Rydberg State Single-Mode Polariton Lasing with Ultralow Threshold via Symmetry Engineering.

Symmetry plays an essential role in the fundamental properties of a physical system. In this work, we report on the realization of tunable single-mode polariton lasing from highly excited Rydberg states via symmetry engineering. By breaking the symmetry of the polaritonic wave function through potential wells and controlling the spatial overlap between the gain region and the eigen mode, we are able to generate single-mode polariton lasing, reversibly and dynamically, from quantized polariton states. Increasing the asymmetry of the potential well, single-mode lasing can be achieved even for the highly excited Rydberg state with a principle quantum number of N = 14. Moreover, as a result of the excellent reservoir-eigen mode overlap and efficient spatial confinement, the threshold of lasing can be reduced up to 6 orders of magnitude, compared with those conventional pumping schemes. Our results present a new strategy toward the realization of thresholdless polariton lasing with dynamical tunability.

Loss of SPRY2 contributes to cancer-associated fibroblasts activation and promotes breast cancer development.

The communication between tumor cells and tumor microenvironment plays a critical role in cancer development. Cancer-associated fibroblasts (CAFs) are the major components of the tumor microenvironment and take part in breast cancer formation and progression. Here, by comparing the gene expression patterns in CAFs and normal fibroblasts, we found SPRY2 expression was significantly decreased in CAFs and decreased SPRY2 expression was correlated with worse prognosis in breast cancer patients. SPRY2 knockdown in fibroblasts promoted tumor growth and distant metastasis of breast cancer in mice. Loss of stromal SPRY2 expression promoted CAF activation dependent on glycolytic metabolism. Mechanically, SPRY2 suppressed Y10 phosphorylation of LDHA and LDHA activity by interfering with the interaction between LDHA and SRC. Functionally, SPRY2 knockdown in fibroblasts enhanced the stemness of tumor cell dependent on glycolysis in fibroblasts. Collectively, this work identified SPRY2 as a negative regulator of CAF activation, and SPRY2 in CAFs may potentially be therapeutically targeted in breast cancer treatment.

Neutrophil extracellular traps mediate TLR9/Merlin axis to resist ferroptosis and promote triple negative breast cancer progression.

Neutrophil and neutrophil extracellular traps (NETs) were reported to be associated with tumor development, but the exact role and concrete mechanisms are still poorly understood, especially in triple negative breast cancer (TNBC). In this study, our results exhibited that NETs formation in TNBC tissues was higher than that in non-TNBC tissues, and NETs formation was distinctly correlated with tumor size, ki67 level and lymph node metastasis in TNBC patients. Subsequent in vivo experiments demonstrated that NETs inhibition could suppress TNBC tumor growth and lung metastasis. Further in vitro experiments uncovered that oncogenic function of NETs on TNBC cells were possibly dependent on TLR9 expression. We also found that neutrophils from peripheral blood of TNBC patients with postoperative fever were prone to form NETs and could enhance the proliferation and invasion of TNBC cells. Mechanistically, we revealed that NETs could interact with TLR9 to decrease Merlin phosphorylation which contributed to TNBC cell ferroptosis resistance. Our work provides a novel insight into the mechanism of NETs promoting TNBC progression and blocking the key modulator of NETs might be a promising therapeutic strategy in TNBC.

Relaxation Oscillations of an Exciton-Polariton Condensate Driven by Parametric Scattering.

We report the observation of coherent oscillations in the relaxation dynamics of an exciton-polariton condensate that were driven by parametric scattering processes. As a result of the interbranch scattering scheme and the nonlinear polariton-polariton interactions, such parametric scatterings exhibit a high scattering efficiency that leads to the fast depletion of the polariton condensate and the periodic shut-off of the bosonic stimulation processes, eventually causing relaxation oscillations. Employing polariton-reservoir interactions, the oscillation dynamics in the time domain can be projected onto the energy space. In theory, our simulations using the open-dissipative Gross-Pitaevskii equation are in excellent agreement with experimental observations. Surprisingly, the oscillation patterns, including many excitation pulses, are clearly visible in our time-integrated images, implying the high stability of the relaxation oscillations driven by polariton parametric scatterings.

A Magnetically Driven Tandem Chip Enables Rapid Isolation and Multiplexed Profiling of Extracellular Vesicles.

