From 5ba48567fa8689ec7841f3773f86bce0ee0d7448 Mon Sep 17 00:00:00 2001
From: Payal Solanki <solankipayal290696@gmail.com>
Date: Thu, 9 Feb 2023 20:33:01 +0530
Subject: [PATCH 01/24] partial_transpose included

---
 qiskit/quantum_info/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qiskit/quantum_info/__init__.py b/qiskit/quantum_info/__init__.py
index 45a8d46e4765..19b7513e41c9 100644
--- a/qiskit/quantum_info/__init__.py
+++ b/qiskit/quantum_info/__init__.py
@@ -131,6 +131,7 @@
 from .states import Statevector, DensityMatrix, StabilizerState
 from .states import (
     partial_trace,
+    partial_transpose,
     state_fidelity,
     purity,
     entropy,

From a93623a77c580203af434bd25d03235198526086 Mon Sep 17 00:00:00 2001
From: Payal Solanki <solankipayal290696@gmail.com>
Date: Thu, 9 Feb 2023 20:33:42 +0530
Subject: [PATCH 02/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 53 ++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 04be491855d8..66ec434fa080 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -15,7 +15,7 @@
 """
 
 import numpy as np
-
+import math
 from qiskit.exceptions import QiskitError
 from qiskit.quantum_info.states.statevector import Statevector
 from qiskit.quantum_info.states.densitymatrix import DensityMatrix
@@ -155,3 +155,54 @@ def _funm_svd(matrix, func):
     unitary1, singular_values, unitary2 = la.svd(matrix)
     diag_func_singular = np.diag(func(singular_values))
     return unitary1.dot(diag_func_singular).dot(unitary2)
+
+
+
+
+def partial_transpose(state,qargs):
+    """Return partially transposed density matrix. 
+
+    Args:
+        state (DensityMatrix): the input state.
+        qargs (list): The subsystems to be transposed.
+
+    Returns:
+        DensityMatrix: The partially transposed density matrix.
+
+    Raises:
+        QiskitError: if input state is invalid.
+        QiskitError: if indices of subsystems are invalid
+        
+    """
+    state = _format_state(state, validate=False)
+    n = len(state.dims())
+    l = np.zeros(2**n,int)
+    for i in range(2**n):
+        x = 0
+        for k in qargs:
+            x = x + (((i >> (k)) % 2)*2**k)
+        l[i] = x
+    if not(set(qargs).issubset(set(np.arange(n)))):
+            raise QiskitError("Indices of subsystems to be transposed are invalid")
+    ptden = np.empty((2**n, 2**n),complex)
+    ptden[:] = np.nan
+    if isinstance(state, Statevector):
+        state = np.array(state)
+        for i in range(2**n):
+            for j in range(2**n):
+                if math.isnan(ptden[i,j]):
+                    x = i - l[i] + l[j]
+                    y = j - l[j] + l[i]
+                    ptden[i,j] = state[x]*np.conjugate(state[y])
+                    ptden[x,y] = state[i]*np.conjugate(state[j])
+    else:
+        state = np.array(state)
+        for i in range(2**n):
+            for j in range(2**n):
+                if math.isnan(ptden[i,j]):
+                    x = i - l[i] + l[j]
+                    y = j - l[j] + l[i]
+                    ptden[i,j] = state[x,y]
+                    ptden[x,y] = state[i,j]
+        
+    return(DensityMatrix(ptden))
\ No newline at end of file

From 1a162dd159ff2353297a4802070db5bf1864e6de Mon Sep 17 00:00:00 2001
From: Payal Solanki <solankipayal290696@gmail.com>
Date: Thu, 9 Feb 2023 20:33:52 +0530
Subject: [PATCH 03/24] included partial_transpose

---
 qiskit/quantum_info/states/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/__init__.py b/qiskit/quantum_info/states/__init__.py
index 1e49ee353b7b..c303e592f450 100644
--- a/qiskit/quantum_info/states/__init__.py
+++ b/qiskit/quantum_info/states/__init__.py
@@ -15,7 +15,7 @@
 from .statevector import Statevector
 from .stabilizerstate import StabilizerState
 from .densitymatrix import DensityMatrix
-from .utils import partial_trace, shannon_entropy
+from .utils import partial_trace, shannon_entropy,partial_transpose
 from .measures import (
     state_fidelity,
     purity,

From a7cbffe49a3ae40eb48c1781c998e514a93c1a45 Mon Sep 17 00:00:00 2001
From: Payal Solanki <solankipayal290696@gmail.com>
Date: Thu, 9 Feb 2023 20:46:07 +0530
Subject: [PATCH 04/24] included partial_transpose

---
 qiskit/quantum_info/states/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/__init__.py b/qiskit/quantum_info/states/__init__.py
index c303e592f450..ab231932c4fc 100644
--- a/qiskit/quantum_info/states/__init__.py
+++ b/qiskit/quantum_info/states/__init__.py
@@ -15,7 +15,7 @@
 from .statevector import Statevector
 from .stabilizerstate import StabilizerState
 from .densitymatrix import DensityMatrix
-from .utils import partial_trace, shannon_entropy,partial_transpose
+from .utils import partial_trace, shannon_entropy, partial_transpose
 from .measures import (
     state_fidelity,
     purity,

From 95d99a58cdc1f1bb6748bd5b2e01c5c732090c90 Mon Sep 17 00:00:00 2001
From: Payal Solanki <solankipayal290696@gmail.com>
Date: Thu, 9 Feb 2023 20:46:34 +0530
Subject: [PATCH 05/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 34 ++++++++++++++---------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 66ec434fa080..b91a2d45f1f6 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -157,10 +157,8 @@ def _funm_svd(matrix, func):
     return unitary1.dot(diag_func_singular).dot(unitary2)
 
 
-
-
-def partial_transpose(state,qargs):
-    """Return partially transposed density matrix. 
+def partial_transpose(state, qargs):
+    """Return partially transposed density matrix.
 
