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SFQ counter-based precomputation for large-scale cryogenic VQE machines

Yosuke Ueno, Satoshi Imamura, Yuna Tomida, Teruo Tanimoto, Masamitsu Tanaka, Yutaka Tabuchi, Koji Inoue, Hiroshi Nakamura

Abstract

The variational quantum eigensolver (VQE) is a promising candidate that brings practical benefits from quantum computing. However, the required bandwidth in/out of a cryostat is a limiting factor to scale cryogenic quantum computers. We propose a tailored counter-based module with single flux quantum circuits in 4-K stage which precomputes a part of VQE calculation and reduces the amount of inter-temperature communication. The evaluation shows that our system reduces the required bandwidth by 97%, and with this drastic reduction, total power consumption is reduced by 93% in the case where 277 VQE programs are executed in parallel on a 10000-qubit machine.

SFQ counter-based precomputation for large-scale cryogenic VQE machines

Abstract

The variational quantum eigensolver (VQE) is a promising candidate that brings practical benefits from quantum computing. However, the required bandwidth in/out of a cryostat is a limiting factor to scale cryogenic quantum computers. We propose a tailored counter-based module with single flux quantum circuits in 4-K stage which precomputes a part of VQE calculation and reduces the amount of inter-temperature communication. The evaluation shows that our system reduces the required bandwidth by 97%, and with this drastic reduction, total power consumption is reduced by 93% in the case where 277 VQE programs are executed in parallel on a 10000-qubit machine.
Paper Structure (25 sections, 14 equations, 5 figures, 3 tables)

This paper contains 25 sections, 14 equations, 5 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Background
  3. Variational Quantum Eigensolver (VQE)
  4. Expectation value calculation in VQE
  5. Group measurement (GM)
  6. Single flux quantum (SFQ) logic
  7. Related work on inter-temperature bandwidth reduction in SQCs
  8. Inter-temperature bandwidth modeling of VQE machines
  9. Baseline system design
  10. Bandwidth for inter-temperature communication
  11. Case without GM
  12. Case with GM
  13. Analysis on bandwidth bottleneck
  14. Precomputation at the 4-K stage
  15. Precomputation without GM
  16. ...and 10 more sections

Figures (5)

  • Figure 1: (a) Baseline and (b) proposed system designs of SQC with their VQE procedures.
  • Figure 2: Inter-temperature communication timing in baseline VQE machine without (with) GM
  • Figure 3: Inter-temperature communication in VQE using proposed architecture
  • Figure 4: Circuit diagram of our precomputation SFQ circuit
  • Figure 5: Required bandwidth and power dissipation of baseline and proposed systems without and with GM for (a) single- and (b)---(c) multi-program cases. Power dissipation includes heat inflow and peripherals power consumption.