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23 Nov 2020

Interview "Revolution in Quantum Physics" in Fon-Times

Fon-Times Interview mit Dominik Zumbühl. Seit rund zwanzig Jahren läuft die zweite Revolution der Quantenphysik. Neue Experimente führen vor Augen, dass sie die verrückte Welt der Quantenphysik genutzt werden kann, um nützliche Dinge…

05 Nov 2020

Published in PRB (Editor's Suggestion): Out-of-plane corrugations in graphene heterostructures

Even when sandwiched between atomically flat hBN crystals, surprisingly, graphene still exhibits ripples, even in absence of bubbles. These out-of-plane corrugations reduce mobility and suppress weak localization in an in-plane magnetic…

27 Oct 2020

On arXiv: Reducing the hydrogen content in liquid helium

Molecular hydrogen can block liquid He (LHe) intake capillaries typically used on 1K pots of many cryostats, causing severe disruption to the experiments. Here, we measure molecular hydrogen content in the liquifier helium gas supply and…

22 Oct 2020

On arXiv: Isotropic and Anisotropic g-factor Corrections in GaAs Quantum Dots

The spin splitting defines the qubit energy and is one of the fundamental properties of a semiconductor electron in a magnetic field. Here, we measure and separate the isotropic and anisotropic corrections to the bulk g-factor in two GaAs…

12 Oct 2020

On arXiv: Quantum measurement induced a many-body transition

The act of measurement in quantum mechanics is still mysterious and not microscopically understood. In our work, we show that even a weak (non-projective) measurement of a quantum dot system with an adjacent detector can result in a…

02 Oct 2020

On arXiv: Deep Reinforcement Learning for Efficient Measurement of Quantum Devices

Deep reinforcement learning is an emerging machine learning approach which can teach a computer to learn from actions and rewards similar to the way humans learn from experience. Here, we use this approach for fully automatic identification…

23 Sep 2020

Published in New Journal of Physics: Fine-tuning with unsuperv. embedding learning

We demonstrate an algorithm capable of fine-tuning several device parameters at once. The algorithm acquires a measurement, scores it using a variational auto-encoder, and optimizes gate voltage via the score in real-time in an…

17 Sep 2020

Group Hike to Wissigstock 2'887m

Shot of the brave thirteen who took it upon themselves to hike all the way to the top of Wissigstock at 2'887 meters altitude... refreshed and slightly proud... enjoying the breathtaking view from up there!

04 Sep 2020 / Research

New SNI PhD School Project Approved with Floris Braakman and Martino Poggio

The SNI has approved the PhD student project "Scanning Nanowire Quantum Dot" lead by Dr. Floris Braakman, to be carried out in the Poggio and Zumbühl labs, starting in 2021. Congratulations, Floris!

28 Aug 2020

Spin stability record makes the morning radio show!

This morning Dominik tries to explain the 57 seconds spin stability record from Leon and Liqui's experiment to the audience of local radio Basilisk... with Austin Powers background music and a totally baffeled radio show host! listen…

22 Aug 2020

Published in Phys. Rev. Lett.: Edge-State Wave Functions from Momentum-Conserving Tunneling Spectroscopy

We employ the lowest 5 modes of a quantum wire to probe adjacent edge-states in momentum conserving tunneling spectroscopy. Combined with numerical Schrödinger-Poisson simulations this is a powerful technique to probe edge-state wave…

20 Aug 2020

Fully automatic tuning of a quantum device faster than human experts, Nature Comms

Robots taking over the quantum transport lab: In an up to 8D space, our machine learning algorithm tunes the device typically in under 70 minutes, surpassing our best human benchmark (although both human and machine performance can be…

31 Jul 2020

On arXiv: Silicon quantum dot devices with a self-aligned 2nd gate layer

We present silicon finFET quantum dots with perfectly self-aligned 2nd gate layer and gate lengths down to 15 nm. In a double quantum dot, we find Pauli spin blockade with leakage dominated by spin-orbit interaction and extract a hole…

10 Jul 2020

On arXiv: Strong spin-orbit interaction and g-factor renormalization of Ge/Si nanowire hole spins

We report a remarkably strong spin-orbit interaction, with spin-orbit length of 65 nm, comparable to the quantum dot size. Combined with a large orbital effect of the B-field, the strong spin-orbit interaction causes a significant…

03 Jul 2020

Pascal Würsch presents MSc Thesis

Pascal Würsch successfully completed his MSc thesis "Large Quantum Dots for Microkelvin Universal Coulomb Blockade Thermometry in Semiconductors" and presented his results to the group today on zoom. Formally, an ETH Zürich MSc thesis with…