Replica-three stabilizer multi-entropy via graph forms and coarse party partitions
Abstract
Every normalized pure qubit stabilizer state admits a graph form on which opposite nonzero ternary replica characters biject onto two- and three-block party partitions, expressing the replica-three multi-entropy and its coarse-grainings as sums of masked F2 adjacency ranks.
Following the replica convention of Gadde, Krishna and Sharma, Phys. Rev. D 106, 126001, in the anchored form of Akella, Iizuka and Miyata, arXiv:2607.06050v1 Appendix A, a q-party pure N-qubit state psi with colouring col : Fin N to Fin q (allowing empty parties) is contracted over replicas r in (Z/3Z)^{q-1}, with the last party q - 1 acting by the identity. By Van den Nest, Dehaene and De Moor, Phys. Rev. A 69, 022316, and Schlingemann, Quantum Inf. Comput. 2, 307-323, every normalized pure qubit stabilizer state is local-unitary equivalent up to a unit phase to a graph state |Gamma>. Akella and Gadde, arXiv:2610.27080v1 Section II Eqs. (7)-(9) and Appendix A, give an odd-replica rank formula for graph states whose n = 3 specialization groups nonzero F4 labels by equality partition; retaining the factor n^{-(q-2)} yields the coarse-partition rank sum proved below.
Definition 1.1 (Normalized N-qubit graph state).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.graphState (✓ std3).
Source. Repository-derived.
Acknowledgement. M. Van den Nest, J. Dehaene, B. De Moor (2004). Graphical description of the action of local Clifford transformations on graph states. DOI: 10.1103/PhysRevA.69.022316. URL: https://arxiv.org/abs/quant-ph/0308151v2.
Commentary.
Scales the unnormalized binary quadratic phase vector graphAmp(Gamma) by 2^{-N/2} so that |Gamma> has unit Hilbert norm.
Definition 1.2 (Graph form of a pure qubit state).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.IsGraphFormOf (✓ std3).
Source. Repository-derived.
Acknowledgement. M. Van den Nest, J. Dehaene, B. De Moor (2004). Graphical description of the action of local Clifford transformations on graph states. DOI: 10.1103/PhysRevA.69.022316. URL: https://arxiv.org/abs/quant-ph/0308151v2.
Commentary.
Asserts that Gamma is symmetric over ZMod 2 with zero diagonal and that psi equals lambda * (U_0 x … x U_{N-1}) |Gamma> for single-qubit unitaries U(u) and a scalar lambda with ||lambda|| = 1.
Definition 1.3 (Anchored party translation vector).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.partyDelta (✓ std3).
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Assigns the c-th standard basis vector of (Z/3Z)^{q-1} to party c < q - 1 and the zero vector to the last party q - 1.
Definition 1.4 (Party evaluation of a ternary character).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.charEval (✓ std3).
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Evaluates f_t(c) = t . delta_c in Z/3Z, taking value t_c for c < q - 1 and 0 on the last party q - 1.
Definition 1.5 (Fibre partition of a ternary character).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.charPartition (✓ std3).
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Partitions Fin q into the nonempty fibres of charEval(t).
Definition 1.6 (Coarse-grained replica-three multi-entropy).
Formalization. D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.coarseMultiEntropy (✓ std3).
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Evaluates S_3^{(|pi|)} on psi under the coarse-grained colouring induced by the canonical block enumeration of pi.
Theorem 1.7 (Unit replica-one contraction, graph-form existence, and replica-three rank contraction).
Proof. Machine-checked in Lean as D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.graph_form_existence_and_replica_rank_formula (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Shows that Z(1, q, col, psi) = 1 whenever sum_x ||psi(x)||^2 = 1; extracts a symmetric zero-diagonal graph form Gamma for every normalized pure qubit stabilizer state by factoring the reciprocal norm 2^{-N/2} out of the stabilizer normal-form scalar; and proves for every graph form Gamma of psi and every opposite-pair representative set P in (Z/3Z)^{q-1} that psi has unit norm and Z(3, q, col, psi) is a positive real number equal to 2^{-sum_{t in P} rank C(Gamma, delta(col), t)}.
Theorem 1.8 (Bijection of opposite ternary characters onto coarse partitions and the partition-rank sum for S_3^{(q)}).