The protein phenotypes of extracellular vesicles (EVs) have emerged as promising biomarkers for cancer diagnosis and treatment monitoring. However, the technical challenges in rapid isolation and multiplexed molecular detection of EVs have limited their clinical practice. Herein, we developed a magnetically driven tandem chip to achieve streamlined rapid isolation and multiplexed profiling of surface protein biomarkers of EVs. Driven by magnetic force, the magnetic nanomixers not only act as tiny stir bars to promote mass transfer and enhance reaction efficiency of EVs, but also transport on communicating vessels of the tandem chip continuously and expedite the assay workflow. We designed cyclic surface enhancement of Raman scattering (SERS) tags to bind with target EVs and then release them by exonuclease I, eliminating steric hindrance and amplifying the SERS signal of multiple protein biomarkers on EVs. Due to the excellent assay performance, six breast cancer biomarkers were detected simultaneously on EVs using only 10 µL plasma within 1.5 h. The unweighted SUM signature offers great accuracy in discriminating breast cancer patients from healthy donors. Overall, the dynamic magnetic driving tandem chip offers a new avenue to advance the clinical application of EV-based liquid biopsy.

Comparison of adverse drug reactions between tamoxifen and toremifene in breast cancer patients with different CYP2D6 genotypes: A propensity-score matched cohort study.

CYP2D6 gene polymorphism has a profound impact upon the effect of tamoxifen as adjuvant endocrine therapy in breast cancer. However, it had never been reported whether the adverse drug reactions vary by CYP2D6 metabolic status for patients treated with tamoxifen or toremifene. We conducted a retrospective study in breast cancer patients to investigate the impact of CYP2D6 metabolic status on liver dysfunction events, gynecological events and dyslipidemia events. According to CYP2D6*10 (100C → T) genotype, the enrolled patients were further categorized into four cohorts (extensive metabolizers taking tamoxifen [EM + TAM], extensive metabolizers taking toremifene [EM + TOR], intermediate metabolizers taking tamoxifen [IM + TAM], and intermediate metabolizers taking toremifene [IM + TOR]). A total of 192 patients were included in the study, with a median follow-up time of 26.2 months. In EM + TAM cohort, the risks of liver dysfunction events (P = .004) and gynecological events (P = .004) were significantly higher compared to EM + TOR cohort. In IM + TAM cohort, the risks of liver dysfunction events (P = .14) and gynecological events (P = .99) were not significantly different from IM + TOR cohort. A significant decrease of total cholesterol was observed in EM + TAM cohort around 1 year after taking tamoxifen (P < .001). Significant interactions between CYP2D6 metabolic status and endocrine agents were observed in terms of liver dysfunction events (P-interaction = .007) and gynecological events (P-interaction = .026). These findings suggested that CYP2D6 gene polymorphism played a significant role in predicting liver dysfunction, gynecological diseases and lipid metabolism changes among patients taking tamoxifen or toremifene.

Polariton-Polariton Interactions Revealed in a One-dimensional Whispering Gallery Microcavity.

Coulomb interactions are essential to the dynamics and optical properties of exciton-polaritons. Here, we report an experimental observation of polariton-polariton interactions far beyond theory in a one-dimensional whispering gallery microcavity. Based on the unique half-light half-matter nature, we were able to clarify the effects of excitons, quantum confinement, and nonthermalized polariton distribution in the measurements of the polaritonic interactions. Spectacularly, our position-scan and power-scan investigations both revealed that the polariton-polariton interaction strength is up to 2 orders of magnitude larger than theoretical predictions. These results suggest that polaritonic interactions are far more complicated than the expectation and should be re-examined in polariton physics and devices involving polaritonic interactions.

Dynamics of excited-state condensate for optically confined exciton-polaritons.

We report experimental studies on the dynamics of excited-state condensate for exciton-polaritons confined in an optically generated trap. The three-dimensionally confined trap was realized by imposing two optical barriers onto a one-dimensional ZnO whispering gallery microcavity. Experimentally, we characterized the confined polariton condensate by varying the trap width and the barrier height. Theoretically, we calculated the spatial overlap between the polariton wavefunction and the excitonic reservoir. Direct comparison of these results verified that such polariton-reservoir overlap was responsible for the observed excited-state polariton condensate.

Fabry-Perot type polariton modes and their dynamics revealed by Young's interference experiment.

