60 research outputs found
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
Realizing two-qubit gates through mode engineering on a trapped-ion quantum computer
Two-qubit gates are a fundamental constituent of a quantum computer and
typically its most challenging operation. In a trapped-ion quantum computer,
this is typically implemented with laser beams which are modulated in
amplitude, frequency, phase, or a combination of these. The required modulation
becomes increasingly more complex as the quantum computer becomes larger,
complicating the control hardware design. Here, we develop a simple method to
essentially remove the pulse-modulation complexity by engineering the normal
modes of the ion chain. We experimentally demonstrate the required mode
engineering in a three ion chain. This opens up the possibility to trade off
complexity between the design of the trapping fields and the optical control
system, which will help scale the ion trap quantum computing platform.Comment: arXiv admin note: text overlap with arXiv:2104.13870 Updated funding
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