Jiaojian Shi

All Publications

• Solution-phase sample-averaged single-particle spectroscopy of quantum emitters with femtosecond resolution. Nature materials Shi, J., Shen, Y., Pan, F., Sun, W., Mangu, A., Shi, C., McKeown-Green, A., Moradifar, P., Bawendi, M. G., Moerner, W. E., Dionne, J. A., Liu, F., Lindenberg, A. M. 2024

  Abstract

  The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. Systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. Here we utilize a combination of fluorescence correlation spectroscopy and ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity. We employ this approach to study heterogeneous emitters in two-dimensional hexagonal boron nitride. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron-phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Corroborated with theory, this translates to the photon fidelity characterization of cascaded emission efficiency and decoherence time. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.

  View details for DOI 10.1038/s41563-024-01855-7

  View details for PubMedID 38589542

  View details for PubMedCentralID 5615041

• Intrinsic 1[Formula: see text] phase induced in atomically thin 2H-MoTe2 by a single terahertz pulse. Nature communications Shi, J., Bie, Y. Q., Zong, A., Fang, S., Chen, W., Han, J., Cao, Z., Zhang, Y., Taniguchi, T., Watanabe, K., Fu, X., Bulović, V., Kaxiras, E., Baldini, E., Jarillo-Herrero, P., Nelson, K. A. 2023; 14 (1): 5905

  Abstract

  The polymorphic transition from 2H to 1[Formula: see text]-MoTe2, which was thought to be induced by high-energy photon irradiation among many other means, has been intensely studied for its technological relevance in nanoscale transistors due to the remarkable improvement in electrical performance. However, it remains controversial whether a crystalline 1[Formula: see text] phase is produced because optical signatures of this putative transition are found to be associated with the formation of tellurium clusters instead. Here we demonstrate the creation of an intrinsic 1[Formula: see text] lattice after irradiating a mono- or few-layer 2H-MoTe2 with a single field-enhanced terahertz pulse. Unlike optical pulses, the low terahertz photon energy limits possible structural damages. We further develop a single-shot terahertz-pump-second-harmonic-probe technique and reveal a transition out of the 2H-phase within 10 ns after photoexcitation. Our results not only provide important insights to resolve the long-standing debate over the light-induced polymorphic transition in MoTe2 but also highlight the unique capability of strong-field terahertz pulses in manipulating quantum materials.

  View details for DOI 10.1038/s41467-023-41291-w

  View details for PubMedID 37737233

  View details for PubMedCentralID PMC10516973

• Giant room-temperature nonlinearities in a monolayer Janus topological semiconductor. Nature communications Shi, J., Xu, H., Heide, C., HuangFu, C., Xia, C., de Quesada, F., Shen, H., Zhang, T., Yu, L., Johnson, A., Liu, F., Shi, E., Jiao, L., Heinz, T., Ghimire, S., Li, J., Kong, J., Guo, Y., Lindenberg, A. M. 2023; 14 (1): 4953

  Abstract

  Nonlinear optical materials possess wide applications, ranging from terahertz and mid-infrared detection to energy harvesting. Recently, the correlations between nonlinear optical responses and certain topological properties, such as the Berry curvature and the quantum metric tensor, have attracted considerable interest. Here, we report giant room-temperature nonlinearities in non-centrosymmetric two-dimensional topological materials-the Janus transition metal dichalcogenides in the 1 T' phase, synthesized by an advanced atomic-layer substitution method. High harmonic generation, terahertz emission spectroscopy, and second harmonic generation measurements consistently show orders-of-the-magnitude enhancement in terahertz-frequency nonlinearities in 1 T' MoSSe (e.g., > 50 times higher than 2H MoS2 for 18th order harmonic generation; > 20 times higher than 2H MoS2 for terahertz emission). We link this giant nonlinear optical response to topological band mixing and strong inversion symmetry breaking due to the Janus structure. Our work defines general protocols for designing materials with large nonlinearities and heralds the applications of topological materials in optoelectronics down to the monolayer limit.

  View details for DOI 10.1038/s41467-023-40373-z

  View details for PubMedID 37587120

  View details for PubMedCentralID 8282873

• A room-temperature polarization-sensitive CMOS terahertz camera based on quantum-dot-enhanced terahertz-to-visible photon upconversion. Nature nanotechnology Shi, J., Yoo, D., Vidal-Codina, F., Baik, C. W., Cho, K. S., Nguyen, N. C., Utzat, H., Han, J., Lindenberg, A. M., Bulović, V., Bawendi, M. G., Peraire, J., Oh, S. H., Nelson, K. A. 2022

  Abstract

  Detection of terahertz (THz) radiation has many potential applications, but presently available detectors are limited in many aspects of their performance, including sensitivity, speed, bandwidth and operating temperature. Most do not allow the characterization of THz polarization states. Recent observation of THz-driven luminescence in quantum dots offers a possible detection mechanism via field-driven interdot charge transfer. We demonstrate a room-temperature complementary metal-oxide-semiconductor THz camera and polarimeter based on quantum-dot-enhanced THz-to-visible upconversion mechanism with optimized luminophore geometries and fabrication designs. Besides broadband and fast responses, the nanoslit-based sensor can detect THz pulses with peak fields as low as 10 kV cm-1. A related coaxial nanoaperture-type device shows a to-date-unexplored capability to simultaneously record the THz polarization state and field strength with similar sensitivity.

