Commit 33fc48fb authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

add integer multiply 



Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent cb585a05

examples/arithmetic/integer_add.cpp

+34 −0
Original line number Diff line number Diff line
@@ -13,6 +13,20 @@ __qpu__ void test_add_integer_mod(qreg q, qubit anc) { 
  Measure(anc);

}



__qpu__ void test_mul_integer(qreg x, qreg b, qubit anc, int a, int N) {

  // b = 1;

  X(b[0]); 

  // x = |1> + |3>

  X(x[0]);

  H(x[1]);



  // ==> |a*x + b> 

  

  mul_integer_mod(x, b, anc, a, N);

  Measure(b);

  Measure(x);

}



int main(int argc, char **argv) {

  set_shots(1024);

  auto a = qalloc(3);
@@ -38,5 +52,25 @@ int main(int argc, char **argv) { 
  anc.print();

  // anc returns to 0

  qcor_expect(anc.counts()["0"] == 1024);



  // Test modular multiply 

  int a_val = 3;

  // Large modulo => exact answer

  int N_val = 16;

  // More qubits to save the result

  auto b_reg = qalloc(5);

  auto x_reg = qalloc(2);

  auto anc_reg = qalloc(1);

  test_mul_integer::print_kernel(x_reg, b_reg, anc_reg[0], a_val, N_val);

  test_mul_integer(x_reg, b_reg, anc_reg[0], a_val, N_val);

  // x = |1> + |3>; |b> = 1

  // |a*x + b> = |4> + |10>

  b_reg.print();

  qcor_expect(b_reg.counts().size() == 2);

  // 4

  qcor_expect(b_reg.counts()["00100"] > 400);

  // 10 = 8 + 2

  qcor_expect(b_reg.counts()["01010"] > 400);

  x_reg.print();

  return 0;

}
 
 No newline at end of file

lib/impl/integer_arithmetic.hpp

+24 −0
Original line number Diff line number Diff line
@@ -22,6 +22,10 @@ void genAngles(std::vector<double> &io_angles, int a, int nbQubits) { 
    angle *= M_PI;

  }

}



inline void calcPowMultMod(int &result, int i, int a, int N) {

  result = (1 << i) * a % N;

}

} // namespace internal

} // namespace qcor
@@ -114,3 +118,23 @@ __qpu__ void add_integer_mod(qreg q, qubit anc, int a, int N) { 
  compute { qft_opt_swap(q, 0); }

  action { phase_add_integer_mod(q, anc, a, N); }

}



// Modular multiply in phase basis:

// See Fig. 6 of https://arxiv.org/pdf/quant-ph/0205095.pdf  

// |x>|b> ==> |x> |b + ax mod N>

// i.e. if b == 0 ==> the result |ax mod N> is stored in b 

__qpu__ void phase_mul_integer_mod(qreg x, qreg b, qubit anc, int a, int N) {

  for (int i = 0; i < x.size(); ++i) {

    // add operand = 2^i * a

    int operand;

    qcor::internal::calcPowMultMod(operand, i, a, N);

    phase_add_integer_mod::ctrl(x[i], b, anc, operand, N);

  }

}



__qpu__ void mul_integer_mod(qreg x, qreg b, qubit anc, int a, int N) {

  // Bring it to Fourier basis

  // (IQFT automatically)

  compute { qft_opt_swap(b, 0); }

  action { phase_mul_integer_mod(x, b, anc, a, N); }

}