Quantum imaginary time evolution and UD-MIS problem
Pith reviewed 2026-05-23 19:20 UTC · model grok-4.3
The pith
Quantum imaginary time evolution solves unit-disk maximum independent set instances on 6-10 qubit graphs with low failure probability that decreases with shots.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
A procedure based on quantum imaginary time evolution can be applied to solve the unit-disk maximum independent set problem. Numerical simulations on 6, 8 and 10-qubit graph instances establish that the failure probability remains relatively small and decreases rapidly with the number of shots, while a theoretical upper bound on the failure probability of the procedure can be obtained.
What carries the argument
Quantum imaginary time evolution procedure adapted to encode unit-disk maximum independent set instances on qubit graphs.
If this is right
- The procedure produces relatively small failure probabilities on the tested 6-10 qubit UD-MIS instances.
- Failure probability decreases rapidly as the number of shots is increased.
- A theoretical upper bound on failure probability exists for the procedure.
- The approach works for unit-disk graphs encoded directly into the qubit register.
Where Pith is reading between the lines
- The observed scaling with shot count implies that hardware runs could reach high success rates using only moderate numbers of circuit executions.
- The derived bound supplies a tool for estimating reliability before running larger instances.
- Similar encodings could let the same evolution method address other graph-based constraint problems without changing the core algorithm.
Load-bearing premise
The quantum imaginary time evolution procedure can be directly applied to unit-disk maximum independent set instances encoded on 6-10 qubit graphs such that the reported failure probabilities and bound hold.
What would settle it
Performing the procedure on a 6-qubit unit-disk maximum independent set instance and measuring a failure probability that fails to decrease with added shots or exceeds the stated theoretical upper bound would falsify the central findings.
Figures
read the original abstract
In this work we apply a procedure based on the quantum imaginary time evolution method to solve the unit-disk maximum independent set problem. Numerical simulations were performed for instances of 6, 8 and 10-qubits graphs. We have found that the failure probability of the procedure is relatively small and rapidly decreases with the number of shots. In addition, a theoretical upper bound for the failure probability of the procedure was obtained.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript applies a quantum imaginary time evolution (QITE) procedure to solve unit-disk maximum independent set (UD-MIS) instances. It reports numerical simulations on 6-, 8-, and 10-qubit graphs in which the failure probability is relatively small and decreases rapidly with the number of shots, together with a theoretical upper bound on that failure probability.
Significance. If the numerical results and bound are reproducible, the work provides a concrete demonstration that QITE can be mapped to the UD-MIS penalty Hamiltonian on small graphs and yields shot-scalable success rates. The existence of an analytic bound is a positive feature that could guide further analysis. Because the system sizes remain classically simulable, the immediate impact on quantum advantage is modest, but the approach is a useful proof-of-concept for imaginary-time methods in combinatorial optimization.
major comments (2)
- [Abstract] Abstract: the central numerical claims (failure probabilities for 6/8/10-qubit instances and their scaling with shots) are stated without any description of the graph instances chosen, the explicit penalty Hamiltonian, the QITE implementation details (time-step size, Trotterization or approximation scheme, number of steps), the success criterion for an independent set, or the statistical procedure used to estimate failure probability from finite shots. These omissions make the reported probabilities and their shot dependence impossible to verify from the given text.
- [Abstract] Abstract: the theoretical upper bound on failure probability is asserted but no derivation, assumptions, or proof outline is supplied. Because the bound is presented as an independent theoretical result supporting the numerical findings, its derivation steps are load-bearing and must be provided.
Simulated Author's Rebuttal
We thank the referee for the careful review and constructive feedback on the abstract. We agree that additional details are needed for reproducibility and will revise the abstract (and, where appropriate, the main text) to address both points. Below we respond to each major comment.
read point-by-point responses
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Referee: [Abstract] Abstract: the central numerical claims (failure probabilities for 6/8/10-qubit instances and their scaling with shots) are stated without any description of the graph instances chosen, the explicit penalty Hamiltonian, the QITE implementation details (time-step size, Trotterization or approximation scheme, number of steps), the success criterion for an independent set, or the statistical procedure used to estimate failure probability from finite shots. These omissions make the reported probabilities and their shot dependence impossible to verify from the given text.
Authors: We agree that the abstract is too concise and omits information required to verify the numerical results. In the revised manuscript we will expand the abstract to include: (i) the specific families of 6-, 8- and 10-qubit unit-disk graphs considered, (ii) the explicit form of the penalty Hamiltonian used to encode the UD-MIS objective, (iii) the QITE parameters (imaginary-time step size, total number of steps, and whether a first-order Trotter or other approximation is applied), (iv) the success criterion (a measured bit-string is counted as successful only if it encodes a valid maximum independent set), and (v) the statistical procedure (failure probability is estimated from the fraction of shots that fail the success criterion, with binomial confidence intervals). These additions will make the reported probabilities and their shot scaling directly verifiable from the abstract. revision: yes
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Referee: [Abstract] Abstract: the theoretical upper bound on failure probability is asserted but no derivation, assumptions, or proof outline is supplied. Because the bound is presented as an independent theoretical result supporting the numerical findings, its derivation steps are load-bearing and must be provided.
Authors: The derivation of the upper bound appears in the main text, but we accept that the abstract provides no outline of its assumptions or proof strategy. In the revision we will append a single sentence to the abstract that states the key assumptions (the QITE evolution projects onto the ground-state manifold of the penalty Hamiltonian with a gap that grows with the penalty strength, and the measurement is performed after a fixed imaginary time) and sketches the proof (the failure probability is bounded by the norm of the component of the evolved state orthogonal to the ground subspace, which is controlled by the imaginary-time propagator). If the main-text derivation is judged insufficiently detailed, we will also expand that section. revision: yes
Circularity Check
No significant circularity in derivation chain
full rationale
The paper applies standard QITE to UD-MIS instances on 6-10 qubit graphs, reports empirical failure probabilities from direct simulation, and states a theoretical upper bound on failure probability. No equations reduce a claimed prediction or bound to a fitted parameter defined from the same data; no self-citation is invoked as the sole justification for a uniqueness or ansatz step; the mapping and measurement statistics are standard and externally verifiable. The central results remain independent of the reported numerics.
Axiom & Free-Parameter Ledger
Lean theorems connected to this paper
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IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
QITE operator QH(τ,n,D) constructed via measurement-assisted unitaries on domains Dl,j; failure prob. PqiteF(t) = sum |<Ei|ϕqite t>|^2 for Ei>E0+δE
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IndisputableMonolith/Foundation/DimensionForcing.leanalexander_duality_circle_linking unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
Numerical tests on 6-10 qubit UD-MIS graphs; bounds independent of H via degeneracy g and gap δE
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
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0⟩, where H⊗N is the Hadamard gate acting on each qubit
We start with an initial state |ψ0⟩ = H⊗N |0 . . .0⟩, where H⊗N is the Hadamard gate acting on each qubit. In terms of the eigenvectors basis of H, the initial state has the form |ψ0⟩ = 1√ d Pd−1 i=0 |Ei⟩
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Results for 8-qubits graphs In this section we present the results for random graphs of 8 qubits. As in the case of 6-qubit graphs, we obtained that DB performs better than DA in matching the ITE state for large number of iterations. However,DA performs well enough in terms of the failure probability. Again, we obtained that the failure probability decrea...
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Results for 10-qubits graphs In this section we show the results for random graphs of 10 qubits. In this case we only consider 10 random graphs due to the numerical complexity of the calculations. As in the other cases, DA performs well enough in terms of the failure probability, but DB performs better than DA in matching the ITE state for large number of...
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