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Optimized nonadiabatic holonomic quantum computation based on Förster resonance in Rydberg atoms
Shuai Liu, Jun-Hui Shen, Ri-Hua Zheng, Yi-Hao Kang, Zhi-Cheng Shi, Jie Song, Yan Xia
Front. Phys. . 2022, 17 (2 ): 21502-.
https://doi.org/10.1007/s11467-021-1108-3
In this paper, we propose a scheme for implementing the nonadiabatic holonomic quantum computation (NHQC+) of two Rydberg atoms by using invariant-based reverse engineering (IBRE). The scheme is based on Förster resonance induced by strong dipole–dipole interaction between two Rydberg atoms, which provides a selective coupling mechanism to simply the dynamics of system. Moreover, for improving the fidelity of the scheme, the optimal control method is introduced to enhance the gate robustness against systematic errors. Numerical simulations show the scheme is robust against the random noise in control fields, the deviation of dipole–dipole interaction, the Förster defect, and the spontaneous emission of atoms. Therefore, the scheme may provide some useful perspectives for the realization of quantum computation with Rydberg atoms.
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Unselective ground-state blockade of Rydberg atoms for implementing quantum gates
Jin-Lei Wu, Yan Wang, Jin-Xuan Han, Shi-Lei Su, Yan Xia, Yongyuan Jiang, Jie Song
Front. Phys. . 2022, 17 (2 ): 22501-.
https://doi.org/10.1007/s11467-021-1104-7
A dynamics regime of Rydberg atoms, unselective ground-state blockade (UGSB), is proposed in the context of Rydberg antiblockade (RAB), where the evolution of two atoms is suppressed when they populate in an identical ground state. UGSB is used to implement a SWAP gate in one step without individual addressing of atoms. Aiming at circumventing common issues in RAB-based gates including atomic decay, Doppler dephasing, and fluctuations in the interatomic coupling strength, we modify the RAB condition to achieve a dynamical SWAP gate whose robustness is much greater than that of the nonadiabatic holonomic one in the conventional RAB regime. In addition, on the basis of the proposed SWAP gates, we further investigate the implementation of a three-atom Fredkin gate by combining Rydberg blockade and RAB. The present work may facilitate to implement the RAB-based gates of strongly coupled atoms in experiment.
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Experimental investigation of light storage of diffraction-free and quasi-diffraction-free beams in hot atomic gas cell
Chengyuan Wang, Yun Chen, Zibin Jiang, Ya Yu, Mingtao Cao, Dong Wei, Hong Gao, Fuli Li
Front. Phys. . 2022, 17 (2 ): 22503-.
https://doi.org/10.1007/s11467-021-1113-6
In this article we report on the experimental investigation of light storage for several types of diffractionfree beams (Bessel and Airy beams) and quasi-diffraction-free beams by utilizing electromagnetically induced transparency (EIT) technique in a hot atomic gas cell. The experimental results show that the diffraction-free and quasi-diffraction-free beams have better storage performances when compared with ordinary images possessing similar spatial profiles. Meanwhile, the Bessel beams and the quasidiffraction-free images are able to maintain their spatial profiles with a long storage time while the sidelobes of the Airy beam are gradually depleted with the increment of the storage time. We quantitatively analyze the storage results and give physical explanations behind these phenomena. Furthermore, the self-healing of the retrieved diffraction-free beams is verified, signifying that their characteristics preserve well after storage.
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Wide and fast-frequency tuning for a stabilized diode laser
Yunfei Wang, Yuqing Li, Jizhou Wu, Wenliang Liu, Peng Li, Yongming Fu, Jie Ma, Liantuan Xiao, Suotang Jia
Front. Phys. . 2022, 17 (2 ): 22505-.
https://doi.org/10.1007/s11467-021-1117-2
External-cavity diode laser (ECDL) has important applications in many fundamental and applied researches. Here we report a method to fast and widely tune the frequency of a stabilized ECDL. The beat frequency between the ECDL and a frequency-locked reference laser is identified by the voltage-controlled oscillator contained in a phase detector, whose output voltage is subtracted from the flexibly controlled PC signal to generate an error signal for stabilizing the ECDL. The output frequency of the stabilized ECDL can be shifted at a short characteristic time of ~ 150 μs within a range of ~ 620 MHz. The wide and fast-frequency tuning achieved by our method is compared with other previous works. We demonstrated the performance of our method by the efficient sub-Doppler cooling of Cs atoms with the temperature as low as 6 μK.
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Progress of microscopic thermoelectric effects studied by micro- and nano-thermometric techniques
Xue Gong, Ruijie Qian, Huanyi Xue, Weikang Lu, Zhenghua An
Front. Phys. . 2022, 17 (2 ): 23201-.
https://doi.org/10.1007/s11467-021-1101-x
Heat dissipation is one of the most serious problems in modern integrated electronics with the continuously decreasing devices size. Large portion of the consumed power is inevitably dissipated in the form of waste heat which not only restricts the device energy-efficiency performance itself, but also leads to severe environment problems and energy crisis. Thermoelectric Seebeck effect is a green energy-recycling method, while thermoelectric Peltier effect can be employed for heat management by actively cooling overheated devices, where passive cooling by heat conduction is not sufficiently enough. However, the technological applications of thermoelectricity are limited so far by their very low conversion efficiencies and lack of deep understanding of thermoelectricity in microscopic levels. Probing and managing the thermoelectricity is therefore fundamentally important particularly in nanoscale. In this short review, we will first briefly introduce the microscopic techniques for studying nanoscale thermoelectricity, focusing mainly on scanning thermal microscopy (SThM). SThM is a powerful tool for mapping the lattice heat with nanometer spatial resolution and hence detecting the nanoscale thermal transport and dissipation processes. Then we will review recent experiments utilizing these techniques to investigate thermoelectricity in various nanomaterial systems including both (two-material) heterojunctions and (single-material) homojunctions with tailored Seebeck coefficients, and also spin Seebeck and Peltier effects in magnetic materials. Next, we will provide a perspective on the promising applications of our recently developed Scanning Noise Microscope (SNoiM) for directly probing the non-equilibrium transporting hot charges (instead of lattice heat) in thermoelectric devices. SNoiM together with SThM are expected to be able to provide more complete and comprehensive understanding to the microscopic mechanisms in thermoelectrics. Finally, we make a conclusion and outlook on the future development of microscopic studies in thermoelectrics.
