Commit 8027e07e authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Code clean-up 



Formalize the input parameters of the QFT and IQFT runtime library functions.

Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent 8d942466

examples/qrt/multiple_kernels.cpp

+4 −2
Original line number Diff line number Diff line
@@ -8,10 +8,12 @@ __qpu__ void f(qreg q) { 
  X(q[1]);



  // Call qft kernel (defined in a separate header file)

  qft(q, nQubits);  

  int startIdx = 0;

  int shouldSwap = 1;

  qft(q, startIdx, nQubits, shouldSwap);  

  

  // Inverse QFT:

  iqft(q, nQubits);

  iqft(q, startIdx, nQubits, shouldSwap);

  

  // Measure all qubits

  for (int qIdx = 0; qIdx < nQubits; ++qIdx) {

examples/qrt/qft.hpp

+12 −43
Original line number Diff line number Diff line
@@ -5,6 +5,17 @@ 


#include "qalloc.hpp"



// Generic QFT and IQFT algorithms

// Input:

// (1) Qubit register (type qreg)

// (2) The start qubit index and the number of qubits (type integer)

// Note: these two parameters allow us to operate the QFT/IQFT on 

// a contiguous subset of qubits of the register.

// If we want to use the entire register, 

// just pass 0 and number of qubits in the register, respectively.

// (3) shouldSwap flag (as integer):

// If 0, no Swap gates will be added.

// Otherwise, Swap gates are added at the end (QFT) and beginning (IQFT).

__qpu__ void qft(qreg q, int startIdx, int nbQubits, int shouldSwap) {

  for (int qIdx = nbQubits - 1; qIdx >= 0; --qIdx) {

    auto shiftedBitIdx = qIdx + startIdx;
@@ -45,45 +56,3 @@ __qpu__ void iqft(qreg q, int startIdx, int nbQubits, int shouldSwap) { 


  H(q[startIdx + nbQubits - 1]);

}
 
 No newline at end of file
 


// QFT kernel:

// Input: Qubit register and the max qubit index for the QFT,

// i.e. allow us to do QFT on a subset of the register [0, maxBitIdx)

// __qpu__ void qft(qreg q, int maxBitIdx) {

//   // Local Declarations

//   const auto nQubits = maxBitIdx;



//   for (int qIdx = 0; qIdx < nQubits; ++qIdx) {

//     auto bitIdx = nQubits - qIdx - 1;

//     H(q[bitIdx]);

//     for (int j = 0; j < bitIdx; ++j) {

//       const double theta = M_PI/std::pow(2.0, bitIdx - j);

//       CPhase(q[j], q[bitIdx], theta);

//     }

//   }



//   // Swap qubits

//   for (int qIdx = 0; qIdx < nQubits / 2; ++qIdx) {

//     Swap(q[qIdx], q[nQubits - qIdx - 1]);

//   }

// }



// // Inverse QFT

// __qpu__ void iqft(qreg q, int maxBitIdx) {

//   // Local Declarations

//   const auto nQubits = maxBitIdx;

//   // Swap qubits

//   for (int qIdx = 0; qIdx < nQubits / 2; ++qIdx) {

//     Swap(q[qIdx], q[nQubits - qIdx - 1]);

//   }



//   for (int qIdx = 0; qIdx < nQubits - 1; ++qIdx) {

//     H(q[qIdx]);

//     for (int j = 0; j < qIdx + 1; ++j) {

//       const double theta = -M_PI/std::pow(2.0, qIdx + 1 - j);

//       CPhase(q[j], q[qIdx + 1], theta);

//     }

//   }



//   H(q[nQubits - 1]);

// }
 
 No newline at end of file

examples/qrt/qpe_example_qrt.cpp

+3 −1
Original line number Diff line number Diff line
@@ -45,7 +45,9 @@ __qpu__ void QuantumPhaseEstimation(qreg q) { 
  }



  // Inverse QFT on the counting qubits:

  iqft(q, bitPrecision);

  int startIdx = 0;

  int shouldSwap = 1;

  iqft(q, startIdx, bitPrecision, shouldSwap);



  // Measure counting qubits

  for (int qIdx = 0; qIdx < bitPrecision; ++qIdx) {