Proof. Machine-checked in Lean as D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.replica_three_coarse_partition_sum (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Because negation is a bijection of Z/3Z, charEval(-t) = -charEval(t) has the same fibres as charEval(t), giving charPartition(-t) = charPartition(t). For q >= 2 and nonzero t, charEval(t) vanishes at q - 1 and takes at least one nonzero value in Z/3Z, so charPartition(t) has two or three blocks. Identifying Fin q with Option(Fin(q - 1)) reduces injectivity on P to TernaryPartitionOrbit, while assigning 0 to the block of q - 1 and injective values in {1, 2} to the remaining one or two blocks proves surjectivity onto twoOrThreePartitions(q). Counting both sides yields (3^{q-1} - 1)/2 = S(q, 2) + S(q, 3), and C(Gamma, delta(col), t) coincides entrywise with maskedAdj(Gamma, col, charPartition(t)), transforming the replica rank sum into (log 2 / (2 * 3^{q-2})) sum_{pi in Pi_2(q) cup Pi_3(q)} partitionRank(Gamma, col, pi).
Theorem 1.9 (Party-permutation invariance, coarse-graining upper sum, and bipartite off-diagonal rank formula).
Proof. Machine-checked in Lean as D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.party_symmetry_coarse_graining_and_bipartite_entropy (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. S. Akella, N. Iizuka, A. Miyata (2026). Genuine Multi-Entropy in the Toric Code. DOI: 10.48550/arXiv.2607.06050. URL: https://arxiv.org/abs/2607.06050v2.
Commentary.
Pulling partitions back along a surjective party map m : Fin q to Fin k bijects twoOrThreePartitions(k) onto the two- and three-block partitions sigma >= ker(m) while preserving maskedAdj and partitionRank. When m is a permutation tau of Fin q, ker(tau) is the discrete partition bot, proving S(3, q, tau o col, psi) = S(3, q, col, psi). When m comes from any block listing B : Fin k to pi.parts with |pi| >= 2, ker(m) = pi, proving block-order independence S(3, k, coarseCol(pi, B, col), psi) = coarseMultiEntropy(pi, col, psi), recovery coarseMultiEntropy(bot, col, psi) = S(3, q, col, psi), and the upper-sum formula (log 2 / (2 * 3^{|pi|-2})) sum_{sigma >= pi} partitionRank(Gamma, col, sigma). For a two-block partition sigma = {X, Y}, sigma is maximal in twoOrThreePartitions(q) and bipartite_masked_antidiagonal_rank gives partitionRank(Gamma, col, sigma) = 2 rank(offDiagBlock(Gamma, col, X, Y)), so coarseMultiEntropy(sigma, col, psi) = log 2 * rank(Gamma_{X,Y}).
For a two-block partition sigma = {X, Y}, the identity S_3^{(2)}(sigma) = log 2 * rank_{F2}(Gamma_{X,Y}) matches the bipartite Renyi entanglement entropy of a graph state established by Hein, Eisert and Briegel, Phys. Rev. A 69, 062311. As an explicit three-party illustration, for the three-qubit chain graph state with adjacency edges (0, 1) and (1, 2) and one qubit per party (q = 3, col = id), the three two-block partitions {01, 2}, {02, 1}, {12, 0} and the single three-block partition {0, 1, 2} each produce a masked 3 x 3 binary matrix of rank 2; the coarse-partition sum therefore gives S_3^{(3)} = (log 2 / (2 * 3^1)) * (2 + 2 + 2 + 2) = (4/3) log 2, matching the chain formula (1 + 1/n) log 2 at n = 3 in Czech, Feng, Wu and Xie, arXiv:2606.06582v2 Appendix B Eq. (B.9).
References
- Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.IsGraphFormOf - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.charEval - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.charPartition - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.coarseMultiEntropy - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.graphState - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.graph_form_existence_and_replica_rank_formula - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.partyDelta - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.party_symmetry_coarse_graining_and_bipartite_entropy - Truth anchor:
D5/S3/Quantum/Entanglement/StabilizerMultiEntropy/GraphFormReplicaThreeRank.replica_three_coarse_partition_sum - Dependency: D5/S3/Combinatorics/Partitions/CoarseThreeBlockRefinement
- Dependency: D5/S3/Combinatorics/Partitions/TernaryPartitionOrbit
- Dependency: D5/S3/Quantum/Entanglement/StabilizerMultiEntropyCollapse