Non-Hermitian CHSH^(*)Game with a Single Trapped-Ion Qubit

The Clauser-Horne-Shimony-Holt(CHSH)game provides a captivating illustration of the advantages of quantum strategies over classical ones.In a recent study,a variant of the CHSH game leveraging a single qubit system,referred to as the CHSH^(*)game,has been identified.We demonstrate that this mapping relationship between these two games remains effective even for a non-unitary gate.Here we delve into the breach of Tsirelson’s bound in a non-Hermitian system,predicting changes in the upper and lower bounds of the player’s winning probability when employing quantum strategies in a single dissipative qubit system.We experimentally explore the impact of the CHSH^(*)game on the player’s winning probability in a single trapped-ion dissipative system,demonstrating a violation of Tsirelson’s bound under the influence of parity-time(PT)symmetry.These results contribute to a deeper understanding of the influence of non-Hermitian systems on quantum games and the behavior of quantum systems under PT symmetry,which is crucial for designing more robust and efficient quantum protocols.

Topology optimization design of micro-mass sensors for maximizing detection sensitivity

Micro-mass sensors have attracted increasing attention in the field of biomolecular and chemical detec- tion. It has been found that the size, shape, and geometry of the structure may affect the performance of the sensor. As a result, a topology optimization methodology is proposed in this paper for the design of micro-mass sensors. A phase- field function controlled by nodal variables and finite element shape functions is used to describe the configuration of a sen- sor in the constructed optimization problem. The design goal is to maximize the mass detection sensitivity. On the basis of these formulations, an optimization algorithm is constructed using the finite element method and the method of moving asymptotes. Numerical examples are presented to demon- strate the validity of the proposed problem formulation. The results suggest that the performance of the micro-mass sensor can be improved by using the proposed approach.

Quantum simulation of a general anti-PT-symmetric Hamiltonian with a trapped ion qubit

Non-Hermitian systems satisfying parity-time(PT)symmetry have aroused considerable interest owing to their exotic features.Anti-PT symmetry is an important counterpart of the symmetry,and has been studied in various classical systems.Although a Hamiltonian with anti-PT symmetry only differs from its PT-symmetric counterpart in a global phase,the information and energy exchange between systems and environment are different under them.It is also suggested theoretically that anti-PT symmetry is a useful concept in the context of quantum information storage with qubits coupled to a bosonic bath.So far,the observation of anti-PT symmetry in individual quantum systems remains elusive.Here,we implement an anti-PT-symmetric Hamiltonian of a single qubit in a single trapped ion by a designed microwave and optical control-pulse sequence.We characterize the anti-PT phase transition by mapping out the eigenvalues at different ratios between coupling strengths and dissipation rates.The full information of the quantum state is also obtained by quantum state tomography.Our work allows quantum simulation of genuine open-system feature of an anti-PT-symmetric system,which paves the way for utilizing non-Hermitian properties for quantum information processing.

LDPC Decoder for CCSDS Code by Flipping Bits and Fetching Words

The well-known CCSDS(consultative committee for space data systems) LDPC(low density parity check) code for near-earth applications is discussed and used for a case study of Mc Eliece system. First, a data error is picked out with the CCSDS LDPC code. The problem with its generator matrix is illustrated and overcome by a shortened code with some middle code bits deleted. In correspondence, its parity check matrix is also revised with the new quasi-cyclic(QC)-LDPC code. Second, a fast decoding scheme for general QC-LDPC codes is proposed based on flipping bits and fetching words. Besides, a lightweight CCSDS LDPC code based Mc Eliece system can be set up with such codes. The repaired CCSDS LDPC code is supposed to be still useful for communications and storages, and the normalized decoding algorithm is also efficient for general QC-LDPC codes.

Topology optimization of piezocomposite resonator for maximizing excitation strength and synthesizing desired eigenmodes

A topology optimization method is proposed for the design of piezocomposite resonator with the aim of maximizing excitation strength and synthesizing desired eigenmodes. The objective function consists of maximizing the electromechanical coupling strength at the mode of interest. The topology layout of a structure with desired eigenmodes is obtained by adding the modal assurance criterion as additional constraint in the topology optimiza- tion model. Numerical examples are presented and the results illustrate that aside from maximizing the electromechanical coupling strength, the existing eigenmode of the piezo- composite resonator can be modified to be the desired one at the mode of interest.