Compressed Oracle

Zhandry’s compressed-oracle method for tracking a quantum algorithm’s queries to a random function or permutation.

Status	Problem	Tags
	Double-sided zero search Resolved, unconditionally. Carolan (Compressed Permutation Oracles, ePrint 2025/1734, STOC 2026) proves this exact statement – his Problem 3, p. 72, naming it ‘the double-sided zero search problem, due to Unruh’ – as a corollary (Corollary 7.6) of a general predicate-search lower bound (Theorem 7.5) proved directly from his own compressed permutation oracle’s soundness (Theorem 5.19). Unlike Unruh’s own derivation, this proof does not route through Unruh’s CPO-soundness conjecture (c/0036) at all, so it holds regardless of that conjecture’s status.	Compressed Oracle Quantum Query Complexityotherlower-boundresearch-solved
	Compressed permutation oracle soundness Still open as formalized, but the underlying research question – can the compressed-oracle technique be extended to permutations at all – is now resolved in the affirmative by a different construction. Carolan (Compressed Permutation Oracles, ePrint 2025/1734, STOC 2026) proves his own compressed permutation oracle unconditionally sound. That oracle is, in his own words, ‘similar to that of Unruh [Unr23], though we explicitly and unitarily maintain injectivity of the database’ – a change that goes beyond resolving Unruh’s own left-open choice of how the flipping operator acts on non-injective inputs. Whether Unruh’s original construction (for an arbitrary such choice) is itself sound remains, on the reading defended here, unestablished.	Compressed Oracle Pseudorandom Permutations Quantum Query Complexityotherequivalence
	Polynomial Compatibility Conjecture Open in the inverse-polynomial regime. Proved for exponentially small influences by the paper that introduced it, and false for influences at or above \(1/(2d)\); everything between is what the quantum separations depend on. 5 open	Compressed Oracle Quantum Query Complexity Quantum Random Oracle Modelqromassumption