     Args:
         state (DensityMatrix): the input state.
@@ -172,37 +170,37 @@ def partial_transpose(state,qargs):
     Raises:
         QiskitError: if input state is invalid.
         QiskitError: if indices of subsystems are invalid
-        
+
     """
     state = _format_state(state, validate=False)
     n = len(state.dims())
-    l = np.zeros(2**n,int)
+    l = np.zeros(2**n, int)
     for i in range(2**n):
         x = 0
         for k in qargs:
-            x = x + (((i >> (k)) % 2)*2**k)
+            x = x + (((i >> (k)) % 2) * 2**k)
         l[i] = x
-    if not(set(qargs).issubset(set(np.arange(n)))):
-            raise QiskitError("Indices of subsystems to be transposed are invalid")
-    ptden = np.empty((2**n, 2**n),complex)
+    if not (set(qargs).issubset(set(np.arange(n)))):
+        raise QiskitError("Indices of subsystems to be transposed are invalid")
+    ptden = np.empty((2**n, 2**n), complex)
     ptden[:] = np.nan
     if isinstance(state, Statevector):
         state = np.array(state)
         for i in range(2**n):
             for j in range(2**n):
-                if math.isnan(ptden[i,j]):
+                if math.isnan(ptden[i, j]):
                     x = i - l[i] + l[j]
                     y = j - l[j] + l[i]
-                    ptden[i,j] = state[x]*np.conjugate(state[y])
-                    ptden[x,y] = state[i]*np.conjugate(state[j])
+                    ptden[i, j] = state[x] * np.conjugate(state[y])
+                    ptden[x, y] = state[i] * np.conjugate(state[j])
     else:
         state = np.array(state)
         for i in range(2**n):
             for j in range(2**n):
-                if math.isnan(ptden[i,j]):
+                if math.isnan(ptden[i, j]):
                     x = i - l[i] + l[j]
                     y = j - l[j] + l[i]
-                    ptden[i,j] = state[x,y]
-                    ptden[x,y] = state[i,j]
-        
-    return(DensityMatrix(ptden))
\ No newline at end of file
+                    ptden[i, j] = state[x, y]
+                    ptden[x, y] = state[i, j]
+
+    return DensityMatrix(ptden)

From ea9f8f089a2b9c0771d569a79be407e54d9d8c3e Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 13:13:43 +0530
Subject: [PATCH 06/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 50 ++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 04be491855d8..e5ba664238ec 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -15,7 +15,7 @@
 """
 
 import numpy as np
-
+import math
 from qiskit.exceptions import QiskitError
 from qiskit.quantum_info.states.statevector import Statevector
 from qiskit.quantum_info.states.densitymatrix import DensityMatrix
@@ -155,3 +155,51 @@ def _funm_svd(matrix, func):
     unitary1, singular_values, unitary2 = la.svd(matrix)
     diag_func_singular = np.diag(func(singular_values))
     return unitary1.dot(diag_func_singular).dot(unitary2)
+
+def partial_transpose(state,qargs):
+    """Return partially transposed density matrix. 
+
+    Args:
+        state (DensityMatrix): the input state.
+        qargs (list): The subsystems to be transposed.
+
+    Returns:
+        DensityMatrix: The partially transposed density matrix.
+
+    Raises:
+        QiskitError: if input state is invalid.
+        QiskitError: if indices of subsystems are invalid
+        
+    """
+    state = _format_state(state, validate=False)
+    n = len(state.dims())
+    l = np.zeros(2**n,int)
+    for i in range(2**n):
+        x = 0
+        for k in qargs:
+            x = x + (((i >> (k)) % 2)*2**k)
+        l[i] = x
+    if not(set(qargs).issubset(set(np.arange(n)))):
+            raise QiskitError("Indices of subsystems to be transposed are invalid")
+    ptden = np.empty((2**n, 2**n),complex)
+    ptden[:] = np.nan
+    if isinstance(state, Statevector):
+        state = np.array(state)
+        for i in range(2**n):
+            for j in range(2**n):
+                if math.isnan(ptden[i,j]):
+                    x = i - l[i] + l[j]
+                    y = j - l[j] + l[i]
+                    ptden[i,j] = state[x]*np.conjugate(state[y])
+                    ptden[x,y] = state[i]*np.conjugate(state[j])
+    else:
+        state = np.array(state)
+        for i in range(2**n):
+            for j in range(2**n):
+                if math.isnan(ptden[i,j]):
+                    x = i - l[i] + l[j]
+                    y = j - l[j] + l[i]
+                    ptden[i,j] = state[x,y]
+                    ptden[x,y] = state[i,j]
+        
+    return(DensityMatrix(ptden))

From 2ff52941d251659c814f107cda4be2eb9e173535 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 13:14:42 +0530
Subject: [PATCH 07/24] included partial_transpose

---
 qiskit/quantum_info/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qiskit/quantum_info/__init__.py b/qiskit/quantum_info/__init__.py
index 45a8d46e4765..19b7513e41c9 100644
--- a/qiskit/quantum_info/__init__.py
+++ b/qiskit/quantum_info/__init__.py
@@ -131,6 +131,7 @@
 from .states import Statevector, DensityMatrix, StabilizerState
 from .states import (
     partial_trace,
+    partial_transpose,
     state_fidelity,
     purity,
     entropy,

