Commit 8fd767d1 authored by Nguyen, Thien Minh's avatar Nguyen, Thien Minh
Browse files

Work on Steane code impl for standard lib 



Not yet tested.

Signed-off-by: default avatarThien Nguyen <nguyentm@ornl.gov>
parent c79de6e9

lib/impl/qec_factory.hpp

+14 −1
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
#include <functional>

#include "bit_flip_code.hpp"

#include "five_qubit_code.hpp"

#include "seven_qubit_steane_code.hpp"



// Encode a physical qubit into a logical qubit using given scratch qubits.

// Inputs:
@@ -26,7 +27,7 @@ using QecCode = std::tuple<stabilizerGroups, encodeFn, recoverFn>; 
// Code name:

// - "bit-flip"

// - "five-qubit"

// - "seven-qubit"

// - "steane" (7 qubits)

// - "surface-code",

// etc.

QecCode getQecCode(const std::string &in_codeName) {
@@ -52,6 +53,18 @@ QecCode getQecCode(const std::string &in_codeName) { 
        });

    return std::make_tuple(five_qubit_code_stabilizers(), encoder, recover);

  }

  if (in_codeName == "steane") {

    encodeFn encoder(

        [](qreg q, int dataQubitIdx, std::vector<int> scratchQubitIdx) {

          seven_qubit_code_encoder(q, dataQubitIdx, scratchQubitIdx);

        });

    recoverFn recover(

        [](qreg q, std::vector<int> logicalReg, std::vector<int> syndromes) {

          seven_qubit_code_recover(q, logicalReg, syndromes);

        });

    return std::make_tuple(seven_qubit_code_stabilizers(), encoder, recover);

  }

  

  throw std::runtime_error("Error: '" + in_codeName +

                           "' is not a valid QEC code.");

}
 
 No newline at end of file

lib/impl/seven_qubit_steane_code.hpp

0 → 100644
+46 −0
Original line number Diff line number Diff line 
#pragma once



// Distance-3 Steane quantum error correction code with 7 qubits

std::vector<std::vector<qcor::PauliOperator>> seven_qubit_code_stabilizers() {

  static const std::vector<std::vector<qcor::PauliOperator>> STABILIZERS{

      // Steane code has two groups of syndromes to detect X and Z errors.

      // X syndromes

      {qcor::X(0), qcor::X(2), qcor::X(4), qcor::X(6)},

      {qcor::X(1), qcor::X(2), qcor::X(5), qcor::X(6)},

      {qcor::X(3), qcor::X(4), qcor::X(5), qcor::X(6)},

      // Z syndromes

      {qcor::Z(0), qcor::Z(2), qcor::Z(4), qcor::Z(6)},

      {qcor::Z(1), qcor::Z(2), qcor::Z(5), qcor::Z(6)},

      {qcor::Z(3), qcor::Z(4), qcor::Z(5), qcor::Z(6)}};

  return STABILIZERS;

}



__qpu__ void seven_qubit_code_encoder(qreg q, int dataQubitIdx,

                                      std::vector<int> scratchQubitIdx) {

  H(q[scratchQubitIdx[0]]);

  H(q[scratchQubitIdx[2]]);

  H(q[scratchQubitIdx[5]]);

  CX(q[dataQubitIdx], q[scratchQubitIdx[4]]);

  CX(q[scratchQubitIdx[5]], q[scratchQubitIdx[1]]);

  CX(q[scratchQubitIdx[5]], q[scratchQubitIdx[3]]);

  CX(q[scratchQubitIdx[1]], q[dataQubitIdx]);

  CX(q[scratchQubitIdx[2]], q[scratchQubitIdx[4]]);

  CX(q[scratchQubitIdx[0]], q[scratchQubitIdx[4]]);

  CX(q[scratchQubitIdx[4]], q[scratchQubitIdx[5]]);

  CX(q[scratchQubitIdx[2]], q[scratchQubitIdx[3]]);

  CX(q[scratchQubitIdx[0]], q[scratchQubitIdx[1]]);

}



__qpu__ void seven_qubit_code_recover(qreg q, std::vector<int> logicalReg,

                                      std::vector<int> syndromes) {

  auto xSyndromes = {syndromes[0], syndromes[1], syndromes[2]};

  auto zSyndromes = {syndromes[3], syndromes[4], syndromes[5]};

  auto xSyndromeIdx = syndrome_array_to_int(xSyndromes);

  auto zSyndromeIdx = syndrome_array_to_int(zSyndromes);

  if (xSyndromeIdx > 0) {

    Z(q[xSyndromeIdx - 1]);

  }

  if (zSyndromeIdx > 0) {

    X(q[zSyndromeIdx - 1]);

  }

}