Remove documentation links to nonexistent documents and pages (#7506)

Previously, PR #6580 removed notebooks and the faq about calibration
topics that concerned the quantum service that is no longer offered.
However, these links in the TOC were missed at the time and need to be
removed.

Author: mhucka

docs/_book.yaml

@@ -167,10 +167,6 @@ upper_tabs:
         path: /cirq/noise/representing_noise
       ####  CHARACTERIZATION AND COMPENSATION  ####
       - heading: "Characterization and compensation"
-      - title: "Calibration FAQ"
-        path: /cirq/noise/calibration_faq
-      - title: "Floquet Calibration"
-        path: /cirq/noise/floquet_calibration_example
       - title: "Cross-Entropy Benchmarking (XEB)"
         style: accordion
         section:

docs/google/best_practices.ipynb

@@ -517,8 +517,8 @@
     "\n",
     "For more on calibration and detailed instructions on how to perform these procedures, see the following tutorials:\n",
     "\n",
-    "* [Floquet calibration example](../noise/floquet_calibration_example.ipynb)\n",
-    "* [XEB calibration example](../noise/qcvv/xeb_calibration_example.ipynb)"
+    "* [XEB calibration example](../noise/qcvv/xeb_calibration_example.ipynb)\n",
+    "* [Floquet calibration](https://www.youtube.com/watch?v=hYDWOz1r2Ys&t=243s)"
    ]
   }
  ],

docs/hardware/qubit_picking.ipynb

@@ -280,7 +280,7 @@
    "source": [
     "This fsim data would influence you to avoid the `(6,2)-(7,2)` qubit pair, and prefer the top left of the grid for high-priority qubit pairs  (those that have two-qubit gates executed on them many times in your circuit). Additionally, the fact that the `cirq.SycamoreGate` error is so much lower than the `cirq.ISwapPowGate` error means the device was likely calibrated for the `SycamoreGate`, and you should [transform](../transform/transformers.ipynb) your circuit with `cirq.optimize_for_target_gateset` to the `cirq_google.transformers.SycamoreTargetGateset` gate set, if possible.\n",
     "\n",
-    "This particular type of error can be compensated for somewhat, by using [Floquet calibration](../noise/floquet_calibration_example.ipynb), but this is out of scope for this notebook, and may require adaptation to work with the provided processor error data."
+    "This particular type of error can be compensated for somewhat by using [Floquet calibration](https://www.youtube.com/watch?v=hYDWOz1r2Ys&t=243s), but this is out of scope for this notebook, and may require adaptation to work with the provided processor error data."
    ]
   },
   {