From ae400f1e9e4706dc542d1ddbc8b9684c644c4fe5 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 13:15:21 +0530
Subject: [PATCH 08/24] included partial_transpose

---
 qiskit/quantum_info/states/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/__init__.py b/qiskit/quantum_info/states/__init__.py
index 1e49ee353b7b..c303e592f450 100644
--- a/qiskit/quantum_info/states/__init__.py
+++ b/qiskit/quantum_info/states/__init__.py
@@ -15,7 +15,7 @@
 from .statevector import Statevector
 from .stabilizerstate import StabilizerState
 from .densitymatrix import DensityMatrix
-from .utils import partial_trace, shannon_entropy
+from .utils import partial_trace, shannon_entropy,partial_transpose
 from .measures import (
     state_fidelity,
     purity,

From 28ba225b10e8b751c8bc3b4942111a68cf2b5e03 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 13:20:17 +0530
Subject: [PATCH 09/24] included partial_transpose

---
 qiskit/quantum_info/states/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/__init__.py b/qiskit/quantum_info/states/__init__.py
index c303e592f450..ab231932c4fc 100644
--- a/qiskit/quantum_info/states/__init__.py
+++ b/qiskit/quantum_info/states/__init__.py
@@ -15,7 +15,7 @@
 from .statevector import Statevector
 from .stabilizerstate import StabilizerState
 from .densitymatrix import DensityMatrix
-from .utils import partial_trace, shannon_entropy,partial_transpose
+from .utils import partial_trace, shannon_entropy, partial_transpose
 from .measures import (
     state_fidelity,
     purity,

From 91cc3c16afc5a5e03164063f05582e5ff0aa2e15 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 13:20:25 +0530
Subject: [PATCH 10/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 33 +++++++++++++++--------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index e5ba664238ec..b91a2d45f1f6 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -156,8 +156,9 @@ def _funm_svd(matrix, func):
     diag_func_singular = np.diag(func(singular_values))
     return unitary1.dot(diag_func_singular).dot(unitary2)
 
-def partial_transpose(state,qargs):
-    """Return partially transposed density matrix. 
+
+def partial_transpose(state, qargs):
+    """Return partially transposed density matrix.
 
     Args:
         state (DensityMatrix): the input state.
@@ -169,37 +170,37 @@ def partial_transpose(state,qargs):
     Raises:
         QiskitError: if input state is invalid.
         QiskitError: if indices of subsystems are invalid
-        
+
     """
     state = _format_state(state, validate=False)
     n = len(state.dims())
-    l = np.zeros(2**n,int)
+    l = np.zeros(2**n, int)
     for i in range(2**n):
         x = 0
         for k in qargs:
-            x = x + (((i >> (k)) % 2)*2**k)
+            x = x + (((i >> (k)) % 2) * 2**k)
         l[i] = x
-    if not(set(qargs).issubset(set(np.arange(n)))):
-            raise QiskitError("Indices of subsystems to be transposed are invalid")
-    ptden = np.empty((2**n, 2**n),complex)
+    if not (set(qargs).issubset(set(np.arange(n)))):
+        raise QiskitError("Indices of subsystems to be transposed are invalid")
+    ptden = np.empty((2**n, 2**n), complex)
     ptden[:] = np.nan
     if isinstance(state, Statevector):
         state = np.array(state)
         for i in range(2**n):
             for j in range(2**n):
-                if math.isnan(ptden[i,j]):
+                if math.isnan(ptden[i, j]):
                     x = i - l[i] + l[j]
                     y = j - l[j] + l[i]
-                    ptden[i,j] = state[x]*np.conjugate(state[y])
-                    ptden[x,y] = state[i]*np.conjugate(state[j])
+                    ptden[i, j] = state[x] * np.conjugate(state[y])
+                    ptden[x, y] = state[i] * np.conjugate(state[j])
     else:
         state = np.array(state)
         for i in range(2**n):
             for j in range(2**n):
-                if math.isnan(ptden[i,j]):
+                if math.isnan(ptden[i, j]):
                     x = i - l[i] + l[j]
                     y = j - l[j] + l[i]
-                    ptden[i,j] = state[x,y]
-                    ptden[x,y] = state[i,j]
-        
-    return(DensityMatrix(ptden))
+                    ptden[i, j] = state[x, y]
+                    ptden[x, y] = state[i, j]
+
+    return DensityMatrix(ptden)

From d03e70e867c92f4ed4031f70a44fecd744882f7c Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 14:18:34 +0530
Subject: [PATCH 11/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index b91a2d45f1f6..8009d13450bd 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -13,9 +13,8 @@
 """
 Quantum information utility functions for states.
 """
-
-import numpy as np
 import math
+import numpy as np
 from qiskit.exceptions import QiskitError
 from qiskit.quantum_info.states.statevector import Statevector
 from qiskit.quantum_info.states.densitymatrix import DensityMatrix
@@ -174,13 +173,13 @@ def partial_transpose(state, qargs):
     """
     state = _format_state(state, validate=False)
     n = len(state.dims())
-    l = np.zeros(2**n, int)
+    lst = np.zeros(2**n, int)
     for i in range(2**n):
         x = 0
         for k in qargs:
             x = x + (((i >> (k)) % 2) * 2**k)
         l[i] = x
-    if not (set(qargs).issubset(set(np.arange(n)))):
+    if not set(qargs).issubset(set(np.arange(n))):
         raise QiskitError("Indices of subsystems to be transposed are invalid")
     ptden = np.empty((2**n, 2**n), complex)
     ptden[:] = np.nan
@@ -189,8 +188,8 @@ def partial_transpose(state, qargs):
         for i in range(2**n):
             for j in range(2**n):
                 if math.isnan(ptden[i, j]):
-                    x = i - l[i] + l[j]
-                    y = j - l[j] + l[i]
+                    x = i - lst[i] + lst[j]
+                    y = j - lst[j] + lst[i]
                     ptden[i, j] = state[x] * np.conjugate(state[y])
                     ptden[x, y] = state[i] * np.conjugate(state[j])
     else:
@@ -198,8 +197,8 @@ def partial_transpose(state, qargs):
         for i in range(2**n):
             for j in range(2**n):
                 if math.isnan(ptden[i, j]):
-                    x = i - l[i] + l[j]
-                    y = j - l[j] + l[i]
+                    x = i - lst[i] + lst[j]
+                    y = j - lst[j] + lst[i]
                     ptden[i, j] = state[x, y]
                     ptden[x, y] = state[i, j]
 

