committing work done on the benchmark/vqe plugins

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

python/CMakeLists.txt

@@ -38,7 +38,7 @@ add_library(_pyxacc SHARED xacc-py.cpp)
 
 set_target_properties(_pyxacc PROPERTIES PREFIX "")
 
-target_link_libraries(_pyxacc PUBLIC CppMicroServices xacc Boost::graph xacc-pauli)
+target_link_libraries(_pyxacc PUBLIC CppMicroServices xacc Boost::graph xacc-pauli xacc-fermion)
 
 if(APPLE)
    set_target_properties(_pyxacc PROPERTIES INSTALL_RPATH "@loader_path/lib")
@@ -52,3 +52,6 @@ install(TARGETS _pyxacc DESTINATION ${CMAKE_INSTALL_PREFIX})
 install(FILES xacc.py DESTINATION ${CMAKE_INSTALL_PREFIX})
 install(DIRECTORY plugin_generator DESTINATION ${CMAKE_INSTALL_PREFIX})
 install(DIRECTORY benchmark DESTINATION ${CMAKE_INSTALL_PREFIX})
+
+file(GLOB PYDECORATORS ${CMAKE_CURRENT_SOURCE_DIR}/benchmark/vqe/*.py)
+install(FILES ${PYDECORATORS} DESTINATION ${CMAKE_INSTALL_PREFIX}/py-plugins)

python/benchmark/manage.py

@@ -38,7 +38,7 @@ def install_package(install_name):
         xacc.info("Retrieving package and checking requirements..")
         package_path = PLUGIN_INSTALLATIONS[install_name]
         for k,v in MASTER_PACKAGES.items():
-            if install_name in v:
+            if install_name in v and k in REQUIREMENTS:
                 requirement = REQUIREMENTS[k]['module']
                 mdir = k
                 importlib.import_module(requirement)
@@ -118,7 +118,6 @@ def get_packages():
 def main(argv=None):
     opts = parse_args(sys.argv[1:])
     get_packages()
-
     if opts.path:
         set_plugin_path(opts.path)
 

python/benchmark/vqe/ansatzgenerator.py

+from abc import abstractmethod, ABC
+
+
+class AnsatzGenerator(ABC):
+    """
+        Abstract class to be inherited by iPOPO bundles to generate quantum circuit ansatz for quantum computation
+
+        Subclasses must inherit and implement the generate() method to return an XACC Intermediate Representation (IR) Function instance which expresses
+        a composition of instructions to be executed
+    """
+    @abstractmethod
+    def generate(self, inputParams):
+        pass

python/benchmark/vqe/chemistry/hamiltonian_generators/h2_kernel_ham.py

@@ -2,7 +2,6 @@ from pelix.ipopo.decorators import ComponentFactory, Property, Requires, Provide
     Validate, Invalidate, Instantiate
 from hamiltonian_generator import HamiltonianGenerator
 import ast, xacc
-import xaccvqe as vqe
 
 
 @ComponentFactory("xaccKernelH2_hamiltonian_generator_factory")
@@ -18,36 +17,34 @@ class XACCKernelH2(HamiltonianGenerator):
     """
 
