Single Photon Cross-Phase Shifts Can Be Enhanced by Localization in both Frequency and Time
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Quantum Physics arXiv:2606.11516 (quant-ph) [Submitted on 9 Jun 2026] Title:Single Photon Cross-Phase Shifts Can Be Enhanced by Localization in both Frequency and Time Authors:Xinyu Jiao, Vida-Michelle Nixon, Kyle Thompson, Aephraim Steinberg View a PDF of the paper titled Single Photon Cross-Phase Shifts Can Be Enhanced by Localization in both Frequency and Time, by Xinyu Jiao and 2 other authors View PDF HTML (experimental) Abstract:Single-photon optical nonlinearities face a fundamental trade-off: maximum nonlinearity requires both spectral resonance (narrow bandwidth) and high peak intensity (short duration), constraints that are incompatible due to the time-energy uncertainty relation. We demonstrate experimentally that this limitation does not need to exist in cases involving post-selection. We measure a cross-phase shift (XPS) produced by a resonant photon from a narrow-band source that is first transmitted through a cold atomic cloud and then localized in time through detection. The peak size of this XPS is greatly enhanced compared to that of Gaussian single-photon-level pulses without post-selection, benefiting from the narrow bandwidth of the resonant prepared state and the high intensity of the post-selected state simultaneously. We measure enhancements in the peak XPS of 6$\pm$1 at an optical depth (OD) of 2.4$\pm$0.1, and our results are in qualitative agreement across a range of optical depths with the recently developed weak value theory of atomic excitation [Thompson et al., APL Quantum 2, 036108 (2025)] for such post-selected photons. This work uncovers new consequences of having simultaneous knowledge of frequency and time, raising new foundational questions about how a particle behaves, and interacts with other systems, when its preparation and post-selection are non-commuting. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2606.11516 [quant-ph] (or arXiv:2606.11516v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2606.11516 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Xinyu Jiao [view email] [v1] Tue, 9 Jun 2026 23:30:23 UTC (1,194 KB) Full-text links: Access Paper: View a PDF of the paper titled Single Photon Cross-Phase Shifts Can Be Enhanced by Localization in both Frequency and Time, by Xinyu Jiao and 2 other authorsView PDFHTML (experimental)TeX Source view license Ancillary-file links: Ancillary files (details): Supplemental_Materials.pdf Current browse context: quant-ph new | recent | 2026-06 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv (What is alphaXiv?) Links to Code Toggle CatalyzeX Code Finder for Papers (What is CatalyzeX?) DagsHub Toggle DagsHub (What is DagsHub?) GotitPub Toggle Gotit.pub (What is GotitPub?) Huggingface Toggle Hugging Face (What is Huggingface?) ScienceCast Toggle ScienceCast (What is ScienceCast?) Demos Demos Replicate Toggle Replicate (What is Replicate?) Spaces Toggle Hugging Face Spaces (What is Spaces?) Spaces Toggle TXYZ.AI (What is TXYZ.AI?) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower (What are Influence Flowers?) Core recommender toggle CORE Recommender (What is CORE?) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs. Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)