docs/tutorials/google/identifying_hardware_changes.ipynb

@@ -72,7 +72,7 @@
    "source": [
     "You've run your circuit with Google's [Quantum Computing Service](./start.ipynb) and you're getting results that unexpectedly differ from those you saw when you ran your experiment last week. What's the cause of this and what can you do about it?\n",
     "\n",
-    "Your experience may be due to changes in the device that have occurred since the most recent maintenance [Calibration](../../noise/calibration_faq.md#what_is_the_difference_between_the_user-triggered_calibrations_floquet_or_xeb_and_the_maintenance_calibration). Every few days, the QCS devices are calibrated for the highest performance across all of their available qubits and operations. However, in the hours or days since the most recent maintenance calibration, the performance of the device hardware may have changed significantly, affecting your circuit's results.  \n",
+    "Your experience may be due to changes in the device that have occurred since the most recent maintenance calibration. Every few days, the QCS devices are calibrated for the highest performance across all of their available qubits and operations. However, in the hours or days since the most recent maintenance calibration, the performance of the device hardware may have changed significantly, affecting your circuit's results.  \n",
     "\n",
     "The rest of this tutorial will describe these hardware changes, demonstrate how to collect error metrics for identifying if changes have occurred, and provide some examples of how you can compare your metric results to select the most performant qubits for your circuit.\n",
     "For more further reading on qubit picking methodology, see the [Best Practices](../../google/best_practices.ipynb) guide and [Qubit Picking with Loschmidt Echoes](./echoes.ipynb) tutorial. The method presented in the Loschmidt Echoes tutorial is an alternative way to identify hardware changes."
@@ -126,8 +126,11 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "\u001b[?25l   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m0.0/2.0 MB\u001b[0m \u001b[31m?\u001b[0m eta \u001b[36m-:--:--\u001b[0m\r\u001b[2K   \u001b[91m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m\u001b[91m╸\u001b[0m \u001b[32m2.0/2.0 MB\u001b[0m \u001b[31m52.9 MB/s\u001b[0m eta \u001b[36m0:00:01\u001b[0m\r\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m2.0/2.0 MB\u001b[0m \u001b[31m31.4 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
-      "\u001b[?25h\u001b[?25l   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m0.0/597.5 kB\u001b[0m \u001b[31m?\u001b[0m eta \u001b[36m-:--:--\u001b[0m\r\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m597.5/597.5 kB\u001b[0m \u001b[31m33.0 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
+      "\u001b[?25l   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m0.0/2.0 MB\u001b[0m \u001b[31m?\u001b[0m eta \u001b[36m-:--:--\u001b[0m\r",
+      "\u001b[2K   \u001b[91m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m\u001b[91m╸\u001b[0m \u001b[32m2.0/2.0 MB\u001b[0m \u001b[31m52.9 MB/s\u001b[0m eta \u001b[36m0:00:01\u001b[0m\r",
+      "\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m2.0/2.0 MB\u001b[0m \u001b[31m31.4 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
+      "\u001b[?25h\u001b[?25l   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m0.0/597.5 kB\u001b[0m \u001b[31m?\u001b[0m eta \u001b[36m-:--:--\u001b[0m\r",
+      "\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m597.5/597.5 kB\u001b[0m \u001b[31m33.0 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
       "\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m72.0/72.0 kB\u001b[0m \u001b[31m5.3 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
       "\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m425.1/425.1 kB\u001b[0m \u001b[31m25.1 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
       "\u001b[2K   \u001b[90m━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\u001b[0m \u001b[32m2.8/2.8 MB\u001b[0m \u001b[31m56.2 MB/s\u001b[0m eta \u001b[36m0:00:00\u001b[0m\n",
@@ -523,7 +526,7 @@
     "*    You need to map your actual circuit's logical qubits to your selected hardware qubits. This is in general a difficult problem, and the best solution can depend on the specific structure of the circuit to be run. Take a look at the [Qubit Picking with Loschmidt Echoes](./echoes.ipynb) tutorial, which estimates the error rates of gates for your specific circuit. Also, consider [Best Practices#qubit picking](../../google/best_practices.ipynb#qubit_picking) for additional advice on this.\n",
     "*    The [Optimization, Alignment, and Spin Echoes](./spin_echoes.ipynb) tutorial provides resources on how you can improve the reliability of your circuit by: optimizing away redundant or low-impact gates, aligning gates into moments with others of the same type, and preventing decay on idle qubits with by adding spin echoes.\n",
     "*    Other than for qubit picking, you should also use calibration for error compensation. The [Coherent vs incoherent noise with XEB](../../noise/qcvv/coherent_vs_incoherent_xeb.ipynb), [XEB Calibration Example](../../noise/qcvv/xeb_calibration_example.ipynb), [Parallel XEB](../../noise/qcvv/parallel_xeb.ipynb) and [Isolated XEB](../../noise/qcvv/isolated_xeb.ipynb) tutorials demonstrate how to run a classical optimizer on collected two-qubit gate characterization data, identity the true unitary matrix implemented by each gate, and add [Virtual Pauli Z gates](../../hardware/devices.ipynb) to compensate for the identified error, improving the reliability of your circuit.\n",
-    "*    You are also free to use the characterization data to improve the performance of large batches of experiment circuits. In this case you'd want to prepare your characterization ahead of running all your circuits, and use the data to compensate each circuit, right before running them. See [Calibration FAQ](../../noise/calibration_faq.md#i-have-many-circuits-to-calibrate-how-do-i-speed-it-up) for more information."
+    "*    You are also free to use the characterization data to improve the performance of large batches of experiment circuits. In this case you'd want to prepare your characterization ahead of running all your circuits, and use the data to compensate each circuit, right before running them."
    ]
   }
  ],