Commit 4de3a61b authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Merge branch 'master' into tnguyen/update-qasm3

parents 5ee18f03 207fd011

examples/ctrl-gates/simple_hadamard_test.cpp

+6 −3
Original line number Diff line number Diff line
@@ -5,10 +5,13 @@ __qpu__ void h_gate(qreg q) { H(q[0]); } 


int main() {

  int n_state_qubits = 1;

  auto expectation = qcor::hadamard_test(x_gate, x_gate, n_state_qubits);

  print("<X> = ", expectation);

  auto expectation = qcor::hadamard_test(h_gate, x_gate, n_state_qubits);

  print("< + | X | + > = ", expectation);

  

  expectation = qcor::hadamard_test(x_gate, h_gate, n_state_qubits);

  print("<H> = ", expectation);

  print("< 1 | H | 1 > = ", expectation);



  expectation = qcor::hadamard_test(x_gate, x_gate, n_state_qubits);

  print("< 1 | X | 1 > = ", expectation);

  return 0;

}
 
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examples/qcor_demos/ibm_qasm3_demo_082021/intro/hadamard_test.qasm

+21 −10
Original line number Diff line number Diff line 
OPENQASM 3;



// compute < psi | U | psi> 

// let |psi> = |+>, U = X

// < + | X | + > == 1.0

// == < 0 | H X H | 0> == < 0 | Z | 0 > == 1



const n_iters = 100;

double count0, count1;

// compile and run with 

// qcor hadamard_test.qasm 

// ./a.out



// Eigenstate qubit

qubit q;

const n_iters = 100;

double count1;



// Ancilla qubit

qubit a;



// Eigenstate qubit

qubit q;



for i in [0:n_iters] {

    // Generate |+> eigenstate

    x q;

    h q;



    // apply hadamard on ancilla

    h a;



    // Ctrl-U, U == H

    // Ctrl-U, U == X

    cx a, q;



    // apply hadamard again

    h a;



    // measure and reset

    // measure the ancilla

    bit c;

    c = measure a;



    // Reset the qubits

    reset a;

    reset q;



    // Store up the observed bits

    if (c == 1) {
@@ -36,7 +46,8 @@ for i in [0:n_iters] { 
}



// Number of 0s must be ...

count0 = n_iters - count1;

double count0 = n_iters - count1;



double exp_val = (count1 - count0) / (count1 + count0);

print("<+|H|+> = ", exp_val);
 
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// compute the exp val Re(<psi|U|psi>) = P0 - P1

double exp_val = (count0 - count1) / n_iters;

print("<+|X|+> = ", exp_val);
 
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lib/impl/hadamard_test.hpp

+2 −1
Original line number Diff line number Diff line
@@ -42,8 +42,9 @@ double hadamard_test(StatePrep state_prep, Unitary unitary, 
  }

 

  // We have counts, so use that

  // P0 - P1 = <psi|U|psi>

  double count1 = (double)q.counts().find("1")->second;

  double count2 = (double)q.counts().find("0")->second;

  return std::fabs((count1 - count2) / (count1 + count2));

  return (count2 - count1) / (count1 + count2);

}

}  // namespace qcor