Redo example notebook on Quantum Phase Estimation (QPE) #262
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| @@ -11,7 +11,7 @@ sphinx: | |||
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| execute: | |||
| # Exclude some examples from execution (these are still deployed as html pages) | |||
| exclude_patterns: [".venv/*", "Boxes_QPE_example.ipynb", "Forest_portability_example.ipynb", "backends_example.ipynb", "qiskit_integration.ipynb", "comparing_simulators.ipynb", "expectation_value_example.ipynb", "pytket-qujax_heisenberg_vqe.ipynb", "spam_example.ipynb", "tket_benchmarking.ipynb", "entanglement_swapping.ipynb", "pytket-qujax-classification.ipynb"] | |||
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The commit message "Execute QPE notebook" is misleading here. This was the name of an old file from a previous PR.
The QPE notebook is executed on CI.
examples/python/phase_estimation.py
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| qft3_circ = Circuit(3) | ||
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| qft3_circ.H(0) | ||
| qft3_circ.CU1(0.5, 1, 0) | ||
| qft3_circ.CU1(0.25, 2, 0) | ||
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| qft3_circ.H(1) | ||
| qft3_circ.CU1(0.5, 2, 1) | ||
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| qft3_circ.H(2) | ||
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| qft3_circ.SWAP(0, 2) | ||
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| from pytket.circuit.display import render_circuit_jupyter | ||
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| render_circuit_jupyter(qft3_circ) |
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Do all of these need to be in separate cells? There are also other places like this.
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Probably not tbh. Will make them the same cell.
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Ah in fact this was not intended by me.
It is caused by the way the gen-nb script generates notebooks from python files. The p2j library seems to interpret these new lines as separate cells.
I'll see if I can work around this without squashing everything together.
examples/python/phase_estimation.py
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| n_measurement_qubits: int, state_prep_circuit: Circuit, unitary_circuit: Circuit | ||
| ) -> Circuit: | ||
| qpe_circ: Circuit = Circuit() | ||
| n_ancillas = state_prep_circuit.n_qubits |
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Is it common to call these ancillas? It's a little bit odd to me.
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I don't like it either. I think I'll go with n_prep_qubits instead.
Thanks for pointing this out. When I've done QPE in other places I've called them prep qubits instead.
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fixed this. The use of "ancillas" throughout the notebook was actually inconsistent so thanks for pointing this out.
examples/python/phase_estimation.py
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| # we can extract the statevector for $e^{i \frac{\pi}{2}\theta YXXX}|1100\rangle$ using the `Circuit.get_statvector()` method. | ||
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| initial_state = state_circ.get_statevector() | ||
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| # Finally we can prepare our initial state using `StatePreparationBox`. | ||
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| from pytket.circuit import StatePreparationBox | ||
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| state_prep_box = StatePreparationBox(initial_state) |
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Why can't we just use the state_circ constructed above to prepare the initial state?
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I wasn't that happy with this state preparation example using the
state.
Phase estimation seemed like a nice way to include QControlBox, CircBox, PauliExpBox , StatePreparationBox (and perhaps ConjugationBox) all in the same demo.
Maybe I should ask someone from chemistry if they can give me an initial state which is a better fit for StatePreparationBox.
Currently it feels a bit artifical.
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I think what I'm going to do here is just get rid of StatePreparationBox from this notebook and do the state prep with PauliExpBox.
I was just trying to squeeze all boxes into one notebook but PauliExpBox would be way better in this case anyway.
I'll find another way to demo StatePreparationBox in another notebook perhaps.
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I've removed the use of StatePreparationBox.
Just have to fix the simulation results now.
examples/python/phase_estimation.py
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| ham_result = backend.run_circuit(compiled_ham_circ, n_shots=n_shots) | ||
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| plot_qpe_results(ham_result, y_limit=int(1.2 * n_shots), n_strings=5) |
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Can you explain the results a little bit? I think it's quite important to explain what to do if the initial state is not a eigenstate.
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Yeah I should explain the output a bit more.
I think it may be worth just redoing the last example once I've found a better choice of state prep circuit.
examples/python/phase_estimation.py
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| from pytket.passes import DecomposeBoxes | ||
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| DecomposeBoxes().apply(ham_circ) |
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Keep in mind that the next pytket release will wrap some components of ham_circ in ConjugationBoxes, so the subsequent QControlBox will optimise for these boxes. Calling DecomposeBoxes here will remove the ConjugationBoxes.
CalMacCQ
changed the title
Redoing #241 as I ran into a bunch of issues with source control.
Notebook example for Quantum phase estimation based party on ->
https://quantumcomputing.stackexchange.com/questions/32594/how-would-you-draw-the-phase-estimation-circuit-for-the-eigenvalues-of-u-mat/32598#32598