  View details for DOI 10.1038/s41565-022-01243-9

  View details for PubMedID 36329270

• Terahertz Field-Induced Reemergence of Quenched Photoluminescence in Quantum Dots NANO LETTERS Shi, J., Gao, F. Y., Zhang, Z., Utzat, H., Barotov, U., Farahvash, A., Han, J., Deschamps, J., Baik, C., Cho, K., Bulovic, V., Willard, A. P., Baldini, E., Gedik, N., Bawendi, M. G., Nelson, K. A. 2022; 22 (4): 1718-1725

  Abstract

  The continuous and concerted development of colloidal quantum dot light-emitting diodes over the past two decades has established them as a bedrock technology for the next generation of displays. However, a fundamental issue that limits the performance of these devices is the quenching of photoluminescence due to excess charges from conductive charge transport layers. Although device designs have leveraged various workarounds, doing so often comes at the cost of limiting efficient charge injection. Here we demonstrate that high-field terahertz (THz) pulses can dramatically brighten quenched QDs on metallic surfaces, an effect that persists for minutes after THz irradiation. This phenomenon is attributed to the ability of the THz field to remove excess charges, thereby reducing trion and nonradiative Auger recombination. Our findings show that THz technologies can be used to suppress and control such undesired nonradiative decay, potentially in a variety of luminescent materials for future device applications.

  View details for DOI 10.1021/acs.nanolett.1c04873

  View details for Web of Science ID 000776700100035

  View details for PubMedID 35142222

• All-optical fluorescence blinking control in quantum dots with ultrafast mid-infrared pulses. Nature nanotechnology Shi, J., Sun, W., Utzat, H., Farahvash, A., Gao, F. Y., Zhang, Z., Barotov, U., Willard, A. P., Nelson, K. A., Bawendi, M. G. 2021

  Abstract

  Photoluminescence intermittency is a ubiquitous phenomenon, reducing the temporal emission intensity stability of single colloidal quantum dots (QDs) and the emission quantum yield of their ensembles. Despite efforts to achieve blinking reduction by chemical engineering of the QD architecture and its environment, blinking still poses barriers to the application of QDs, particularly in single-particle tracking in biology or in single-photon sources. Here, we demonstrate a deterministic all-optical suppression of QD blinking using a compound technique of visible and mid-infrared excitation. We show that moderate-field ultrafast mid-infrared pulses (5.5mum, 150fs) can switch the emission from a charged, low quantum yield grey trion state to the bright exciton state in CdSe/CdS core-shell QDs, resulting in a significant reduction of the QD intensity flicker. Quantum-tunnelling simulations suggest that the mid-infrared fields remove the excess charge from trions with reduced emission quantum yield to restore higher brightness exciton emission. Our approach can be integrated with existing single-particle tracking or super-resolution microscopy techniques without any modification to the sample and translates to other emitters presenting charging-induced photoluminescence intermittencies, such as single-photon emissive defects in diamond and two-dimensional materials.

  View details for DOI 10.1038/s41565-021-01016-w

  View details for PubMedID 34811550

• Room Temperature Terahertz Electroabsorption Modulation by Excitons in Monolayer Transition Metal Dichalcogenides NANO LETTERS Shi, J., Baldini, E., Latini, S., Sato, S. A., Zhang, Y., Pein, B. C., Shen, P., Kong, J., Rubio, A., Gedik, N., Nelson, K. A. 2020; 20 (7): 5214-5220

  Abstract

  The interaction between off-resonant laser pulses and excitons in monolayer transition metal dichalcogenides is attracting increasing interest as a route for the valley-selective coherent control of the exciton properties. Here, we extend the classification of the known off-resonant phenomena by unveiling the impact of a strong THz field on the excitonic resonances of monolayer MoS2. We observe that the THz pump pulse causes a selective modification of the coherence lifetime of the excitons, while keeping their oscillator strength and peak energy unchanged. We rationalize these results theoretically by invoking a hitherto unobserved manifestation of the Franz-Keldysh effect on an exciton resonance. As the modulation depth of the optical absorption reaches values as large as 0.05 dB/nm at room temperature, our findings open the way to the use of semiconducting transition metal dichalcogenides as compact and efficient platforms for high-speed electroabsorption devices.

  View details for DOI 10.1021/acs.nanolett.0c01134

  View details for Web of Science ID 000548893200068

  View details for PubMedID 32539410