From fc1d6552dd590d7e581d2822264d867b5f200346 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 14:26:52 +0530
Subject: [PATCH 12/24] included partial_transpose

---
 qiskit/quantum_info/states/utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 8009d13450bd..6dc4f533aff9 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -178,7 +178,7 @@ def partial_transpose(state, qargs):
         x = 0
         for k in qargs:
             x = x + (((i >> (k)) % 2) * 2**k)
-        l[i] = x
+        lst[i] = x
     if not set(qargs).issubset(set(np.arange(n))):
         raise QiskitError("Indices of subsystems to be transposed are invalid")
     ptden = np.empty((2**n, 2**n), complex)

From a2c8a05cf22cfe7e2cb1d1af86ac0912141651a8 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 15:33:28 +0530
Subject: [PATCH 13/24] included test for partial transpose

---
 test/python/quantum_info/states/test_utils.py | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 2ea9038eb631..6f4e145fdea2 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -17,7 +17,7 @@
 
 from qiskit.test import QiskitTestCase
 from qiskit.quantum_info.states import Statevector, DensityMatrix
-from qiskit.quantum_info.states import partial_trace, shannon_entropy
+from qiskit.quantum_info.states import partial_trace, shannon_entropy, partial_transpose
 
 
 class TestStateUtils(QiskitTestCase):
@@ -54,7 +54,27 @@ def test_shannon_entropy(self):
         self.assertAlmostEqual(1.229368880382052, shannon_entropy(input_pvec, np.e))
         # Base 10
         self.assertAlmostEqual(0.533908120973504, shannon_entropy(input_pvec, 10))
-
+        
+    def test_statevector_partial_transpose(self):
+        psi = Statevector.from_label("10+")
+        rho1=[[0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0.5+0.j, 0.5+0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0.5+0.j, 0.5+0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j],
+               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
+                0. +0.j, 0. +0.j]]
+	    self.assertEqual(partial_transpose(rho, [0, 1]), rho1)
+    	
 
 if __name__ == "__main__":
     unittest.main()

From 35882a4504e9f5954d071a54dfacdafd64c5d305 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 15:52:55 +0530
Subject: [PATCH 14/24] included test for partial transpose

---
 test/python/quantum_info/states/test_utils.py | 41 +++++++++++--------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 6f4e145fdea2..c7aee09cdb7a 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -57,23 +57,30 @@ def test_shannon_entropy(self):
         
     def test_statevector_partial_transpose(self):
         psi = Statevector.from_label("10+")
-        rho1=[[0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0.5+0.j, 0.5+0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0.5+0.j, 0.5+0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j],
-               [0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j, 0. +0.j,
-                0. +0.j, 0. +0.j]]
-	    self.assertEqual(partial_transpose(rho, [0, 1]), rho1)
+        rho1=  [[0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0]]
+        self.assertEqual(partial_transpose(psi, [0, 1]), rho1)
+        self.assertEqual(partial_transpose(psi, [0, 2]), rho1)
+    
+
+    def test_density_matrix_partial_transpose(self):
+        rho = DensityMatrix.from_label("10+")
+        rho1=  [[0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0, 0, 0, 0]]
+        self.assertEqual(partial_transpose(rho, [0, 1]), rho1)
+        self.assertEqual(partial_transpose(rho, [0, 2]), rho1)
     	
 
 if __name__ == "__main__":

From 3934c8cf00ca82d0ef79279bac2e6fa7986dc762 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 15:54:35 +0530
Subject: [PATCH 15/24] included test for partial transpose

---
 test/python/quantum_info/states/test_utils.py | 41 ++++++++++---------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index c7aee09cdb7a..5813446781ad 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -54,34 +54,37 @@ def test_shannon_entropy(self):
         self.assertAlmostEqual(1.229368880382052, shannon_entropy(input_pvec, np.e))
         # Base 10
         self.assertAlmostEqual(0.533908120973504, shannon_entropy(input_pvec, 10))
-        
+
     def test_statevector_partial_transpose(self):
         psi = Statevector.from_label("10+")
-        rho1=  [[0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0]]
+        rho1 = [
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+        ]
         self.assertEqual(partial_transpose(psi, [0, 1]), rho1)
         self.assertEqual(partial_transpose(psi, [0, 2]), rho1)
-    
 
     def test_density_matrix_partial_transpose(self):
         rho = DensityMatrix.from_label("10+")
-        rho1=  [[0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-                [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0],
-                [0, 0, 0, 0, 0, 0, 0, 0]]
+        rho1 = [
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 0, 0],
+        ]
         self.assertEqual(partial_transpose(rho, [0, 1]), rho1)
         self.assertEqual(partial_transpose(rho, [0, 2]), rho1)
-    	
+
 
 if __name__ == "__main__":
     unittest.main()

