quant-ph digest — 2026-04-28
Scored against Yuan's research programme (Y1–Y6):
- Y1 — arXiv:2502.09704 — iterative warm-started QAOA
- Y2 — arXiv:2304.06915 — quasi-binary portfolio QAOA
- Y3 — arXiv:2410.16265 — QAOA DGMVP portfolio (QST 2026)
- Y4 — arXiv:2603.14744 — Grover + ADMM cardinality-constrained BO
- Y5 — arXiv:2510.08292 — GW speed-ups via Gibbs states + Pauli sparsity
- Y6 — arXiv:2510.11213 — PBR test on IBM Heron2
Source
arXiv listing: https://arxiv.org/list/quant-ph/new (59 new + 18 cross = 77 entries)
Coverage: all 77 entries scored. 11 relevant (score ≥ 1); 66 SKIP (score 0, omitted).
Scoring rubric
0–10 on method/scope/conclusion overlap — max wins. HIGH 8–10 · MED 5–7 · LOW 1–4 · SKIP 0.
Highly relevant (score 8–10) — 0 papers
No paper in today's listing meets the HIGH threshold. The closest matches sit in the MEDIUM bucket below.
Moderately relevant (score 5–7) — 4 papers
Quantum Search without Global Diffusion
- Authors: John Burke, Ciaran McGoldrick
- arXiv: 2604.15435
- Category: new submission — quant-ph; cs.DS
- Score: 6/10 (MED)
- Overlaps with: Y4 (method) — Grover / amplitude amplification with structured (tensor-product) feasible spaces
- Why it matters: The paper restructures Grover's algorithm so the diffusion operator is replaced by local reflections on partitioned subregisters while preserving the quadratic speed-up — directly relevant to Y4's Grover-based construction over a structured cardinality-constrained subspace, suggesting a possible route to localised diffusion that could simplify the search-on-feasible-set step.
Quantum search is among the most important algorithms in quantum computing. At its core is quantum amplitude amplification, a technique that achieves a quadratic speedup over classical search by combining two global reflections: the oracle, which marks the target, and the diffusion operator, which reflects about the initial state. We show that this speedup can be preserved when the oracle is the only global operator, with all other operations acting locally on non-overlapping partitions of the search register. We present a recursive construction that, when the initial and target states both decompose as tensor products over these chosen partitions, admits an exact closed-form solution for the algorithm's dynamics.
Asymptotic optimality of Grover-Radhakrishnan-Korepin algorithm
- Authors: Kun Zhang, Kang-Yuan Chen, Xiao-Hui Wang, Vladimir Korepin
- arXiv: 2604.15886
- Category: new submission — quant-ph
- Score: 6/10 (MED)
- Overlaps with: Y4 (method) — Grover-family algorithms with block-structured search spaces and tight oracle-query lower bounds
- Why it matters: Proves long-conjectured asymptotic optimality of GRK partial search via Pontryagin maximum-principle / bang-bang switching analysis. Y4 builds on Grover-with-structured-feasible-space and quantifies O(√(C(n,k)/M)) scaling — this paper sharpens what optimality means in that family and offers a control-theoretic toolkit (time-optimal control, switching functions) that may be reusable when proving lower bounds for cardinality-constrained Grover variants.
Grover's algorithm is a cornerstone of quantum algorithms and is strictly optimal in oracle-query complexity. While the full search problem admits no further improvement, one may trade accuracy for speed in the partial search problem, where the task is to identify only the block containing the target item. The best known quantum algorithm for the partial search problem is the Grover-Radhakrishnan-Korepin (GRK) algorithm, whose optimality has long been conjectured but not proved. In this work, we prove the optimality of GRK in the large-block limit. We formulate partial search as a time-optimal control problem and apply the Pontryagin maximum principle to derive the switching-function dynamics, establish the bang-bang structure of regular extremals, and exclude non-optimal switching patterns.
Overcoming the Lamb Shift in System-Bath Models via KMS Detailed Balance: High-Accuracy Thermalization with Time-Bounded Interactions
- Authors: Hongrui Chen, Zhiyan Ding, Ruizhe Zhang
- arXiv: 2604.15616
- Category: new submission — quant-ph
- Score: 5/10 (MED)
- Overlaps with: Y5 (method) — quantum Gibbs-state preparation with provable accuracy and mixing-time bounds
- Why it matters: Y5 leans on quantum Gibbs states of Pauli-sparse Hamiltonians as the engine for SDP relaxations; this paper proves that any Lindbladian whose transition part satisfies KMS detailed balance has a fixed point arbitrarily close to the Gibbs state in the weak-coupling limit, with explicit mixing-time bounds via a perturbation framework. Useful as a citable building block when justifying the cost-model assumptions behind quantum Gibbs sampling for SDP.
We investigate quantum thermal state preparation algorithms based on system-bath interactions and uncover a surprising phenomenon in the weak-coupling regime. We rigorously prove that, if the system-bath interaction is engineered so that the transition part of the approximate Lindbladian generator satisfies the KMS detailed balance condition, then the unique fixed point of the dynamics can be made arbitrarily close to the Gibbs state in the weak-coupling limit, regardless of the structure of the Lamb shift term. Importantly, this remains true even when the approximate Lindbladian differs substantially from the ideal Davies generator and the Lamb shift term does not commute with the thermal state.
