QuantumComputinglib learn · inspect · formalize
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Structure before circuit tricks

Data loading without a free QRAM assumption

An algorithm with few abstract queries can still be expensive when the query unitary is built from real data.

research target setting:explicit-data-charged-access

\[T_{\rm total}=T_{\rm build}+Q\,T_{\rm query}+T_{\rm update}+T_{\rm readout}\]

Frozen target and input model

Identify succinct data classes for which explicit access construction preserves the intended algorithmic advantage.

Access model: Classical stored arrays, QROM, arithmetic formulas and physical QRAM are separate settings with explicit initialization, updates and memory costs.

  • Fix data bit length, update frequency and reuse count
  • Charge controlled/inverse queries when the algorithm uses them
  • Compare against a classical algorithm with the same access assumptions

Desired result, not an achieved bound

A full cost theorem for one succinct data representation, not universal polylogarithmic loading of an arbitrary array.

General sparse-access and block-encoding constructions can require near-linear cost in matrix dimension. Sparsity does not make all entries free.

Dependency-ready execution route

01

Define the exact classical/quantum access interface.

Acceptance: Separate data construction, coherent calls, memory and update costs.

planned; no claimed closure

02

Compile one formula, sparse-index or repeated-block supplier.

Acceptance: Basis-action theorem and count of actual access primitives.

planned; no claimed closure

03

Reinsert access costs into a downstream algorithm.

Acceptance: A comparison using the same input/output model and total cost, not query count alone.

planned; no claimed closure

Next bounded advance: Reuse existing sparse/LCU routes only after auditing their oracle contracts and compiler frontiers.

Reusable mathematics

No local transport theorem is bound to this record. Do not infer formal truth from its position in the atlas.

Lower-bound comparison contract

source-audit-pending

Port a pinned circuit-capacity/access lower bound with precision and ancilla assumptions intact.

Same-model key: setting:explicit-data-charged-access

Diagnostic examples, not proofs

  • Repeated structured blocks
  • Sparse matrices with formulaic index/value access
  • Amortized repeated-query workloads

Primary-source ledger

Circuit complexity of quantum access models for encoding classical data

primary-text-checked Results: circuit complexity lower bound; construction of LCU-based block-encoding; Methods: state preparation

Explicit access construction is not a free oracle. PREPARE together with SELECT and uncomputation can supply a block encoding; a single prepared state alone does not determine an arbitrary operator.

Download bounded agent / contributor packet

python3 website/scripts/research_atlas.py context --route spw-no-qram