From 2a220785f8ad19548fcf7d7507637ce9dd6a0aa2 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 16:08:57 +0530
Subject: [PATCH 16/24] added docstring

---
 test/python/quantum_info/states/test_utils.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 5813446781ad..661d507e5e25 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -56,6 +56,7 @@ def test_shannon_entropy(self):
         self.assertAlmostEqual(0.533908120973504, shannon_entropy(input_pvec, 10))
 
     def test_statevector_partial_transpose(self):
+        """Test partial_transpose function on statevectors"""
         psi = Statevector.from_label("10+")
         rho1 = [
             [0, 0, 0, 0, 0, 0, 0, 0],
@@ -71,6 +72,7 @@ def test_statevector_partial_transpose(self):
         self.assertEqual(partial_transpose(psi, [0, 2]), rho1)
 
     def test_density_matrix_partial_transpose(self):
+        """Test partial_transpose function on density matrices"""
         rho = DensityMatrix.from_label("10+")
         rho1 = [
             [0, 0, 0, 0, 0, 0, 0, 0],

From 788f960622bcaefad82d38ff6dd8ea7094f74c0a Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 16:39:17 +0530
Subject: [PATCH 17/24] included DensityMatrix(rho1)

---
 test/python/quantum_info/states/test_utils.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 661d507e5e25..522726a115e3 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -68,8 +68,8 @@ def test_statevector_partial_transpose(self):
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0],
         ]
-        self.assertEqual(partial_transpose(psi, [0, 1]), rho1)
-        self.assertEqual(partial_transpose(psi, [0, 2]), rho1)
+        self.assertEqual(partial_transpose(psi, [0, 1]), DensityMatrix(rho1))
+        self.assertEqual(partial_transpose(psi, [0, 2]), DensityMatrix(rho1))
 
     def test_density_matrix_partial_transpose(self):
         """Test partial_transpose function on density matrices"""
@@ -84,8 +84,8 @@ def test_density_matrix_partial_transpose(self):
             [0, 0, 0, 0, 0, 0, 0, 0],
             [0, 0, 0, 0, 0, 0, 0, 0],
         ]
-        self.assertEqual(partial_transpose(rho, [0, 1]), rho1)
-        self.assertEqual(partial_transpose(rho, [0, 2]), rho1)
+        self.assertEqual(partial_transpose(rho, [0, 1]), DensityMatrix(rho1))
+        self.assertEqual(partial_transpose(rho, [0, 2]), DensityMatrix(rho1))
 
 
 if __name__ == "__main__":

From a3a16fb8e42b6f63e6d688c336d4bb4f959eb316 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 16:48:39 +0530
Subject: [PATCH 18/24] changed rho1

---
 test/python/quantum_info/states/test_utils.py | 30 +++++++------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 522726a115e3..7ab3bedc8edf 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -58,32 +58,22 @@ def test_shannon_entropy(self):
     def test_statevector_partial_transpose(self):
         """Test partial_transpose function on statevectors"""
         psi = Statevector.from_label("10+")
-        rho1 = [
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-        ]
+        rho1=np.zeros((8,8),complex)
+        rho1[4,4]=0.5
+        rho1[4,5]=0.5
+        rho1[5,4]=0.5
+        rho1[5,5]=0.5
         self.assertEqual(partial_transpose(psi, [0, 1]), DensityMatrix(rho1))
         self.assertEqual(partial_transpose(psi, [0, 2]), DensityMatrix(rho1))
 
     def test_density_matrix_partial_transpose(self):
         """Test partial_transpose function on density matrices"""
         rho = DensityMatrix.from_label("10+")
-        rho1 = [
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-            [0, 0, 0, 0, 0.5, 0.5, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-            [0, 0, 0, 0, 0, 0, 0, 0],
-        ]
+        rho1=np.zeros((8,8),complex)
+        rho1[4,4]=0.5
+        rho1[4,5]=0.5
+        rho1[5,4]=0.5
+        rho1[5,5]=0.5
         self.assertEqual(partial_transpose(rho, [0, 1]), DensityMatrix(rho1))
         self.assertEqual(partial_transpose(rho, [0, 2]), DensityMatrix(rho1))
 

From c498c77f806c3183d62f7621e2e33abfe65917d7 Mon Sep 17 00:00:00 2001
From: PayalSolanki2906 <solankipayal290696@gmail.com>
Date: Fri, 10 Feb 2023 17:11:30 +0530
Subject: [PATCH 19/24] addition of release note

---
 .../notes/adding-partial-transpose-040a6ff00228841b.yaml     | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 releasenotes/notes/adding-partial-transpose-040a6ff00228841b.yaml

diff --git a/releasenotes/notes/adding-partial-transpose-040a6ff00228841b.yaml b/releasenotes/notes/adding-partial-transpose-040a6ff00228841b.yaml
new file mode 100644
index 000000000000..6744ea4bcfcc
--- /dev/null
+++ b/releasenotes/notes/adding-partial-transpose-040a6ff00228841b.yaml
@@ -0,0 +1,5 @@
+
+features:
+  - |
+    The partial transpose operation has been integrated into the quantum_info module, allowing for partial transposition of matrices.
+    This operation is key in detecting entanglement between bipartite quantum system.