     def generate(self, inputParams):
-        src = """__qpu__ kernel() {
-            0.7080240949826064
-            -1.248846801817026 0 1 0 0
-            -1.248846801817026 1 1 1 0
-            -0.4796778151607899 2 1 2 0
-            -0.4796778151607899 3 1 3 0
-            0.33667197218932576 0 1 1 1 1 0 0 0
-            0.0908126658307406 0 1 1 1 3 0 2 0
-            0.09081266583074038 0 1 2 1 0 0 2 0
-            0.331213646878486 0 1 2 1 2 0 0 0
-            0.09081266583074038 0 1 3 1 1 0 2 0
-            0.331213646878486 0 1 3 1 3 0 0 0
-            0.33667197218932576 1 1 0 1 0 0 1 0
-            0.0908126658307406 1 1 0 1 2 0 3 0
-            0.09081266583074038 1 1 2 1 0 0 3 0
-            0.331213646878486 1 1 2 1 2 0 1 0
-            0.09081266583074038 1 1 3 1 1 0 3 0
-            0.331213646878486 1 1 3 1 3 0 1 0
-            0.331213646878486 2 1 0 1 0 0 2 0
-            0.09081266583074052 2 1 0 1 2 0 0 0
-            0.331213646878486 2 1 1 1 1 0 2 0
-            0.09081266583074052 2 1 1 1 3 0 0 0
-            0.09081266583074048 2 1 3 1 1 0 0 0
-            0.34814578469185886 2 1 3 1 3 0 2 0
-            0.331213646878486 3 1 0 1 0 0 3 0
-            0.09081266583074052 3 1 0 1 2 0 1 0
-            0.331213646878486 3 1 1 1 1 0 3 0
-            0.09081266583074052 3 1 1 1 3 0 1 0
-            0.09081266583074048 3 1 2 1 0 0 1 0
-            0.34814578469185886 3 1 2 1 2 0 3 0
-            }"""
+        src = """0.7080240949826064
+- 1.248846801817026 0^ 0
+- 1.248846801817026 1^ 1
+- 0.4796778151607899 2^ 2
+- 0.4796778151607899 3^ 3
++ 0.33667197218932576 0^ 1^ 1 0
++ 0.0908126658307406 0^ 1^ 3 2
++ 0.09081266583074038 0^ 2^ 0 2
++ 0.331213646878486 0^ 2^ 2 0
++ 0.09081266583074038 0^ 3^ 1 2
++ 0.331213646878486 0^ 3^ 3 0
++ 0.33667197218932576 1^ 0^ 0 1
++ 0.0908126658307406 1^ 0^ 2 3
++ 0.09081266583074038 1^ 2^ 0 3
++ 0.331213646878486 1^ 2^ 2 1
++ 0.09081266583074038 1^ 3^ 1 3
++ 0.331213646878486 1^ 3^ 3 1
++ 0.331213646878486 2^ 0^ 0 2
++ 0.09081266583074052 2^ 0^ 2 0
++ 0.331213646878486 2^ 1^ 1 2
++ 0.09081266583074052 2^ 1^ 3 0
++ 0.09081266583074048 2^ 3^ 1 0
++ 0.34814578469185886 2^ 3^ 3 2
++ 0.331213646878486 3^ 0^ 0 3
++ 0.09081266583074052 3^ 0^ 2 1
++ 0.331213646878486 3^ 1^ 1 3
++ 0.09081266583074052 3^ 1^ 3 1
++ 0.09081266583074048 3^ 2^ 0 1
++ 0.34814578469185886 3^ 2^ 2 3"""
         inputParams['rdm-source'] = src
-        return vqe.compile(src)
+        return xacc.getObservable('fermion', src)

python/benchmark/vqe/chemistry/hamiltonian_generators/rbh_4q_sto3g.py

@@ -2,9 +2,6 @@ from pelix.ipopo.decorators import ComponentFactory, Property, Requires, Provide
     Validate, Invalidate, Instantiate
 from hamiltonian_generator import HamiltonianGenerator
 import ast, xacc
-import xaccvqe as vqe
-from xaccvqe import PauliOperator
-
 
 @ComponentFactory("rbh_4q_sto3g_hamiltonian_generator_factory")
 @Provides("hamiltonian_generator")

python/benchmark/vqe/chemistry/hamiltonian_generators/tapered_frozencore.py

@@ -3,7 +3,7 @@ from pelix.ipopo.decorators import ComponentFactory, Property, Requires, Provide
 
 from frozencore import FrozenCoreHamiltonian
 import xacc
-from xaccvqe import PauliOperator
+from xacc import PauliOperator
 
