No advantage from classical assistance for energy-constrained bosonic dephasing channelsResearch Paper
Motivation
We prove that four capacities of single-mode bosonic dephasing channels coincide under an average photon-number constraint: the unassisted quantum capacity, the unassisted private capacity, the two-way classically assisted quantum capacity, and the two-way public-classically assisted private capacity. The assistance may be interactive: the parties can exchange classical messages between channel uses and choose subsequent inputs based on earlier outcomes. For every finite value of the constraint, their common value is the coherent information optimized over Fock-diagonal input states satisfying the constraint. The proof uses a relative entropy comparison with the completely dephasing channel to derive chain rules for the Rains relative entropy and the relative entropy of entanglement. These chain rules give an upper bound on the rates achievable by adaptive protocols whose mean input photon number is constrained on average over all channel uses. We also show that both chain rules are attained by canonical purifications of finite-energy Fock-diagonal states. △ Less
This mission is the statement-level formalization of No advantage from classical assistance for energy-constrained bosonic dephasing channels (arXiv:2610.13854v1). Every numbered result of the paper was scanned. The results stated here are open sorry goals, ready for solvers to prove.
What is formalized
1 statements of the paper are in Lean 4 (Mathlib 0df444a). The goal theorem is Fock dephasing absorbs bosonic dephasing on either side (Lemma 2.2, Eq. (23), PDF p. 6). The milestones are the other numbered results, in the paper's order, each quoting the paper.
The paper's own objects are the definition item of this mission. Objects shared across papers come from the prove2quantum library and from earlier papers' missions, listed as references.
Provenance: prove2quantum's pipeline drafted each statement (gpt-6.1-sol on Stanford's Sherlock cluster). A blind read-back, written without seeing the paper, is attached to every item. An independent moderator compared each statement against the paper and passed the whole paper without edits.
Deferred results
13 results of the paper are not stated yet, because the library lacks an interface they need:
- Abstract / Eq. (1): All four operational finite-energy capacities and the countable Fock-diagonal coherent-information supremum. (hard)
- Lemma 2.1: Degradable CPTP channels on arbitrary separable output/environment spaces, complementary dilation, output-entropy supremum, and operational Q, P, Cp. (hard)
- Lemma 2.3: Base-2 extended von Neumann entropy of positive trace-one operators on l²(N), complementary environment mixture, and extended mean photon number. (hard)
- Corollary 2.1: Both the non-diagonal-input coherent-information comparison and the operational capacity formula over all countable photon distributions. (hard)
- Lemma 3.1: Infinite-dimensional Umegaki relative entropy between normalized states and identity-tensored dephasing on a general separable reference, including pure-input equality. (hard)
- Lemma 3.2: Countable strongly complete orthogonal pinching on general separable Hilbert spaces and signed extended relative entropy with arbitrary positive trace-class second argument. (hard)
- Theorem 3.1: Identity-tensored channels on general trace-class operators and signed extended relative entropy for unrestricted positive sigma. (hard)
- Theorem 3.2: Rains infimum with Hilbert–Schmidt partial transpose and extended trace norm, before and after the moving Alice/Bob cut. (hard)
- Theorem 3.3: Two-way adaptive operational quantum capacity with countably decomposable LOCC and unconditional average energy. (hard)
- Theorem 3.4: Relative entropy of entanglement over the trace-norm-closed product-state convex hull, on arbitrary separable local memories and the moving cut. (hard)
- Theorem 3.5: Operational assisted private capacity with arbitrary retained shields, twisting, squared fidelity, and public environments/transcripts, together with operational Q and P. (hard)
- Corollary 3.1: Constructed normalized countable canonical purification, its dephasing-channel output, and both infinite-dimensional entanglement infima. (hard)
- Lemma A.1: Countable maximally correlated states on paired orthonormal families, arbitrary extending dephasing bases, finite marginal entropy, and the infinite-dimensional Rains infimum. (hard)
Selected references
- No advantage from classical assistance for energy-constrained bosonic dephasing channels, arXiv:2610.13854v1, https://arxiv.org/abs/2610.13854v1