Hot-Band Absorption Can Mimic Entangled Two-Photon Absorption

Mikhaylov, Alexander; Wilson, Ryan N.; Parzuchowski, Kristen M.; Mazurek, Michael D.; Camp, Charles H.; Stevens, Martin J.; Jimenez, Ralph

doi:10.1021/acs.jpclett.1c03751

Cited by 26 publications

(18 citation statements)

References 33 publications

(66 reference statements)

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“…As previously discussed, we conclude that despite the reproducibility of these results, because the purported ETPA signal occurs for |τ| ≫ T e (and is very similar to that obtained for τ = 0), it in fact cannot be attributed to ETPA. Recent experimental work has pointed out that this type of behavior might be due to one-photon loss mechanisms, such as hot-band absorption, that could mimic ETPA. We believe this type discussion will motivate future investigations toward finding single-photon-loss-independent metrics (or witnesses) for ETPA, such as our own analysis in terms of the Γ quantity [see eq ] which is indeed linear-loss-independent.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study of the Validity of Entangled Two-Photon Absorption Measurements in Organic Compounds

et al. 2022

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Entangled two-photon absorption (ETPA) has recently become a topic of lively debate, mainly due to the apparent inconsistencies in the experimentally reported ETPA cross sections of organic molecules obtained by a number of groups. In this work, we provide a thorough experimental study of ETPA in the organic molecules Rhodamine B (RhB) and zinc tetraphenylporphirin (ZnTPP). Our contribution is 3-fold: first, we reproduce previous results from other groups; second, we on the one hand determine the effects of different temporal correlationsintroduced as a controllable temporal delay between the signal and idler photons to be absorbedon the strength of the ETPA signal, and on the other hand, we introduce two concurrent and equivalent detection systems with and without the sample in place as a useful experimental check; third, we introduce, and apply to our data, a novel method to quantify the ETPA rate based on taking into account the full photon-pair behavior rather than focusing on singles or coincidence counts independently. Through this experimental setup we find that, surprisingly, the purported ETPA signal is not suppressed for a temporal delay much greater than the characteristic photon-pair temporal correlation time. While our results reproduce the previous findings from other authors, our full analysis indicates that the signal observed is not actually due to ETPA but simply to linear losses. Interestingly, for higher RhB concentrations, we find a two-photon signal that, contrary to expectations, likewise does not correspond to ETPA.

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Section: Resultsmentioning

confidence: 99%

Experimental Study of the Validity of Entangled Two-Photon Absorption Measurements in Organic Compounds

et al. 2022

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“…Recently, theoretical and experimental measurements have emphasized the importance of resonant or near-resonant real states to achieve large two-photon-entangled interactions. 42,43,51 The results of this paper indicate that caution must be taken when measuring entangled two-photon events because single-photon scattering and other reported single-photon processes such as hot band absorption 52 will mimic linear absorption at low powers. Only by characterizing the entangled state, instead of relying solely on intensity measurements, can a definitive conclusion be reached.…”

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confidence: 86%

Single-Photon Scattering Can Account for the Discrepancies among Entangled Two-Photon Measurement Techniques

Hickam

Harper

et al. 2022

J. Phys. Chem. Lett.

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Entangled photon pairs are predicted to linearize and increase the efficiency of two-photon absorption, allowing continuous wave laser diodes to drive ultrafast time-resolved spectroscopy and nonlinear processes. Despite a range of theoretical studies and experimental measurements, inconsistencies persist about the value of the entanglement enhanced interaction cross section. A spectrometer is constructed that can temporally and spectrally characterize the entangled photon state before, during, and after any potential two-photon excitation event. For the molecule Rhodamine 6G, which has a virtual state pathway, any entangled two-photon interaction is found to be equal to or lower than classical, single photon scattering events. This result can account for the discrepancies between the wide variety of entangled two-photon absorption cross sections reported from different measurement techniques. The reported instrumentation can unambiguously separate classical and entangled effects and therefore is of importance for the growing field of nonlinear and multiphoton entangled spectroscopy.TOC GRAPHICS KEYWORDS (Word Style "BG_Keywords"). Entangled two-photon absorption, Rhodamine 6G, entangled light matter interactions, virtual state pathways, off-resonant scattering

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“…Much initial interest centered on the possibility of using single photon pairs to carry out two photon absorption that is linear in photon number for microscopy. Currently this remains a controversial topic 10 but new sources such as bright squeezed vacuums, may change the picture in the future. The possibility of using the quantum state of light as a parameter for the coherent control of material properties was described theoretically by Ishida et al ().…”

Section: Looking Forwardmentioning

confidence: 99%