Quantum-Inspired Simulation of 2D Turbulent Rayleigh-Bénard Convection
- Authors: Nis-Luca van Hülst, Mario Guillaume Cecile, Hai-Yen Van, Tomohiro Hashizume, Eugene de Villiers, Dieter Jaksch
- arXiv: 2604.16179
- Category: cross submission — physics.flu-dyn; physics.comp-ph; quant-ph
- Score: 5/10 (MED)
- Overlaps with: Y5 (conclusion) — quantum-inspired classical algorithms; bond-dimension scaling as the analogue of "dequantisation" for fluid problems
- Why it matters: Y5 demonstrates a quantum-inspired classical SDP solver scaling to 250 variables on a desktop. This paper applies MPS to buoyancy-driven turbulent convection and finds bond dimension χ grows without saturation up to Ra=1011, in contrast to isothermal cases — a useful negative datapoint about when "quantum-inspired" tensor-network methods stop dequantising tractably. Worth citing as an example of the boundary of MPS-based dequantisation.
Turbulent thermal convection governs heat transport in systems ranging from stellar interiors to industrial heat exchangers. Two-dimensional Rayleigh-Bénard convection serves as a paradigm for these flows, reproducing key features such as thin boundary layers, large-scale circulation, and sustained plume dynamics. While Matrix Product State (MPS) methods have demonstrated significant compression of isothermal turbulent fields, their application to buoyancy-driven flows with active thermal coupling has remained unexplored. We apply MPS to two-dimensional Rayleigh-Bénard convection with dynamical simulations up to Ra = 10^{10}. An a priori decomposition of DNS snapshots up to Ra = 10^{11} shows that the bond dimension χ required to represent the flow fields grows without saturation, in contrast to the plateauing of χ reported for velocity fields in isothermal 2D turbulence.
Tangential (score 1–4) — 7 papers
- 2604.15441 · score 4/10 · Quantum computation at the edge of chaos — VQA trainability via topological-entanglement-entropy regulariser; tangentially relevant to QAOA layerwise / barren-plateau themes in Y1, Y3.
- 2604.15693 · score 4/10 · Observable-Guided Generator Selection for Improving Trainability in QML — Pauli-string generator pools selected to maximise gradient sensitivity and minimise Hessian interference; method-adjacent to Y1/Y3 trainability and to Y5's Pauli-sparse decompositions.
- 2604.15427 · score 3/10 · Tensor Networks with Belief Propagation Cannot Feasibly Simulate Google's Quantum Echoes Experiment — classical-simulation lower bound for a quantum-advantage claim; same broad debate (quantum vs classical separation) as Y5's dequantisation framing but in a different domain.
- 2604.16164 · score 2/10 · A unified framework for efficient quantum simulation of nonlinear spectroscopy — runs a parameter-shift-rule algorithm on IBM superconducting hardware; only NISQ-on-IBM scope overlap with Y3/Y6.
- 2604.16190 · score 2/10 · Coherence dynamics in Simon's quantum algorithm — quantum-algorithm coherence accounting; same "structured oracle algorithm" family as Grover (Y4) but very different problem.
- 2604.16107 · score 2/10 · Entanglement and photoelectron holography in dissociative photoionization: molecular quantum eraser — interference / which-way / Bell-like state foundations test, tangential to PBR-style foundations work in Y6.
- 2604.16051 · score 2/10 · Comment on "A General Framework for Constructing Local Hidden-state Models to Determine the Steerability" — local hidden-variable / hidden-state model construction; foundations-adjacent to PBR / ontic-vs-epistemic themes in Y6.
Summary table
| Score | arXiv ID | Short title | Overlaps | arXiv |
|---|---|---|---|---|
| 6 | 2604.15435 | Quantum Search without Global Diffusion | Y4 (method) | link |
| 6 | 2604.15886 | Asymptotic optimality of GRK algorithm | Y4 (method) | link |
| 5 | 2604.15616 | Lamb-shift–KMS Gibbs state preparation | Y5 (method) | link |
| 5 | 2604.16179 | Quantum-Inspired MPS Rayleigh-Bénard | Y5 (conclusion) | link |
| 4 | 2604.15441 | Quantum computation at the edge of chaos | Y1, Y3 (method) | link |
| 4 | 2604.15693 | Observable-guided generator selection in QML | Y1, Y3, Y5 (method) | link |
| 3 | 2604.15427 | TNBP cannot simulate Google echoes | Y5 (conclusion) | link |
| 2 | 2604.16164 | Quantum sim of nonlinear spectroscopy on IBM | Y3, Y6 (scope) | link |
| 2 | 2604.16190 | Coherence in Simon's algorithm | Y4 (method) | link |
| 2 | 2604.16107 | Molecular quantum eraser | Y6 (scope) | link |
| 2 | 2604.16051 | Comment on LHS-models steerability framework | Y6 (scope) | link |