{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T13:14:17Z","timestamp":1788268457930,"version":"build-2803163510"},"reference-count":34,"publisher":"AIP Publishing","issue":"9","funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["524452181"],"award-info":[{"award-number":["524452181"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["398816777"],"award-info":[{"award-number":["398816777"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,9,7]]},"abstract":"<jats:p>Time-resolved electronic circular dichroism (TR-ECD) and time-resolved circular dichroism (TRCD) probe chiral exciton dynamics prepared by an ultrafast pump and interrogated by a weak circular probe. The measured signal is a causal mixed electric\u2013magnetic response, whereas imaginary-time methods require a sufficiently stationary reference. Here, we introduce a Kubo\u2013Martin\u2013Schwinger-gated criterion that determines, at each pump\u2013probe delay, whether the selected TRCD-like response can be represented by a conditional one-exciton Gibbs ensemble or requires explicit real-time or Keldysh dynamics. The diagnostic combines a state-level distance from the conditional reference with an integrated spectral distance for the reciprocal E1\u2013M1 response. We apply the protocol to three literature-constrained Frenkel-exciton models: a Ress-type squaraine-polymer squeezed helix, a cisoid indolenine squaraine B hexamer, and a helical perylene-bisimide stack. The results show that early nonthermal states are non-admissible, whereas intramanifold population relaxation and the decay of coherence memory can open a Matsubara-admissible delay window before complete excited-state recovery. The resulting gate identifies when imaginary-time methods can be used without imposing a stationary description on a genuinely nonequilibrium chiroptical response.<\/jats:p>","DOI":"10.1063\/5.0344268","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T12:21:22Z","timestamp":1788265282000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Kubo\u2013Martin\u2013Schwinger-gated imaginary-time reconstruction of time-resolved electronic circular dichroism in organic excitonic aggregates"],"prefix":"10.1063","volume":"165","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2412-9859","authenticated-orcid":false,"given":"Christian","family":"Tantardini","sequence":"first","affiliation":[{"name":"Center for Integrative Petroleum Research, King Fahd University of Petroleum and Minerals 1 , Dhahran 31261,","place":["Saudi Arabia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9243-9461","authenticated-orcid":false,"given":"Caterina","family":"Cocchi","sequence":"additional","affiliation":[{"name":"Friedrich-Schiller-Universit\u00e4t Jena, Institut f\u00fcr Festk\u00f6rpertheorie und -Optik 2 , 07743 Jena,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,9,1]]},"reference":[{"key":"2026090108203216900_c1","doi-asserted-by":"publisher","first-page":"033104","DOI":"10.1063\/1.5009468","article-title":"Near shot-noise limited time-resolved circular dichroism pump-probe spectrometer","volume":"89","year":"2018","journal-title":"Rev. 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