Solver Properties

The properties that characterize behaviors and supported features of SAPI solvers[1] can be queried through SAPI. This chapter defines these properties[2].

[1]Ocean software also provides classical solvers such as dwave-greedy that you can run locally. See the Ocean documentation for information on parameters of such solvers.
[2]Ocean software classes such as the DWaveSampler class may include various other properties that are derived and stored client-side, not read from SAPI in the properties dict; for example, the dwave.cloud.solver.BaseSolver might derive an avg_load property. See the Ocean documentation for those properties.

The examples below use the following setup:

>>> from dwave.system import DWaveSampler, LeapHybridSampler, LeapHybridCQMSampler
...
>>> qpu_advantage = DWaveSampler(solver={'topology__type': 'pegasus'})
>>> qpu_2000q = DWaveSampler(solver={'topology__type': 'chimera'})
>>> hybrid_bqm_sampler = LeapHybridSampler()
>>> hybrid_cqm_sampler = LeapHybridCQMSampler()

anneal_offset_ranges

Supported on: QPU and VFYC Solvers

Array of ranges of valid anneal offset values, in normalized offset units, for each qubit. The negative values represent the largest number of normalized offset units by which a qubit’s anneal path may be delayed. The positive values represent the largest number of normalized offset units by which a qubit’s anneal path may be advanced.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["anneal_offset_ranges"][50:55]       
[[-0.6437569799443247, 0.5093937328282595],
 [-0.6409899716199288, 0.5697835920492209],
 [-0.6468663649068287, 0.5211452841036136],
 [-0.6435316809914349, 0.5011584701861175],
 [-0.6500326191157569, 0.5392206819650301]]

anneal_offset_step

Supported on: QPU and VFYC Solvers

Quantization step size of anneal offset values in normalized units.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["anneal_offset_step"]      
-0.00017565852000668507

anneal_offset_step_phi0

Supported on: QPU and VFYC Solvers

Quantization step size in physical units (annealing flux-bias units): \(\Phi_0\).

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["anneal_offset_step_phi0"]           
1.486239425109832e-05

annealing_time_range

Supported on: QPU and VFYC Solvers

Range of time, in microseconds with a resolution of 0.01 \(\mu s\), possible for one anneal (read). The lower limit in this range is the fastest quench possible for this solver.

Default annealing time is specified by the default_annealing_time property.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["annealing_time_range"]
[1.0, 2000.0]

beta_range

Supported on: Sampling Emulators

Range of values for beta.

Default \(\beta\) is specified by the default_beta property.

category

Supported on: Leap’s Hybrid Solvers, QPU & VFYC Solvers, and Emulators

Type of solver; for example,

  • qpu—quantum computers such as the Advantage.
  • hybrid—quantum-classical hybrid; typically one or more classical algorithms run on the problem while outsourcing to a quantum processing unit (QPU) parts of the problem where it benefits most.
  • software—emulators such as a sampling emulator.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["category"]
'hybrid'

chip_id

Supported on: QPU and VFYC Solvers

Name of the solver.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["chip_id"]             
'Advantage_system1.1'

couplers

Supported on: QPU and VFYC Solvers, and Emulators

Couplers in the working graph. A coupler contains two elements [q1, q2], where both q1 and q2 appear in the list of working qubits, in the range [0, num_qubits - 1] and in ascending order (i.e., q1 < q2). These are the couplers that can be programmed with nonzero \(J\) values.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["couplers"][:5]           
[[30, 31], [31, 32], [32, 33], [33, 34], [34, 35]]

default_annealing_time

Supported on: QPU and VFYC Solvers

Default time, in microseconds with a resolution of 0.01 \(\mu s\), for one anneal (read). You can change the annealing time for a given problem by using the annealing_time or anneal_schedule parameters, but do not exceed the upper limit given by the annealing_time_range property.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["default_annealing_time"]        
20.0

default_beta

Supported on: Sampling Emulators

Default value for \(\beta\).

default_programming_thermalization

Supported on: QPU and VFYC Solvers

Default time, in microseconds with a resolution of 0.01 \(\mu s\), that the system waits after programming the QPU for it to return to base temperature. This value contributes to the total qpu_programming_time, which is returned by SAPI with the problem solutions.

