a0\u00a0\u00a0 published work [1] on qubit readout with a non-perturbative \u00a0\u00a0\u00a0\u00a0\u00a0 cross-Kerr coupling engineered by a transmon molecule circuit. A \u00a0\u00a0\u00a0\u00a0\u00a0 new sample with optimized design and parameters shows a readout \u00a0\u00a0\u00a0\u00a0\u00a0 fidelity of 99.21% measured using a parametric amplifier and a \u00a0\u00a0\u00a0\u00a0\u00a0 high Quantum Non- Demolition (QND) fidelity of 97% [2]. \u00a0\u00a0\u00a0\u00a0\u00a0 Interestingly, these results have been achieved with 89 photons in \u00a0\u00a0\u00a0\u00a0\u00a0 the readout mode. In addition, we have observed suppression of \u00a0\u00a0\u00a0\u00a0\u00a0 measurement-induced state transitions (MIST) up to high photon \u00a0\u00a0\u00a0\u00a0\u00a0 counts above 300 [3]. This effect can be explained by the symmetry \u00a0\u00a0\u00a0\u00a0\u00a0 of the coupling, which is tunable with a magnetic field. All of \u00a0\u00a0\u00a0\u00a0\u00a0 these measurements were corroborated by a theoretical study, a \u00a0\u00a0\u00a0\u00a0\u00a0 numerical analysis of the spectra associated with the nonlinearly \u00a0\u00a0\u00a0\u00a0\u00a0 coupled circuit, and simulations of the corresponding classical \u00a0\u00a0\u00a0\u00a0\u00a0 dynamics[3].<\/p>

[1] R. Dassonneville, et al., \u201cFast high-fidelity quantum\u00a0\u00a0\u00a0\u00a0\u00a0 nondemolition qubit readout via a nonperturbative cross-Kerr\u00a0\u00a0\u00a0\u00a0\u00a0 coupling\u201d, Phys. Rev. X 10, 011045 (2020).
[2] C. Mori, et al., \u201cHigh-power readout of a transmon qubit using a nonlinear coupling\u201d, arXiv 2507.03642 (2025).
[3] C. Mori, et al., \u201cSuppression of measurement-induced state transitions in cos-coupling transmon readout\u201d, arXiv 2509.05126 (2025).<\/p>

Short Bio: <\/strong><\/span>Olivier Buisson is a senior CNRS researcher (Directeur de Recherche) and the director of the LANEF consortium in Grenoble. His main research areas concern mesoscopic physics and superconducting qubits. Coordinator of The ANR Projet Octaves (2021-2025). In 1999, he initiated quantum dynamics in superconducting qubits and proposed Quantum ElectroDynamics experiments using superconducting qubits. He experimentally studies a large variety of superconducting qubits since then. In 1990, he was contracted to the CRTBT-CNRS lab in Grenoble and studied plasma modes in thin superconducting films. Post-doctoral research in Rio de Janeiro with Prof. Paulo Costa Ribiero and Mauro Doria on biophysics and modelization of anisotropic superconductors. PhD (1990) at the Joseph Fourier University (Grenoble) on superconducting mesoscopic disks and superconducting networks under the supervision of Bernard Pannetier. <\/span><\/p>

Website: https:\/\/sqc.cnrs.fr\/members<\/a>\u00a0<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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19\/03\/2026<\/h3>

h 16:00 Room 0M04 – Physics Department\u00a0<\/p>

Online:\u00a0Online participation via MS Teams\u00a0link<\/a><\/p>

In case your access is denied, log out from your institutional account and open MS Teams in your web browser.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Speaker: Matteo Carrega (CNR, SPIN, Genova)<\/strong><\/h3>

Nonreciprocal Superconducting Transport in Hybrid Josephson junctions<\/strong><\/span><\/h3>

Abstract
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The development of quantum technologies relies on our ability to coherently control quantum systems, engineer their interactions, and understand the fundamental limits imposed by quantum mechanics. In this perspective, quantum thermodynamics provides a framework to describe energy exchange, dissipation, and nonequilibrium effects in mesoscopic devices, while quantum circuit theory offers powerful tools to model and design complex superconducting architectures.

In this talk, we will first present an overview of our theoretical works at the interface between quantum thermodynamics and superconducting quantum circuits, focusing on energy transport, dissipation, and quantum coherence\u00a0 phenomena.

In the second part, we will discuss a close theoretical\u2013experimental collaboration on hybrid Josephson junctions based on high-quality InSb nanoflags. Owing to their strong spin\u2013orbit coupling and ballistic transport, these systems constitute a versatile platform to explore nonreciprocal superconducting transport. We demonstrate supercurrent rectification \u2014 the dissipationless analog of the conventional diode \u2014 arising from the interplay of spin\u2013orbit interaction and magnetic fields. Under microwave irradiation, the observation of half-integer Shapiro steps reveals nonequilibrium dynamics linked to a skewed current\u2013phase relation. To directly probe this key quantity, we realized SQUID interferometers based on InSb nanoflag junctions, whose interference patterns highlight significant higher-harmonic contributions.

These results illustrate how combining theoretical insight with advanced nanofabrication enables controlled engineering of hybrid superconducting devices, paving the way toward novel functionalities for future quantum technologies.

REFERENCES
[1] B. Turini et al., Nano Letters 22, 8502 (2022).
[2] A. Lombardi et al., Commun. Materials 6, 272 (2025).

[3] A. Iorio et al., Phys. Rev. Res. 5, 033015 (2023).
[4] A. Chieppa et al., NanoLetters 39, 14412 (2025).<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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14\/05\/2026 h 16:00 Room 0M03- Physics Department\u00a0 Online:\u00a0Online participation via MS Teams\u00a0link In case your access is denied, log out from your institutional account and open MS Teams in your web browser. Speaker: Fabrizio Minganti (Alice & Bob, Paris) Cats, …<\/p>\n

Academic year 2025\/2026<\/span> Leggi tutto »<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-946","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/pages\/946","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/comments?post=946"}],"version-history":[{"count":14,"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/pages\/946\/revisions"}],"predecessor-version":[{"id":965,"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/pages\/946\/revisions\/965"}],"wp:attachment":[{"href":"https:\/\/www.qst.unina.it\/index.php\/wp-json\/wp\/v2\/media?parent=946"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}