Autonomous frequency locking for zero-offset microcomb

The stabilization of optical frequency comb conventionally relies on active electronic feedback loops and stable frequency references. Here, we propose a new approach for autonomous frequency locking (AFL) to generate a zero-offset frequency comb based on cooperative nonlinear optical processes in a microcavity. In a simplified few-mode system, AFL enables the concept of fractional harmonic generation as a zero-offset multi-laser reference for measuring the carrier envelope offset frequency ($f_{\mathrm{ceo}}$) of frequency combs spanning less than one octave, such as 1/3 octave. Combining with Kerr comb generation in a microcaivity, AFL is further applied to directly generate zero-$f_{\mathrm{ceo}}$ soliton comb that is robust against fluctuations in pump laser and cavity resonances. Numerical simulations validate the AFL scheme, showing good agreement with analytical prediction of the locking condition. This work presents a new pathway for exploring novel frequency locking mechanisms and technologies using integrated photonic devices, and also appeals further investigations of cooperative nonlinear optics processes in microcavities

Supplement 1: Hybrid-cascaded generation of tripartite telecom photons using an atomic ensemble and a nonlinear waveguide

Supplemental Document Originally published in Optica on 20 July 2015 (optica-2-7-642

Coupling Two Distant Double Quantum Dots with a Microwave Resonator

We fabricated a hybrid device with two distant graphene double quantum dots (DQDs) and a microwave resonator. A nonlinear response is observed in the resonator reflection amplitude when the two DQDs are jointly tuned to the vicinity of the degeneracy points. This observation can be well fitted by the Tavis–Cummings (T–C) model which describes two two-level systems coupling with one photonic field. Furthermore, the correlation between the DC currents in the two DQDs is studied. A nonzero cross-current correlation is observed which has been theoretically predicted to be an important sign of nonlocal coupling between two distant systems. Our results explore T–C physics in electronic transport and also contribute to the study of nonlocal transport and future implementations of remote electronic entanglement

Doubly and Triply Coupled Nanowire Antennas

Nanoantenna is one of the most important optical components for light harvesting. In this study, we show experimental evidence of interactions between coupled nanowires by comparing the fluorescence properties of quantum dots on single nanowire as well as doubly and triply coupled nanowire arrays. Because of the localized surface plasmon mode, there are strong polarization dependences in this photon–plasmon–exciton conversion process. It is interesting that both the polarization-dependent enhancement and the degree of fluorescence polarization are more pronounced for triply coupled nanowires than that of doubly coupled nanowire, while the case of single nanowire is weakest. Our theoretical analysis indicates the above phenomena can be ascribed to the coupled plasmon from the nanowire antennas. Our investigations demonstrate a potential method to control the polarization of emitters using coupled nanowire arrays

Learning imaging mechanism directly from optical microscopy observations

Optical microscopy image plays an important role in scientific research through the direct visualization of the nanoworld, where the imaging mechanism is described as the convolution of the point spread function (PSF) and emitters. Based on a priori knowledge of the PSF or equivalent PSF, it is possible to achieve more precise exploration of the nanoworld. However, it is an outstanding challenge to directly extract the PSF from microscopy images. Here, with the help of self-supervised learning, we propose a physics-informed masked autoencoder (PiMAE) that enables a learnable estimation of the PSF and emitters directly from the raw microscopy images. We demonstrate our method in synthetic data and real-world experiments with significant accuracy and noise robustness. PiMAE outperforms DeepSTORM and the Richardson-Lucy algorithm in synthetic data tasks with an average improvement of 19.6\% and 50.7\% (35 tasks), respectively, as measured by the normalized root mean square error (NRMSE) metric. This is achieved without prior knowledge of the PSF, in contrast to the supervised approach used by DeepSTORM and the known PSF assumption in the Richardson-Lucy algorithm. Our method, PiMAE, provides a feasible scheme for achieving the hidden imaging mechanism in optical microscopy and has the potential to learn hidden mechanisms in many more systems

Coupling a Germanium Hut Wire Hole Quantum Dot to a Superconducting Microwave Resonator

Realizing a strong coupling between spin and resonator is an important issue for scalable quantum computation in semiconductor systems. Benefiting from the advantages of a strong spin–orbit coupling strength and long coherence time, the Ge hut wire, which is proposed to be site-controlled grown for scalability, is considered to be a promising candidate to achieve this goal. Here we present a hybrid architecture in which an on-chip superconducting microwave resonator is coupled to the holes in a Ge quantum dot. The charge stability diagram can be obtained from the amplitude and phase responses of the resonator independently from the DC transport measurement. Furthermore, we estimate the hole-resonator coupling rate of <i>g</i>_c/2π = 148 MHz in the single quantum dot-resonator system and estimate the spin–resonator coupling rate <i>g</i>_s/2π to be in the range 2–4 MHz. We anticipate that strong coupling between hole spins and microwave photons in a Ge hut wire is feasible with optimized schemes in the future

Theory Simulation Of the Fine-Grained Uncertainty Relation

<div>The supplemental material shows the numerical simulations for the cases of different states which are determined by the parameters, c1, c2 and c3.</div

Supplement 1: Experimental detection of polarization-frequency quantum correlations in a photonic quantum channel by local operations

Supplemental document Originally published in Optica on 20 December 2015 (optica-2-12-1014