{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2018:FLRS7DXV6BYCD74CADPXFVPIUD","short_pith_number":"pith:FLRS7DXV","canonical_record":{"source":{"id":"1803.02401","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2018-03-06T19:46:05Z","cross_cats_sorted":[],"title_canon_sha256":"7ceb320ac5f5954cec5a99c316a5373f21f9a347245c03e091e0e7104ebb5ccf","abstract_canon_sha256":"2291d807bec195753d0c6ef0ae6ee235b536b3e68184a58c59ecb69d13fbb9bf"},"schema_version":"1.0"},"canonical_sha256":"2ae32f8ef5f07021ff8200df72d5e8a0e015c06ae13b9951d02fcaaa0253018e","source":{"kind":"arxiv","id":"1803.02401","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1803.02401","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"arxiv_version","alias_value":"1803.02401v1","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1803.02401","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"pith_short_12","alias_value":"FLRS7DXV6BYC","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_16","alias_value":"FLRS7DXV6BYCD74C","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_8","alias_value":"FLRS7DXV","created_at":"2026-05-18T12:32:22Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2018:FLRS7DXV6BYCD74CADPXFVPIUD","target":"record","payload":{"canonical_record":{"source":{"id":"1803.02401","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2018-03-06T19:46:05Z","cross_cats_sorted":[],"title_canon_sha256":"7ceb320ac5f5954cec5a99c316a5373f21f9a347245c03e091e0e7104ebb5ccf","abstract_canon_sha256":"2291d807bec195753d0c6ef0ae6ee235b536b3e68184a58c59ecb69d13fbb9bf"},"schema_version":"1.0"},"canonical_sha256":"2ae32f8ef5f07021ff8200df72d5e8a0e015c06ae13b9951d02fcaaa0253018e","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:15:27.950238Z","signature_b64":"BEzysZXqF17gdjzoIku/bCXgBZu368aMK1SqPVq0jyD+vAL3sKZ6SVq9VbeyKf2M+v1x7YJGJjCxizx0SU/ZCQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"2ae32f8ef5f07021ff8200df72d5e8a0e015c06ae13b9951d02fcaaa0253018e","last_reissued_at":"2026-05-18T00:15:27.949532Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:15:27.949532Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1803.02401","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":"2026-05-18T00:15:27Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"LaLSU51Bjh0UXr2eFLo2ax5/9ao0vpGSeZLtVjP8SkuTQ1F58JsIzS/KRixyRTcOtsVEYMhblj9kLEkhWrQjDg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-30T06:08:32.540747Z"},"content_sha256":"7f5c123f0ba1e523144602d87ae2bdcbbd8c8b6ed661e176e47c322bc814c68b","schema_version":"1.0","event_id":"sha256:7f5c123f0ba1e523144602d87ae2bdcbbd8c8b6ed661e176e47c322bc814c68b"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2018:FLRS7DXV6BYCD74CADPXFVPIUD","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Low-noise heralded single photons from cascaded downconversion","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"quant-ph","authors_text":"Deny R. Hamel, Evan Meyer-Scott, Patrick F. Poitras","submitted_at":"2018-03-06T19:46:05Z","abstract_excerpt":"Heralded single photon sources are often implemented using spontaneous parametric downconversion, but their quality can be restricted by optical loss, double pair emission and detector dark counts. Here, we show that the performance of such sources can be improved using cascaded downconversion, by providing a second trigger signal to herald the presence of a single photon, thereby reducing the effects of detector dark counts. We find that for a setup with fixed detectors, an improved heralded second-order correlation function $g^{(2)}$ can always be achieved with cascaded downconversion given "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1803.02401","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":"2026-05-18T00:15:27Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"wkb7I3xCQ5AP8eiRQXmbeRENqiWHurzH+mX8sSzzTkKUlhSODFkNQBws9zit72KUDZPVsgMQNzkhGxMPkHzZAA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-30T06:08:32.541102Z"},"content_sha256":"b1bc86d003cb09380624b9735f4268c7cd22d4b50230ae495c57b553de9fc4ba","schema_version":"1.0","event_id":"sha256:b1bc86d003cb09380624b9735f4268c7cd22d4b50230ae495c57b553de9fc4ba"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/FLRS7DXV6BYCD74CADPXFVPIUD/bundle.json","state_url":"https://pith