 @ComponentFactory("taperedfrozencore_hamiltonian_generator_factory")
 @Provides("hamiltonian_generator")

python/benchmark/vqe/hamiltonian_generator.py

+from abc import abstractmethod, ABC
+
+
+class HamiltonianGenerator(ABC):
+    """
+        Abstract class to be inherited by iPOPO bundles to generate a Hamiltonian for quantum computation
+
+        Subclasses must inherit and implement the generate() method to return an XACC-VQE PauliOperator
+    """
+    @abstractmethod
+    def generate(self, data):
+        pass

python/benchmark/vqe/install.ini

@@ -7,10 +7,3 @@ chemistry: /chemistry
 chem-hams: /chemistry/hamiltonian_generators
 chem-ansatze: /chemistry/ansatz_generators
 
-
-[Requirements]
-# Put the master dir name (VQE) and any requirement info for
-# the Python module required to use the plugins
-vqe: {"module": "xaccvqe",
-      "repo": "https://github.com/ornl-qci/xacc-vqe.git",
-      "dir": "xacc-vqe"}
\ No newline at end of file

python/benchmark/vqe/vqe.py

+from pelix.ipopo.decorators import (ComponentFactory, Property, Instantiate)
+import ast
+import xacc
+from xacc import BenchmarkAlgorithm
+from vqe_base import VQEBase
+
+@ComponentFactory("vqe_benchmark_factory")
+@Property("_name", "name", "vqe")
+@Instantiate("vqe_benchmark")
+class VQE(VQEBase):
+    """
+        Algorithm class inherited from VQEBase to execute the VQE algorithm
+    """
+    def __init__(self):
+        super().__init__()
+
+    def execute(self, inputParams):
+        """
+            Inherited method with algorithm-specific implementation
+
+            Parameters:
+                inputParams - a dictionary of input parameters obtained from .ini file
+
+        """
+        super().execute(inputParams)
+        # self.vqe_options_dict['task'] = 'vqe'
+        # if self.optimizer is not None:
+        #     self.optimizer.optimize(self.op, self.buffer, self.optimizer_options, self.vqe_options_dict)
+        # else:
+        execParams = {'accelerator': self.qpu, 'ansatz': self.ansatz, 'observable': self.op, 'optimizer':self.optimizer}
+        vqe = xacc.getAlgorithm('vqe', execParams)
+        vqe.execute(self.buffer)
+
+        return self.buffer
+
+    def analyze(self, buffer, inputParams):
+        super().analyze(buffer, inputParams)

