{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2011:ZBZ7EB4ZNTPFLJPUB7EEDG3EM4","short_pith_number":"pith:ZBZ7EB4Z","canonical_record":{"source":{"id":"1110.6681","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2011-10-31T03:09:36Z","cross_cats_sorted":[],"title_canon_sha256":"ca2d7e45f7a8d0da3be65d000124a58ffff2e71829a57a9cf105563bbbe4949e","abstract_canon_sha256":"bcd4971df14f0c4b6c5a1cd7dff28b0f1c0fd276d40b3d63fb0a80a15469112a"},"schema_version":"1.0"},"canonical_sha256":"c873f207996cde55a5f40fc8419b64671a1b214099727054e623bbdcea4e7ee1","source":{"kind":"arxiv","id":"1110.6681","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1110.6681","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"arxiv_version","alias_value":"1110.6681v1","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1110.6681","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"pith_short_12","alias_value":"ZBZ7EB4ZNTPF","created_at":"2026-05-18T12:26:47Z"},{"alias_kind":"pith_short_16","alias_value":"ZBZ7EB4ZNTPFLJPU","created_at":"2026-05-18T12:26:47Z"},{"alias_kind":"pith_short_8","alias_value":"ZBZ7EB4Z","created_at":"2026-05-18T12:26:47Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2011:ZBZ7EB4ZNTPFLJPUB7EEDG3EM4","target":"record","payload":{"canonical_record":{"source":{"id":"1110.6681","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2011-10-31T03:09:36Z","cross_cats_sorted":[],"title_canon_sha256":"ca2d7e45f7a8d0da3be65d000124a58ffff2e71829a57a9cf105563bbbe4949e","abstract_canon_sha256":"bcd4971df14f0c4b6c5a1cd7dff28b0f1c0fd276d40b3d63fb0a80a15469112a"},"schema_version":"1.0"},"canonical_sha256":"c873f207996cde55a5f40fc8419b64671a1b214099727054e623bbdcea4e7ee1","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T01:59:49.844042Z","signature_b64":"DPW+C9JmSzJf/jlTRue9siiP+jebX74xjrOTdFNDdzdB4U5n0Q/skU9h1cpYlhvJvz8K++hlRHo56LVa+8jKDw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"c873f207996cde55a5f40fc8419b64671a1b214099727054e623bbdcea4e7ee1","last_reissued_at":"2026-05-18T01:59:49.843526Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T01:59:49.843526Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1110.6681","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:59:49Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"2/IpZNuS/NkZxa0f0TwNTr1xYYXfFfsbjfNmJu5bvh3/jEQLLEEjv6GPv5IIi+CrKGdP7ZdSEQKT8+ywOU/8Bg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-30T20:22:54.110784Z"},"content_sha256":"393680a3a75b309b79f89ac9d299637fde03071972c05dbf084eb8d00b2a764b","schema_version":"1.0","event_id":"sha256:393680a3a75b309b79f89ac9d299637fde03071972c05dbf084eb8d00b2a764b"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2011:ZBZ7EB4ZNTPFLJPUB7EEDG3EM4","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"On the optimal measurement for quantum discord of two-qubit states","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"quant-ph","authors_text":"Chunxiao Sun, Fengjian Jiang, Jiangfeng Du, Mingjun Shi, Xinhu Yan","submitted_at":"2011-10-31T03:09:36Z","abstract_excerpt":"We present an efficient method to solve the quantum discord of two-qubit X states exactly. A geometric picture is used to clarify whether and when the general POVM measurement is superior to von Neumann measurement. We show that either the von Neumann measurement or the three-element POVM measurement is optimal, and more interestingly, in the latter case the components of the postmeasurement ensemble are invariant for a class of states."