Commit 12b1d060 authored by Mccaskey, Alex's avatar Mccaskey, Alex
Browse files

demonstrate use of ctrl on exp_i_theta and circuit opt with iterate qpe quasimo workflow 



Signed-off-by: Mccaskey, Alex's avatarAlex McCaskey <mccaskeyaj@ornl.gov>
parent 0ddaa322

examples/quasimo/IterativeQpeVqe.cpp

+4 −0
Original line number Diff line number Diff line
@@ -25,16 +25,20 @@ int main(int argc, char **argv) { 
      QuaSiMo::ModelFactory::createModel(eigen_state_prep, H, 2, 0);



  // Instantiate an IQPE workflow

  // NOTE: can turn off exp_i_theta compute-action-uncompute with {"cau-opt", false}

  auto workflow =

      QuaSiMo::getWorkflow("iqpe", {{"time-steps", 8}, {"iterations", 8}});



  auto result = workflow->execute(problemModel);

  const double phaseValue = result.get<double>("phase");

  const double energy = result.get<double>("energy");

  auto n_insts = result.get<std::vector<int>>("n-kernel-instructions");



  std::cout << "Final phase = " << phaseValue << "\n";

  // Expect: ~ -1.7 (due to limited bit precision)

  std::cout << "Energy = " << energy << "\n";



  print("N Instructions at Iter:");

  for (auto [i,n] : enumerate(n_insts)) print("iter", i, ":" , n);

  return 0;

}
 
 No newline at end of file

lib/quasimo/impls/ansatz_generator/trotter.cpp

+9 −3
Original line number Diff line number Diff line 
#include "trotter.hpp"



#include "xacc_service.hpp"



namespace qcor {
@@ -12,11 +13,16 @@ Ansatz TrotterEvolution::create_ansatz(Observable *obs, 
  if (params.keyExists<double>("dt")) {

    dt = params.get<double>("dt");

  }



  // always default to true

  auto cau_opt = params.get_or_default("cau-opt", true);



  // Just use exp_i_theta for now

  // TODO: formalize a standard library kernel for this.

  auto expCirc = std::dynamic_pointer_cast<xacc::quantum::Circuit>(

      xacc::getService<xacc::Instruction>("exp_i_theta"));

  expCirc->expand({{"pauli", obs->toString()}});

  expCirc->expand({{"pauli", obs->toString()},

                   {"__internal_compute_action_uncompute_opt__", cau_opt}});

  result.circuit = expCirc->operator()({dt});

  result.nb_qubits = expCirc->nRequiredBits();

lib/quasimo/impls/workflow/iterative_qpe.cpp

+19 −4
Original line number Diff line number Diff line
@@ -15,13 +15,18 @@ bool IterativeQpeWorkflow::initialize(const HeterogeneousMap &params) { 
  if (params.keyExists<int>("iterations")) {

    num_iters = params.get<int>("iterations");

  }



  // defaults to true all the way down, this really 

  // just gives us a way to turn it off

  cau_opt = params.get_or_default("cau-opt", true);



  return (num_steps >= 1) && (num_iters >= 1);

}



std::shared_ptr<CompositeInstruction>

IterativeQpeWorkflow::constructQpeTrotterCircuit(

    std::shared_ptr<Observable> obs, double trotter_step, size_t nbQubits,

    double compensatedAncRot, int steps, int k, double omega) {

    double compensatedAncRot, int steps, int k, double omega, bool cau_opt) {

  auto provider = xacc::getIRProvider("quantum");

  auto kernel = provider->createComposite("__TEMP__QPE__LOOP__");

  // Ancilla qubit is the last one in the register.
@@ -38,7 +43,7 @@ IterativeQpeWorkflow::constructQpeTrotterCircuit( 
  // TODO: support other methods (e.g. Suzuki)

  auto method = xacc::getService<AnsatzGenerator>("trotter");

  auto trotterCir =

      method->create_ansatz(obs.get(), {{"dt", trotter_step}}).circuit;

      method->create_ansatz(obs.get(), {{"dt", trotter_step}, {"cau-opt", cau_opt}}).circuit;

  // std::cout << "Trotter circ:\n" << trotterCir->toString() << "\n";



  // Controlled-U
@@ -82,7 +87,7 @@ std::shared_ptr<CompositeInstruction> IterativeQpeWorkflow::constructQpeCircuit( 
  auto provider = xacc::getIRProvider("quantum");

  const double trotterStepSize = -2 * M_PI / num_steps;

  auto kernel = constructQpeTrotterCircuit(obs, trotterStepSize, obs->nBits(),

                                           0.0, num_steps, k, omega);

                                           0.0, num_steps, k, omega, cau_opt);

  const auto nbQubits = obs->nBits();



  // Ancilla qubit is the last one in the register
@@ -133,6 +138,7 @@ IterativeQpeWorkflow::execute(const QuantumSimulationModel &model) { 
  // We're using XACC IR construction API here, since using QCOR kernels here

  // seems to be complicated.

  double omega_coef = 0.0;

  std::vector<int> n_instructions;

  // Iterates over the num_iters

  // k runs from the number of iterations back to 1

  for (int iterIdx = 0; iterIdx < num_iters; ++iterIdx) {
@@ -148,6 +154,15 @@ IterativeQpeWorkflow::execute(const QuantumSimulationModel &model) { 


    auto iterQpe = constructQpeCircuit(stretchedObs, k, -2 * M_PI * omega_coef);

    kernel->addInstruction(iterQpe);

    int count = 0;

    xacc::InstructionIterator iter(kernel);

    while(iter.hasNext()) {

      auto next = iter.next();

      if (next->isEnabled() && !next->isComposite()) {

        count++;

      }

    }

    n_instructions.push_back(count);

    // Executes the iterative QPE algorithm:

    auto temp_buffer = xacc::qalloc(stretchedObs->nBits() + 1);

    // std::cout << "Kernel: \n" << kernel->toString() << "\n";
@@ -184,7 +199,7 @@ IterativeQpeWorkflow::execute(const QuantumSimulationModel &model) { 
    // omega_coef = " << omega_coef << "\n";

  }



  return {{"phase", omega_coef},

  return {{"phase", omega_coef}, {"n-kernel-instructions", n_instructions},

          {"energy", ham_converter.computeEnergy(omega_coef)}};

}

} // namespace QuaSiMo

lib/quasimo/impls/workflow/iterative_qpe.hpp

+3 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ public: 


  static std::shared_ptr<CompositeInstruction> constructQpeTrotterCircuit(

      std::shared_ptr<Observable> obs, double trotter_step, size_t nbQubits,

      double compensatedAncRot = 0, int steps = 1, int k = 1, double omega = 0);

      double compensatedAncRot = 0, int steps = 1, int k = 1, double omega = 0, bool cau_opt = true);



private:

  std::shared_ptr<CompositeInstruction>
@@ -38,6 +38,8 @@ private: 
  // Number of iterations (>=1)

  int num_iters;

  HamOpConverter ham_converter;



  bool cau_opt = true;

};

} // namespace QuaSiMo

} // namespace qcor
 
 No newline at end of file