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<jats:p>The Dirac–Weyl equation characterized quasi-particles in the T3 lattice are studied under external magnetic field using the generalized uncertainty principle (GUP). The energy spectrum of the quasi-particles is found by the Nikiforov–Uvarov method. Based on the energy spectrum obtained, the thermodynamic properties are given, and the influence of the GUP on the statistical properties of systems is discussed. The results show that the energy and thermodynamic functions of massless Dirac–Weyl fermions in the T3 lattice depend on the variation of the GUP parameter.</jats:p>

<jats:p>We study steered coherence (SC) and entanglement in a three-spin Heisenberg <jats:italic>XX</jats:italic> model under twisted boundary conditions and show that their strengths can be significantly enhanced by tuning the twist angle. The optimal twist angle <jats:italic>θ</jats:italic> <jats:sub>opt</jats:sub> for achieving the maximum <jats:italic>l</jats:italic> <jats:sub>1</jats:sub> norm of SC is <jats:italic>π</jats:italic> in the region of weak field <jats:italic>B</jats:italic> and decreases gradually from <jats:italic>π</jats:italic> to 0 when <jats:italic>B</jats:italic> increases after a critical value, while for the relative entropy of SC, <jats:italic>θ</jats:italic> <jats:sub>opt</jats:sub> equals <jats:italic>π</jats:italic> in the weak field region and 0 otherwise. The entanglement and the critical temperature above which the entanglement vanishes can also be significantly enhanced by tuning the twist angle from 0 to <jats:italic>π</jats:italic>.</jats:p>

<jats:p>A universal locking model for single ion optical clocks was built based on a simple integrator and a double integrator. Different integrator algorithm parameters have been analyzed in both numerical simulations and experiments. The frequency variation measured by the comparison of two optical clocks coincides well with the simulation results for different second integrator parameters. According to the experimental results, the sensitivity of the servo error influenced by laser frequency drift with the addition of a double integrator was suppressed by a factor of 107. In a week-long comparison of optical clocks, the relative uncertainty of the servo error is determined to be 1.9 × 10<jats:sup>−18</jats:sup>, which is meaningful for the systematic uncertainty of the transportable single <jats:sup>40</jats:sup>Ca<jats:sup>+</jats:sup> ion optical clock entering the 10<jats:sup>−18</jats:sup> level.</jats:p>

<jats:p>The combination of an oscillating and a static field is used to study the creation and annihilation phenomena during the pair creation process. The time evolution, spatial density and momentum distribution of the created particles for a fermionic system are presented, which demonstrate that with the increasing static field intensity, the number of the created particles experiences a distinguishable decrease in every period of the oscillating field, which is caused by the annihilation phenomena between the created electrons and positrons.</jats:p>

<jats:p>We investigate the nonlocal advantage of quantum coherence (NAQC) and entanglement for two spins coupled via the Heisenberg interaction and under the intrinsic decoherence. Solutions of this decoherence model for the initial spin-1/2 and spin-1 maximally entangled states are obtained, based on which we calculate the NAQC and entanglement. In the weak region of magnetic field, the NAQC behaves as a damped oscillation with the time evolves, while the entanglement decays exponentially (behaves as a damped oscillation) for the spin-1/2 (spin-1) case. Moreover, the decay of both the NAQC and entanglement can be suppressed significantly by tuning the magnetic field and anisotropy of the spin interaction to some decoherence-rate-determined optimal values.</jats:p>

<jats:p>As superconducting quantum circuits are scaling up rapidly towards the noisy intermediate-scale quantum (NISQ) era, the demand for electronic control equipment has increased significantly. To fully control a quantum chip of <jats:italic>N</jats:italic> qubits, the common method based on up-conversion technology costs at least 2 × <jats:italic>N</jats:italic> digital-to-analog converters (DACs) and <jats:italic>N</jats:italic> IQ mixers. The expenses and complicate mixer calibration have become a hinderance for intermediate-scale quantum control. Here we propose a universal control scheme for superconducting circuits, fully based on parametric modulation. To control <jats:italic>N</jats:italic> qubits on a chip, our scheme only requires <jats:italic>N</jats:italic> DACs and no IQ mixer, which significantly reduces the expenses. One key idea in the control scheme is to introduce a global pump signal for single-qubit gates. We theoretically explain how the universal gates are constructed using parametric modulation. The fidelity analysis shows that parametric single-qubit (two-qubit) gates in the proposed scheme can achieve low error rates of 10<jats:sup>−4</jats:sup>, with a gate time of about 60 ns (100 ns).</jats:p>

<jats:p>Homomorphic encryption has giant advantages in the protection of privacy information. In this paper, we present a new kind of probabilistic quantum homomorphic encryption scheme for the universal quantum circuit evaluation. Firstly, the pre-shared non-maximally entangled states are utilized as auxiliary resources, which lower the requirements of the quantum channel, to correct the errors in non-Clifford gate evaluation. By using the set synthesized by Clifford gates and <jats:italic>T</jats:italic> gates, it is feasible to perform the arbitrary quantum computation on the encrypted data. Secondly, our scheme is different from the previous scheme described by the quantum homomorphic encryption algorithm. From the perspective of application, a two-party probabilistic quantum homomorphic encryption scheme is proposed. It is clear what the computation and operation that the client and the server need to perform respectively, as well as the permission to access the data. Finally, the security of probabilistic quantum homomorphic encryption scheme is analyzed in detail. It demonstrates that the scheme has favorable security in three aspects, including privacy data, evaluated data and encryption and decryption keys.</jats:p>

<jats:p>We demonstrate an active reset protocol in a superconducting quantum circuit. The thermal population on the excited state of a transmon qubit is reduced through driving the transitions between the qubit and an ancillary qubit. Furthermore, we investigate the efficiency of this approach at different temperatures. The result shows that population in the first excited state can be dropped from 7% to 2.55% in 27 ns at 30 mK. The efficiency improves as the temperature increases. Compared to other schemes, our proposal alleviates the requirements for measurement procedure and equipment. With the increase of qubit integration, the fast reset technique holds the promise of improving the fidelity of quantum control.</jats:p>

<jats:p>Within the framework of continuum model, we study the projective representation of emergent <jats:italic>D</jats:italic> <jats:sub>6</jats:sub> point group in twisted bilayer graphene. We then construct tight-binding models of the lowest bands without and with external electromagnetic fields, based on the projective representation.</jats:p>

<jats:p>Removal of spiral waves in cardiac muscle is necessary because of their threat to life. Common methods for this removal are to apply a local disturbance to the media, such as a periodic forcing. However, most of these methods accelerate the beating of the cardiac muscle, resulting in the aggravation of the ventricular tachycardia, which directly threatens life. In the present study, in order to clear off spiral waves, a global pulse-disturbance is applied to the media based on three models of cardiac muscle. It is found that the spiral waves are eliminated and the frequency of the cardiac muscle is decreased in a short time, and finally, the state of the medium reaches the normal oscillation, which supports a target waves. Our method sheds light on the removal of spiral waves in cardiac muscle and can prevent the ventricular tachycardia as well as the ventricular fibrillation.x</jats:p>