Isaac L. Chuang

Microarchitectures for Heterogeneous Superconducting Quantum Computers

  1. Samuel Stein,
  2. Sara Sussman,
  3. Teague Tomesh,
  4. Charles Guinn,
  5. Esin Tureci,
  6. Sophia Fuhui Lin,
  7. Wei Tang,
  8. James Ang,
  9. Srivatsan Chakram,
  10. Ang Li,
  11. Margaret Martonosi,
  12. Fred T. Chong,
  13. Andrew A. Houck,
  14. Isaac L. Chuang,
  15. and Michael Austin DeMarco
Noisy Intermediate-Scale Quantum Computing (NISQ) has dominated headlines in recent years, with the longer-term vision of Fault-Tolerant Quantum Computation (FTQC) offering significant
potential albeit at currently intractable resource costs and quantum error correction (QEC) overheads. For problems of interest, FTQC will require millions of physical qubits with long coherence times, high-fidelity gates, and compact sizes to surpass classical systems. Just as heterogeneous specialization has offered scaling benefits in classical computing, it is likewise gaining interest in FTQC. However, systematic use of heterogeneity in either hardware or software elements of FTQC systems remains a serious challenge due to the vast design space and variable physical constraints. This paper meets the challenge of making heterogeneous FTQC design practical by introducing HetArch, a toolbox for designing heterogeneous quantum systems, and using it to explore heterogeneous design scenarios. Using a hierarchical approach, we successively break quantum algorithms into smaller operations (akin to classical application kernels), thus greatly simplifying the design space and resulting tradeoffs. Specializing to superconducting systems, we then design optimized heterogeneous hardware composed of varied superconducting devices, abstracting physical constraints into design rules that enable devices to be assembled into standard cells optimized for specific operations. Finally, we provide a heterogeneous design space exploration framework which reduces the simulation burden by a factor of 10^4 or more and allows us to characterize optimal design points. We use these techniques to design superconducting quantum modules for entanglement distillation, error correction, and code teleportation, reducing error rates by 2.6x, 10.7x, and 3.0x compared to homogeneous systems.
arxiv pdf

Quantum simulation of molecular vibronic spectra on a superconducting bosonic processor

  1. Christopher S. Wang,
  2. Jacob C. Curtis,
  3. Brian J. Lester,
  4. Yaxing Zhang,
  5. Yvonne Y. Gao,
  6. Jessica Freeze,
  7. Victor S. Batista,
  8. Patrick H. Vaccaro,
  9. Isaac L. Chuang,
  10. Luigi Frunzio,
  11. Liang Jiang,
  12. S. M. Girvin,
  13. and Robert J. Schoelkopf
The efficient simulation of quantum systems is a primary motivating factor for developing controllable quantum machines. A controllable bosonic machine is naturally suited for simulating
systems with underlying bosonic structure, exploiting both quantum interference and an intrinsically large Hilbert space. Here, we experimentally realize a bosonic superconducting processor that combines arbitrary state preparation, a complete set of Gaussian operations, plus an essential non-Gaussian resource – a novel single-shot photon number resolving measurement scheme – all in one device. We utilize these controls to simulate the bosonic problem of molecular vibronic spectra, extracting the corresponding Franck-Condon factors for photoelectron processes in H2O, O3, NO2, and SO2. Our results demonstrate the versatile capabilities of the circuit QED platform, which can be extended to include non-Gaussian operations for simulating an even wider class of bosonic systems.
arxiv pdf