We report experimental studies on the Fabry-Perot (F-P) type polariton modes and their dynamics using a modified Young's double-slit interference technique. The technique was based on the angle-resolved micro-photoluminescence spectroscopy and optimized for nanostructure measurements. Using this technique, we directly revealed the parity of the F-P type polariton modes from the angle-dependent interference spectra. Moreover, clear features of mode competition were observed from the power dependence of the interference patterns. The observed competition behaviors can be well simulated by a five-level rate equation model.

Strongly coupled exciton-surface plasmon polariton from excited-subband transitions of single-walled carbon nanotubes.

We report experimental observation of strong coupling between surface plasmon polariton (SPP) propagating on a thin silver film and excitons from excited-subband transtitions of single-walled carbon nanotubes (SWNTs). Clear anti-crossing behaviors were observed from attenuated total reflection measurements when the SPP energy approaches the 2nd subband transition of (6,5) SWNTs. The maximum Rabi splitting of the plasmon-exciton mixed states was extracted to be up to ~166.2 meV. Moreover, the splitting was found to be dependent linearly on the square root of the SWNTs concentration, in good agreement with theoretical prediction.

Spin-resolved Purcell effect in a quantum dot microcavity system.

We demonstrate the spin selective coupling of the exciton state with cavity mode in a single quantum dot (QD)-micropillar cavity system. By tuning an external magnetic field, each spin polarized exciton state can be selectively coupled with the cavity mode due to the Zeeman effect. A significant enhancement of spontaneous emission rate of each spin state is achieved, giving rise to a tunable circular polarization degree from -90% to 93%. A four-level rate equation model is developed, and it agrees well with our experimental data. In addition, the coupling between photon mode and each exciton spin state is also achieved by varying temperature, demonstrating the full manipulation over the spin states in the QD-cavity system. Our results pave the way for the realization of future quantum light sources and the quantum information processing applications.

Room-temperature polariton parametric scattering driven by a one-dimensional polariton condensate.

We demonstrate a novel way to realize room-temperature polariton parametric scattering in a one-dimensional ZnO microcavity. The polariton parametric scattering is driven by a polariton condensate, with a balanced polariton pair generated at the adjacent polariton mode. This parametric scattering is experimentally investigated by the angle-resolved photoluminescence spectroscopy technique under different pump powers and it is well described by the rate equation of interacting bosons. The direct relation between the intensity of the scattered polariton signal and that of the polariton reservoir is acquired under nonresonant excitation, exhibiting the explicit nonlinear characteristic of this room-temperature polariton parametric process.

Algorithm-Assisted Detection and Imaging of microRNAs in Living Cancer Cells via the Disassembly of Plasmonic Core-Satellite Probes Coupled with Strand Displacement Amplification.

Acute detection and high-resolution imaging of microRNAs (miRNAs) in living cancer cells have attracted great attention in clinical diagnosis and therapy. However, current methods suffer from low detection sensitivity or heavy dependence on expensive and sophisticated spectrometers. Herein, a novel algorithm-assisted system of detecting and imaging miRNAs in living cancer cells was developed via the disassembly of plasmonic core-satellite probes coupled with strand displacement amplification (SDA). The target miRNAs in the system could trigger the disassembly of plasmonic core-satellite probes, leading to the color change in the scattering light of the probes, which could be captured by dark-field microscopy (DFM). The concentration of the target miRNAs was obtained by analyzing the dark-field image based on the proposed algorithm with a detection limit of 2 pM for miRNA-21. Thus, the performance in terms of simplicity and sensitivity of the system compared with one of the conventional spectrophotometers was well presented, which could inspire more clinical applications of inexpensive, intelligent, and rapid screening of cancer cells. The application software based on the proposed algorithm running on the Android platform was also developed, demonstrating the potential of remote diagnosis.

Magnetic field control of the quantum chaotic dynamics of hydrogen analogs in an anisotropic crystal field.

We report magnetic field control of the quantum chaotic dynamics of hydrogen analogues in an anisotropic solid state environment. The chaoticity of the system dynamics was quantified by means of energy level statistics. We analyzed the magnetic field dependence of the statistical distribution of the impurity energy levels and found a smooth transition between the Poisson limit and the Wigner limit, i.e., transition between regular Poisson and fully chaotic Wigner dynamics. The effect of the crystal field anisotropy on the quantum chaotic dynamics, which manifests itself in characteristic transitions between regularity and chaos for different field orientations, was demonstrated.

