Quantum computational advantage is a bounded claim that a quantum method outperforms the best relevant classical methods on a defined task and metric under stated constraints. Portfolio value is broader: faster learning, reduced risk, and strategic options can justify research without demonstrating computational advantage. This chapter evaluates both, while keeping those claims separate.
This chapter turns quantum advantage into a portfolio-management and kill-criteria discipline.
View diagram source
flowchart LR
Idea[Use-case idea] --> Baseline[Classical baseline]
Baseline --> Quantum[Quantum candidate]
Quantum --> Evidence[Evidence package]
Evidence --> Value[Decision value]
Value --> Gate{Continue?}
Gate -- yes --> Invest[Increase investment]
Gate -- no --> Kill[Kill or park]Advantage must be defined against a baseline
A quantum workflow must be compared with relevant alternatives. A computational-advantage claim requires strong classical algorithms for the same task, accuracy and resource accounting, including applicable heuristics and approximations. Comparisons with laboratory experiments or business-as-usual processes can establish practical value; they do not by themselves establish computational advantage.
| Baseline | Quantum must improve |
|---|---|
| classical exact solver | scale, cost, or time-to-answer |
| classical heuristic | solution quality, robustness, or explanation |
| physical experiment | experiment planning, search efficiency, or risk |
| manual process | decision speed or consistency |
| no current capability | feasibility or strategic option value |
View diagram source
flowchart TB
Candidate[Quantum candidate] --> Compare[Compare against baseline]
BaselineA[Exact classical] --> Compare
BaselineB[Heuristic classical] --> Compare
BaselineC[Physical experiment] --> Compare
BaselineD[Business process] --> Compare
Compare --> Advantage[Bounded advantage statement]Unit economics
The economic unit should be “validated result” or “decision supported,” not “shot,” “job,” or “circuit.” Jobs and shots are inputs. Validated decisions are outputs.
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flowchart LR
Spend[Spend] --> QPU[QPU time]
Spend --> Staff[Staff time]
Spend --> Compute[Classical compute]
Spend --> Evidence[Evidence and review]
QPU --> Validated[Validated result]
Staff --> Validated
Compute --> Validated
Evidence --> Validated
Validated --> Decision[Decision value]| Cost element | Hidden multiplier |
|---|---|
| QPU access | queue delay, reservation waste |
| shot budget | mitigation overhead |
| staff time | experiment design and debugging |
| classical compute | simulation, optimization, post-processing |
| governance | review, audit, evidence retention |
| opportunity cost | delayed classical alternative |
Kill criteria
Kill criteria make quantum programs stronger. They prevent sunk-cost behavior and free resources for better candidates.
View diagram source
flowchart TD
Gate[Portfolio gate] --> Evidence{Evidence improved?}
Evidence -- no --> Baseline{Baseline beaten?}
Evidence -- yes --> Continue[Continue]
Baseline -- no --> Kill[Kill or park]
Baseline -- yes --> Risk{Risk acceptable?}
Risk -- yes --> Continue
Risk -- no --> Redesign[Redesign]Examples:
| Gate | Kill or park if |
|---|---|
| feasibility | workload cannot fit target envelope within planned horizon |
| baseline | quantum path cannot beat agreed classical baseline on any useful dimension |
| evidence | result remains unreproducible after defined attempts |
| economics | cost per validated decision exceeds threshold |
| strategic | use case no longer maps to business or research priority |
Real options framing
Some quantum investments are options, not immediate ROI projects. An option is valuable if it preserves future capability under uncertainty.
View diagram source
flowchart LR
Investment[Small investment] --> Learning[Learning]
Learning --> Option[Future option]
Option --> Trigger{Trigger event?}
Trigger -- hardware improves --> Exercise[Scale program]
Trigger -- no progress --> Expire[Let option expire]Option investments still need kill rules. A technology-watch project can be small and useful; it should not silently become a large program without evidence.
Portfolio tiers
View diagram source
quadrantChart
title Quantum portfolio map
x-axis Low strategic value --> High strategic value
y-axis Low evidence --> High evidence
quadrant-1 Scale selectively
quadrant-2 Watch and learn
quadrant-3 Kill or archive
quadrant-4 Harden evidence
Chemistry surrogate: [0.75, 0.55]
Optimization demo: [0.40, 0.35]
PQC migration: [0.85, 0.90]
Public benchmark: [0.65, 0.70]The portfolio should include near-term operationally valuable work, quantum-safe security work, strategic learning, and carefully bounded research. It should not be a collection of demos.
Advantage statement template
For workload class <X>, against baseline <Y>, under constraints <Z>,
the quantum-enabled workflow provides <value dimension> with evidence level <E>,
at estimated cost <C>, by date or maturity trigger <T>.Operating rule
Quantum advantage is a managed claim. Define the baseline, unit economics, evidence threshold, and kill criteria before expanding investment.
Additional technical sources: [R270].