From 3832e745eaa0fe32fe90218aaec32b286c9874e4 Mon Sep 17 00:00:00 2001
From: PayalSolanki29 <solankipayal290696@gmail.com>
Date: Thu, 16 Feb 2023 08:56:07 +0530
Subject: [PATCH 20/24] fix

---
 qiskit/quantum_info/states/utils.py | 72 +----------------------------
 1 file changed, 1 insertion(+), 71 deletions(-)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index e9f82996b1b2..21abb6d5b344 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -13,12 +13,8 @@
 """
 Quantum information utility functions for states.
 """
-import math
+
 import numpy as np
-<<<<<<< HEAD
-import math
-=======
->>>>>>> 8e2684ac7e3791a12afaa700959173c7627362ef
 from qiskit.exceptions import QiskitError
 from qiskit.quantum_info.states.statevector import Statevector
 from qiskit.quantum_info.states.densitymatrix import DensityMatrix
@@ -160,69 +156,3 @@ def _funm_svd(matrix, func):
     return unitary1.dot(diag_func_singular).dot(unitary2)
 
 
-def partial_transpose(state, qargs):
-    """Return partially transposed density matrix.
-
-    Args:
-        state (DensityMatrix): the input state.
-        qargs (list): The subsystems to be transposed.
-
-    Returns:
-        DensityMatrix: The partially transposed density matrix.
-
-    Raises:
-        QiskitError: if input state is invalid.
-        QiskitError: if indices of subsystems are invalid
-
-    """
-    state = _format_state(state, validate=False)
-    n = len(state.dims())
-<<<<<<< HEAD
-    l = np.zeros(2**n, int)
-=======
-    lst = np.zeros(2**n, int)
->>>>>>> 8e2684ac7e3791a12afaa700959173c7627362ef
-    for i in range(2**n):
-        x = 0
-        for k in qargs:
-            x = x + (((i >> (k)) % 2) * 2**k)
-<<<<<<< HEAD
-        l[i] = x
-    if not (set(qargs).issubset(set(np.arange(n)))):
-=======
-        lst[i] = x
-    if not set(qargs).issubset(set(np.arange(n))):
->>>>>>> 8e2684ac7e3791a12afaa700959173c7627362ef
-        raise QiskitError("Indices of subsystems to be transposed are invalid")
-    ptden = np.empty((2**n, 2**n), complex)
-    ptden[:] = np.nan
-    if isinstance(state, Statevector):
-        state = np.array(state)
-        for i in range(2**n):
-            for j in range(2**n):
-                if math.isnan(ptden[i, j]):
-<<<<<<< HEAD
-                    x = i - l[i] + l[j]
-                    y = j - l[j] + l[i]
-=======
-                    x = i - lst[i] + lst[j]
-                    y = j - lst[j] + lst[i]
->>>>>>> 8e2684ac7e3791a12afaa700959173c7627362ef
-                    ptden[i, j] = state[x] * np.conjugate(state[y])
-                    ptden[x, y] = state[i] * np.conjugate(state[j])
-    else:
-        state = np.array(state)
-        for i in range(2**n):
-            for j in range(2**n):
-                if math.isnan(ptden[i, j]):
-<<<<<<< HEAD
-                    x = i - l[i] + l[j]
-                    y = j - l[j] + l[i]
-=======
-                    x = i - lst[i] + lst[j]
-                    y = j - lst[j] + lst[i]
->>>>>>> 8e2684ac7e3791a12afaa700959173c7627362ef
-                    ptden[i, j] = state[x, y]
-                    ptden[x, y] = state[i, j]
-
-    return DensityMatrix(ptden)

From 11d5adc80a395081ce964b8025110004b4b4cc4c Mon Sep 17 00:00:00 2001
From: PayalSolanki29 <solankipayal290696@gmail.com>
Date: Thu, 16 Feb 2023 09:43:13 +0530
Subject: [PATCH 21/24] fix

---
 qiskit/quantum_info/__init__.py               |  1 -
 qiskit/quantum_info/states/__init__.py        |  2 +-
 test/python/quantum_info/states/test_utils.py | 23 +------------------
 3 files changed, 2 insertions(+), 24 deletions(-)

diff --git a/qiskit/quantum_info/__init__.py b/qiskit/quantum_info/__init__.py
index 19b7513e41c9..45a8d46e4765 100644
--- a/qiskit/quantum_info/__init__.py
+++ b/qiskit/quantum_info/__init__.py
@@ -131,7 +131,6 @@
 from .states import Statevector, DensityMatrix, StabilizerState
 from .states import (
     partial_trace,
-    partial_transpose,
     state_fidelity,
     purity,
     entropy,
diff --git a/qiskit/quantum_info/states/__init__.py b/qiskit/quantum_info/states/__init__.py
index ab231932c4fc..1e49ee353b7b 100644
--- a/qiskit/quantum_info/states/__init__.py
+++ b/qiskit/quantum_info/states/__init__.py
@@ -15,7 +15,7 @@
 from .statevector import Statevector
 from .stabilizerstate import StabilizerState
 from .densitymatrix import DensityMatrix
-from .utils import partial_trace, shannon_entropy, partial_transpose
+from .utils import partial_trace, shannon_entropy
 from .measures import (
     state_fidelity,
     purity,
diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index 7ab3bedc8edf..a791e146588a 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -55,28 +55,7 @@ def test_shannon_entropy(self):
         # Base 10
         self.assertAlmostEqual(0.533908120973504, shannon_entropy(input_pvec, 10))
 
