Debug QUnitMulti::TrySeparate()

unitaryfund · Nov 6, 2024 · c4594a5 · c4594a5
1 parent 610b9cf
commit c4594a5
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Showing 3 changed files with 48 additions and 10 deletions.
diff --git a/include/qunit.hpp b/include/qunit.hpp
@@ -34,6 +34,7 @@ class QUnit : public QParity, public QInterface {
     bool useHostRam;
     bool isReactiveSeparate;
     bool useTGadget;
+    bool isBdt;
     bitLenInt thresholdQubits;
     real1_f separabilityThreshold;
     real1_f roundingThreshold;
@@ -119,6 +120,14 @@ class QUnit : public QParity, public QInterface {
         }
 
         const bitLenInt length = dest->GetQubitCount();
+
+        if ((!length) || (length == qubitCount)) {
+            return true;
+        }
+
+        if (!isBdt) {
+            return QInterface::TryDecompose(start, dest, error_tol);
+        }
 
         if ((start + length) > qubitCount) {
             throw std::invalid_argument("QUnit::TryDecompose qubit range out-of-bounds!");

diff --git a/src/qunit.cpp b/src/qunit.cpp
@@ -70,6 +70,7 @@ QUnit::QUnit(std::vector<QInterfaceEngine> eng, bitLenInt qBitCount, const bitCa
     , freezeBasis2Qb(false)
     , useHostRam(useHostMem)
     , useTGadget(true)
+    , isBdt(false)
     , thresholdQubits(qubitThreshold)
     , separabilityThreshold(sep_thresh)
     , logFidelity(0.0)
@@ -80,6 +81,17 @@ QUnit::QUnit(std::vector<QInterfaceEngine> eng, bitLenInt qBitCount, const bitCa
 {
     if (engines.empty()) {
         engines.push_back(QINTERFACE_STABILIZER_HYBRID);
+    } else {
+        for (size_t i = 0U; i < engines.size(); ++i) {
+            QInterfaceEngine e = engines[i];
+            if ((e == QINTERFACE_CPU) || (e == QINTERFACE_OPENCL) || (e == QINTERFACE_CUDA) || (e == QINTERFACE_HYBRID) || (e == QINTERFACE_BDT_HYBRID)) {
+                break;
+            }
+            if (e == QINTERFACE_BDT) {
+                isBdt = true;
+                break;
+            }
+        }
     }
 
     isReactiveSeparate = (separabilityThreshold > FP_NORM_EPSILON_F);

diff --git a/test/tests.cpp b/test/tests.cpp
@@ -2833,9 +2833,6 @@ TEST_CASE_METHOD(QInterfaceTestFixture, "test_isfinished")
 
 TEST_CASE_METHOD(QInterfaceTestFixture, "test_tryseparate")
 {
-    const bool isStabilizerQBdt =
-        (testSubSubEngineType == QINTERFACE_BDT) && (testSubEngineType == QINTERFACE_STABILIZER_HYBRID);
-
     qftReg->SetPermutation(85);
 
     int i;
@@ -2846,10 +2843,6 @@ TEST_CASE_METHOD(QInterfaceTestFixture, "test_tryseparate")
 
     for (i = 0; i < 8; i++) {
         qftReg->TrySeparate(i);
-        if (!isStabilizerQBdt) {
-            const std::vector<bitLenInt> toSep{ (bitLenInt)i };
-            qftReg->TrySeparate(toSep, FP_NORM_EPSILON_F);
-        }
     }
 
     REQUIRE_THAT(qftReg, HasProbability(0, 8, 85));
@@ -2860,10 +2853,34 @@ TEST_CASE_METHOD(QInterfaceTestFixture, "test_tryseparate")
     qftReg->CNOT(0, 2);
     qftReg->CNOT(0, 2);
     qftReg->TrySeparate(0, 1);
-    if (!isStabilizerQBdt) {
-        const std::vector<bitLenInt> toSep{ 0, 1 };
-        qftReg->TrySeparate(toSep, FP_NORM_EPSILON_F);
+    qftReg->CNOT(0, 1);
+    qftReg->Z(0);
+    qftReg->H(0);
+    REQUIRE_THAT(qftReg, HasProbability(0, 8, 1));
+}
+
+TEST_CASE_METHOD(QInterfaceTestFixture, "test_tryseparate_tolerance")
+{
+    qftReg->SetPermutation(85);
+
+    bitLenInt i;
+
+    qftReg->QFT(0, 8);
+
+    qftReg->IQFT(0, 8);
+
+    for (i = 0; i < 8; i++) {
+        qftReg->TrySeparate(std::vector<bitLenInt>({ i }), FP_NORM_EPSILON);
     }
+
+    REQUIRE_THAT(qftReg, HasProbability(0, 8, 85));
+
+    qftReg->SetPermutation(0);
+    qftReg->H(0);
+    qftReg->CNOT(0, 1);
+    qftReg->CNOT(0, 2);
+    qftReg->CNOT(0, 2);
+    qftReg->TrySeparate({ 0, 1 }, FP_NORM_EPSILON);
     qftReg->CNOT(0, 1);
     qftReg->Z(0);
     qftReg->H(0);