python/benchmark/vqe/vqe_base.py

+from xacc import BenchmarkAlgorithm
+import xacc
+import ast
+import time
+import os
+from pelix.ipopo.decorators import (Provides, Requires, BindField, UnbindField)
+#
+#    VQEBase is an abstract class that implements the VQE algorithm using XACC.
+#    VQE and VQEEnergy are iPOPO bundles that inherit from this class to execute the algorithm and analyze results.
+#
+#    Methods:
+#        bind_dicts - Required for using iPOPO service registry
+#        unbind_dicts - Required for using iPOPO service registry
+#        execute - executes the VQE algorithm according to input configurations
+#        analyze - analyzes the AcceleratorBuffer produced from execute()
+@Provides("benchmark_algorithm")
+@Requires("_ansatz_generators", "ansatz_generator", aggregate=True)
+@Requires("_hamiltonian_generators", "hamiltonian_generator", aggregate=True)
+@Requires("_vqe_optimizers", "vqe_optimization", aggregate=True, optional=True)
+class VQEBase(BenchmarkAlgorithm):
+
+    def __init__(self):
+        self.hamiltonian_generators = {}
+        self.ansatz_generators = {}
+        self.vqe_optimizers = {}
+        self.vqe_options_dict = {}
+        self.n_qubits = 0
+        self.buffer = None
+        self.ansatz = None
+        self.op = None
+        self.qpu = None
+
+    @BindField('_vqe_optimizers')
+    @BindField('_ansatz_generators')
+    @BindField('_hamiltonian_generators')
+    def bind_dicts(self, field, service, svc_ref):
+        """
+        This method is intended to be inherited by iPOPO bundle subclasses.
+        Binds the service references of the available molecule and ansatz generators.
+        """
+        if svc_ref.get_property('hamiltonian_generator'):
+            generator = svc_ref.get_property('hamiltonian_generator')
+            self.hamiltonian_generators[generator] = service
+        if svc_ref.get_property('ansatz_generator'):
+            generator = svc_ref.get_property('ansatz_generator')
+            self.ansatz_generators[generator] = service
+        if svc_ref.get_property('vqe_optimizer'):
+            optimizer = svc_ref.get_property('vqe_optimizer')
+            self.vqe_optimizers[optimizer] = service
+
+    @UnbindField("_vqe_optimizers")
+    @UnbindField('_ansatz_generators')
+    @UnbindField('_hamiltonian_generators')
+    def unbind_dicts(self, field, service, svc_ref):
+        """
+            This method is intended to be inherited by iPOPO bundle subclasses.
+            Unbinds the service references of the available molecule and ansatz generators when the instance is killed
+        """
+        if svc_ref.get_property('hamiltonian_generator'):
+            generator = svc_ref.get_property('hamiltonian_generator')
+            del self.hamiltonian_generators[generator]
+        if svc_ref.get_property('ansatz_generator'):
+            generator = svc_ref.get_property('ansatz_generator')
+            del self.ansatz_generators[generator]
+        if svc_ref.get_property('vqe_optimizer'):
+            optimizer = svc_ref.get_property('vqe_optimizer')
+            del self.vqe_optimizers[optimizer]
+
+    def execute(self, inputParams):
+        """
+        This method is intended to be inherited by vqe and vqe_energy subclasses to allow algorithm-specific implementation.
+        This superclass method adds extra information to the buffer and allows XACC settings options to be set before executing VQE.
+
+        Parameters:
+        inputParams : dictionary
+                    a dictionary of input parameters obtained from .ini file
+
+        return QPU Accelerator buffer
+
+        Options used (obtained from inputParams):
+            'qubit-map': map of logical qubits to physical qubits
+            'n-execs': number of sampler executions of measurements
+            'initial-parameters': list of initial parameters for the VQE algorithm
+
+            'restart-from-file': AcceleratorDecorator option to allow restart of VQE algorithm
+            'readout-error': AcceleratorDecorator option for readout-error mitigation
+
+        """
+        self.qpu = xacc.getAccelerator(inputParams['accelerator'])
+        xaccOp = self.hamiltonian_generators[inputParams['hamiltonian-generator']].generate(
+            inputParams)
+        self.ansatz = self.ansatz_generators[inputParams['name']].generate(
+            inputParams, xaccOp.nBits())
+        if 'qubit-map' in inputParams:
+            qubit_map = ast.literal_eval(inputParams['qubit-map'])
+            xaccOp, self.ansatz, n_qubits = xaccvqe.mapToPhysicalQubits(
+                xaccOp, self.ansatz, qubit_map)
+        else:
+            n_qubits = xaccOp.nBits()
+        self.op = xaccOp
+        self.n_qubits = n_qubits
+        self.buffer = self.qpu.createBuffer('q', n_qubits)
