Speculative Quantum Gate Compilation for QPU Dead Time Reduction

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Solution Overview

Problem

The coherence time of existing quantum computers limits the execution of hybrid quantum algorithms, as the CPU must recompile parts of the algorithm based on measurement results, leading to increased waiting times and potential errors.

Innovation Solution

A computer-implemented method where the CPU forms result predictions and generates sets of quantum gates speculatively, based on anticipated measurement results, allowing the QPU to execute quantum gates immediately upon measurement completion, thereby minimizing dead time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the CPU waits for measurement results before compiling quantum gates, then compilation accuracy is improved, but QPU dead time increases

Engineering Contradiction:
Improvecompilation accuracyVSAvoidQPU dead time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The CPU performs speculative compilation in advance by predicting possible measurement results and pre-compiling quantum gates for each predicted outcome. This preliminary action eliminates the need to wait for actual measurement results before having gates ready, thus reducing QPU dead time while maintaining compilation accuracy through subsequent validation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the actual measurement result is compared with predicted results, and the correctness of speculative compilation is validated. If the predicted result matches the actual result, the pre-complied gates are used; otherwise, new compilation is performed. This feedback loop ensures compilation accuracy while minimizing idle time

Inventive Principle:
Principle #23Feedback

2Loss of time

If speculative compilation is performed for all possible measurement results, then QPU dead time is reduced, but CPU computational load increases

Engineering Contradiction:
ImproveQPU dead timeVSAvoidCPU computational load
Core Design Contradiction:
Loss of timeVSUse of energy by moving object

Solution Approach 1:

Instead of performing uniform speculative compilation for all possible measurement results, the system applies local quality by focusing computational resources on the most likely predicted outcomes. The CPU prioritizes compilation for measurement results with higher probability, allocating computational load selectively rather than uniformly across all possibilities

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts compilation parameters based on measurement result probabilities. For highly probable outcomes, full speculative compilation is performed; for less probable outcomes, compilation depth or priority is reduced. This parameter adjustment optimizes the balance between reducing QPU dead time and managing CPU computational load

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS20250028990A1Quantum compiling
Publication Date: 2025.01.23 TECH UNIV BERLIN
  • US20250028990A1 patent drawing
  • US20250028990A1 patent drawing
  • US20250028990A1 patent drawing

AI summary

A quantum computer, comprising: at least one CPU and at least one QPU. The CPU includes: a branch predictor configured to form one or more result predictions or algorithm branches of a result of a measurement being performed or to be performed by the QPU; a compiler configured to generate respective sets of quantum gates corresponding to each of the one or more result predictions by performing respective one or more compilation tasks, each of the compilation tasks comprising compiling a portion of a hybrid quantum algorithm; and a quantum gate selector configured to receiving the result of the measurement and respond by passing to the QPU a set of quantum gates from the sets of quantum gates that corresponds to the result of the measurement.