ML4Q Projects
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Scientific Structure
The scientific structure of ML4Q is spanned by four focus areas, each addressing a specific set of problems relevant to the cluster’s mission. All focus areas include theoretical as well as experimental components and transcend the boundaries of disciplines and institution.
F1: Fundamentals and technology for topological interfaces
(coordinators: Morgenstern & Rosch)
F2: Majorana qubits
(coordinators: Ando & Hassler)
F3: Decoherence, measurements, and error correction
(coordinators: DiVincenzo & Kollath)
F4: Quantum connectivity
(coordinators: Bluhm & Köhl)
Core Projects
P1.1:
Interfaces between topological insulators and superconductors
Topological insulators in contact with super-conductors allow for realizing Majorana states. Improving the quality of these interfaces is decisive for the robustness of the Majorana states and resulting qubits. This project is supplemented by an open-call project on noise mechanisms in topological-insulator superconductor heterostructures.
Participants
Grützmacher (J, coordinator)
Ando (C)
Blügel (J)
Grüneis (C)
Mayer (A)
Morgenstern (A)
Mussler (J)
Plucinski (J)
Schäpers (J)
Open Call PIs:
Bocquillon (C)
Catelani (J)
Dickel (C)
Dickel/MAchnes/Motzoi/Rol (C/J/Orange Quantum Systems)
Mayer/Luysberg (J)
Mourik/Barends (J)
Stellmer/Grüneis/Plucinski (B/C/J)
P1.2:
Topological-insulator nanowires for Majorana states
We believe that nanowires of topological insulators in contact with superconductors are ideal building blocks for Majorana devices. We will explore different approaches to make and control such wires.
Participants
Ando (C, coordinator)
Grützmacher (J)
Lu (USC)
Mayer (A)
Morgenstern (A)
Mussler (J)
Rosch (C)
Schäpers (J)
Open Call PIs:
Mourik/Barends (J)
P1.3:
Controlling and probing ultra-clean interfaces
Novel fabrication techniques in ultra-high vacuum (UHV) are required for high-quality devices. We will develop new nanostructuring techniques and methods to probe Majorana states directly in UHV.
Participants
Morgenstern (A, coordinator)
Grützmacher (J)
Mussler (J)
Stampfer (A)
Tautz (J)
Voigtländer (J)
Open Call PIs:
Volmer/Stampfer/Beschoten (A)
P1.4:
Majorana states and parafermions in ultracold-atom systems
With ultracold atoms we will be able to realize and explore novel topological states and interfaces that are motivated by condensed matter systems. This project is supplemented by an open-call project on Aharanov-Bohm caging.
Participants
Weitz (B, coordinator)
Diehl (C)
Köhl (B)
Kollath (B)
Rosch (C)
Open Call PIs:
Rizzi/Diehl (C)
P2.1:
Majorana qubits based on topological-insulator nanowires
Majorana qubits will be built from topological-insulator nanowires and superconductors. We aim to demonstrate not only simple qubit operations but also the non-Abelian nature of Majoranas by braiding.
Participants
Ando (C, coordinator)
Altland (C)
Bluhm (A)
Egger (D)
Fink (IST Austria)
Grützmacher (J)
Hassler (A)
Lu (USC)
Mussler (J)
Schäpers (J)
Stampfer (A)
Open Call PIs:
Dickel/MAchnes/Motzoi/Rol (C/J/Orange Quantum Systems)
Mourik/Barends (J)
P2.2:
Alternative platforms for Majorana qubits
We will explore how superconducting vortices,
quantum anomalous Hall insulators, and graphene can be used to realize Majorana qubits.
Participants
Ando (C, coordinator)
Altland (C)
Bluhm (A)
Egger (D)
Fink (IST Austria)
Hassler (A)
Morgenstern (A)
Stampfer (A)
Open Call PIs:
Bocquillon (C)
Mourik/Barends (J)
P2.3:
Advanced Majorana-qubit designs
With Majorana box qubits one can realize new types of codes to implement active and passive error correction tailored to this computational platform.
Participants
Hassler (A, coordinator)
Altland (C)
Ando (C)
Egger (D)
P3.1:
Topology in and out of equilibrium
Concepts of topology are combined with a microscopic description of noise and dephasing. These ideas will be explored in ultracold-atom experiments and applied to the Majorana-based designs.
Participants
Diehl (C, coordinator)
Altland (C)
DiVincenzo (A/J)
Hassler (A)
Köhl (B)
Kollath (B)
P3.2:
Theory of error characterization, mitigation, and correction
Noise and resulting errors are the main factor limiting quantum computing devices. In this theory project, we will characterize the noise and its origins, validate devices and protocols and improve error-correction codes.
Participants
Gross (C, coordinator)
Bruss (D)
Calarco (C/J)
DiVincenzo (A/J)
Terhal (J)
Trebst (C)
Open Call PIs:
Mourik/Barends (J)
Wilhelm-Mauch (J)
P3.3:
Electron shuttling for spin-qubit surface code
To realize topological error correction one needs reliable building blocks connected by quantum links. We develop a quantum bus to shuttle spin qubits over micron-scale distances. This will be used to make and test connected arrays of spin qubits for error-correcting surface codes.
Participants
Bluhm (A, coordinator)
DiVincenzo (A/J)
Knoch (A)
Schreiber (A)
Open Call PIs:
Calarco (C)
Mourik/Barends (J)
Müller (A)
P4.1:
Multipartite quantum networks
What type of novel quantum protocols can be used on quantum networks involving several nodes? We will study this question theoretically and will realize in experiments a novel source of entangled photons that can be distributed to multiple nodes.
Participants
Bruss (D, coordinator)
Gross (C)
Grützmacher (J)
Kroha (B)
Weitz (B)
Open Call PIs:
Dung/Wahl (B)
P4.2:
Quantum links
We expect that future quantum technologies will build on networks linking solid-state qubits to flying qubits made from light. We will coherently couple a spin qubit to light, use this to build a heterogeneous network involving spin qubits and trapped ions, and couple Majorana states to microwave photons.
Participants
Bluhm (A)
Ando (C)
Fink (IST Austria)
Kardynal (J)
Köhl (B)
Linden (B)
Meschede (B)
Pawlis (J)
Stampfer (A)
Stellmer (B)
Open Call PIs:
Hofferberth/Stellmer/Fröhlich/Molter (B/FHR/ITWM)
Jungbluth/Loosen (ILT)
Kurzmann (A)
Pfeifer/Hofferberth/Linden (B)
Stellmer/Grüneis/Plucinski (B/C/J)
Witzens (A)