qat.core.Job

class qat.core.Job(psi_0=None, parameter_map=None, **kwargs)

A high level wrapper for the Job thrift class.

Instance attributes:

• circuit (Circuit): circuit to execute

• schedule (Schedule): schedule to execute

• type (ProcessingType): type of Job

• observable (Observable, optional): the observable (required if job type is of type 1, i.e observable sampling)

• qubits (list<int>, optional): measured qubits

• nbshots (int): number of required shots: if 0, do maximal number of shots

• aggregate_data (bool): contract corresponding result object

• amp_threshold (float, optional): amplitude values under this threshold are considered null

• parameter_map (dict[str, complex], optional): read-only attribute containing all the binded variables with their values

compile(stack=None, specs=None)

Compiles the job given some QPU or stack.

If the first argument is a QPU, then this call is equivalent to:

qpu.compile(job)

Otherwise, if the first argument is a Plugin, this is equivalent to:

plugin.compile(job, specs)

Parameters

• stack (QPUHandler or AbstractPlugin) – a plugin or a qpu

• specs (optional, HardwareSpecs) – optionally, some specs (only used when qpu is a Plugin)

Returns

a compiled job or a batch of jobs if the compilation produced

several jobs

Return type

Job or Batch

differentiate(vname, method=None, **kwargs)

Generates a collection of variational jobs such that the sum of their energies equates the partial derivative of the job’s energy w.r.t to a given variable.

\[\frac{\partial }{\partial \theta_j} \langle \psi(\theta) | H | \psi(\theta) \rangle = \sum_i \langle\psi_i(\theta) | H_i |\psi_i(\theta) \rangle\]

where \((|\psi\rangle, H)\) is the input job and \((|\psi_i\rangle, H_i)\) are the output jobs.

Supported methods are:

• shift-rule uses the chain rule for product differentiation together with a shift rule. This method generates \(2k\) jobs where \(k\) is the number of rotations parametrized by the variable.

• h-test performs a Hadamard test and a modifies the observable to sample in order to encode the appropriate post-selection induced by the Hadamard test. It generates \(k\) jobs where \(k\) is the number of rotations parametrized by the variable. These jobs have an additional qubit and have observables that are (at most) twice as large as the initial observable.

Parameters

• vname (str) – a variable name.

• method (str, optional) – the method to use. Default ‘shift-rule’.

• kwargs (dict) – any additional parameter that can be passed to the differentiation method.

Returns

a list of jobs

Return type

list<Job>

Warning

The method can be called only on a job containing an observable.

dump(fname)

Dumps the job in a binary file.

Parameters

fname (str) – the file name

eval(parameters=None, qpu=None)

Runs the job for a given (possibly empty) list of parameters and unpacks the result into a real value.

These two pieces of code are equivalent:

value = job.eval(x=x, qpu=qpu)

job_to_run = job(**{v: p for v, p in zip(job.get_variables(), x)})
value = qpu.submit(job).value.real

Parameters

• parameters (optional, np.array) – an array of values (should be of same length as job.get_variables())

• qpu (optional, QPUHandler) – the QPU to use for the evaluation

Returns

the result of the job evaluation

Return type

float or Result

classmethod from_bytes(data: bytes)

Builds a job from raw bytes object

classmethod from_thrift(tobject)

Builds a Job from a thrift job

get_variables()

Returns the sorted list of all variables appearing in the job

gradient(method=None, **kwargs)

Generates a collection of groups of jobs such that the sum of the energy of each group equates the partial derivative of the job’s energy w.r.t each of its variable.

The collection is returned as a map mapping variable names to job list.

This method has several backends, see differentiate() for more details.

Parameters

• method (str, optional) – the differentiation method

• kwargs (dict) – additional arguments passed to the differentiation method

Returns

a map associating variable names to list of jobs

Return type

map<str, list<Job>>

classmethod load(fname)

Loads the Job from a binary file.

Parameters

fname (str) – the file name

Returns

Job

property parameter_map: dict

Get the parameter map stored in a thrift dictionary

Returns

dictionary of binded variables

Return type

dict[str, complex]

property psi_0

Get initial state

Returns

the initial state

Return type

str or np.ndarray

run(qpu=None, meta_data=None)

Runs the job on a qpu.

The two following lines of code are equivalent:

result = job.run(qpu)
# and
result = qpu.submit(job)

Parameters

qpu (optional, QPUHandler) – the target qpu. If None, import the default qpu (via get_default_qpu())

Returns

a result

Return type

Result

shift_qbits(offset)

Shifts the job’s qbits by a given offset. Consequently icreases the number of qubits of the job by the same offset.

Acts in place.

Parameters

offset (int) – the offset

property threshold

Computes the probability threshold. States having a probaility lower than this value must be removed from the result

Returns

probability threshold

Return type

float

to_cpp()

Cast the Job into a Thrift object not meant for serialized transmission, but rather for C++ code.

to_thrift()

Cast the Job into a pure Thrift object