Relativistic Quantum Information Forum - Recent Posts

Conceptual Foundations of QFT Workshop, Vienna, 1-3 June 2026

Maria Papageorgiou — Mon, 02 Feb 2026 13:17:26 +0000

Registration is now open until February 28

https://www.iqoqi-vienna.at/news-events/conceptual-foundations-of-qft

Multi-time quantum process tomography on a superconducting qubit

Christina_giarmatzi — Thu, 22 Jan 2026 00:25:26 +0000

Current quantum technologies are at the cusp of becoming useful, but still face formidable obstacles such as noise. Noise severely limits the ability to scale quantum devices to the point that they would offer an advantage over classical devices. To understand the sources of noise it is necessary to fully characterise the quantum processes occurring across many time steps; only this would reveal any time-correlated noise called non-Markovian. Previous efforts have attempted such a characterisation but obtained only a limited reconstruction of such multi-time processes. In this work, we fully characterise a multi-time quantum process on superconducting hardware using in-house and cloud-based quantum processors. We achieve this by employing sequential measure-and-prepare operations combined with post-processing. Employing a recently developed formalism for multi-time processes, we detect general multi-time correlated noise. We also detect quantum correlated noise which demonstrates that part of the noise originates from quantum sources, such as physically nearby qubits on the chip.

Multi-Time Quantum Process Tomography On A Superconducting Qubit, Christina Giarmatzi, Tyler Jones, Alexei Gilchrist, Prasanna Pakkiam, Arkady Fedorov, Fabio Costa, Quantum 9, 1952 (2025). https://quantum-journal.org/papers/q-2025-12-18-1952/

Conceptual Foundations of QFT Workshop, Vienna, 1-3 June 2026

Maria Papageorgiou — Mon, 19 Jan 2026 16:37:59 +0000

Interdisciplinary workshop on the foundations of QFT uniting philosophical, historical, and mathematical perspectives of relativistic quantum physics.

link: https://www.iqoqi-vienna.at/de/news-events/conceptual-foundations-of-qft

RE: Upcoming WG1 online Seminars

Vilasini — Tue, 06 Jan 2026 12:46:33 +0000

Hello everyone!

We hope this message finds you well and wish you all the best for the New Year 2026!

This is to announce the schedule for the upcoming WG1 online seminars. We will not have a seminar in January as our usual schedule of 2nd Thursday of the month coincides with the holiday/travel season for most potential speakers and participants. The schedule for the next seminars from February to April are as follows.
The titles, abstracts and zoom links will be shared closer to the dates.

1. 12th February 2026 at 15:00 CET by Robert Oeckl (Professor, National Autonomous University of Mexico)

2. 12th March 2026 at 10:00 CET by Jan Mandrysch (Postdoctoral researcher, IQOQI Vienna)

3. 9th April 2026 at 15:00 CET by Maria Papageorgiou (Postdoctoral researcher, IQOQI Vienna)

Wish you a great first month of the year and hope to see many of you at the upcoming online seminars!

On behalf of:
Kasia Rejzner (Professor of Mathematics, University of York, WG1 leader)
V. Vilasini (Research Faculty in Quantum Information Theory, Inria, Université Grenoble Alpes, WG1 co-leader)

RE: STSM

Maria_Jivulescu — Thu, 18 Dec 2025 11:16:59 +0000

Hi, everybody! There is an open call for STSM and ITC&YR Grants, with deadline 15 January.

RE: Operational Models of Temperature Superpositions

CarolynWood — Wed, 17 Dec 2025 01:27:53 +0000

Apologies, the link above is a bit hard to see, and I'm not sure how to edit my post. Here are the paper details with the link:

Carolyn E. Wood, Harshit Verma, Fabio Costa, and Magdalena Zych, "Operational models of temperature superpositions", Phys. Rev. Research 7, 043243

Causalworlds 2026: The 3rd International Conference on Quantum, Classical, and Relativistic Causality

Vilasini — Wed, 10 Dec 2025 13:18:52 +0000

Dear everyone,

We are pleased to announce the following conference which might be of interest to the RQI community and the RQI COST Action, and we welcome submissions for contributed talks and posters.

