dr.David
Rhodus
The bookREFERENCE COLLECTION Contents
Chapter 6466 / 232

Analog and Non-Gate Quantum Workflows

Operating Quantum Computers · 2 min read

Not every useful quantum workflow is a universal gate-model circuit. Neutral-atom analog Hamiltonian simulation, quantum annealing, and specialized quantum-classical hybrid solvers expose different programming contracts and different operating risks.

Amazon Braket documents Analog Hamiltonian Simulation as a paradigm where a program is defined by time-dependent and space-dependent Hamiltonian parameters rather than a sequence of gates [R115]. D-Wave's Ocean tools and Leap hybrid solvers expose optimization workflows based on quadratic and nonlinear models rather than gate circuits [R116]. These systems need the same operational seriousness as gate-model QPUs, but the artifacts and validation methods differ.

64.1 Workflow taxonomy

DIAGRAM
Diagram loads as you read
64.1 Workflow taxonomy · Figure 1
View diagram source
flowchart TB
    QuantumWorkflow[Quantum workflow] --> Gate[Gate model]
    QuantumWorkflow --> Analog[Analog Hamiltonian simulation]
    QuantumWorkflow --> Annealing[Annealing / quadratic models]
    QuantumWorkflow --> HybridSolver[Managed hybrid solver]
    QuantumWorkflow --> FTEstimate[Fault-tolerant estimate]

A platform should not force all quantum work into a circuit-shaped abstraction. It should expose workload-specific contracts.

64.2 Analog Hamiltonian contract

DIAGRAM
Diagram loads as you read
64.2 Analog Hamiltonian contract · Figure 2
View diagram source
flowchart LR
    Problem[Physical / graph problem] --> Geometry[Atom geometry]
    Geometry --> Hamiltonian[Hamiltonian schedule]
    Hamiltonian --> Discretize[Device discretization]
    Discretize --> Run[AHS run]
    Run --> Measurements[Measurements]
    Measurements --> Interpret[Domain interpretation]

The artifact is not a gate list. It is a physical program: geometry, drive fields, detuning schedules, interaction assumptions, and device discretization.

64.3 Annealing and hybrid optimization contract

DIAGRAM
Diagram loads as you read
64.3 Annealing and hybrid optimization contract · Figure 3
View diagram source
flowchart LR
    BusinessProblem[Business problem] --> Model[Quadratic / nonlinear model]
    Model --> Constraints[Constraints and penalties]
    Constraints --> Solver[Quantum-classical solver]
    Solver --> Samples[Samples / candidates]
    Samples --> Feasibility[Feasibility check]
    Feasibility --> Decision[Decision support]

The core risk is not circuit depth. It is formulation quality: variables, constraints, penalty weights, scaling, and interpretation.

64.4 Validation by contract type

DIAGRAM
Diagram loads as you read
64.4 Validation by contract type · Figure 4
View diagram source
flowchart TB
    Validation[Validation] --> GateVal[Gate model validation]
    Validation --> AnalogVal[Analog validation]
    Validation --> AnnealVal[Annealing validation]
    GateVal --> CircuitMetrics[Depth, fidelity, counts]
    AnalogVal --> PhysicalMetrics[geometry, schedule, observable]
    AnnealVal --> OptMetrics[feasibility, objective, gap]

Do not reuse the wrong metrics. AHS validation should emphasize physical-program consistency and observable interpretation. Annealing validation should emphasize model formulation, feasibility, and baseline comparison.

64.5 Evidence package variants

DIAGRAM
Diagram loads as you read
64.5 Evidence package variants · Figure 5
View diagram source
erDiagram
    EVIDENCE_PACKAGE ||--|| WORKLOAD_CONTRACT : includes
    WORKLOAD_CONTRACT ||--o{ ARTIFACT : defines
    WORKLOAD_CONTRACT ||--o{ VALIDATION : requires

    WORKLOAD_CONTRACT {
        string workload_type
        string schema_version
        string target_profile
        string budget_policy
    }
    ARTIFACT {
        string artifact_type
        string hash
        string uri
    }

Artifact examples:

Workload Required artifacts
Gate model source, circuit, transpiled circuit, target snapshot, shot results
AHS geometry, Hamiltonian schedule, discretized program, device properties, measurement results
Annealing model, constraints, penalty policy, solver parameters, samples, feasibility report
Hybrid solver problem model, solver version, run parameters, candidates, classical baseline

64.6 Cost and capacity risks

DIAGRAM
Diagram loads as you read
64.6 Cost and capacity risks · Figure 6
View diagram source
flowchart LR
    Workload[Non-gate workload] --> Hidden[Hidden expansion]
    Hidden --> Capacity[Capacity usage]
    Hidden --> Cost[Cost]
    Hidden --> Interpretability[Interpretability risk]

Managed hybrid solvers can obscure how much work occurs under the hood. This is useful for productivity and risky for governance. Require cost and solver-parameter reporting.

64.7 Baseline selection

DIAGRAM
Diagram loads as you read
64.7 Baseline selection · Figure 7
View diagram source
flowchart TB
    Result[Quantum result] --> Baselines{Baselines}
    Baselines --> Exact[Exact small instance]
    Baselines --> Heuristic[Classical heuristic]
    Baselines --> Relaxation[Relaxation / bound]
    Baselines --> Prior[Prior production method]

For optimization, a result is only meaningful relative to a baseline and a constraint-feasibility check. For analog simulation, compare to tractable small systems, known limits, or experimentally validated observables.

64.8 Routing across workload families

DIAGRAM
Diagram loads as you read
64.8 Routing across workload families · Figure 8
View diagram source
flowchart LR
    Request[Problem request] --> Classifier{Problem structure}
    Classifier --> Circuit[Gate-model path]
    Classifier --> AHS[AHS path]
    Classifier --> Anneal[Annealing path]
    Classifier --> Classical[Classical path]
    Circuit --> Evidence[Evidence]
    AHS --> Evidence
    Anneal --> Evidence
    Classical --> Evidence

The platform should sometimes say: this is not a quantum workload. That is a feature, not a failure.

64.9 Governance differences

DIAGRAM
Diagram loads as you read
64.9 Governance differences · Figure 9
View diagram source
flowchart TB
    Governance[Governance] --> Common[Common controls]
    Governance --> Specific[Workload-specific controls]
    Common --> Owner[Owner]
    Common --> Budget[Budget]
    Common --> Evidence[Evidence]
    Specific --> Physics[Physical parameters]
    Specific --> Formulation[Optimization formulation]
    Specific --> Solver[Solver version]

Common controls cover ownership, budget, access, evidence, and review. Specific controls cover the scientific or mathematical structure of the workload.

64.10 Operating rule

Abstraction should follow physics and problem structure.

DIAGRAM
Diagram loads as you read
64.10 Operating rule · Figure 10
View diagram source
flowchart LR
    Problem[Problem] --> Contract[Native contract]
    Contract --> Target[Appropriate target]
    Target --> Evidence[Appropriate evidence]

A good platform supports gate, analog, annealing, and hybrid workloads without pretending they are the same thing.