Create a bloq for galois multiplication by NoureldinYosri · Pull Request #1557 · quantumlib/Qualtran

NoureldinYosri · 2025-02-15T02:37:40Z

This is the final PR in the series #1554, #1533, and #1516. These PRs implemented the GF($2^n$) multiplication construction from https://arxiv.org/abs/1910.02849v2 which has a toffoli complexity of $n^{\log_2{3}}$

tanujkhattar

Left a round of comments, mainly around the API of the bloqs.

tanujkhattar · 2025-02-18T17:23:27Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

-    galois_field: 'galois.FieldArrayMeta'
+    m_x: Poly = attrs.field(converter=lambda x: x if isinstance(x, Poly) else Poly.Degrees(x))
+    element_repr: Literal['int', 'poly', 'power'] = attrs.field(default='int', eq=False)


Why this change? For users who just want a bloq that can multiply a constant to a GF register, the previous API of specifying a "const" and "galois_field" type was more intuitive. Needing to specify m_x and element_repr explicitly is more verbose. Why do we need this change?

qualtran/_infra/data_types.py

tanujkhattar · 2025-02-19T19:31:59Z

qualtran/_infra/data_types.py

    degree: SymbolicInt
    irreducible_poly: Optional['galois.Poly'] = attrs.field()
-    element_repr: Literal["int", "poly", "power"] = attrs.field(default='int')
+    element_repr: Literal["int", "poly", "power"] = attrs.field(default='int', eq=False)


Please add a test to data_types_test.py with examples of which QGF types should be equal and which should be different.

Also, can you remind me again why we needed to add element_repr to the QGF class in the first place? ]

It looks like its a property of the GF class that can be easily modified by calling gf_type.repr(int). If this is used mainly as a tool for debugging and visualizing the field elements, then its better to not have it as part of the QGF class and simply change the property on the underlying QGF.galois_field type wherever needed.

https://mhostetter.github.io/galois/v0.3.5/api/galois.FieldArray.element_repr/

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

tanujkhattar · 2025-02-19T19:39:49Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+            sub-quadratic Toffoli gate count](https://arxiv.org/abs/1910.02849v2) Section 3.1
+    """
+
+    m_x: Poly = attrs.field(converter=lambda x: x if isinstance(x, Poly) else Poly.Degrees(x))


Please consider taking the galois field type GF everywhere instead of taking Poly type. It makes the API simpler. You could also consider taking the QGF type directly, which encoded all the necessary information about the underlying field and represents the type of the quantum register on which you wish to perform the operations.

The signature of all the bloqs would change to dtype: QGF and other parameters like k: SymbolicInt here and const: const above for multiplication by a constant and dtype: QGF and uncompute: bool for GF2Mul bloq below.

tanujkhattar · 2025-02-19T19:50:36Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+class _GF2MulImpl(Bloq):
+    """Multiply two GF2 numbers (or binary polynomials) modulu m(x)."""
+
+    m_x: Poly = attrs.field(converter=lambda x: x if isinstance(x, Poly) else Poly.Degrees(x))


Change to dtype: QGF instead

tanujkhattar · 2025-02-19T19:51:04Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+                Register('f', dtype=self.qgf),
+                Register('g', dtype=self.qgf),
+                Register('h', dtype=self.qgf),


Preferably change to x, y, result but it's also fine if you want to leave it as is since it's a private bloq.

keeping for the private bloq but changed for the public bloq

tanujkhattar · 2025-02-19T19:51:30Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+class _GF2MulImpl(Bloq):
+    """Multiply two GF2 numbers (or binary polynomials) modulu m(x)."""


Please add a more detailed docstring if possible. How is this bloq different from GF2Mul below ?

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

tanujkhattar · 2025-02-19T19:53:22Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+    def build_composite_bloq(
+        self, bb: 'BloqBuilder', f: 'Soquet', g: 'Soquet', h: Optional['Soquet'] = None
+    ) -> Dict[str, 'Soquet']:


I'd personally prefer taking a **soqs: 'SoquetT' and simply popping the necessary registers and avoiding the need to use a cast and a dedicated early return based on the if self.uncompute condition.

tanujkhattar · 2025-02-19T23:45:17Z

qualtran/bloqs/gf_arithmetic/gf2_multiplication.py

+        g = bb.join(g_arr, self.qgf)
+        h = bb.join(h_arr, self.qgf)
+        return {'f': f, 'g': g, 'h': h}
+


Please implement a build_call_graph to support symbolic cost analysis.

build_call_graph is already implemented for the public bloq ... this is a private bloq that will never appear to users ... it's used by the public bloq in a add_from statement

mpharrigan · 2025-03-03T22:45:44Z

What's the status of this?

NoureldinYosri · 2025-03-25T07:13:16Z

@tanujkhattar ptal, I addressed all of your comments

@mpharrigan I got distracted by other things .. this PR is ready for another reivew

mpharrigan · 2025-03-31T23:37:47Z

how long do you expect test_gf2mulmod_classical_action_slow to take

NoureldinYosri · 2025-04-01T02:05:38Z

@mpharrigan I'm almost sure that it wasn't that slow when I wrote it ... anyway #1611

NoureldinYosri added 2 commits February 14, 2025 12:00

checkpoint

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Create a bloq for galois multiplication

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NoureldinYosri requested review from mpharrigan and tanujkhattar February 15, 2025 02:39

NoureldinYosri added 2 commits February 18, 2025 14:06

fix QGF

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tanujkhattar requested changes Feb 19, 2025

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tanujkhattar reviewed Feb 19, 2025

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NoureldinYosri and others added 3 commits March 25, 2025 00:05

address comments

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nit

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Merge branch 'main' into galois_mod_mul

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NoureldinYosri added 5 commits March 25, 2025 00:21

nit

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docs

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tanujkhattar approved these changes Mar 31, 2025

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Merge branch 'main' into galois_mod_mul

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NoureldinYosri merged commit ed6170e into quantumlib:main Mar 31, 2025
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NoureldinYosri mentioned this pull request Apr 1, 2025

Create a bloq for Semi-Classical QFT #1610

Closed

		class _GF2MulImpl(Bloq):
		"""Multiply two GF2 numbers (or binary polynomials) modulu m(x)."""

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NoureldinYosri Mar 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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mpharrigan commented Mar 3, 2025

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NoureldinYosri commented Feb 15, 2025 •

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