+        self.buffer.addExtraInfo('hamiltonian', str(xaccOp))
+        self.buffer.addExtraInfo('ansatz-qasm', self.ansatz.toString('q').replace('\\n', '\\\\n'))
+        pycompiler = xacc.getCompiler('xacc-py')
+        self.buffer.addExtraInfo('ansatz-qasm-py', '\n'.join(pycompiler.translate('q',self.ansatz).split('\n')[1:]))
+        self.optimizer = None
+        self.optimizer_options = {}
+        if 'optimizer' in inputParams and inputParams['optimizer'] in self.vqe_optimizers:
+            self.optimizer = self.vqe_optimizers[inputParams['optimizer']]
+            if 'method' in inputParams:
+                self.optimizer_options['method'] = inputParams['method']
+            if 'options' in inputParams:
+                self.optimizer_options['options'] = ast.literal_eval(inputParams['options'])
+            if 'user-params' in inputParams:
+                self.optimizer_options['options']['user_params'] = ast.literal_eval(inputParams['user-params'])
+        else:
+            xacc.info("No classical optimizer specified. Setting to default XACC optimizer.")
+            if 'options' in inputParams:
+                self.optimizer_options['options'] = ast.literal_eval(inputParams['options'])
+            self.optimizer = xacc.getOptimizer('nlopt', self.optimizer_options)
+
+        self.buffer.addExtraInfo('accelerator', inputParams['accelerator'])
+        if 'n-execs' in inputParams:
+            xacc.setOption('sampler-n-execs', inputParams['n-execs'])
+            self.qpu = xacc.getAcceleratorDecorator('improved-sampling', self.qpu)
+
+        if 'restart-from-file' in inputParams:
+            xacc.setOption('vqe-restart-file', inputParams['restart-from-file'])
+            self.qpu = xacc.getAcceleratorDecorator('vqe-restart',self.qpu)
+            self.qpu.initialize()
+
+        if 'readout-error' in inputParams and inputParams['readout-error']:
+            self.qpu = xacc.getAcceleratorDecorator('ro-error',self.qpu)
+
+        if 'rdm-purification' in inputParams and inputParams['rdm-purification']:
+            self.qpu = xacc.getAcceleratorDecorator('rdm-purification', self.qpu)
+
+        self.vqe_options_dict = {'accelerator': self.qpu, 'ansatz': self.ansatz}
+
+        if 'initial-parameters' in inputParams:
+            self.vqe_options_dict['vqe-params'] = ','.join([str(x) for x in ast.literal_eval(inputParams['initial-parameters'])])
+
+        xacc.setOptions(inputParams)
+
+    def analyze(self, buffer, inputParams):
+        """
+        This method is also to be inherited by vqe and vqe_energy subclasses to allow for algorithm-specific implementation.
+
+        This superclass method always generates a .csv file with measured expectation values for each kernel and calculated energy of each iteration.
+
+        Parameters:
+        inputParams : dictionary
+                    a dictionary of input parameters obtained from .ini file
+        buffer : XACC AcceleratorBuffer
+                AcceleratorBuffer containing VQE results to be analyzed
+
+        Options used (in inputParams):
+            'readout-error': generate .csv file with readout-error corrected expectation values and calculated energy for each kernel and iteration.
+            'richardson-extrapolation': run Richardson-Extrapolation on the resulting Accelerator buffer (generating 4 more .csv files of expectation values and energies)
+            'rich-extra-iter': the number of iterations of Richardson-Extrapolation
+        """
+        ps = buffer.getAllUnique('parameters')
+        timestr = time.strftime("%Y%m%d-%H%M%S")
+        exp_csv_name = "%s_%s_%s_%s" % (os.path.splitext(buffer.getInformation('file-name'))[0],
+                                        buffer.getInformation('accelerator'),"exp_val_z",
+                                        timestr)
+        f = open(exp_csv_name+".csv", 'w')
+        exp_columns = [c.getInformation('kernel') for c in buffer.getChildren('parameters',ps[0])] + ['<E>']
+        f.write(str(exp_columns).replace('[','').replace(']','') + '\n')
+        for p in ps:
+            energy = 0.0
+            for c in buffer.getChildren('parameters', p):
+                exp = c.getInformation('exp-val-z')
+                energy += exp * c.getInformation('coefficient') if c.hasExtraInfoKey('coefficient') else 0.0
+                f.write(str(exp)+',')
+            f.write(str(energy)+'\n')
+        f.close()
+        if 'readout-error' in inputParams:
+            ro_exp_csv_name = "%s_%s_%s_%s" % (os.path.splitext(buffer.getInformation('file-name'))[0],
+                                        buffer.getInformation('accelerator'),"ro_fixed_exp_val_z",
+                                        timestr)
+            f = open(ro_exp_csv_name+'.csv', 'w')
