Full-Stack, Real-System Quantum Computer Studies: Architectural Comparisons and Design Insights

In recent years, Quantum Computing (QC) has progressed to the point where small working prototypes are available for use. Termed Noisy Intermediate-Scale Quantum (NISQ) computers, these prototypes are too small for large benchmarks or even for Quantum Error Correction, but they do have sufficient resources to run small benchmarks, particularly if compiled with optimizations to make use of scarce qubits and limited operation counts and coherence times. QC has not yet, however, settled on a particular preferred device implementation technology, and indeed different NISQ prototypes implement qubits with very different physical approaches and therefore widely-varying device and machine characteristics. Our work performs a full-stack, benchmark-driven hardware-software analysis of QC systems. We evaluate QC architectural possibilities, software-visible gates, and software optimizations to tackle fundamental design questions about gate set choices, communication topology, the factors affecting benchmark performance and compiler optimizations. In order to answer key cross-technology and cross-platform design questions, our work has built the first top-to-bottom toolflow to target different qubit device technologies, including superconducting and trapped ion qubits which are the current QC front-runners. We use our toolflow, TriQ, to conduct {\em real-system} measurements on 7 running QC prototypes from 3 different groups, IBM, Rigetti, and University of Maryland. From these real-system experiences at QC's hardware-software interface, we make observations about native and software-visible gates for different QC technologies, communication topologies, and the value of noise-aware compilation even on lower-noise platforms. This is the largest cross-platform real-system QC study performed thus far; its results have the potential to inform both QC device and compiler design going forward.Comment: Preprint of a publication in ISCA 201

A Unified Research Data Infrastructure for Catalysis Research – Challenges and Concepts

Modern research methods produce large amounts of scientifically valuable data. Tools to process and analyze such data have advanced rapidly. Yet, access to large amounts of high-quality data remains limited in many fields, including catalysis research. Implementing the concept of FAIR data (Findable, Accessible, Interoperable, Reusable) in the catalysis community would improve this situation dramatically. The German NFDI initiative (National Research Data Infrastructure) aims to create a unique research data infrastructure covering all scientific disciplines. One of the consortia, NFDI4Cat, proposes a concept that serves all aspects and fields of catalysis research. We present a perspective on the challenging path ahead. Starting out from the current state, research needs are identified. A vision for a integrating all research data along the catalysis value chain, from molecule to chemical process, is developed. Respective core development topics are discussed, including ontologies, metadata, required infrastructure, IP, and the embedding into research community. This Concept paper aims to inspire not only researchers in the catalysis field, but to spark similar efforts also in other disciplines and on an international level. © 2021 The Authors. ChemCatChem published by Wiley-VCH Gmb

A Unified Research Data Infrastructure for Catalysis Research – Challenges and Concepts

Modern research methods produce large amounts of scientifically valuable data. Tools to process and analyze such data have advanced rapidly. Yet, access to large amounts of high‐quality data remains limited in many fields, including catalysis research. Implementing the concept of FAIR data (Findable, Accessible, Interoperable, Reusable) in the catalysis community would improve this situation dramatically. The German NFDI initiative (National Research Data Infrastructure) aims to create a unique research data infrastructure covering all scientific disciplines. One of the consortia, NFDI4Cat, proposes a concept that serves all aspects and fields of catalysis research. We present a perspective on the challenging path ahead. Starting out from the current state, research needs are identified. A vision for a integrating all research data along the catalysis value chain, from molecule to chemical process, is developed. Respective core development topics are discussed, including ontologies, metadata, required infrastructure, IP, and the embedding into research community. This Concept paper aims to inspire not only researchers in the catalysis field, but to spark similar efforts also in other disciplines and on an international level.DFG, 441926934, NFDI4Cat – NFDI für Wissenschaften mit Bezug zur Katalys

Background-free detection and mixed-species crystals in micro- and macroscopic ion-traps for scalable QIP

Scalability and the implementation of fault tolerant quantum gates are the two main challenges which must be overcome in order to unlock the vast potential of quantum computing. This thesis describes work with calcium ions trapped in both microscopic and macroscopic linear Paul traps addressing both of these issues. We describe the assembly of a microstructured multi-zone ion trap which forms part of our group's contribution to the European "Microtrap" collaboration. We report the successful trapping of ions and characterization of the trap as well as a measurement of the heating rate. In miniaturized trap structures such as this one, background scattered light from the cooling beam causes difficulties. We introduce and demonstrate experimentally two techniques to overcome this problem. The first achieves background-free detection of ions using different repumping methods to enable the filtering out of the excitation wavelength. The second makes possible background-free readout of trapped ion qubits by separating in time the excitation and detection steps The second half of the thesis describes our experimental efforts towards implementing a two-qubit entangling gate with a mixed-species crystal. We describe the setup and characterization of a new macroscopic trap including the trapping and coherent manipulation of the internal states of both 40Ca+ and 43Ca+ ions. We accomplish the simultaneous independent readout of two qubits implemented in a 40Ca+ - 43Ca+ ion pair. We also present the setup and characterization of two injection-locked frequency-doubled Raman lasers and demonstrate coherent manipulation as well as a measurement of the off-resonant photon scattering error they introduce. Finally, we use them to achieve sideband cooling to the motional ground state of a mixed species ion crystal. </p