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Thermal conductivity of micro/nano-porous polymers: Prediction models and applications
Haiyan Yu, Haochun Zhang, Jinchuan Zhao, Jing Liu, Xinlin Xia, Xiaohu Wu
Front. Phys. . 2022, 17 (2 ): 23202-.
https://doi.org/10.1007/s11467-021-1107-4
Micro/nano-porous polymeric material is considered a unique industrial material due to its extremely low thermal conductivity, low density, and high surface area. Therefore, it is necessary to establish an accurate thermal conductivity prediction model suiting their applicable conditions and provide a theoretical basis for expanding their applications. In this work, the development of the calculation model of equivalent thermal conductivity of micro/nano-porous polymeric materials in recent years is summarized. Firstly, it reviews the process of establishing the overall equivalent thermal conductivity calculation model for micro/nanoporous polymers. Then, the predicted calculation models of thermal conductivity are introduced separately according to the conductive and radiative thermal conductivity models. In addition, the thermal conduction part is divided into the gaseous thermal conductivity model, solid thermal conductivity model and gas–solid coupling model. Finally, it is concluded that, compared with other porous materials, there are few studies on heat transfer of micro/ nanoporous polymers, especially on the particular heat transfer mechanisms such as scale effects at the micro/nanoscale. In particular, the following aspects of porous polymers still need to be further studied: micro scaled thermal radiation, heat transfer characteristics of particular morphologies at the nanoscales, heat transfer mechanism and impact factors of micro/nanoporous polymers. Such studies would provide a more accurate prediction of thermal conductivity and a broader application in energy conversion and storage systems.
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Structure search of two-dimensional systems using CALYPSO methodology
Pengyue Gao, Bo Gao, Shaohua Lu, Hanyu Liu, Jian Lv, Yanchao Wang, Yanming Ma
Front. Phys. . 2022, 17 (2 ): 23203-.
https://doi.org/10.1007/s11467-021-1109-2
The dimensionality of structures allows materials to be classified into zero-, one-, two-, and threedimensional systems. Two-dimensional (2D) systems have attracted a great deal of attention and typically include surfaces, interfaces, and layered materials. Due to their varied properties, 2D systems hold promise for applications such as electronics, optoelectronics, magnetronics, and valleytronics. The design of 2D systems is an area of intensive research because of the rapid development of ab initio structure-searching methods. In this paper, we highlight recent research progress on accelerating the design of 2D systems using the CALYPSO methodology. Challenges and perspectives for future developments in 2D structure prediction methods are also presented.
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Emerging of two-dimensional materials in novel memristor
Zhican Zhou, Fengyou Yang, Shu Wang, Lei Wang, Xiaofeng Wang, Cong Wang, Yong Xie, Qian Liu
Front. Phys. . 2022, 17 (2 ): 23204-.
https://doi.org/10.1007/s11467-021-1114-5
The rapid development of big-data analytics (BDA), internet of things (IoT) and artificial intelligent Technology (AI) demand outstanding electronic devices and systems with faster processing speed, lower power consumption, and smarter computer architecture. Memristor, as a promising Non-Volatile Memory (NVM) device, can effectively mimic biological synapse, and has been widely studied in recent years. The appearance and development of two-dimensional materials (2D material) accelerate and boost the progress of memristor systems owing to a bunch of the particularity of 2D material compared to conventional transition metal oxides (TMOs), therefore, 2D material-based memristors are called as new-generation intelligent memristors. In this review, the memristive (resistive switching) phenomena and the development of new-generation memristors are demonstrated involving grapheme (GR), transition-metal dichalcogenides (TMDs) and hexagonal boron nitride (h -BN) based memristors. Moreover, the related progress of memristive mechanisms is remarked.
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Strain induced topological transitions in twisted double bilayer graphene
Guoyu Luo, Xinyu Lv, Lu Wen, Zhiqiang Li, Zhenbing Dai
Front. Phys. . 2022, 17 (2 ): 23502-.
https://doi.org/10.1007/s11467-021-1146-x
We theoretically study the band structures and the valley Chern numbers of the AB–AB and AB–BA stacked twisted double bilayer graphene under heterostrain effect. In the absence of heterostrain, due to the constrains by the spatial symmetries, the central two flat bands of the AB–AB are topological trivial bands, while in the AB–BA they have a finite Chern number. The heterostrain breaks all the point group symmetries and the constrains are lifted, hence the topological properties of the two arrangements can be tuned by different strain magnitudes ϵ and directions ϕ . The heterostrain has dissimilar impacts on the Chern numbers of the AB–AB and AB–BA, owing to their different band gaps, and these gaps can be modified by a vertical electric field. Our results show that the topological transitions for both arrangements occur in the ϵ range of 0.1%–0.4%, which can be realized in the graphene-based sample.
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16 articles