LeapHybridCqm

Leap’s quantum-classical hybrid solvers are intended to solve arbitrary application problems formulated as quadratic models. This solver accepts arbitrarily structured problems formulated as CQMs, with any constraints represented natively.

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Compatible Backends

The LeapHybridCqm algorithm supports the following backends:

• DWaveQpu

By default, LeapHybridCqm uses the DWaveQpu backend.

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Initialization

The following section outlines the default configurations of LeapHybridCqm. You can also specify other compatible backends for the algorithm. When backend=None is specified, the default backend will be initialized automatically. In this case, if the backend requires a token, it will be taken from the environment variables.

Default Configuration

from luna_quantum.solve.parameters.algorithms import LeapHybridCqm

algorithm = LeapHybridCqm(
    backend=None,
    time_limit=None,
    spin_variables=None
)

Parameter Details

For a complete overview of available parameters and their usage, see the LeapHybridCqm API Reference.

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Usage

from luna_quantum import LunaSolve

LunaSolve.authenticate("<YOUR_LUNA_API_KEY>")

# Define your model and algorithm
model = ...
algorithm = ...

solve_job = algorithm.run(model, name="my-solve-job")

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API Reference

Bases: LunaAlgorithm[DWaveQpu]

Parameters for D-Wave's Leap Hybrid Constrained Quadratic Model (CQM) solver.

The Leap Hybrid CQM solver extends hybrid quantum-classical optimization to handle constrained problems, allowing both linear and quadratic constraints alongside the quadratic objective function. This enables solving many practical optimization problems in their natural formulation without manual penalty conversion.

The solver is suitable for mixed binary, integer, and continuous problems with thousands of variables and constraints.

Attributes:

Name	Type	Description
time_limit	float | int | None	Maximum running time in seconds. Longer limits generally yield better solutions but increase resource usage. Default is None, which uses the service's default time limit (typically problem-size dependent).
spin_variables	list[str] | None	Variables to represent as spins (-1/+1) rather than binary (0/1) values. Useful for problems naturally formulated in spin space. Default is None, which uses binary representation for all discrete variables.

backend class-attribute instance-attribute

backend: BACKEND_TYPE | None = Field(default=None, exclude=True, repr=False)

model_config class-attribute instance-attribute

model_config = ConfigDict(
    arbitrary_types_allowed=True, extra="allow", validate_assignment=True
)

spin_variables class-attribute instance-attribute

spin_variables: list[str] | None = None

time_limit class-attribute instance-attribute

time_limit: float | int | None = None

get_compatible_backends classmethod

get_compatible_backends() -> tuple[type[DWaveQpu], ...]

Check at runtime if the used backend is compatible with the solver.

Returns:

Type	Description
tuple[type[IBackend], ...]	True if the backend is compatible with the solver, False otherwise.

get_default_backend classmethod

get_default_backend() -> DWaveQpu

Return the default backend implementation.

This property must be implemented by subclasses to provide the default backend instance to use when no specific backend is specified.

Returns:

Type	Description
IBackend	An instance of a class implementing the IBackend interface that serves as the default backend.

run

run(
    model: Model | str,
    name: str | None = None,
    backend: BACKEND_TYPE | None = None,
    client: LunaSolve | str | None = None,
    *args: Any,
    **kwargs: Any,
) -> SolveJob

Run the configured solver.

Parameters:

Name	Type	Description	Default
model	Model or str	The model to be optimized or solved. It could be an Model instance or a string identifier representing the model id.	required
name	str | None	If provided, the name of the job. Defaults to None.	None
backend	BACKEND_TYPE | None	Backend to use for the solver. If not provided, the default backend is used.	None
client	LunaSolve or str	The client interface used to interact with the backend services. If not provided, a default client will be used.	None
*args	Any	Additional arguments that will be passed to the solver or client.	()
**kwargs	Any	Additional keyword parameters for configuration or customization.	{}

Returns:

Type	Description
SolveJob	The job object containing the information about the solve process.