Remove discussion of addresses from API and docs and replace with "CI…

… strings" (#54)

* Remove discussion of addresses

* Add release note

* Fix docs

* Update warning

* Don't specify base-10 integers

docs/how_tos/choose_subspace_dimension.ipynb

@@ -113,7 +113,7 @@
    "source": [
     "from qiskit_addon_sqd.configuration_recovery import recover_configurations\n",
     "from qiskit_addon_sqd.fermion import (\n",
-    "    bitstring_matrix_to_sorted_addresses,\n",
+    "    bitstring_matrix_to_ci_strs,\n",
     "    flip_orbital_occupancies,\n",
     "    solve_fermion,\n",
     ")\n",
@@ -176,8 +176,8 @@
     "        int_occs = np.zeros((n_batches, 2 * num_orbitals))\n",
     "        cs = []\n",
     "        for j in range(n_batches):\n",
-    "            addresses = bitstring_matrix_to_sorted_addresses(batches[j], open_shell=open_shell)\n",
-    "            int_d[j] = len(addresses[0]) * len(addresses[1])\n",
+    "            ci_strs = bitstring_matrix_to_ci_strs(batches[j], open_shell=open_shell)\n",
+    "            int_d[j] = len(ci_strs[0]) * len(ci_strs[1])\n",
     "            energy_sci, coeffs_sci, avg_occs, spin = solve_fermion(\n",
     "                batches[j],\n",
     "                hcore,\n",

docs/how_tos/integrate_dice_solver.ipynb

@@ -29,7 +29,7 @@
     "from qiskit_addon_sqd.configuration_recovery import recover_configurations\n",
     "from qiskit_addon_sqd.counts import counts_to_arrays, generate_counts_uniform\n",
     "from qiskit_addon_sqd.fermion import (\n",
-    "    bitstring_matrix_to_sorted_addresses,\n",
+    "    bitstring_matrix_to_ci_strs,\n",
     "    flip_orbital_occupancies,\n",
     ")\n",
     "from qiskit_addon_sqd.subsampling import postselect_and_subsample\n",
@@ -100,9 +100,9 @@
     "    int_e = np.zeros(n_batches)\n",
     "    int_occs = np.zeros((n_batches, 2 * num_orbitals))\n",
     "    for j in range(n_batches):\n",
-    "        addresses = bitstring_matrix_to_sorted_addresses(batches[j], open_shell=open_shell)\n",
+    "        ci_strs = bitstring_matrix_to_ci_strs(batches[j], open_shell=open_shell)\n",
     "        energy_sci, wf_mags, avg_occs = solve_dice(\n",
-    "            addresses,\n",
+    "            ci_strs,\n",
     "            active_space_path,\n",
     "            os.path.abspath(\".\"),\n",
     "            spin_sq=spin_sq,\n",

docs/how_tos/project_pauli_operators_onto_hilbert_subspaces.ipynb

@@ -26,7 +26,7 @@
     "This package provides two tools to perform this projection:\n",
     "\n",
     "- ``qiskit_addon_sqd.qubit.matrix_elements_from_pauli()``: is a lower-level function\n",
-    "that returns the non-zero matrix elements of a Pauli string and the corresponding addresses\n",
+    "that returns the non-zero matrix elements of a Pauli string and the corresponding indices\n",
     "of the non-zero elements.\n",
     "\n",
     "- ``qiskit_addon_sqd.qubit.project_operator_to_subspace()``: is a higher-level function that \n",
@@ -92,7 +92,7 @@
    "id": "5707b93c",
    "metadata": {},
    "source": [
-    "### First method: nonzero matrix elements and addresses."
+    "### First method: nonzero matrix elements and indices."
    ]
   },
   {
@@ -142,11 +142,9 @@
     "operator_from_matrix_elements = coo_matrix((d, d), dtype=\"complex128\")\n",
     "\n",
     "for pauli in hamiltonian.paulis:\n",
-    "    matrix_elements, row_addresses, col_addresses = matrix_elements_from_pauli(\n",
-    "        bitstring_matrix, pauli\n",
-    "    )\n",
+    "    matrix_elements, row_indices, col_indices = matrix_elements_from_pauli(bitstring_matrix, pauli)\n",
     "    operator_from_matrix_elements += coo_matrix(\n",
-    "        (matrix_elements, (row_addresses, col_addresses)), (d, d)\n",
+    "        (matrix_elements, (row_indices, col_indices)), (d, d)\n",
     "    )"
    ]
   },

