InAs-Al Hybrid Devices Passing the Topological Gap Protocol

6 Jul 2022  ·  Morteza Aghaee, Arun Akkala, Zulfi Alam, Rizwan Ali, Alejandro Alcaraz Ramirez, Mariusz Andrzejczuk, Andrey E Antipov, Pavel Aseev, Mikhail Astafev, Bela Bauer, Jonathan Becker, Srini Boddapati, Frenk Boekhout, Jouri Bommer, Esben Bork Hansen, Tom Bosma, Leo Bourdet, Samuel Boutin, Philippe Caroff, Lucas Casparis, Maja Cassidy, Anna Wulf Christensen, Noah Clay, William S Cole, Fabiano Corsetti, Ajuan Cui, Paschalis Dalampiras, Anand Dokania, Gijs de Lange, Michiel de Moor, Juan Carlos Estrada Saldaña, Saeed Fallahi, Zahra Heidarnia Fathabad, John Gamble, Geoff Gardner, Deshan Govender, Flavio Griggio, Ruben Grigoryan, Sergei Gronin, Jan Gukelberger, Sebastian Heedt, Jesús Herranz Zamorano, Samantha Ho, Ulrik Laurens Holgaard, William Hvidtfelt Padkær Nielsen, Henrik Ingerslev, Peter Jeppesen Krogstrup, Linda Johansson, Jeffrey Jones, Ray Kallaher, Farhad Karimi, Torsten Karzig, Cameron King, Maren Elisabeth Kloster, Christina Knapp, Dariusz Kocon, Jonne Koski, Pasi Kostamo, Mahesh Kumar, Tom Laeven, Thorvald Larsen, Kongyi Li, Tyler Lindemann, Julie Love, Roman Lutchyn, Michael Manfra, Elvedin Memisevic, Chetan Nayak, Bas Nijholt, Morten Hannibal Madsen, Signe Markussen, Esteban Martinez, Robert McNeil, Andrew Mullally, Jens Nielsen, Anne Nurmohamed, Eoin O'Farrell, Keita Otani, Sebastian Pauka, Karl Petersson, Luca Petit, Dima Pikulin, Frank Preiss, Marina Quintero Perez, Katrine Rasmussen, Mohana Rajpalke, Davydas Razmadze, Outi Reentila, David Reilly, Richard Rouse, Ivan Sadovskyy, Lauri Sainiemi, Sydney Schreppler, Vadim Sidorkin, Amrita Singh, Shilpi Singh, Sarat Sinha, Patrick Sohr, Tomaš Stankevič, Lieuwe Stek, Henri Suominen, Judith Suter, Vicky Svidenko, Sam Teicher, Mine Temuerhan, Nivetha Thiyagarajah, Raj Tholapi, Mason Thomas, Emily Toomey, Shivendra Upadhyay, Ivan Urban, Saulius Vaitiekėnas, Kevin Van Hoogdalem, Dmitrii V. Viazmitinov, Steven Waddy, David Van Woerkom, Dominik Vogel, John Watson, Joseph Weston, Georg W. Winkler, Chung Kai Yang, Sean Yau, Daniel Yi, Emrah Yucelen, Alex Webster, Roland Zeisel, Ruichen Zhao ·

We present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes. The devices are fabricated from high-mobility two-dimensional electron gases in which quasi-one-dimensional wires are defined by electrostatic gates. These devices enable measurements of local and non-local transport properties and have been optimized via extensive simulations to ensure robustness against non-uniformity and disorder. Our main result is that several devices, fabricated according to the design's engineering specifications, have passed the topological gap protocol defined in Pikulin \textit{et al.} [arXiv:2103.12217]. This protocol is a stringent test composed of a sequence of three-terminal local and non-local transport measurements performed while varying the magnetic field, semiconductor electron density, and junction transparencies. Passing the protocol indicates a high probability of detection of a topological phase hosting Majorana zero modes as determined by large-scale disorder simulations. Our experimental results are consistent with a quantum phase transition into a topological superconducting phase that extends over several hundred millitesla in magnetic field and several millivolts in gate voltage, corresponding to approximately one hundred micro-electron-volts in Zeeman energy and chemical potential in the semiconducting wire. These regions feature a closing and re-opening of the bulk gap, with simultaneous zero-bias conductance peaks at \textit{both} ends of the devices that withstand changes in the junction transparencies. The extracted maximum topological gaps in our devices are 20-$60\,\mu$eV. This demonstration is a prerequisite for experiments involving fusion and braiding of Majorana zero modes.

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