You can change this value using the programming_thermalization parameter, but be aware that values lower than the default accelerate solving at the expense of solution quality.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["default_programming_thermalization"]   
1000.0

default_readout_thermalization

Supported on: QPU and VFYC Solvers

Default time, in microseconds with a resolution of 0.01 \(\mu s\), that the system waits after each state is read from the QPU for it to cool back to base temperature. This value contributes to the qpu_delay_time_per_sample field, which is returned by SAPI with the problem solutions.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["default_readout_thermalization"]   
0.0

extended_j_range

Supported on: QPU and VFYC Solvers

Extended range of values possible for the coupling strengths (quadratic coefficients), \(J\), for this solver. Strong negative couplings may be necessary for some embeddings; however, such chains may require additional calibration through the flux_biases parameter to compensate for biases introduced by strong negative couplings. See also per_qubit_coupling_range.

extended \(J\) ranges and flux-bias offsets cannot be used with autoscaling (auto_scale) or spin-reversal transforms (num_spin_reversal_transforms).

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["extended_j_range"]
[-2.0, 1.0]

h_gain_schedule_range

Supported on: QPU and VFYC Solvers

Range of the time-dependent gain applied to qubit biases for this solver.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["h_gain_schedule_range"]        
[-4.0, 4.0]

h_range

Supported on: QPU and VFYC Solvers

Range of values possible for the qubit biases (linear coefficients), \(h\), for this solver.

The auto_scale parameter, which rescales \(h\) and \(J\) values in the problem to use as much of the range of \(h\) (h_range) and the range of \(J\) (j_range) as possible, enables you to submit problems with values outside these ranges and have the system automatically scale them to fit.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["h_range"]
[-2.0, 2.0]

j_range

Supported on: QPU and VFYC Solvers

Range of values possible for the coupling strengths (quadratic coefficients), \(J\), for this solver.

The auto_scale parameter, which rescales \(h\) and \(J\) values in the problem to use as much of the range of \(h\) (h_range) and the range of \(J\) (j_range) as possible, enables you to submit problems with values outside these ranges and have the system automatically scale them to fit.

See also extended_j_range.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["j_range"]               
[-1.0, 1.0]

max_anneal_schedule_points

Supported on: QPU and VFYC Solvers

Maximum number of points permitted in a PWL waveform submitted to change the default anneal schedule.

For reverse annealing, the maximum number of points allowed is one more than the number given in the max_anneal_schedule_points property.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["max_anneal_schedule_points"]   
12

max_h_gain_schedule_points

Supported on: QPU and VFYC Solvers

Maximum number of points permitted in a PWL waveform submitted to set a time-dependent gain on linear coefficients (qubit biases, see the h parameter) in the Hamiltonian.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["max_h_gain_schedule_points"]     
20

maximum_number_of_biases

Supported on: Leap’s Hybrid Solvers

Maximum number of biases, both linear and quadratic in total, accepted by the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["maximum_number_of_biases"]    
200000000

maximum_number_of_constraints

Supported on: Leap’s Hybrid CQM Solver

Maximum number of constraints accepted by the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["maximum_number_of_constraints"]   
100000

maximum_number_of_quadratic_variables

Supported on: Leap’s Hybrid CQM Solver

Maximum number of variables that have interactions (quadratic biases)—counted across all constraints (meaning that the same variable can be counted multiple times if it appears in interactions in more than one constraint)—accepted by the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["maximum_number_of_quadratic_variables"]   
15000000

maximum_number_of_variables

Supported on: Leap’s Hybrid Solvers

Maximum number of problem variables accepted by the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["maximum_number_of_variables"]    
1000000

maximum_time_limit_hrs

Supported on: Leap’s Hybrid Solvers

Maximum allowed run time, in hours, that can be specified for the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["maximum_time_limit_hrs"]     
24.0

minimum_time_limit

Supported on: Leap’s Hybrid BQM and DQM Solvers

Minimum required run time, in seconds, the solver must be allowed to work on the given problem. Specifies the minimum time as a piecewise-linear curve defined by a set of floating-point pairs. The second element is the minimum required time; the first element in each pair is some measure of the problem, dependent on the solver:

  • For hybrid BQM solvers, this is the number of variables.
  • For hybrid DQM solvers, this is a combination of the numbers of interactions, variables, and cases that reflects the “density” of connectivity between the problem’s variables.