+            f.write(str(exp_columns).replace('[','').replace(']','')+'\n')
+            for p in ps:
+                energy = 0.0
+                for c in buffer.getChildren('parameters', p):
+                    exp = c.getInformation('ro-fixed-exp-val-z')
+                    energy += exp * c.getInformation('coefficient') if c.hasExtraInfoKey('coefficient') else 0.0
+                    f.write(str(exp)+',')
+                f.write(str(energy)+'\n')
+            f.close()
+
+        if 'richardson-extrapolation' in inputParams and inputParams['richardson-extrapolation']:
+            from scipy.optimize import curve_fit
+            import numpy as np
+
+            angles = buffer.getInformation('vqe-angles')
+            qpu = self.vqe_options_dict['accelerator']
+            self.vqe_options_dict['accelerator'] = xacc.getAcceleratorDecorator('rich-extrap',qpu)
+            self.vqe_options_dict['task'] = 'compute-energy'
+            xaccOp = self.op
+            self.vqe_options_dict['vqe-params'] = ','.join([str(x) for x in angles])
+            fileNames = {r:"%s_%s_%s_%s" % (os.path.splitext(buffer.getInformation('file-name'))[0],
+                            buffer.getInformation('accelerator'),
+                            'rich_extrap_'+str(r), timestr)+'.csv' for r in [1,3,5,7]}
+
+            nRE_Execs = 2 if not 'rich-extrap-iter' in inputParams else int(inputParams['rich-extrap-iter'])
+            if nRE_Execs < 2:
+                print('Richardson Extrapolation needs more than 1 execution. Setting to 2.')
+                nRE_execs = 2
+
+            for r in [1,3,5,7]:
+                f = open(fileNames[r], 'w')
+                xacc.setOption('rich-extrap-r',r)
+
+                for i in range(nRE_Execs):
+                    richardson_buffer = qpu.createBuffer('q', self.n_qubits)
+                    results = xaccvqe.execute(xaccOp, richardson_buffer, **self.vqe_options_dict)
+
+                    ps = richardson_buffer.getAllUnique('parameters')
+                    for p in ps:
+                        f.write(str(p).replace('[', '').replace(']', ''))
+                        energy = 0.0
+                        for c in richardson_buffer.getChildren('parameters', p):
+                            exp = c.getInformation('ro-fixed-exp-val-z') if c.hasExtraInfoKey('ro-fixed-exp-val-z') else c.getInformation('exp-val-z')
+                            energy += exp * c.getInformation('coefficient')
+                            f.write(','+str(exp))
+                        f.write(','+str(energy)+'\n')
+                f.close()
+
+            nParams = len(ps[0])
+            columns = ['t{}'.format(i) for i in range(nParams)]
+
+            kernelNames = [c.getInformation('kernel') for c in buffer.getChildren('parameters',ps[0])]
+            columns += kernelNames
+            columns.append('E')
+
+            dat = [np.genfromtxt(fileNames[1], delimiter=',', names=columns),
+                np.genfromtxt(fileNames[3], delimiter=',', names=columns),
+                np.genfromtxt(fileNames[5], delimiter=',', names=columns),
+                np.genfromtxt(fileNames[7], delimiter=',', names=columns)]
+
+            allExps = [{k:[] for k in kernelNames} for i in range(4)]
+            allEnergies = []
+
+            temp = {r:[] for r in range(4)}
+
+            for i in range(nRE_Execs):
+                for r in range(4):
+                    for term in kernelNames:
+                        allExps[r][term].append(dat[r][term][i])
+                    temp[r].append(dat[r]['E'][i])
+
+            evars = [np.std(temp[r]) for r in range(4)]
+            xVals = [1,3,5,7]
+
+            avgExps = {k:[np.mean(allExps[r][k]) for r in range(4)] for k in kernelNames}
+            varExps = {k:[np.std(allExps[r][k]) for r in range(4)] for k in kernelNames}
+            energies = [np.mean(temp[r]) for r in range(4)]
+
+            def linear(x, a, b):
+                return a*x+b
+
+            def exp(x, a,b):
+                return a*np.exp(b*x)# + b
+
+            def quad(x, a, b, c):
+                return a*x*x + b*x + c
+
+            print('\nnoisy energy: ', energies[0], '+-', evars[0])
+
+            res = curve_fit(linear, xVals, energies, [1,energies[0]], sigma=evars)
+            print('\nrich linear extrap: ', res[0][1],'+- ', np.sqrt(np.diag(res[1])[1]))
+
+            res_exp = curve_fit(exp, xVals, energies, [0,0], sigma=evars)
+            print('\nrich exp extrap: ', exp(0,res_exp[0][0],res_exp[0][1]), '+-', np.sqrt(np.diag(res_exp[1])[1]))
+
+            res_q = curve_fit(quad, xVals, energies, [0,0,0], sigma=evars)
+            print("\nrich quad extrap: ", quad(0, res_q[0][0], res_q[0][1], res_q[0][2]), "+-", np.sqrt(np.diag(res_q[1])[2]))

