Phonon-assisted resonant tunneling through a triple-quantum-dot: a phonon-signal detector

We study the effect of electron-phonon interaction on current and zero-frequency shot noise in resonant tunneling through a series triple-quantum-dot coupling to a local phonon mode by means of a nonperturbative mapping technique along with the Green function formulation. By fixing the energy difference between the first two quantum dots to be equal to phonon frequency and sweeping the level of the third quantum dot, we find a largely enhanced current spectrum due to phonon effect, and in particular we predict current peaks corresponding to phonon-absorption and -emission assisted resonant tunneling processes, which shows that this system can be acted as a sensitive phonon-signal detector or as a cascade phonon generator.Comment: 3 pages, 3 figure

Optimal limits of cavity optomechanical cooling in the strong coupling regime

Laser cooling of mesoscopic mechanical resonators is of great interest for both fundamental studies and practical applications. We provide a general framework to describe the cavity-assisted backaction cooling in the strong coupling regime. By studying the cooling dynamics, we find that the temporal evolution of mean phonon number oscillates as a function of the optomechanical coupling strength depending on frequency mixing. The further analytical result reveals that the optimal cooling limit is obtained when the system eigenmodes satisfy the frequency matching condition. The reduced instantaneous-state cooling limits with dynamic dissipative cooling approach are also presented. Our study provides a guideline for optimizing the backaction cooling of mesoscopic mechanical resonators in the strong coupling regime.Comment: 8 pages, 6 figure

Realization of broadband index-near-zero modes in nonreciprocal magneto-optical heterostructures

Epsilon-near-zero (ENZ) metamaterial with the relative permittivity approaching zero has been a hot research subject in the past decades. The wave in the ENZ region has infinite phase velocity ($v=1/\sqrt{\varepsilon\mu}$), whereas it cannot efficiently travel into the other devices or air due to the impedance mismatch or near-zero group velocity. In this paper, we demonstrate that the tunable index-near-zero (INZ) modes with vanishing wavenumbers ($k=0$) and nonzero group velocities ($v_\mathrm{g} \neq 0$) can be achieved in nonreciprocal magneto-optical systems. This kind of INZ modes has been experimentally demonstrated in the photonic crystals at Dirac point frequencies and that impedance-matching effect has been observed as well. Our theoretical analysis reveals that the INZ modes exhibit tunability when changing the parameter of the one-way (nonreciprocal) waveguides. Moreover, owing to the zero-phase-shift characteristic and decreasing $v_\mathrm{g}$ of the INZ modes, several perfect optical buffers (POBs) are proposed in the microwave and terahertz regimes. The theoretical results are further verified by the numerical simulations performed by the finite element method. Our findings may open the new avenues for research in the areas of ultra -strong or -fast nonlinearity, perfect cloaking, high-resolution holographic imaging and wireless communications

Accurate Direct Measurements of Far-Field Thermal Infrared Emission and its Dynamics

Accurate direct measurements of far-field thermal infrared emission become increasingly important because conventional methods, relying on indirect assessments, such as reflectance/transmittance, are inaccurate or even unfeasible to characterize state-of-art devices with novel spectra, directionalities, and polarizations. The direct collection of the far-field emission from these tiny devices is also challenging because of their shrinking footprints and uncontrollable radiation noises from their surroundings. Here, we demonstrate a microscopic lock-in FTIR system that realizes significant improvement in signal-to-noise ratio (SNR) by combining a microscope and a lock-in amplifier with an FTIR. The lock-in FTIR is ultrasensitive, with a specific detectivity 10^6 times higher than commercial ones, to overcome the optical loss and background noise during the emission light collection. Based on an analytical model of the signal detection process, we also explore the combination of modulated Joule heating and global heating to fulfill the potential of our system for noise reduction. Our findings show that, compared to previous studies, more than 3 times lower temperatures are sufficient to generate a measurable signal. Under a heating temperature of around 125 {\deg}C, we can achieve an SNR of about 23.7, which is far above the true-signal-threshold (SNR of about 3.0). Furthermore, the system can respond fast enough (up to 175kHz) to record spectral-resolved dynamics of microdevices in the frequency domain. The measurable frequency range can be extended up to MHz or even GHz level by a high-speed circuit model. We believe the system together with the analytical signal processing can be beneficial for next-generation thermal infrared material and device exploration, boosting the applications in lighting, sensing, imaging, and energy harvesting on a small scale.Comment: 19 pages, 4 figure

Additive manufacturing of monolithic microwave dielectric ceramic filters via digital light processing

Microwave dielectric ceramics are employed in filters as electromagnetic wave propagation media. Based on additive manufacturing (AM) techniques, microwave dielectric ceramic filters with complex and precise structures can be fabricated to satisfy filtering requirements. Digital light processing (DLP) is a promising AM technique that is capable of producing filters with high accuracy and efficiency. In this paper, monolithic filters made from Al2O3 and TiO2, with a molar ratio of 9:1 (0.9 Al2O3-0.1 TiO2), were fabricated by DLP. The difference in the dielectric properties between the as-sintered and post-annealed samples at different temperatures was studied. The experimental results showed that when sintered at 1550 °C for 2 h and post annealed at 1000 °C for 5 h, 0.9 Al2O3-0.1 TiO2 exhibited excellent dielectric properties: εr = 12.4, Q × f = 111,000 GHz, τf = +1.2 ppm/°C. After comparing the measured results with the simulated ones in the passband from 6.5 to 9 GHz, it was concluded that the insertion loss (IL) and return loss (RL) of the filter meet the design requirements

Effect of renin-angiotensin-aldosterone system inhibitors on survival outcomes in cancer patients treated with immune checkpoint inhibitors: a systematic review and meta-analysis

BackgroundEffect of renin-angiotensin-aldosterone system inhibitors (RAASIs) in combination with immune checkpoint inhibitors (ICIs) on prognoses in cancer patients remains controversial. This study systematically evaluated the effect of RAASIs on survival outcomes in cancer patients receiving ICIs treatment and provided an evidence-based reference for the rational use of RAASIs and ICIs combination therapy in clinical practice.MethodsStudies evaluating the prognosis of RAASIs-used versus RAASIs-free in cancer patients receiving ICIs treatment from inception to 1 November 2022 were retrieved by searching PubMed, Cochrane Library, Web of Science, Embase, and major conference proceedings. Studies in English reporting hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS) and/or progression-free survival (PFS) were included. Statistical analyses were conducted using the software Stata 17.0.ResultsA total of 12 studies containing 11739 patients were included, comprising ~4861 patients in the RAASIs-used and ICIs-treated group and ~6878 patients in RAASIs-free and ICIs-treated group. The pooled HR was 0.85 (95%CI, 0.75–0.96; P = 0.009) for OS and 0.91 (95%CI, 0.76–1.09; P = 0.296) for PFS, indicating a positive effect of RAASIs concomitant with ICIs on cancer patients. This effect was observed especially in patients with urothelial carcinoma (HR, 0.53; 95%CI, 0.31-0.89; P = 0.018) and renal cell carcinoma (HR, 0.56; 95%CI, 0.37-0.84; P = 0.005) on OS.ConclusionConcomitant use of RAASIs and ICIs enhanced the efficacy of ICIs and this combination regimen was associated with significantly improved OS and a trend towards better PFS. RAASIs can be considered as adjuvant drugs when hypertensive patients receive ICIs treatment. Our results provide an evidence-based reference for the rational use of the RAASIs and ICIs combination therapy to improve the efficacy of ICIs in clinical practice.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD42022372636; https://inplasy.com/, identifier INPLASY2022110136