13 June 2023
from 14:30 to 16:00

MCQST Colloquium | Andreas Wallraff (ETH Zurich)

MCQST Colloquium

Address / Location

MPI of Quantum Optics | Herbert Walther Lecture Hall

Hans-Kopferman-Straße 1



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The MCQST Colloquium Series features interdisciplinary talks given by visiting international speakers. The monthly colloquium covers topics spanning all MCQST research units and will be broadcast live via Zoom for audiences worldwide. The main goal of the series is to create the framework for idea exchange, to strengthen links with QST leading groups worldwide, as well as to act as an integral part of the local educational environment.

MCQST Colloquium: Andreas Wallraff

We are excited to invite you to the colloquium talk by Andreas Wallraff (ETH Zurich). You can join us in-person at the Max Planck Institute of Quantum Optics at the above address, or online via the Zoom link below:

Meeting ID: 998 9779 8115
Passcode: mcqst2023

Talk Information

Loophole-free Bell Inequality Violation with Superconducting Circuits

View inside a section of the 30-metre-long quantum connection. Several layers of copper shielding circled around each other. © ETH Zurich / D. Winkler
Superposition, entanglement, and non-locality constitute fundamental features of quantum physics. Remarkably, the fact that quantum physics does not follow the principle of locality can be experimentally demonstrated in Bell tests performed on pairs of spatially separated, entangled quantum systems. While Bell tests were explored over the past 50 years, only relatively recently experiments free of so-called loopholes succeeded. Here, we demonstrate a loophole-free violation of Bell’s inequality with superconducting circuits. To evaluate a CHSH-type Bell inequality, we deterministically entangle a pair of qubits and perform fast, and high-fidelity measurements along randomly chosen bases on the qubits connected through a cryogenic link spanning 30 meters. Evaluating more than one million experimental trials, we find an average S-value of 2.0747 ± 0.0033, violating Bell’s inequality by more than 22 standard deviations [1]. Our work demonstrates that non-locality is a viable new resource in quantum information technology realized with superconducting circuits with applications in quantum communication, quantum computing and fundamental physics.

[1] S. Storz et al., Nature 617, 265–270 (2023)

Work done in collaboration with Simon Storz, Josua Schaer, Anatoly Kulikov, Paul Magnard, Philipp Kurpiers, Janis Luetolf, Theo Walter, Adrian Copetudo, Kevin Reuer, Abdulkadir Akin, Jean-Claude Besse, Mihai Gabureac, Graham J. Norris, Andres Rosario, Ferran Martin, Jose Martinez, Waldimar Amaya, Morgan W. Mitchell, Carlos Abellan, Jean-Daniel Bancal, Nicolas Sangouard, Baptiste Royer, Alexandre Blais, and Andreas Wallraff

About the speaker

Since January 2012 Andreas Wallraff is a Full Professor for Solid State Physics in the Department of Physics at ETH Zurich. He joined the department in January 2006 as a Tenure Track Assistant Professor and was promoted to Associate Professor in January 2010. Previously, he has obtained degrees in physics from Imperial College of Science and Technology, London, U.K., Rheinisch Westfälische Technische Hochschule (RWTH) Aachen, Germany and did research towards his Masters degree at the Research Center Jülich, Germany. During his doctoral research he investigated the quantum dynamics of vortices in superconductors and observed for the first time the tunneling and energy level quantization of an individual vortex for which he obtained a PhD degree in physics from the University of Erlangen-Nuremberg. During the four years he spent as a research scientist at Yale University in New Haven, CT, USA he performed experiments in which the coherent interaction of a single photon with a single quantum electronic circuit was observed for the first time. His research is focused on the experimental investigation of quantum effects in superconducting electronic circuits for performing fundamental quantum optics experiments and for applications in quantum information processing. His group at ETH Zurich engages in research on micro and nano-electronics, also on hybrid quantum systems combining superconducting electronic circuits with semiconductor quantum dots, making use of fast and sensitive microwave techniques at ultra-low temperatures.
For more information see the group's webpage.

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