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We investigate the adiabatic evolution of light in nonlinear waveguide couplers via resonance-locked inverse engineering based on stimulated Raman adiabatic passage (STIRAP). The longitudinal varying propagation coefficients of the waveguides are designed to eliminate dynamically the nonlinear effect, which induce the non-adiabatic oscillations. We show that different light evolutions such as complete light transfer, light split and light return can be realized adiabatically with appropriate choices of the detunings even in the nonlinear regime. The features open new opportunities for the realization of all-optical nonlinear devices with high fidelity in integrated optics.

We investigate the charging process of quantum battery (QB) systems in an extended Dicke model with both atomic interactions and an external driving field. We focus on the effects of the atomic interaction and the external driving field on the charging performance of QB and find that the maximum stored energy of QB has a critical phenomenon. We analyze the critical behavior and obtain the analytical expression of the critical atomic interaction. The dependence of the maximum stored energy, the energy quantum fluctuations and the maximum charging power on the number $N$ of the two-level systems are also discussed. In particular, for the maximum charging power, we obtain the quantum advantage of the QB, which approximately satisfies a superlinear scaling relation $P_{max}\propto N^{\alpha}$, where scaling exponent $\alpha$ varies with the number $N$ of the two-level systems. In the ultra-strong coupling regime, the atomic interaction can lead to a faster battery charging, and the quantum advantage $\alpha = 1.88$ can be achieved. While in the deep-strong coupling regime, the quantum advantage of the QB's maximum charging power is the same as that of the Dicke QB, i.e., $\alpha=1.5$.

We propose a cavity-Heisenberg spin chain (CHS) quantum battery (QB) with the long-range interactions and investigate its charging process. The performance of the CHS QB is substantially improved compared to the Heisenberg spin chain (HS) QB. When the number of spins $N \gg 1$, the quantum advantage $\alpha$ of the QB's maximum charging power can be obtained, which approximately satisfies a superlinear scaling relation $P_{max} \propto N^{\alpha}$. For the CHS QB, $\alpha$ can reach and even exceed $1.5$, while the HS QB can only reach about $\alpha=0.75$. We find that the maximum stored energy of the CHS QB has a critical phenomenon. By analyzing the Wigner function, von Neumann entropy, and logarithmic negativity, we demonstrate that entanglement can be a necessary ingredient for QB to store more energy, but not sufficient.

Bose-Einstein condensation (BEC) trapped in quadruple-well potential with complex coupling provides a great useful platform in theoretical and experimental researches. Utilizing analytical and numerical methods, we investigate tunneling dynamics and the reciprocity of quantum transport of BEC in quadruple-well potential formed by the laser-assisted transition. According to the investigation, the tunneling dynamics of BEC in this system is independent of dissipation and complex coupling between wells caused by Raman coupling laser. By adjusting the coupling phase, the coherent destruction of tunneling can be observed. Meanwhile, this system provides an applicable proposal for reciprocal quantum switch by using the tunneling dynamics of BEC.

The spin-orbit-coupled (SOC) ultracold atomic gases provide unique opportunities for exploring exotic quantum phases and introduce new capabilities into the quantum simulation. In this paper, we study the coherent control of spin states in SOC Bose–Einstein condensate (BEC) by exploiting and implementing the general concept of Landau–Zener–Stueckelberg–Majorana (LZSM) interference. For a SOC BEC, the Landau–Zener (LZ) transition between the dressed eigenlevels occurs as the BEC is accelerated through the SOC-avoided crossing, which corresponds to a breakdown of the spin momentum locking. In our scheme, two LZ pulses are separated by an intermediate holding period of variable duration. The nice LZSM interference patterns can be generated and controlled by controlling several parameters, corresponding to coherent control of the spin state of the SOC BEC. In particular, the destructive and constructive patterns of LZSM interference are observed and well explained through analytical analysis. Our results suggest a potential application of the LZSM interferometry in calibrating the spin states of a SOC BEC.

Quantum batteries are energy storage devices that satisfy quantum mechanical principles. How to improve the battery's performance such as stored energy and power is a crucial element in the quantum battery. Here, we investigate the charging and discharging dynamics of a three-level counterdiabatic stimulated Raman adiabatic passage quantum battery via shortcuts to adiabaticity, which can compensate for undesired transitions to realize a fast adiabatic evolution through the application of an additional control field to an initial Hamiltonian. The scheme can significantly speed up the charging and discharging processes of a three-level quantum battery and obtain more stored energy and higher power compared with the original stimulated Raman adiabatic passage. We explore the effect of both the amplitude and the delay time of driving fields on the performances of the quantum battery. Possible experimental implementation in superconducting circuit and nitrogen-vacancy center is also discussed.

