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Cut outdated Clifford+RZ info
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WrathfulSpatula committed Aug 1, 2023
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Expand Up @@ -57,8 +57,6 @@ For example:

is a valid file, with 0 ancillae. It is theoretically relatively easy to prepare this result of unitary circuit simulation on a quantum hardware device: first prepare the stabilizer state, (with purely Clifford gates,) then apply the (potentially non-Clifford) 2x2 matrices over the same sequential qubit index order. This can represent a universal quantum state of the logical qubits.

`QrackSimulator` now has a method `set_hardware_encoded()`. The default value of this setting is `false`, which causes ancilla "magic state" qubit "channels" to be encoded depending on post-selection. If this setting is `false`, hardware decoding depends on the ancilla qubits all measuring as \|0>, for the correct overall state preparation. However, if this setting is `true`, then every other ancilla qubit (starting with the second-occurring ancilla) is an "open channel" that starts out coding an identity gate, (or "no operation,") but can be re-encoded to avoid the post-selection requirement. To do so, after preparing the state as described in the file, perform `H` gate on all auxiliary, identity-encoding ancilla channels, act `CZ` from each "coding" ancilla to its "identity" partner, then act `H` again on the auxiliary, identity-encoding ancilla. Now, terminal measurement can occur without post-selection, and all logical qubits are deterministically in the intended state, in the ideal.

It might be helpful to look at Qiskit's `Clifford <https://qiskit.org/documentation/stubs/qiskit.quantum_info.Clifford.html>_` and `Clifford.to_circuit() <https://qiskit.org/documentation/stubs/qiskit.quantum_info.Clifford.to_circuit.html#qiskit.quantum_info.Clifford.to_circuit>_` to convert this stabilizer state representation to a state preparation circuit.

.. toctree::
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