摘要：
Based on the analysis of the physical thermal model for a microbolometer under pulse bias, a new temperature compensation method for microbolometric focal plane array is proposed to compensate the substrate temperature fluctuation in microbolometric array. The self-heating and infrared responding voltage expressions of the microbolometer under pulse current bias are derived from the heat balance equation of the physical thermal model for the microbolometer, and these two expressions indicate that the microbolometer self-heating and infrared voltage responsivity expressions are dependent on the substrate temperature of the microbolometer with some other constant characteristic parameters. Through the obtained expressions, different pulse bias currents are provided to the microbolometer and its corresponding blind element at different substrate temperatures to get the same voltage responsivity of the microbolometer at different ambient temperatures. The proposed temperature compensation method can be utilized for a microbolometric focal plane array with low-power consumption and high temperature-resolution.
摘要：
By using a torsion pendulum and a rotating eightfold symmetric attractor with dual modulation of both the interested signal and the gravitational calibration signal, a new test of the gravitational inverse-square law at separations down to 295 μm is presented. A dual-compensation design by adding masses on both the pendulum and the attractor was adopted to realize a null experiment. The experimental result shows that, at a 95% confidence level, the gravitational inverse-square law holds ( |α|≤1) down to a length scale λ=59 μm. This work establishes the strongest bound on the magnitude α of Yukawa-type deviations from Newtonian gravity in the range of 70–300 μm, and improves the previous bounds by up to a factor of 2 at the length scale λ≈160 μm.
摘要：
The ground state of interacting spin chains in external magnetic fields can undergo a quantum phase transition (QPT) characterized by dramatic changes at a critical value of the magnetic field. In this paper, we use Bell-type inequalities to study the multipartite correlations (including multipartite entanglement and multipartite nonlocality in an n-spin subsystem) in the QPT of an infinite XY chain. An efficient numerical optimization procedure is proposed to figure out the violation measure Mn of the inequalities. For n≤7, the magnetic-field ( λ) dependence of Mn is studied. We find the derivative of Mn is divergent exactly at the QPT point λc=1 for any n. In addition, with the increase of n, Mn converges quickly for λ<λc and converges very slowly for λ>λc, which can be regarded as another signal for the QPT. Furthermore, in the vicinity of λc, high-order Bell-type inequalities will be violated as long as n is large enough. This indicates that high-level multipartite correlation will be present when the system is in the vicinity of the QPT point. Nevertheless, genuine n-partite entanglement or genuine n-partite nonlocality is not observed in the QPT.
摘要：
In this paper, using the infinite time-evolving block decimation (iTEBD) algorithm and Bell-type inequalities, we investigate multipartite quantum nonlocality in an infinite one-dimensional quantum spin- 12 XXZ system. High hierarchy of multipartite nonlocality can be observed in the gapless phase of the model, while only the lowest hierarchy of multipartite nonlocality is observed in most regions of the gapped antiferromagnetic phase. Thereby, Bell-type inequalities disclose different correlation structures in the two phases of the system. Furthermore, at the infinite-order quantum phase transition (QPT, or Kosterlitz-Thouless QPT) point of the model, the correlation measures always show a local minimum value, regardless of the length of the subchains. It indicates that relatively low hierarchy of multipartite nonlocality would be observed at the infinite-order QPT point in a Bell-type experiment. The result is in contrast to the existing results of the second-order QPT in the one-dimensional XY model, where multipartite nonlocality with the highest hierarchy has been observed. Thus, multipartite nonlocality provides an alternative perspective to distinguish between these two kinds of QPTs. Reliable clues for the existence of tripartite quantum entanglement have also been found.
