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Effect of polarization force on the Jeans instability in collisional dusty plasmas

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Plasma Science and Technology 2018年第3期20卷 39-42页

作者： A ABBASI M R RASHIDIAN VAZIRI Photonics and quantum technologies Research School Nuclear Science & Technology Research Institute

The Jeans instability in collisional dusty plasmas has been analytically investigated by considering the polarization force effect. Instabilities due to dust-neutral and ion-neutral drags can occur in electrostatic waves of collisional dusty plasmas with self-gravitating particles. In this study, the effect of gravitational force on heavy dust particles is considered in tandem with both the polarization and electrostatic forces. The theoretical framework has been developed and the dispersion relation and instability growth rate have been derived, assuming the plane wave approximation. The derived instability growth rate shows that, in collisional dusty plasmas, the Jeans instability strongly depends on the magnitude of the polarization force.

关键词： dusty plasmas Jeans instability instabilities in plasmas

Magnetic lattices for ultracold atoms and degenerate quantum gases

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Science Bulletin 2016年第14期61卷 1097-1106页

作者： Yibo Wang Prince Surendran Smitha Jose Tien Tran Ivan Herrera Shannon Whitlock Russell Mc Lean Andrei Sidorov Peter Hannaford Centre for quantum and Optical Science Swinburne University of Technology Dodd-Walls Centre for Photonic and quantum technologies Department of Physics University of Auckland Physikalisches Institut Universitt Heidelberg

We review recent developments in the use of magnetic lattices as a complementary tool to optical lattices for trapping periodic arrays of ultracold atoms and degenerate quantum gases. Recent advances include the realisation of Bose–Einstein condensation in multiple sites of a magnetic lattice of one-dimensional microtraps, the trapping of ultracold atoms in square and triangular magnetic lattices,and the fabrication of magnetic lattice structures with submicron period suitable for quantum tunnelling ***, we describe a proposal to utilise long-range interacting Rydberg atoms in a large spacing magnetic lattice to create interactions between atoms on neighbouring sites.

关键词： Magnetic lattices Ultracold atoms Degenerate quantum gases - quantum simulation

quantum computation with surface-state electrons by rapid population passages

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1718-1724页

作者： SHI Xuan WEI LianFu OH Choo Hiap quantum Optoelectronics Laboratory School of Physics and Technology Southwest Jiaotong University Centre for quantum technologies and Department of Physics National University of Singapore State Key Laboratory of Optoelectronic Materials and technologies School of Physics Science and Engineering Sun Yet-sen University

quantum computation requires coherently controlling the evolutions of ***,these manipulations are implemented by precisely designing the durations(such as theπ-pulses)of the Rabi oscillations and tunable interbit *** this requirement,herein we show that the desired population transfers between the logic states can be deterministically realized(and thus quantum computation could be implemented)both adiabatically and non-adiabatically,by performing the duration-insensitive quantum *** proposal is specifically demonstrated with the surface-state of electrons floating on the liquid helium,but could also be applied to the other artificially controllable systems for quantum computing.

关键词： quantum computation surface-state electrons rapid population passages

Stark-Chirped Rapid Adiabatic Passage in Presence of Dissipation for quantum Computation

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Communications in Theoretical Physics 2014年第2期61卷 235-240页

作者：石轩 C.H.Oh 韦联福 quantum Optoelectronics Laboratory School of Physics and Technology Southwest Jiaotong University Centre for quantum technologies and Department of Physics National University of Singapore State Key Laboratory of Optoelectronic Materials and technologies School of Physics Science and Engineering Sun Yet-sen University

Stark-chirped rapid adiabatic passage(SCRAP) is an important technique used for coherent quantum controls. In this paper we investigate how the practically-existing dissipation of the system influences on the efficiency of the passage, and thus the fidelities of the SCRAP-based quantum gates. With flux-biased Josephson qubits as a specifical example, our results show clearly that the efficiency of the logic gates implemented by SCRAP are robust against the weak dissipation. The influence due to the non-adiabtic transitions between the adiabatic passages is comparatively significantly small. Therefore, the SCRAP-based logic gates should be feasible for the realistic physical systems with noises.