python/benchmark/vqe/vqe_energy.py

+from pelix.ipopo.decorators import (ComponentFactory, Property, Instantiate)
+import ast
+import configparser
+import xacc
+import time
+import os
+from xacc import BenchmarkAlgorithm
+from vqe_base import VQEBase
+
+@ComponentFactory("vqe-energy_benchmark_factory")
+@Property("_name", "name", "vqe-energy")
+@Instantiate("vqe-energy_benchmark")
+class VQEEnergy(VQEBase):
+    """
+        Algorithm class inherited from VQEBase to execute the 'compute-energy' task of VQE
+    """
+    def __init__(self):
+        super().__init__()
+
+    def execute(self, inputParams):
+        """
+            Inherited method with algorithm-specific implementation
+
+            Parameters:
+                inputParams - a dictionary of input parameters obtained from .ini file
+
+            - sets XACC VQE task to 'compute-energy'
+        """
+        super().execute(inputParams)
+        self.vqe_options_dict['task'] = 'compute-energy'
+        energy = xaccvqe.execute(self.op, self.buffer, **self.vqe_options_dict).energy
+
+        if 'rdm-purification' in self.qpu.name():
+            p = self.buffer.getAllUnique('parameters')
+            child = self.buffer.getChildren('parameters', p[0])
+            energy = child[1].getInformation('purified-energy')
+            self.buffer.addExtraInfo('vqe-energy', energy)
+
+        return self.buffer
+
+    def analyze(self, buffer, inputParams):
+        super().analyze(buffer, inputParams)

python/benchmark/vqe/vqe_param_sweep.py

+from pelix.ipopo.decorators import (ComponentFactory, Property, Instantiate)
+import ast
+import configparser
+import xacc
+import time
+import os
+from xacc import BenchmarkAlgorithm
+from vqe_base import VQEBase
+
+@ComponentFactory("param-sweep_benchmark_factory")
+@Property("_name", "name", "param-sweep")
+@Instantiate("param-sweep_benchmark")
+class ParamSweep(VQEBase):
+    """
+        Algorithm class inherited from VQEBase to execute the 'compute-energy' task of VQE
+    """
+    def __init__(self):
+        super().__init__()
+
+    def linspace(self, a, b, n=100):
+        if n < 2:
+            return b
+        diff = (float(b) - a)/(n - 1)
+        return [diff * i + a  for i in range(n)]
+
+    def execute(self, inputParams):
+        """
+            Inherited method with algorithm-specific implementation
+
+            Parameters:
+                inputParams - a dictionary of input parameters obtained from .ini file
+
+            - sets XACC VQE task to 'compute-energy'
+            - executes a parameter-sweep
+        """
+        super().execute(inputParams)
+        pi = 3.141592653589793
+        self.vqe_options_dict['task'] = 'compute-energy'
+
+        if inputParams['upper-bound'] == 'pi':
+            up_bound = pi
+        else:
+            up_bound = ast.literal_eval(inputParams['upper-bound'])
+
+        if inputParams['lower-bound'] == '-pi':
+            low_bound = -pi
+        else:
+            low_bound = ast.literal_eval(inputParams['lower-bound'])
+
+        num_params = ast.literal_eval(inputParams['num-params'])
+
+        self.energies = []
+        self.angles = []
+        for param in self.linspace(low_bound, up_bound, num_params):
+            self.angles.append(param)
+            self.vqe_options_dict['vqe-params'] = str(param)
+            energy = xaccvqe.execute(self.op, self.buffer, **self.vqe_options_dict).energy
+