Grain Boundary Induced Ultralow Threshold Random Laser in a Single GaTe Flake.

Random lasing is a lasing phenomenon realized in random media, and it has attracted a great deal of attention in recent years. An essential requirement for strong random lasing is to achieve strong and recurrent scattering among grain boundaries of a disordered structure. Herein, we report a random laser (RL) based on individual polycrystalline GaTe microflakes (MFs) with a lasing threshold of 4.15 kW cm-2, about 1-2 orders of magnitude lower than that of the reported single GaN microwire random laser. The strongly enhanced light scattering and trapping benefit from the reduced grain size in the polycrystalline GaTe MF, resulting in a ultralow threshold. We also investigate the dependence of spatially localized cavities' dimension on the pumping intensity profile and temperature. The findings provide a feasible route to realize RL with a low threshold and small size, opening up a new avenue in fulfilling many potential optoelectronic applications of RL.

Room temperature exciton-polariton condensate in an optically-controlled trap.

We report experimental studies on the optical properties of an exciton polariton condensate confined in an optically defined trap at room temperature. As a result of the parabolic profile of the optical trap, the polariton condensate redistributes itself in simple harmonic oscillator states, forming an analog of the gravity pendulum. We observed the coexistence of two harmonic oscillator modes in a single trap, which were confirmed to be confined modes connected by longitudinal optical (LO) phonons using Raman spectroscopy. Clear features of mode competition behaviors were observed for these two harmonic oscillators when the injection rate of polaritons was varied. The observed mode competition was successfully simulated by a three-level rate equation model. In addition, as a result of the bosonic stimulation in the trap region, up to ∼88% of the injected polaritons were successfully trapped when polariton lasing takes place.

Realization of an all-optically controlled dynamic superlattice for exciton-polaritons.

Exciton-polaritons, formed by the strong coupling between excitons and cavity-confined photons, are the building blocks of polaritonic devices. In this work, we report experimental realization of an all-optically controlled dynamic superlattice for polaritons working in the ultraviolet wavelength range at room temperature. The optical superlattice was realized on a one-dimensional (1D) ZnO microrod using an array of periodically arranged laser spots. Polaritonic mini-band features were clearly observed by both momentum- and real-space imaging spectroscopy. By controlling the periodicity of the laser spots, we demonstrated that the band structures of polaritons can be well controlled by external lasers. Theoretically, by extending the Kronig-Penney model to the polariton system, we calculated the polaritonic mini-bands and found it to be in good agreement with our experimental observations. By imaging the polariton flow in real space, the lifetime of polaritons and their relationship with their exitonic fractions were also extracted. The polaritonic superlattices demonstrated in this work are fully reconfigurable and optically controlled, and our results could thus stimulate the development of polaritonic all-optical devices.

Relative ordering between bright and dark excitons in single-walled carbon nanotubes.

The ordering and relative energy splitting between bright and dark excitons are critical to the optical properties of single-walled carbon nanotubes (SWNTs), as they eventually determine the radiative and non-radiative recombination processes of generated carriers. In this work, we report systematic high-field magneto-optical study on the relative ordering between bright and dark excitons in SWNTs. We identified the relative energy position of the dark exciton unambiguously by brightening it in ultra-high magnetic field. The bright-dark excitonic ordering was found to depend not only on the tube structure, but also on the type of transitions. For the 1(st) sub-band transition, the bright exciton appears to be higher in energy than its dark counterpart for any chiral species and is robust against environmental effect. While for the 2(nd) sub-band, their relative ordering was found to be chirality-sensitive: the bright exciton can be either higher or lower than the dark one, depending on the specific nanotube structures. These findings provide new clues for engineering the optical and electronic properties of SWNTs.

Electrically pumped waveguide lasing from ZnO nanowires.

Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods.

Realization of anisotropic diamagnetic kepler problem in a solid state environment.

The anisotropic diamagnetic Kepler problem (ADKP) is realized experimentally by the orbital electrons of a P donor in Si under magnetic fields. The interference of electron wave packets which leads to quasi-Landau resonances (QLR) were observed. Applying the closed-orbit theory to an anisotropic solid state environment, we have identified orbits responsible for the QLR manifesting the quantum chaotic behavior in Rydberg atoms. The excellent consistency between the measured spectra and theoretical calculation provides unambiguous evidence of quantum chaotic dynamics of electrons in the ADKP.