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1110.6681","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:59:49Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"bO6yXjEWOywMflUKxSzm2QLaUACxNOVAvM0KXvhpRH6U+GRdhXB39cNco938ArSI0NnfHMRlA9ebBwv+7nUPAw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-30T20:22:54.111481Z"},"content_sha256":"3ed0d1591a36e5e8d1ac3a14e9c555bea6cb3cd1b041fadc284540a122f60fc0","schema_version":"1.0","event_id":"sha256:3ed0d1591a36e5e8d1ac3a14e9c555bea6cb3cd1b041fadc284540a122f60fc0"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/bundle.json","state_url":"https://pith.science/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-05-30T20:22:54Z","links":{"resolver":"https://pith.science/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4","bundle":"https://pith.science/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/bundle.json","state":"https://pith.science/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/state.json","well_known_bundle":"https://pith.science/.well-known/pith/ZBZ7EB4ZNTPFLJPUB7EEDG3EM4/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2011:ZBZ7EB4ZNTPFLJPUB7EEDG3EM4","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"bcd4971df14f0c4b6c5a1cd7dff28b0f1c0fd276d40b3d63fb0a80a15469112a","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2011-10-31T03:09:36Z","title_canon_sha256":"ca2d7e45f7a8d0da3be65d000124a58ffff2e71829a57a9cf105563bbbe4949e"},"schema_version":"1.0","source":{"id":"1110.6681","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1110.6681","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"arxiv_version","alias_value":"1110.6681v1","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1110.6681","created_at":"2026-05-18T01:59:49Z"},{"alias_kind":"pith_short_12","alias_value":"ZBZ7EB4ZNTPF","created_at":"2026-05-18T12:26:47Z"},{"alias_kind":"pith_short_16","alias_value":"ZBZ7EB4ZNTPFLJPU","created_at":"2026-05-18T12:26:47Z"},{"alias_kind":"pith_short_8","alias_value":"ZBZ7EB4Z","created_at":"2026-05-18T12:26:47Z"}],"graph_snapshots":[{"event_id":"sha256:3ed0d1591a36e5e8d1ac3a14e9c555bea6cb3cd1b041fadc284540a122f60fc0","target":"graph","created_at":"2026-05-18T01:59:49Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"We present an efficient method to solve the quantum discord of two-qubit X states exactly. A geometric picture is used to clarify whether and when the general POVM measurement is superior to von Neumann measurement. We show that either the von Neumann measurement or the three-element POVM measurement is optimal, and more interestingly, in the latter case the components of the postmeasurement ensemble are invariant for a class of states.","authors_text":"Chunxiao Sun, Fengjian Jiang, Jiangfeng Du, Mingjun Shi, Xinhu Yan","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2011-10-31T03:09:36Z","title":"On the optimal measurement for quantum discord of two-qubit states"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1110.6681","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:393680a3a75b309b79f89ac9d299637fde03071972c05dbf084eb8d00b2a764b","target":"record","created_at":"2026-05-18T01:59:49Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"bcd4971df14f0c4b6c5a1cd7dff28b0f1c0fd276d40b3d63fb0a80a15469112a","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2011-10-31T03:09:36Z","title_canon_sha256":"ca2d7e45f7a8d0da3be65d000124a58ffff2e71829a57a9cf105563bbbe4949e"},"schema_version":"1.0","source":{"id":"1110.6681","kind":"arxiv","version":1}},"canonical_sha256":"c873f207996cde55a5f40fc8419b64671a1b214099727054e623bbdcea4e7ee1","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"c873f207996cde55a5f40fc8419b64671a1b214099727054e623bbdcea4e7ee1","first_computed_at":"2026-05-18T01:59:49.843526Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T01:59:49.843526Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"DPW+C9JmSzJf/jlTRue9siiP+jebX74xjrOTdFNDdzdB4U5n0Q/skU9h1cpYlhvJvz8K++hlRHo56LVa+8jKDw==","signature_status":"signed_v1","signed_at":"2026-05-18T01:59:49.844042Z","signed_message":"canonical_sha256_bytes"},"source_id":"1110.6681","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:393680a3a75b309b79f89ac9d299637fde03071972c05dbf084eb8d00b2a764b","sha256:3ed0d1591a36e5e8d1ac3a14e9c555bea6cb3cd1b041fadc284540a122f60fc0"],"state_sha256":"c8419e0cee24f83e37a38fa21b98983b7a1b6dd3ed08a24d1e5b12c61b107f54"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"N0HqPDzCZp6uqJXKBBkrrRONeCsfbVxhOfc9+wxzWsu0q9Nr+hYSgIbRaY4MBz/CKefTCfzHSqwaDeS38funDA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-30T20:22:54.114752Z","bundle_sha256":"56b61f24d0db38d8d51690d54034803ae5eb0e74dfba57f635449f6285b00104"}}