Hope to see many of you there!

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Causalworlds 2026 - First Call for Papers

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Causalworlds 2026: The 3rd International Conference on Quantum, Classical, and Relativistic Causality

Grenoble, France, June 22-26, 2026

https://causalworlds2026.inria.fr

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Presentation and scope

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Understanding causality is foundational to science and has wide-ranging applications, yet there are several distinct notions of causation. Recently, there have been important developments on the role of causality in quantum physics, relativistic physics and their interplay. These have unearthed a plethora of deep and fascinating questions regarding the nature of causation in physical theories, emergence of space-time structure and how relativistic principles can shape the landscape of quantum information processing. At the same time, causal reasoning is central in classical statistics, and has become a crucial tool in machine learning, with applications ranging from big data to healthcare. The interface between classical and quantum causality has also been crucial for identifying when and how quantum theory can surpass classical models in information processing. Causalworlds aims to bring together researchers from different areas of physics, computer science, mathematics and philosophy working on such questions related to causality, both from fundamental and applied perspectives, to provide a venue for cross-pollination of ideas and techniques across these disciplines and consolidate efforts towards a more unified understanding of causation.

The scope of the conference includes (but is not limited to):

* Quantum and classical causal inference and causal models

* The role of causal structure in information processing

* Indefinite causality and quantum reference frames

* Cyclic causality and time symmetry

* Causality in quantum field theory and quantum gravity

* Experiments in causality and applications

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Important Dates

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* Paper submission deadline: Feb 20, 2026 (AoE)

* Paper notification: Late March, 2026

* Conference: June 22-26, 2026

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Submission Guidelines

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We invite submissions of papers for talk and/or posters. Submissions for a talk will automatically be considered for a poster if not accepted for a talk.

* Talk: Submission will consist of a 3 page (excluding references) extended abstract, together with a link to the full paper (published or preprint) or a draft of the manuscript if not yet publicly available.

* Poster: Submission will consist of a short plaintext abstract. Work in progress is welcome.

Submissions will be considered via EasyChair: https://easychair.org/conferences?conf=cw2026

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Invited Speakers

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To be announced shortly.

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Organising Committee

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* Alastair Abbott (Inria)

* Cyril Branciard (Institut Néel)

* Mehdi Mhalla (LIG)

* Kuntal Sengupta (Institut Néel)

* V. Vilasini (Inria)

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PC Chairs

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* Alastair Abbott (Inria)

* Elie Wolfe (Perimeter Institute)

The programme committee will be announced shortly.

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Causalworlds Steering Committee

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* Hlér Kristjánsson (Université de Montréal & Mila)

* V. Vilasini (Inria)

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Previous editions:

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* Causalworlds 2024 at Perimeter Institute for Theoretical Physics, Canada (https://events.perimeterinstitute.ca/event/69/)
-Link to talk recordings of Causalworlds 2024: https://pirsa.org/c24018
-Link to an article about Causalworlds 2024: https://perimeterinstitute.ca/news/causation-rules-our-lives-how-does-it-work-quantum-realm

* Causalworlds 2022 at ETH Zürich, Switzerland (https://causalworlds.ethz.ch/)
-Link to talk recordings of Causalworlds 2022: https://www.youtube.com/@CausalWorlds

Operational Models of Temperature Superpositions

CarolynWood — Mon, 08 Dec 2025 05:15:59 +0000

Dear colleagues, I'd like to draw your attention to our recent publication, which touches on topics relevant to the RQI community. Please find the abstract below:

An interacting quantum system and thermal bath can reach thermal equilibrium, resulting in the system and bath acquiring the same temperature. But how does a delocalized quantum system thermalize with a bath whose local temperature varies as, for example, in the Tolman effect? Here, we formulate two scenarios in which the notion of a “superposition of temperatures” may arise: first, a probe interaction with two different baths dependent on the state of another quantum system (a control); and second, a probe interaction with a single bath whose purified state is a superposition of states that each correspond to different temperatures. We show that the two scenarios are fundamentally different and can be operationally distinguished. Moreover, we show that the final probe state is sensitive to the specific realization of the thermalizing channels, and that our results hold for partial and prethermalization cases. Our models may be applied to scenarios involving joint quantum and relativistic phenomena, and explain some recent results found in quantum interference of relativistic probes thermalizing with Unruh or Hawking radiation.