The minimum time for any particular problem is a linear interpolation calculated on two pairs that represent the relevant range for the given measure of the problem. For example, if minimum_time_limit for a hybrid BQM solver were [[1, 0.1], [100, 10.0], [1000, 20.0]], then the minimum time for a 50-variable problem would be 5 seconds, the linear interpolation of the first two pairs that represent problems with between 1 to 100 variables.

For more details, see the Ocean samplers documentation for solver methods that calculate this parameter, and their descriptions.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["minimum_time_limit"]       
[[1, 3.0],
 [1024, 3.0],
 [4096, 10.0],
 [10000, 40.0],
 [30000, 200.0],
 [100000, 600.0],
 [1000000, 600.0]]

minimum_time_limit_s

Supported on: Leap’s Hybrid CQM Solver

Minimum required run time, in seconds, the solver must be allowed to work on any given problem.

For more details, see the Ocean samplers documentation for solver methods that calculate the default runtime of a given problem.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["minimum_time_limit_s"]       
5

num_biases_multiplier

Supported on: Leap’s Hybrid CQM Solver

Multiplier used in the internal calculation of the minimum run time, minimum_time_limit_s, the solver must be allowed to work on the given problem.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["num_biases_multiplier"]       
4.65705646e-06

num_constraints_multiplier

Supported on: Leap’s Hybrid CQM Solver

Multiplier used in the internal calculation of the minimum run time, minimum_time_limit_s, the solver must be allowed to work on the given problem.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["num_constraints_multiplier"]       
6.44385747e-09

num_qubits

Supported on: QPU and VFYC Solvers, and Emulators

Total number of qubits, both working and nonworking, in the QPU.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["num_qubits"]               
5760

num_reads_range

Supported on: QPU and VFYC Solvers, and Emulators

Range of values possible for the number of reads that you can request for a problem.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["num_reads_range"]
[1, 10000]

num_variables_multiplier

Supported on: Leap’s Hybrid CQM Solver

Multiplier used in the internal calculation of the minimum run time, minimum_time_limit_s, the solver must be allowed to work on the given problem.

Example

For the solver configured in the example setup above,

>>> hybrid_cqm_sampler.properties["num_variables_multiplier"]       
0.000157411458

parameters

Supported on: Leap’s Hybrid Solvers, QPU & VFYC Solvers, and Emulators

List of the parameters supported for the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["parameters"]             
{'time_limit': 'Maximum requested runtime in seconds.'}

per_qubit_coupling_range

Supported on: QPU and VFYC Solvers

Coupling range permitted per qubit for this solver.

Strong negative couplings may be necessary for some embeddings, and can be enabled by using the extended_j_range range of \(J\) values. However, the total couplings for a qubit must not exceed the range specified by this property. Also, chains may require additional calibration through the flux_biases parameter to compensate for biases introduced by strong negative couplings.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["per_qubit_coupling_range"]        
[-18.0, 15.0]

problem_run_duration_range

Supported on: QPU and VFYC Solvers

Range of time, in microseconds with a resolution of 0.01 \(\mu s\), that a submitted problem is allowed to run.

The run-duration for a given problem, which is compared with this range, is calculated according to the following formula:

\begin{equation} Duration = ((P_1 + P_2) * P_3) + P_4 \end{equation}

where \(P_1\), \(P_2\), \(P_3\), and \(P_4\) are the values specified for the annealing_time (or anneal_schedule), readout_thermalization, num_reads (samples), and programming_thermalization parameters, respectively.