A quantum battery is a temporary energy-storage system. We constructed the quantum battery model of an N-spin chain with nearest-neighbor hopping interaction and investigated the charging process of the quantum battery. We obtained the maximum energy in the quantum battery charged by a coherent cavity driving field or a thermal heat bath. We confirmed that for a finite-length spin chain, thermal charging results in a nonzero ergotropy, contradicting a previous result: that an incoherent heat source cannot charge a single-spin quantum battery. The nearest-neighbor hopping interaction induces energy band splitting, which enhances the energy storage and the ergotropy of the quantum battery. We found a critical point in the energy and ergotropy resulting from the ground-state quantum phase transition, after which the energy significantly enhance. Finally, we also found that disorder increased the energy of the quantum battery.

We investigate high-fidelity multiple beam splitting in Hermitian and non-Hermitian symmetric coupled waveguides with one input and 2N output waveguide channels. In Hermitian systems, we realize adiabatically light splitting in resonant case based on the stimulated Raman adiabatic passage (STIRAP) and arbitrary proportion from the middle waveguide to outer waveguides in propagation coefficients mismatch case using shortcuts to adiabaticity (STA) technique. In non-Hermitian systems with even waveguides being dissipative, the compact and robust beam splitting can be achieved by eliminating the non-adiabatic coupling via the non-Hermitian STA method. We further verify the feasibility of our theoretical predictions by means of the beam propagation method (BPM). The suggested multiple beam splitters open new opportunities for the realization of on-chip high-bandwidth photonics with high fidelity in short distances., Accepted

Accurate segmentation of different sub-regions of gliomas including peritumoral edema, necrotic core, enhancing and non-enhancing tumor core from multimodal MRI scans has important clinical relevance in diagnosis, prognosis and treatment of brain tumors. However, due to the highly heterogeneous appearance and shape, segmentation of the sub-regions is very challenging. Recent development using deep learning models has proved its effectiveness in the past several brain segmentation challenges as well as other semantic and medical image segmentation problems. Most models in brain tumor segmentation use a 2D/3D patch to predict the class label for the center voxel and variant patch sizes and scales are used to improve the model performance. However, it has low computation efficiency and also has limited receptive field. U-Net is a widely used network structure for end-to-end segmentation and can be used on the entire image or extracted patches to provide classification labels over the entire input voxels so that it is more efficient and expect to yield better performance with larger input size. In this paper we developed a deep-learning-based segmentation method using an ensemble of 3D U-Nets with different hyper-parameters. Furthermore, we estimated the uncertainty of the segmentation from the probabilistic outputs of each network and studied the correlation between the uncertainty and the performances. Preliminary results showed effectiveness of the segmentation model. Finally, we developed a linear model for survival prediction using extracted imaging and non-imaging features, which, despite the simplicity, can effectively reduce overfitting and regression errors.

We investigate the Demkov–Kunike transition in a nonlinear two-level system. We find that nonlinearity can dramatically affect the transition dynamics. We show the asymmetry of transition probability in different initial modes. For the weak interaction, the transition probability could be quickly stabilized at 100% in the initial state $$\psi _{1}$$ and could be optionally obtained from zero to 100% over a very wide range of external parameters in the initial state $$\psi _{2}$$ . For the strong interaction, the quantum transition of the two states could be completely blocked. In the adiabatic case, for different initial modes we analyze the asymmetry of transition probability by the eigenenergy level structure of the system. We also show the influence of static detuning on transition probability. Possible applications of our theory to actual physical systems are discussed.

We investigate the creation of stable heteronuclear polyatomic molecules based on the three-body and higher order Efimov state via a generalized stimulated Raman adiabatic passage scheme. Within the mean-field approximation, we establish the multi-path conversion models and derive the dark state solutions. The multi-path atom–polymer conversion dynamics and interference effect are studied. We show that the multi-path constructive interference permits higher conversion efficiency, resulting in a state that is closer to the ideal dark state solutions. The effects on the conversion efficiency of the single-photon detuning, the strength of the Rabi pulse, the spontaneous emission from intermediate states and the interaction between the particles are also discussed. Our results not only include the previous ultracold molecule formation techniques, such as the single-path polyatomic molecule, double-path pentamer and triple-path trimer, but also open a possible route for the multi-path formation of more complex polyatomic molecules.

The production of ultracold molecules is one of the most exciting topics in the field of ultracold physics, which has important theoretical values and broad application prospects. We propose an ultracold atom-molecule conversion model in a closed-loop three-level system based on three available transitions, in which the population dynamics depends on three coupling fields and global phase. We investigate the atom-molecule conversion dynamics in the closed-loop three-level system. We show the distribution of population on excited molecular state and ground molecular state with arbitrary proportion can be achieved by adjusting pulse amplitudes of the external fields properly. We also explore the effects of time delay, pulse width and global phase on the conversion process. The results show that, by tuning these parameters, the stable atom-molecule conversion with arbitrary proportion can be realized.