PhysicalCostModel#

qualtran.surface_code.PhysicalCostModel

A model for estimating physical costs from algorithm counts.

qualtran.surface_code.PhysicalCostModel(
    physical_params, data_block, factory, qec_scheme
)

The model is parameterized by 1) properties of the target hardware architecture encapsulated in the data class PhysicalParameters, and 2) Execution protocol design choices.

We further factor the design choices into a) the data block design for storing algorithm qubits, b) the magic state factory construction, and c) the error suppression ability of the code.

Each method for computing physical costs take AlgorithmSummary inputs: the number of algorithm qubits and the number of algorithm gates. Output quantities include the wall-clock time, the number of physical qubits, and the probability of failure due to the physical realization of the algorithm.

Time costs#

The amount of time to run an algorithm is modeled as the greater of two quantities: The number of cycles required to generate enough magic states (via the factory), and the number of cycles required to consume the magic states (via the data_block). The model assumes that the rate of magic state generation is slower than the reaction limit. Each cycle takes a fixed amount of wall-clock time, given by architecture.

Space costs#

The number of physical qubits is the sum of the number of factory qubits and data block qubits.

Error#

We assume the constituent error probabilities are sufficiently low to permit a first-order approximation for combining sources of error. The total error is the sum of error probabilities due to magic state production (via factory) and data errors (via data_block). Note that the total error in data storage depends on the number of cycles, which depends on the factory design.

Args

physical_params

The physical parameters of the target hardware

data_block

The design of the data block

factory

The construction of the magic state factory/ies

qec_scheme

The scheme used to suppress errors.

Attributes

data_block

 

factory

 

logical_error_model

 

physical_params

 

qec_scheme

 

Methods#

n_cycles

View source

n_cycles(
    algo_summary: 'AlgorithmSummary'
) -> int

The number of error correction cycles required to execute the algorithm.

duration_hr

View source

duration_hr(
    algo_summary: 'AlgorithmSummary'
)

The duration in hours required to execute the algorithm.

n_phys_qubits

View source

n_phys_qubits(
    algo_summary: 'AlgorithmSummary'
) -> int

The number of physical qubits required to execute the algorithm

error

View source

error(
    algo_summary: 'AlgorithmSummary'
) -> float

The total error rate of executing the algorithm.

make_gidney_fowler

View source

@classmethod
make_gidney_fowler(
    data_d: int
)

make_beverland_et_al

View source

@classmethod
make_beverland_et_al(
    data_d: int,
    data_block_name: str = 'compact',
    factory_ds: Tuple = (9, 3, 3)
)

__ne__

__ne__(
    other
)

Check equality and either forward a NotImplemented or return the result negated.

__eq__

__eq__(
    other
)

Method generated by attrs for class PhysicalCostModel.