ITP-quantumseminare November 2023

itp-quantumseminare@lists.phys.ethz.ch

1 participants
4 discussions

Today's QIT Seminar at 14:00pm in HIT E 41.1
by Ladina Hausmann 28 Nov '23

28 Nov '23

Hi all, Today Pablo Alvarez Dominguez will tell us about his master thesis "Characterization of clocks in the absence of an external temporal reference". See below for the abstract. The talk will take place today at 2pm in HIT E 41.1 Best, Ladina **** Title: Characterization of clocks in the absence of an external temporal reference Abstract: In this master thesis, the main question of how to quantitatively measure the accuracy of a clock without the need of an ideal or external reference frame is addressed. Several cases are studied, such as when one has access to infinitely many copies of the clock to be characterized, when the number of copies is limited or when these copies do not behave the same way due to, for example, relativistic effects. Finally, some case uses of the results are showcases, including a thought experiment for testing quantum gravity.

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Tomorrow's QIT Seminar at 14:00pm in HIT E 41.1
by Ladina Hausmann 20 Nov '23

20 Nov '23

Hi all, Tomorrow Maria Radisch will tell us about her master thesis "The Page-Wootters Formalism and Multipartite Clock Systems". See below for the abstract. The talk will take place at 2pm in HIT E 41.1 Best, Ladina **** Title: The Page-Wootters Formalism and Multipartite Clock Systems Abstract: The Wheeler-DeWitt Equation states that within a theory of Quantum Gravity the physical quantum states of our universe are annihilated by the Hamiltonian of the theory and thus do not evolve in time. So how come we are able to observe evolution in our universe? The Page-Wootters formalism provides a way to regain the dynamical description of a subsystem of the universe with respect to an internal temporal reference frame – a quantum clock. In my talk, I will present this formalism in its simplest form and discuss how we can construct a time observable for such a clock. Next, we will see that when we consider the quantum clock to be a physical system consisting of multiple subsystems, applying the Page-Wootters formalism as before raises a few problems. Using the main results from my Master’s thesis, I will show that a notion of subsystems can only be maintained with respect to a subclock if the total clock Hamiltonian has energy degeneracies. We will see that such a degenerate clock Hamiltonian prevents us from constructing a time observable on the multipartite clock system in the way it is usually done in the Page-Wootters formalism.

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Tomorrow's QIT Seminar at 14:00pm in HIT E 41.1
by Ladina Hausmann 13 Nov '23

13 Nov '23

Hi all, Tomorrow Ian Hesner will tell us about his master thesis at IBM entitled "Implementing and Benchmarking a Floquet Code on Superconducting Hardware". See below for the abstract. The talk will take place at 2 pm in HIT E 41.1 Best, Ladina *** Title: Implementing and Benchmarking a Floquet Code on Superconducting Hardware Abstract: Floquet codes are a novel style of quantum error correcting code with dynamically- generated logical observables defined on a hexagonal lattice. The hexagonal layout makes it an excellent candidate to fit on the heavy-hex layout of IBM Quantum devices. In this work, we view the Floquet code through the anyonic model of topological quantum computing to define a planar implementation that fits on existing devices. Actually running the Floquet code on IBM’s ibm_sherbrooke Eagle device shows that current devices are still well above Floquet code thresholds. Further work investigated a benchmarking technique to more accurately compare simulation data to real device data. Typically, simulation results for running quantum error correcting codes compare quite poorly to results obtained from real devices. Average detector triggering likelihoods were explored to be used as an intermediate parameter to directly compare the two. With this as an intermediate parameter, an effective-p value could be derived for a real device, comparing the complex noise landscape of a real device to a flat noise model defined by a single parameter p. This effective-p value does a much better job of simulating real device performance over other standard Pauli noise model techniques. It was found that for the best locations that can fit a Floquet code on ibm_sherbrooke, it has an effective-p value of just over 2%.

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Tomorrow's QIT Seminar at 14:00pm in HIT E 41.1
by Ladina Hausmann 06 Nov '23

06 Nov '23

Hi all, Tomorrow Riccardo Cicchetti will tell us about his master thesis with Ramona Wolf "Steering toward secure communication". See below for the abstract. The talk will take place at 2pm in HIT E 41.1 Best, Ladina Title: Steering toward secure communication Abstract: In QKD, there always is a trade-off between the assumptions in and the practicality of the protocols. Solutions prioritising one over the other are well-established in the QKD literature, and progressively more often implemented. Quantum steering is a physical phenomenon that would allow to find a middle-ground between these extremes, resulting in interesting novel protocols. In this presentation, I will explain the challenges and the potential of steering-based QKD, its implementation and the security proof.

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ITP-quantumseminare November 2023