docs/how_tos/select_open_closed_shell.ipynb

@@ -182,10 +182,10 @@
     }
    ],
    "source": [
-    "from qiskit_addon_sqd.fermion import bitstring_matrix_to_sorted_addresses\n",
+    "from qiskit_addon_sqd.fermion import bitstring_matrix_to_ci_strs\n",
     "\n",
-    "addresses = bitstring_matrix_to_sorted_addresses(batches[0], open_shell=open_shell)\n",
-    "print(addresses)"
+    "ci_strs = bitstring_matrix_to_ci_strs(batches[0], open_shell=open_shell)\n",
+    "print(ci_strs)"
    ]
   },
   {
@@ -277,15 +277,14 @@
     }
    ],
    "source": [
-    "addresses_up = addresses[0]\n",
-    "addresses_dn = addresses[1]\n",
+    "ci_strs_up, ci_strs_dn = ci_strs\n",
     "\n",
     "print(\"Basis elements of the subspace:\")\n",
     "\n",
-    "for address_up in addresses_up:\n",
-    "    for address_dn in addresses_dn:\n",
+    "for ci_str_up in ci_strs_up:\n",
+    "    for ci_str_dn in ci_strs_dn:\n",
     "        format_name = \"{0:0\" + str(num_orbitals) + \"b}\"\n",
-    "        print(\"|\" + format_name.format(address_up) + format_name.format(address_dn) + \">\")"
+    "        print(\"|\" + format_name.format(ci_str_up) + format_name.format(ci_str_dn) + \">\")"
    ]
   },
   {
@@ -436,13 +435,13 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "(array([1, 4], dtype=int64), array([2, 8], dtype=int64))\n"
+      "(array([2, 8], dtype=int64), array([1, 4], dtype=int64))\n"
      ]
     }
    ],
    "source": [
-    "addresses = bitstring_matrix_to_sorted_addresses(batches[0], open_shell=open_shell)\n",
-    "print(addresses)"
+    "ci_strs = bitstring_matrix_to_ci_strs(batches[0], open_shell=open_shell)\n",
+    "print(ci_strs)"
    ]
   },
   {
@@ -484,23 +483,22 @@
      "output_type": "stream",
      "text": [
       "Basis elements of the subspace:\n",
-      "|00010010>\n",
-      "|00011000>\n",
-      "|01000010>\n",
-      "|01001000>\n"
+      "|00100001>\n",
+      "|00100100>\n",
+      "|10000001>\n",
+      "|10000100>\n"
      ]
     }
    ],
    "source": [
-    "addresses_up = addresses[0]\n",
-    "addresses_dn = addresses[1]\n",
+    "ci_strs_up, ci_strs_dn = ci_strs\n",
     "\n",
     "print(\"Basis elements of the subspace:\")\n",
     "\n",
-    "for address_up in addresses_up:\n",
-    "    for address_dn in addresses_dn:\n",
+    "for ci_str_up in ci_strs_up:\n",
+    "    for ci_str_dn in ci_strs_dn:\n",
     "        format_name = \"{0:0\" + str(num_orbitals) + \"b}\"\n",
-    "        print(\"|\" + format_name.format(address_up) + format_name.format(address_dn) + \">\")"
+    "        print(\"|\" + format_name.format(ci_str_up) + format_name.format(ci_str_dn) + \">\")"
    ]
   },
   {