June 2023 - ITP-quantumseminare - lists.phys.ethz.ch

QIT seminar on Tuesday at 1:30pm in E41.1
by Ladina Hausmann 23 Jun '23

23 Jun '23

Hi all, On Tuesday our visitor from the university of Naples, Giulia Gubitosi, will tell us about "Fundamental decoherence from quantum spacetime". See below for the abstract. The talk will take place at 1:30pm in HIT E 41.1. Best, Ladina *** Title: Fundamental decoherence from quantum spacetime Abstract: I will show that quantum properties of spacetime, encoded by noncommutativity at the Planck scale, lead to a generalized time evolution of quantum systems in which pure states can evolve into mixed states. Specifically, a Lindblad equation arises naturally as the evolution equation of quantum systems living in a noncommutative spacetime, where the symmetry generators are deformed and described by nontrivial Hopf algebras. This leads to a fundamental decoherence mechanism by which the density operator of a quantum system asymptotically approaches a maximally mixed state. By analysing the decoherence time for the evolution of a free particle I will also show that that the Planck mass is the maximum allowed mass for elementary quantum systems.

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Tomorrow's QIT Seminar at 13:30pm in HIT F 11.1 (New time and different room!)
by Ladina Hausmann 19 Jun '23

19 Jun '23

Hi all, Tomorrow Jan Seyfried will tell us about his semester thesis with Christopher Chubb and Marco Tomamichel from the National University of Singapore entitled "A new approach to the sample complexity of quantum state tomography". See below for the abstract. The talk will take place at 13:30pm in HIT F 11.1. Best, Ladina Title: A new approach to the sample complexity of quantum state tomography Abstract: In this semester thesis we explore a new approach to obtain lower bounds on the sample complexity of quantum state tomography as a function of the size of the confidence region, the allowed error probability, as well as the dimension and the rank of the system. To achieve this, we aim to combine the second-order approximation to the classical capacity of quantum channels with previous work on tomography by Haah et al. While issues arise with the direct application of the second-order approximation to our problem, we are able to derive the best known lower bound for the general case, using underlying ideas of the second-order approach. In addition, the upper bound found by Haah et al. can easily be modified to include the allowed error probability. The resulting bounds are tight up to logarithmic factors.

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No QIT seminar this week
by Ladina Hausmann 12 Jun '23

12 Jun '23

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

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No QIT seminar this week
by Ladina Hausmann 12 Jun '23

12 Jun '23

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

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Tomorrow's QIT Seminar at 4pm in HIT E 41.1
by Ladina Hausmann 06 Jun '23

06 Jun '23

Hi all, Tomorrow Sébastien Garmier will tell us about his master thesis supervised by Esteban Castro Ruiz and myself entitled “Transformations between Imperfect Quantum Reference Frames". See below for the abstract. The talk will take place at 4pm in HIT E 41.1. Best, Ladina Title: Transformations between Imperfect Quantum Reference Frames Abstract: Starting from the point of view of an observer, we provide a new construction for unitary quantum reference frame transformations between observer perspectives, and under physical assumptions derive the existence of an observer-independent, external view. The non-trivial problem of reversibly transforming between physically relevant imperfect reference frames is solved by embedding such frames in perfect ones. Thanks to this embedding, our approach allows transforming into the perspective of an imperfect quantum reference frame, in a way which is consistent with the rich information theory of such frames. We explore the consequences of the embedding and explain the point of view of an observer whose frame is imperfect. The findings are applied to imperfect reference frames for one-dimensional Galilei transformations, in light of potential future applications in quantum gravity.

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