关键词： adiabatic passage dissipation quantum computation

Optical forces on neutral atoms in the presence of fluctuating laser fields:numerical analysis

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Communications in Theoretical Physics 2023年第1期75卷 130-137页

作者： Forough Bozorgzadeh Masoud Yousefi Mohsen Akbari Physics Department College of SciencesShiraz UniversityShirazIran quantum Optics Group Iranian Center for Quantum Technologies(ICQT’s)TehranIran quantum Optics Lab Department of PhysicsKharazmi UniversityTehranIran

Doppler cooling of^(88)Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser *** a semi-classical approach,we show that the relevant physical quantities in the cooling process,such as optical forces,the damping coefficient,Doppler temperature,and atom number in the trap,are strongly affected by the laser amplitude and phase *** find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating *** implies an additional heating mechanism exists due to the laser ***,our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.

关键词： force of light laser cooling and trapping laser fluctuations magneto-optical trap(MOT) phase diffusion two-level atom

Continuous-Variable quantum Computation in Circuit QED

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Chinese Physics Letters 2023年第11期40卷 14-17页

作者： Xiaozhou Pan Pengtao Song Yvonne Y.Gao Centre for quantum technologies National University of SingaporeSingapore Department of Physics National University of SingaporeSingapore

quantum computation (QC) offers the promise of enhanced computational capabilities and drastic accelerations in solving complex tasks such as quantum chemistry^([1,2])and prime factorization.^([3])Various physical implementations for practical QC are being pursued across the academic and industrial research *** ones include trapped ions,^([4])nuclear spin,^([5]).

关键词： acceleration quantum quantum

Why quantum adiabatic computation and D-Wave computers are so attractive?

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Science Bulletin 2017年第11期62卷 741-742页

作者： Zhangqi Yin Zhaohui Wei Center for quantum Information Institute for Interdisciplinary Information SciencesTsinghua University Centre for quantum technologies National University of Singapore School of Physical and Mathematical Sciences Nanyang Technological University

Because of the possibility that improves our computational capability dramatically,in the past two decades quantum computation has been attracting more and more ***,in recent years remarkable progresses have been made for theoretical researches and experimental implementations in this area,which will probably bring us quantum computer able to beat

关键词：量子计算机绝热计算吸引力计算能力实验实现

Axis-symmetric Onsager clustered states of point vortices in a bounded domain

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Communications in Theoretical Physics 2023年第9期75卷 51-58页

作者： Yanqi Xiong Jiawen Chen Xiaoquan Yu Graduate School of China Academy of Engineering Physics Beijing 100193China Department of Physics Centre for Quantum Scienceand Dodd-Walls Centre for Photonic and Quantum TechnologiesUniversity of OtagoDunedinNew Zealand

We study axis-symmetric Onsager clustered states of a neutral point vortex system confined to a two-dimensional disc. Our analysis is based on the mean field of bounded point vortices in the microcanonical ensemble. The clustered vortex states are specified by the inverse temperature β and the rotation frequency ω, which are the conjugate variables of energy E and angular momentum L,respectively. The formation of the axis-symmetric clustered vortex states(azimuthal angle independent) involves the separating of vortices with opposite circulation and the clustering of vortices with the same circulation around the origin and edge. The state preserves SO(2) symmetry while breaking Z_2 symmetry. We find that, near the uniform state, the rotation-free clustered state(ω = 0) emerges at particular values of L^(2)/E and β. At large energies, we obtain asymptotically exact vortex density distributions, whose validity condition gives rise to the lower bound of β for the rotation-free states. Noticeably, the obtained vortex density distribution near the edge at large energies provides a novel exact vortex density distribution for the corresponding chiral vortex system.

关键词： vortex clusters negative temperature exact solutions quantum vortices

Experimental symmetric private information retrieval with measurement-device-independent quantum network

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Light(Science & Applications) 2022年第10期11卷 2399-2405页

作者： Chao Wang Wen Yu Kon Hong Jie Ng Charles C.-W.Lim Department of Electrical&Computer Engineering National University of SingaporeSingaporeSingapore Centre for quantum technologies National University of SingaporeSingaporeSingapore

Secure information retrieval is an essential task in today's highly digitised *** some applications,it may be necessary that user query's privacy and database content's security are *** these settings,symmetric private information retrieval(SPIR)could be employed,but its implementation is known to be demanding,requiring a private key-exchange network as the base ***,we report for the first time a realisation of provably-secure SPIR supported by a quantum-secure key-exchange *** SPIR scheme looks at biometric security,offering secure retrieval of 582-byte fingerprint files from a database with 800 *** experimental results clearly demonstrate the feasibility of SPIR with quantum secure communications,thereby opening up new possibilities in secure distributed data storage and cloud computinq over the future quantum Internet.

关键词： database network quantum