-    def test_statevector_partial_transpose(self):
-        """Test partial_transpose function on statevectors"""
-        psi = Statevector.from_label("10+")
-        rho1=np.zeros((8,8),complex)
-        rho1[4,4]=0.5
-        rho1[4,5]=0.5
-        rho1[5,4]=0.5
-        rho1[5,5]=0.5
-        self.assertEqual(partial_transpose(psi, [0, 1]), DensityMatrix(rho1))
-        self.assertEqual(partial_transpose(psi, [0, 2]), DensityMatrix(rho1))
-
-    def test_density_matrix_partial_transpose(self):
-        """Test partial_transpose function on density matrices"""
-        rho = DensityMatrix.from_label("10+")
-        rho1=np.zeros((8,8),complex)
-        rho1[4,4]=0.5
-        rho1[4,5]=0.5
-        rho1[5,4]=0.5
-        rho1[5,5]=0.5
-        self.assertEqual(partial_transpose(rho, [0, 1]), DensityMatrix(rho1))
-        self.assertEqual(partial_transpose(rho, [0, 2]), DensityMatrix(rho1))
-
+    
 
 if __name__ == "__main__":
     unittest.main()

From 0ab74ea29131d4b4654635ec94a509da185e2882 Mon Sep 17 00:00:00 2001
From: PayalSolanki29 <solankipayal290696@gmail.com>
Date: Thu, 16 Feb 2023 11:26:21 +0530
Subject: [PATCH 22/24] fir partial_transpose

---
 qiskit/quantum_info/states/densitymatrix.py   | 26 +++++++++++++++++++
 qiskit/quantum_info/states/utils.py           |  2 --
 .../quantum_info/states/test_densitymatrix.py | 11 ++++++++
 test/python/quantum_info/states/test_utils.py |  3 +--
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/qiskit/quantum_info/states/densitymatrix.py b/qiskit/quantum_info/states/densitymatrix.py
index 435c02e535cf..33cfb5912ee7 100644
--- a/qiskit/quantum_info/states/densitymatrix.py
+++ b/qiskit/quantum_info/states/densitymatrix.py
@@ -809,3 +809,29 @@ def to_statevector(self, atol=None, rtol=None):
 
         psi = evecs[:, np.argmax(evals)]  # eigenvectors returned in columns.
         return Statevector(psi)
+
+    def partial_transpose(self, qargs):
+        """Return partially transposed density matrix.
+
+        Args:
+            qargs (list): The subsystems to be transposed.
+
+        Returns:
+            DensityMatrix: The partially transposed density matrix.
+
+        Raises:
+            QiskitError: if input state is invalid.
+
+        """
+        from qiskit.quantum_info.states import utils
+
+        state = utils._format_state(self, validate=False)
+        arr = state._data.reshape(state._op_shape.tensor_shape)
+        qargs = len(state._op_shape.dims_l()) - 1 - np.array(qargs)
+        n = len(state.dims())
+        lst = list(range(2 * n))
+        for i in qargs:
+            lst[i], lst[i + n] = lst[i + n], lst[i]
+        rho = np.transpose(arr, lst)
+        rho = np.reshape(rho, state._op_shape.shape)
+        return DensityMatrix(rho)
diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 21abb6d5b344..88cbcc6e3330 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -154,5 +154,3 @@ def _funm_svd(matrix, func):
     unitary1, singular_values, unitary2 = la.svd(matrix)
     diag_func_singular = np.diag(func(singular_values))
     return unitary1.dot(diag_func_singular).dot(unitary2)
-
-
diff --git a/test/python/quantum_info/states/test_densitymatrix.py b/test/python/quantum_info/states/test_densitymatrix.py
index 6a619094ce3e..9f596fa1f13c 100644
--- a/test/python/quantum_info/states/test_densitymatrix.py
+++ b/test/python/quantum_info/states/test_densitymatrix.py
@@ -1202,6 +1202,17 @@ def test_drawings(self):
             with self.subTest(msg=f"draw('{drawtype}')"):
                 dm.draw(drawtype)
 
+    def test_density_matrix_partial_transpose(self):
+        """Test partial_transpose function on density matrices"""
+        rho = DensityMatrix.from_label("10+")
+        rho1 = np.zeros((8, 8), complex)
+        rho1[4, 4] = 0.5
+        rho1[4, 5] = 0.5
+        rho1[5, 4] = 0.5
+        rho1[5, 5] = 0.5
+        self.assertEqual(DensityMatrix.partial_transpose(rho, [0, 1]), DensityMatrix(rho1))
+        self.assertEqual(DensityMatrix.partial_transpose(rho, [0, 2]), DensityMatrix(rho1))
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/test/python/quantum_info/states/test_utils.py b/test/python/quantum_info/states/test_utils.py
index a791e146588a..2ea9038eb631 100644
--- a/test/python/quantum_info/states/test_utils.py
+++ b/test/python/quantum_info/states/test_utils.py
@@ -17,7 +17,7 @@
 
 from qiskit.test import QiskitTestCase
 from qiskit.quantum_info.states import Statevector, DensityMatrix
-from qiskit.quantum_info.states import partial_trace, shannon_entropy, partial_transpose
+from qiskit.quantum_info.states import partial_trace, shannon_entropy
 
 
 class TestStateUtils(QiskitTestCase):
@@ -55,7 +55,6 @@ def test_shannon_entropy(self):
         # Base 10
         self.assertAlmostEqual(0.533908120973504, shannon_entropy(input_pvec, 10))
 
-    
 
 if __name__ == "__main__":
     unittest.main()

From d944e23aea202baf966340a6baa7856339dd862b Mon Sep 17 00:00:00 2001
From: "Payal D. Solanki" <solankipayal290696@gmail.com>
Date: Thu, 16 Feb 2023 12:04:18 +0530
Subject: [PATCH 23/24] Update utils.py