RE: Quantum signatures of proper time in optical ion clocks

Albert Roura — Mon, 01 Dec 2025 20:39:16 +0000

Thank you, Josh, for starting this discussion on the interesting work that you presented in your talk.

Just for clarification: rather than "engineering" the state, I was talking about a choice of trapping potentials that leads to the same frequencies at the trap minima for both internal states. This property guarantees that both the motion of the atoms near the trap minima and the ground-state energy of the potentials are the same for the two internal states.

More specifically, I was saying that for some applications the kind of effect that you considered can be regarded as a problem, but it can be circumvented by "engineering" the trapping potential. This is possible in cases where the trapping potential for the two internal states can be separately adjusted. A particularly relevant example is the optical potential in optical atomic clocks based on neutral atoms trapped in optical lattices, as I briefly explain next.

Indeed, if one uses a "magic" wavelength for the optical lattice, the optical potential is the same for both internal states. However, the frequency of the approximately harmonic function at the minima of the potential will be slightly different due to the mass difference \Delta m = \Delta E / c^2 between atoms in the two different internal states, i.e. \Omega_1 \neq \Omega_2. This in turn implies a different ground-state energy for the atom's center-of-mass degree of freedom in each lattice site, \hbar \Omega_1 / 2 \neq \hbar \Omega_2 / 2, which can be a problem.

Nevertheless, for blue-detuned optical lattices, one can choose a suitable laser wavelength, differing only slightly from the "magic" wavelength, that leads to different optical potentials but with the same frequencies \Omega_1 = \Omega_2 at the minima. In fact, this wavelength would be automatically selected in the usual calibration process performed in such experiments. A more detailed discussion can be found in sec. IV.C (page 8) of this reference: https://doi.org/10.1103/PhysRevX.10.021014

There it is also explained that the effects due to \Omega_1 \neq \Omega_2 for the "magic" wavelength typically lie beyond the sensitivity of the state-of-the-art atomic clocks based on neutral atoms trapped in optical lattices. For clocks using charged ions, where the electrostatic trapping potential is the same for atoms in both internal states, one also has \Omega_1 \neq \Omega_2. Compared to optical lattices, the effect can be a bit larger because the frequencies at the minimum of the trapping potential are typically larger in this case.

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The other discussion point that I brought up at the end of the seminar had to do with the conceptual interpretation of the results presented and their (partial) relation to time dilation. I can elaborate on that in a separate post.

How to acknowledge the COST action

Charis Anastopoulos — Wed, 26 Nov 2025 17:22:51 +0000

We would like to encourage you to acknowledge the Action in relevant publications that have benefited from those activities. Such acknowledgements are important for any future assessment of the Action's impact.

Please, acknowledge the Action in publications that

1. benefited from Action activities (online seminars, conferences/workshops, forum interactions and so on);

2. were initiated/inspired during Action activities;

3. involve international collaboration fostered or facilitated by the Action;

4. are outputs of STSMs;

5. are entirely outputs of COST activities (review articles for the WGs, write-up of an invited talk in a COST conference, lecture notes in Action schools, and so on).

For cases 1-3, you can write:

``The authors have benefited from the activities of COST Action CA23115: Relativistic Quantum Information, funded by COST (European Cooperation in Science and Technology)."

possibly with an additional phrase explaining the type of benefit.

For case 4, please acknowledge the STSM as a grant, e.g., you may write:

``This work was supported by an a STSM Grant from COST Action CA23115: Relativistic Quantum Information, funded by COST (European Cooperation in Science and Technology).".

For case 5, please write:

``This work is supported from COST Action CA23115: Relativistic Quantum Information, funded by COST (European Cooperation in Science and Technology).".

Writing the number CA23115 is the most important component of the acknowledgement, as this is the keyword that will be searched.

In some cases, you might want to include the Action as a citation in your document (in papers, research proposals, and so on). I suggest the following

COST Action ``Relativistic Quantum Information'' (CA23115). URL: https://rqi-cost.org