Note

This is not the actual QPU access time of a given problem as that includes programming time and readout time. For more information, see the QPU Solver Datasheet guide.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["problem_run_duration_range"]       
[0.0, 1000000.0]

programming_thermalization_range

Supported on: QPU and VFYC Solvers

Range of time, in microseconds with a resolution of 0.01 \(\mu s\), possible for the system to wait after programming the QPU for it to cool back to base temperature. This value contributes to the total qpu_programming_time, which is returned by SAPI with the problem solutions.

You can change this value using the programming_thermalization parameter, but be aware that values lower than the default accelerate solving at the expense of solution quality.

Default value for a solver is given in the default_programming_thermalization property.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["programming_thermalization_range"]   
[0.0, 10000.0]

quota_conversion_rate

Supported on: Leap’s Hybrid Solvers, QPU and VFYC Solvers

Rate at which user or project quota is consumed for the solver as a ratio to QPU solver usage. Different solver types may consume quota at different rates.

Time is deducted from your quota according to:

\[\frac{num\_seconds}{quota\_conversion\_rate}\]

See the QPU Solver Datasheet guide for more information.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["quota_conversion_rate"]
1

qubits

Supported on: QPU and VFYC Solvers, and Emulators

Indices of the working qubits in the working graph.

Note

In a D-Wave QPU, the set of qubits and couplers that are available for computation is known as the working graph. The yield of a working graph is typically less than the total number of qubits and couplers that are fabricated and physically present in the QPU.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["qubits"][:5]         
[30, 31, 32, 33, 34]

readout_thermalization_range

Supported on: QPU and VFYC Solvers

Range of time, in microseconds with a resolution of 0.01 \(\mu s\), possible for the system to wait after each state is read from the QPU for it to cool back to base temperature. This value contributes to the qpu_delay_time_per_sample field, which is returned by SAPI with the problem solutions.

Default readout thermalization time is specified in the default_readout_thermalization property.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["readout_thermalization_range"]       
[0.0, 10000.0]

supported_problem_types

Supported on: Leap’s Hybrid Solvers, QPU & VFYC Solvers, and Emulators

Indicates what problem types are supported for the solver.

QPU and QPU-like solvers support the following energy-minimization problem types:

  • qubo—Quadratic unconstrained binary optimization (QUBO) problems; use \(0/1\)-valued variables.
  • ising—Ising model problems; use \(-1/1\)-valued variables.

Hybrid solvers support the following energy-minimization problem types:

  • bqm—binary quadratic model (BQM) problems; use \(0/1\)-valued variables and \(-1/1\)-valued variables; constraints are typically represented as penalty models.
  • cqm—constrained quadratic model (CQM) problems; use both binary-valued variables (both \(0/1\)-valued variables and \(-1/1\)-valued variables) and integer-valued variables; support constraints natively.
  • dqm—discrete quadratic model (DQM) problems; use variables that can represent a set of values such as {red, green, blue, yellow} or {3.2, 67}; constraints are typically represented as penalty models.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["supported_problem_types"]       
['ising', 'qubo']

tags

Supported on: QPU and VFYC Solvers

May hold attributes about a solver that you can use to have a client program choose one solver over another.

Example

For the solver configured in the example setup above,

>>> qpu_2000q.properties["tags"]          
['lower_noise']

topology

Supported on: QPU and VFYC Solvers

Indicates the topology type (chimera or pegasus) and shape of the QPU graph.

Example

The topology seen in this example is a C16 Chimera graph, meaning that the D-Wave 2000Q QPU has 16 x 16 blocks of Chimera unit cells, and each unit cell has K4,4 connectivity.

For the solver configured in the example setup above,

>>> qpu_2000q.properties["topology"]                    
{'type': 'chimera', 'shape': [16, 16, 4]}

version

Supported on: Leap’s Hybrid Solvers

Version number of the solver.

Example

For the solver configured in the example setup above,

>>> hybrid_bqm_sampler.properties["version"]                 
'2.0'

vfyc

Supported on: QPU and VFYC Solvers

Flag indicating whether this solver is a VFYC solver.

Example

For the solver configured in the example setup above,

>>> qpu_advantage.properties["vfyc"]              
False