---
 qiskit/quantum_info/states/utils.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qiskit/quantum_info/states/utils.py b/qiskit/quantum_info/states/utils.py
index 88cbcc6e3330..04be491855d8 100644
--- a/qiskit/quantum_info/states/utils.py
+++ b/qiskit/quantum_info/states/utils.py
@@ -15,6 +15,7 @@
 """
 
 import numpy as np
+
 from qiskit.exceptions import QiskitError
 from qiskit.quantum_info.states.statevector import Statevector
 from qiskit.quantum_info.states.densitymatrix import DensityMatrix

From 84bd4502d2f00799a0ede9db10b6fd84b99e3621 Mon Sep 17 00:00:00 2001
From: ikkoham <ikkoham@users.noreply.github.com>
Date: Wed, 12 Apr 2023 23:17:25 +0900
Subject: [PATCH 24/24] refactor and add tests

---
 qiskit/quantum_info/states/densitymatrix.py   | 15 ++-----
 .../quantum_info/states/test_densitymatrix.py | 40 +++++++++++--------
 2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/qiskit/quantum_info/states/densitymatrix.py b/qiskit/quantum_info/states/densitymatrix.py
index 8a7c41022daa..124a382f01d1 100644
--- a/qiskit/quantum_info/states/densitymatrix.py
+++ b/qiskit/quantum_info/states/densitymatrix.py
@@ -823,20 +823,13 @@ def partial_transpose(self, qargs):
 
         Returns:
             DensityMatrix: The partially transposed density matrix.
-
-        Raises:
-            QiskitError: if input state is invalid.
-
         """
-        from qiskit.quantum_info.states import utils
-
-        state = utils._format_state(self, validate=False)
-        arr = state._data.reshape(state._op_shape.tensor_shape)
-        qargs = len(state._op_shape.dims_l()) - 1 - np.array(qargs)
-        n = len(state.dims())
+        arr = self._data.reshape(self._op_shape.tensor_shape)
+        qargs = len(self._op_shape.dims_l()) - 1 - np.array(qargs)
+        n = len(self.dims())
         lst = list(range(2 * n))
         for i in qargs:
             lst[i], lst[i + n] = lst[i + n], lst[i]
         rho = np.transpose(arr, lst)
-        rho = np.reshape(rho, state._op_shape.shape)
+        rho = np.reshape(rho, self._op_shape.shape)
         return DensityMatrix(rho)
diff --git a/test/python/quantum_info/states/test_densitymatrix.py b/test/python/quantum_info/states/test_densitymatrix.py
index eeb5b07685f9..8886e35cc288 100644
--- a/test/python/quantum_info/states/test_densitymatrix.py
+++ b/test/python/quantum_info/states/test_densitymatrix.py
@@ -12,21 +12,20 @@
 
 """Tests for DensityMatrix quantum state class."""
 
-import unittest
 import logging
-from ddt import ddt, data
+import unittest
+
 import numpy as np
+from ddt import data, ddt
 from numpy.testing import assert_allclose
 
-from qiskit.test import QiskitTestCase
-from qiskit import QiskitError
-from qiskit import QuantumRegister, QuantumCircuit
-from qiskit.circuit.library import HGate, QFT
-
-from qiskit.quantum_info.random import random_unitary, random_density_matrix, random_pauli
-from qiskit.quantum_info.states import DensityMatrix, Statevector
+from qiskit import QiskitError, QuantumCircuit, QuantumRegister
+from qiskit.circuit.library import QFT, HGate
 from qiskit.quantum_info.operators.operator import Operator
 from qiskit.quantum_info.operators.symplectic import Pauli, SparsePauliOp
+from qiskit.quantum_info.random import random_density_matrix, random_pauli, random_unitary
+from qiskit.quantum_info.states import DensityMatrix, Statevector
+from qiskit.test import QiskitTestCase
 
 logger = logging.getLogger(__name__)
 
@@ -1204,14 +1203,21 @@ def test_drawings(self):
 
     def test_density_matrix_partial_transpose(self):
         """Test partial_transpose function on density matrices"""
-        rho = DensityMatrix.from_label("10+")
-        rho1 = np.zeros((8, 8), complex)
-        rho1[4, 4] = 0.5
-        rho1[4, 5] = 0.5
-        rho1[5, 4] = 0.5
-        rho1[5, 5] = 0.5
-        self.assertEqual(DensityMatrix.partial_transpose(rho, [0, 1]), DensityMatrix(rho1))
-        self.assertEqual(DensityMatrix.partial_transpose(rho, [0, 2]), DensityMatrix(rho1))
+        with self.subTest(msg="separable"):
+            rho = DensityMatrix.from_label("10+")
+            rho1 = np.zeros((8, 8), complex)
+            rho1[4, 4] = 0.5
+            rho1[4, 5] = 0.5
+            rho1[5, 4] = 0.5
+            rho1[5, 5] = 0.5
+            self.assertEqual(rho.partial_transpose([0, 1]), DensityMatrix(rho1))
+            self.assertEqual(rho.partial_transpose([0, 2]), DensityMatrix(rho1))
+
+        with self.subTest(msg="entangled"):
+            rho = DensityMatrix([[0, 0, 0, 0], [0, 0.5, -0.5, 0], [0, -0.5, 0.5, 0], [0, 0, 0, 0]])
+            rho1 = DensityMatrix([[0, 0, 0, -0.5], [0, 0.5, 0, 0], [0, 0, 0.5, 0], [-0.5, 0, 0, 0]])
+            self.assertEqual(rho.partial_transpose([0]), DensityMatrix(rho1))
+            self.assertEqual(rho.partial_transpose([1]), DensityMatrix(rho1))
 
     def test_clip_probabilities(self):
         """Test probabilities are clipped to [0, 1]."""