Fractional gates updates

docs/guides/fractional-gates.ipynb

@@ -385,6 +385,26 @@
     "Read the guide on [primitive options](/docs/guides/runtime-options-overview) to learn more about customizing the error mitigation and suppression techniques for a given quantum workload."
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "58fba520-5d6e-4647-8cb7-2c8790eb8127",
+   "metadata": {},
+   "source": [
+    "## Which backends support fractional gates?\n",
+    "\n",
+    "Not all backends support fractional gates. Run `service.backends(use_fractional_gates=True)` to find those that do. A fake backend supports fractional gates only if the related \"real\" backend supports them.\n",
+    "\n",
+    "Note that fake backends don't support fractional gates by default, since fractional gates are disabled by default. To enable fractional gates on a fake backend that supports them, refresh its configuration.\n",
+    "\n",
+    "Example:\n",
+    "\n",
+    "```python\n",
+    "service = QiskitRuntimeService()\n",
+    "fake_backend = FakeBoston()\n",
+    "fake_backend.refresh(service=service, use_fractional_gates=True)\n",
+    "```"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "bf0a38a6-60d1-4848-bbde-df19bb496510",