February 2026 - ITP-quantumseminare

QIT seminars next week
by Ladina Hausmann 27 Feb '26

27 Feb '26

Hi all, Next week we will have two seminars: (1) On Monday at 13:00 in HIT K52, our visitor Andrea di Biagio will tell us about “The simple reason classical gravity can entangle: a tale of two localities”. See below for the abstract. (2) On Wednesday at 10:00 in HIT E 41.1, Jie-qiang Wu will give a talk about the covariant phase space formalism. Best, Ladina Title: The simple reason classical gravity can entangle: a tale of two localities Abstract: Since the Bose et al. and Marletto and Vedral papers, more and more papers have appeared claiming that theories with a classical gravitational field do lead to gravity-induced entanglement (GIE), seemingly contradicting several theory-independent claims that local interactions with a classical system cannot lead to entanglement, both in quantum and post-quantum theory. We will review the no-go theorems and critically assess their assumptions. We will see that the informations-theoretic notion of locality they employ (based on subsystem decomposition) is distinct from the spacetime notion of locality natural to field theories like gravity. This limits the reach of the possible theory-independent claims about GIE. These shortcomings are beautifully exemplified by the recent Nature paper by Aziz and Howl. Their surprising claim that quantum field theory on a classical, fixed, curved spacetime predicts GIE has generated some controversy. Their lengthy perturbative computation is hard to follow, however we will see via high level arguments that the effect is indeed allowed because the locality assumption of the no-go theorems does not hold.

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No seminar this week
by Ladina Hausmann 24 Feb '26

24 Feb '26

Hi all, The speaker for the planned talk on Thursday cancelled, so there is no seminar this week. If all goes according to plan, we will resume next Monday. Best, Ladina

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No Seminar this week
by Ladina Hausmann 16 Feb '26

16 Feb '26

Hi all, There is no seminar scheduled for this week. For the remainder of the semester, the seminar will take place on Mondays at 15:00. Best, Ladina

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No seminar this week
by Ladina Hausmann 09 Feb '26

09 Feb '26

Hi all, There is no seminar planned for this week. Best, Ladina

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Tuesday's seminar at 11:15 in HIT E41.1
by Ladina Hausmann 02 Feb '26

02 Feb '26

Hi all, This week, our visitor, Pedro Barrios Hita, will talk about “Quantum mechanics based on real numbers: A consistent description”. See below for the abstract. The talk will take place at 11:15 in HIT E41.1. Best, Ladina %%%%%%%%%%%%%%%%% Title: Quantum mechanics based on real numbers: A consistent description Abstract: Complex numbers play a crucial role in quantum mechanics. However, their necessity remains debated: whether they are fundamental or merely convenient. Recently, it was shown that any real-number quantum theory satisfying certain postulates can be falsified with multipartite experiments. We show that a physically motivated postulate about composite quantum systems allows to construct quantum mechanics based on real numbers that reproduces predictions for all multipartite quantum experiments. Thus, we argue that real-valued quantum mechanics cannot be falsified, and therefore the use of complex numbers is a matter of convenience.

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