pith:TWHQNFXL
Fault-Tolerant Resource Comparison of Qudit and Qubit Encodings for Diagonal Quadratic Operators
Qudit encodings can cut non-Clifford costs by constant factors over qubits for diagonal quadratic operators at small d in LCU settings, but qubits scale better asymptotically and dominate product formulas.
arxiv:2604.26792 v2 · 2026-04-29 · quant-ph
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Record completeness
Claims
Within the constructive models studied here, product-formula implementations would require an exponentially stronger per-primitive synthesis advantage for qudits to win asymptotically, while in the LCU setting the qubit encoding is asymptotically cheaper in d. Nevertheless, the finite-d threshold analysis identifies low dimensional regions in which qudits can yield meaningful constant-factor savings, particularly for LCU-based implementations.
Because tight synthesis bounds for general single-qudit rotations are not known, we express the qudit constructions in terms of embedded two-level SU(2) rotations; this modeling choice and the idealized negligible-overhead qubit-qudit code-switching model are load-bearing for the break-even conditions and T-count comparisons.
Qudit encodings for quadratic diagonal evolutions require exponentially stronger synthesis advantages than qubits to win asymptotically in product formulas but can yield constant-factor savings in LCU at low d.
Receipt and verification
| First computed | 2026-05-21T02:05:03.597506Z |
|---|---|
| Builder | pith-number-builder-2026-05-17-v1 |
| Signature | Pith Ed25519
(pith-v1-2026-05) · public key |
| Schema | pith-number/v1.0 |
Canonical hash
9d8f0696eb58ab56873fddedd9bbece3b2ec1ce678d25a567fc2a285b2ba8b08
Aliases
· · · · ·Agent API
Verify this Pith Number yourself
curl -sH 'Accept: application/ld+json' https://pith.science/pith/TWHQNFXLLCVVNBZ73XW5TO7M4O \
| jq -c '.canonical_record' \
| python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: 9d8f0696eb58ab56873fddedd9bbece3b2ec1ce678d25a567fc2a285b2ba8b08
Canonical record JSON
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"license": "http://creativecommons.org/licenses/by/4.0/",
"primary_cat": "quant-ph",
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