One shared unitary transforms several orthogonal inputs while a weighted objective orders multiple eigenstates.
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One shared unitary transforms several orthogonal inputs while a weighted objective orders multiple eigenstates. This record separates the reusable method idea from any one molecule, Hamiltonian, optimizer, or device.
No input port at this edge: the record publishes no gate sequence and no register, so there is nothing here to read one off — and unlike a declared hole, nothing has been recorded about what belongs here.
Nothing in the Atlas meets this end.
The edge is real and its shape is not. Somebody read the source and recorded that it does not state what leaves here. The record still publishes a 3-wire register, so what is withheld is the rest: whether it carries qubits or classical bits, and what a next stage would have to assume.
17 entries line up on shape, composition unverified. Named below.
This record publishes no gate sequence, and unlike a bare literature entry it says so on purpose: somebody read the source and recorded which part is missing and why, with a citation — the gap is listed further down this page. The register width above is what the record does publish. What it withholds is the rest of that edge, so the entries below are candidates whose widths line up and nothing more; a block may ship with a hole, but never with a guess in the hole. See all 1 →
Only the register widths line up. This entry's source does not state what crosses this edge, so whether it carries qubits or classical bits is unknown — along with everything a width does not carry. These are the entries a filled-in gap could connect to, not entries that connect.
This record is named by the layer graph at:
Takes A Hermitian H reachable as a sum of terms that can be measured separately; a statement of which state is wanted — an index k, a symmetry sector, or a target energy to sit nearest; for most of the methods here, the ground state already solved, and for the deflation route every lower state as well; a target additive error and a shot budget. Returns A scalar estimate — of that eigenvalue, or of the gap between it and the ground state — together with the run budget it consumed. Some methods return a whole low-energy subspace at once and others return one state per run, and that difference is a cost, not a convenience.
One shared unitary transforms several orthogonal inputs while a weighted objective orders multiple eigenstates. In a complete experiment, the method must be paired with a defined qubit Hamiltonian, reference state, parameterized circuit, measurement grouping, classical optimizer, stopping rule, and error analysis. The catalog therefore treats it as a literature-backed algorithm record rather than pretending that one generic snippet is the paper's implementation. Use the cited source to recover assumptions and compare energy error, variance, circuit resources, measurement cost, optimizer evaluations, and robustness under the same instance and budget.
METHOD: Subspace-search VQE
SCOPE: One shared unitary transforms several orthogonal inputs while a weighted objective orders multiple eigenstates.
This is a literature method record, not a fixed circuit.
Supply: Hamiltonian, reference state, ansatz, optimizer, measurement plan, and stopping rule.A reference record, not runnable source. Leona cannot execute it, so it cannot be saved to your Library as a circuit.
Compare Variational quantum eigensolver with the strongest classical method for the same instance, input budget, and output metric.
This reference exposes a quantum circuit pattern; it does not imply an application-level speedup without a matched benchmark.
Report input loading, circuit depth, repetitions, classical preprocessing, post-processing, and wall-clock time together.
What the source itself reports — not how Leona verified this record. “Not checked” means nobody has read the source for that axis; “not in this source” means somebody has, and it is not there.
The paper reports no error or precision figures for its own 4-qubit simulations — there is no data table behind the simulated results, so the accuracy an implementer should expect is not recoverable from this source. Owner review of arXiv:1810.09434, G1 field B5-9, 2026-08-06.
Primary or survey context for Subspace-search VQE; consult the paper for assumptions and implementation details.
arxiv.org/abs/1810.09434 ↗