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Remove 60-bit broadcast limit, plus typo (#3963)
Closes #3953 Also closes typo reported in #3960
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‎docs/guides/classical-feedforward-and-control-flow.ipynb‎

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@@ -309,74 +309,39 @@
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" In the previous code example, the first two `if_test`s on `c0` are considered one broadcast because the content of `c0` did not change, and thus does not need to be re-broadcasted. The `if_test` on `c1` is a second broadcast. The first one broadcasts all three bits in `c0` and the second broadcasts just one bit, making a total of four broadcasted bits.\n",
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"\n",
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" Currently, if you broadcast 60 bits each time, then the job can have approximately 300 broadcasts. If you broadcast just one bit each time, however, then the job can have 2400 broadcasts.\n",
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"- Limitations on classical registers:\n",
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" - The operand used in an `if_test` statement must be 32 or fewer bits. Thus, if you are comparing an entire `ClassicalRegister`, the size of that `ClassicalRegister` must be 32 or fewer bits. If you are comparing just a single bit from a `ClassicalRegister`, however, that `ClassicalRegister` can be of any size (since the operand is only one bit).\n",
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"\n",
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" For example, the \"invalid\" code block does not work because `cr` is more than 32 bits. You can, however, use a classical register wider than 32 bits if you are testing only one bit, as shown in the \"valid\" code block.\n",
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"\n",
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" <Tabs>\n",
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" <TabItem value=\"Invalid\" label=\"Invalid\">\n",
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" ```python\n",
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" cr = ClassicalRegister(50)\n",
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" qr = QuantumRegister(50)\n",
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" circuit = QuantumCircuit(qr, cr)\n",
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" ...\n",
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" circ.measure(qr, cr)\n",
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" with circ.if_test((cr, 15)):\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" <TabItem value=\"Valid\" label=\"Valid\">\n",
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" ```python\n",
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" cr = ClassicalRegister(50)\n",
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" qr = QuantumRegister(50)\n",
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" circuit = QuantumCircuit(qr, cr)\n",
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" ...\n",
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" circ.measure(qr, cr)\n",
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" with circ.if_test((cr[5], 1)):\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" </Tabs>\n",
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" - Qiskit Runtime cannot _broadcast_ (a bit is broadcasted if it's used in an `if_test` statement) more than 60 bits at a time. You can explicitly ensure that you are working with different broadcasts by adding barriers.\n",
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"\n",
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" <Tabs>\n",
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" <TabItem value=\"Invalid\" label=\"Invalid\">\n",
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" The following code block does not work because it contains 64 broadcasted bits:\n",
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" ```python\n",
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" cr1 = ClassicalRegister(32)\n",
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" cr2 = ClassicalRegister(32)\n",
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" qr = QuantumRegister(64)\n",
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" circuit = QuantumCircuit(qr, cr1, cr2)\n",
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" ...\n",
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" circ.measure(qr[0:32], cr1)\n",
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" circ.measure(qr[32:], cr2)\n",
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" with circ.if_test((cr1, 32)): # 32 bits are broadcasted here\n",
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" ...\n",
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" with circ.if_test((cr2, 32)): # Another 32 bits are broadcasted here, exceeding the limit!\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" <TabItem value=\"Valid\" label=\"Valid\">\n",
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" ```python\n",
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" cr1 = ClassicalRegister(32)\n",
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" cr2 = ClassicalRegister(32)\n",
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" qr = QuantumRegister(64)\n",
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" ...\n",
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" circ.measure(qr[0:32], cr1)\n",
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" with circ.if_test((cr1, 32)):\n",
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" ...\n",
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" circ.barrier()\n",
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" circ.measure(qr[32:], cr2)\n",
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" with circ.if_test((cr2, 32)):\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" </Tabs>\n",
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"\n",
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"- The operand used in an `if_test` statement must be 32 or fewer bits. Thus, if you are comparing an entire `ClassicalRegister`, the size of that `ClassicalRegister` must be 32 or fewer bits. If you are comparing just a single bit from a `ClassicalRegister`, however, that `ClassicalRegister` can be of any size (since the operand is only one bit).\n",
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"\n",
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" For example, the \"Not valid\" code block does not work because `cr` is more than 32 bits. You can, however, use a classical register wider than 32 bits if you are testing only one bit, as shown in the \"Valid\" code block.\n",
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"\n",
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" <Tabs>\n",
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" <TabItem value=\"Not valid\" label=\"Not valid\">\n",
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" ```python\n",
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" cr = ClassicalRegister(50)\n",
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" qr = QuantumRegister(50)\n",
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" circuit = QuantumCircuit(qr, cr)\n",
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" ...\n",
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" circ.measure(qr, cr)\n",
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" with circ.if_test((cr, 15)):\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" <TabItem value=\"Valid\" label=\"Valid\">\n",
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" ```python\n",
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" cr = ClassicalRegister(50)\n",
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" qr = QuantumRegister(50)\n",
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" circuit = QuantumCircuit(qr, cr)\n",
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" ...\n",
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" circ.measure(qr, cr)\n",
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" with circ.if_test((cr[5], 1)):\n",
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" ...\n",
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" ```\n",
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" </TabItem>\n",
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" </Tabs>\n",
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"\n",
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"- Nested conditionals are not allowed. For example, the following code block will not work because it has an `if_test` inside another `if_test`:\n",
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" <Tabs>\n",
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" <TabItem value=\"Invalid\" label=\"Invalid\">\n",
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" <TabItem value=\"Not valid\" label=\"Not valid\">\n",
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" ```python\n",
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" c1 = ClassicalRegister(1, \"c1\")\n",
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" c2 = ClassicalRegister(2, \"c2\")\n",

‎docs/guides/qpu-information.mdx‎

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@@ -195,7 +195,7 @@ You can also view your available QPUs by using the [backends API.](/docs/api/qis
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```python
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QiskitRuntimeService(instance="my_instance_CRN")
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service.backend()
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service.backends()
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```
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<span id="native-gates"></span>

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