.science/pith/FLRS7DXV6BYCD74CADPXFVPIUD/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/FLRS7DXV6BYCD74CADPXFVPIUD/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":"2026-05-30T06:08:32Z","links":{"resolver":"https://pith.science/pith/FLRS7DXV6BYCD74CADPXFVPIUD","bundle":"https://pith.science/pith/FLRS7DXV6BYCD74CADPXFVPIUD/bundle.json","state":"https://pith.science/pith/FLRS7DXV6BYCD74CADPXFVPIUD/state.json","well_known_bundle":"https://pith.science/.well-known/pith/FLRS7DXV6BYCD74CADPXFVPIUD/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:FLRS7DXV6BYCD74CADPXFVPIUD","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":"2291d807bec195753d0c6ef0ae6ee235b536b3e68184a58c59ecb69d13fbb9bf","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2018-03-06T19:46:05Z","title_canon_sha256":"7ceb320ac5f5954cec5a99c316a5373f21f9a347245c03e091e0e7104ebb5ccf"},"schema_version":"1.0","source":{"id":"1803.02401","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1803.02401","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"arxiv_version","alias_value":"1803.02401v1","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1803.02401","created_at":"2026-05-18T00:15:27Z"},{"alias_kind":"pith_short_12","alias_value":"FLRS7DXV6BYC","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_16","alias_value":"FLRS7DXV6BYCD74C","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_8","alias_value":"FLRS7DXV","created_at":"2026-05-18T12:32:22Z"}],"graph_snapshots":[{"event_id":"sha256:b1bc86d003cb09380624b9735f4268c7cd22d4b50230ae495c57b553de9fc4ba","target":"graph","created_at":"2026-05-18T00:15:27Z","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":"Heralded single photon sources are often implemented using spontaneous parametric downconversion, but their quality can be restricted by optical loss, double pair emission and detector dark counts. Here, we show that the performance of such sources can be improved using cascaded downconversion, by providing a second trigger signal to herald the presence of a single photon, thereby reducing the effects of detector dark counts. We find that for a setup with fixed detectors, an improved heralded second-order correlation function $g^{(2)}$ can always be achieved with cascaded downconversion given ","authors_text":"Deny R. Hamel, Evan Meyer-Scott, Patrick F. Poitras","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2018-03-06T19:46:05Z","title":"Low-noise heralded single photons from cascaded downconversion"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1803.02401","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":"sha256:7f5c123f0ba1e523144602d87ae2bdcbbd8c8b6ed661e176e47c322bc814c68b","target":"record","created_at":"2026-05-18T00:15:27Z","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":"2291d807bec195753d0c6ef0ae6ee235b536b3e68184a58c59ecb69d13fbb9bf","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2018-03-06T19:46:05Z","title_canon_sha256":"7ceb320ac5f5954cec5a99c316a5373f21f9a347245c03e091e0e7104ebb5ccf"},"schema_version":"1.0","source":{"id":"1803.02401","kind":"arxiv","version":1}},"canonical_sha256":"2ae32f8ef5f07021ff8200df72d5e8a0e015c06ae13b9951d02fcaaa0253018e","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"2ae32f8ef5f07021ff8200df72d5e8a0e015c06ae13b9951d02fcaaa0253018e","first_computed_at":"2026-05-18T00:15:27.949532Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:15:27.949532Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"BEzysZXqF17gdjzoIku/bCXgBZu368aMK1SqPVq0jyD+vAL3sKZ6SVq9VbeyKf2M+v1x7YJGJjCxizx0SU/ZCQ==","signature_status":"signed_v1","signed_at":"2026-05-18T00:15:27.950238Z","signed_message":"canonical_sha256_bytes"},"source_id":"1803.02401","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:7f5c123f0ba1e523144602d87ae2bdcbbd8c8b6ed661e176e47c322bc814c68b","sha256:b1bc86d003cb09380624b9735f4268c7cd22d4b50230ae495c57b553de9fc4ba"],"state_sha256":"90be1ecd09e8b57e70b44db85ac05f61f9e02ace2981922aea9ca630e01ab913"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"/bssjztZ3SGpsmRe4GvR+CNZ8bDOfkwqzt4GAWW2uMVSfTxWUTapDYPc+CK+3cvzDbtQ8d3Ryq3VppgByxhkCQ==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-30T06:08:32.543414Z","bundle_sha256":"ae27610292fdadf235e4c8e6da4e97f8241fc21820307ebd9f00164870e09b39"}}