基于可调谐滤波器的带中心波长自动跟踪光纤光栅动态波长解调技术的研究

研究了基于可调谐滤波器(TOF)的带中心波长自动跟踪光纤光栅动态波长解调技术。实验表明,解调仪特别适合在传感FBG(fiber Bragg grating)存在大幅度静态波长变化时对微幅度动态波长变化进行检测,动态波长检测分辨率为0.007pm/Hz。上电时,TOF对中心波长为1292.50~1308.50nm范围内的光纤光栅具有自动跟踪的能力,克服了TOF不稳定对系统的影响。     

The Reality in Bohmian Quantum Mechanics or Can You Kill with an Empty Wave Bullet?

Several situations, in which an empty wave causes an observable effect, are reviewed. They include an experiment showing surrealistic trajectories proposed by Englert et al. and protective measurement of the density of the quantum state. Conditions for observable effects due to empty waves are derived. The possibility (in spite of the existence of these examples) of minimalistic interpretation of Bohmian quantum mechanics in which only Bohmian positions supervene on our experience is discussed.     

The processes of ordering and formation of two-dimensional glasses at metal surfaces

Using the experimental results obtained for the Dy-Mo(1 1 2) system, we discuss the possibilities and mechanisms of formation of two-dimensional (2D) glasses on metal surfaces. It has been found that in the coverage range 0.07 < θ < 0.58, ordered Dy superstructures formed and observed at T < 400 K are irreversibly destroyed by annealing to higher temperatures and turn into an amorphous (glass) structure on cooling. It is supposed that this conversion is caused by the formation, at T > 400 K, of a Dy-Mo surface alloy in which the rate of Dy surface diffusion is strongly reduced in comparison with its value in the absence of alloying. As a result, the mobility of Dy adatoms becomes too low at the temperatures corresponding to the ordered equilibrium state of the surface, and this state cannot be achieved in reasonable relaxation time. This interpretation is corroborated by the experimental data on substantial suppression of surface diffusion in some coadsorbed layers. Since surface glasses contact with ordered (crystalline) substrates, their structure may have a peculiar character different from that of “conventional” metal glasses. Surface glasses can find a number of applications as rather stable systems that combine low dimensionality, specific electronic structure of their constituents and extremely high density of defects.     

Growth and characterization of InAs quantum dots with low-density and long emission wavelength

The growth parameters affecting the deposition of self-assembled InAs quantum dots （QDs） on GaAs substrate by low-pressure metal-organic chemical vapor deposition （MOCVD） are reported. The low-density InAs QDs （- 5 × 10^8cm^-2） are achieved using high growth temperature and low InAs coverage. Photoluminescence （PL） measurements show the good optical quality of low-density QDs. At room temperature, the ground state peak wavelength of PL spectrum and full-width at half-maximum （FWHM） are 1361 nm and 23 meV （35 nm）, respectively, which are obtained as the GaAs capping layer grown using triethylgallium （TEG） and tertiallybutylarsine （TBA）. The PL spectra exhibit three emission peaks at 1361, 1280, and 1204 nm, which correspond to the ground state, the first excited state, and the second excited state of the ODs, respectively.     

Local eddy current measurements in pulsed fields

This work presents new eddy current measurements in pulsed fields. A commercial point pick-up coil is used to detect the induction signal along the radius of Cu and Al samples with cylindrical shape and diameters between 5 and 35 mm. Local eddy current measurements were performed on the surface of conducting materials due to the small dimensions of the coil. A simple electrical circuit, used as a model, is proposed to describe the local eddy current effect in pulsed fields. The proposed model allows to calculate the phase shift angle between the signal proportional to eddy currents and the applied external field in a pulsed field magnetometer.     

Controlled quantum state sharing of arbitrary two-qubit states with five-qubit cluster states

In this paper, we propose a controlled quantum state sharing scheme to share an arbitrary two-qubit state using a five-qubit cluster state and the Bell state measurement. In this scheme, the five-qubit cluster state is shared by a sender (Alice), a controller (Charlie), and a receiver (Bob), and the sender only needs to perform the Bell-state measurements on her particles during the quantum state sharing process, the controller performs a single-qubit projective measurement on his particles, then the receiver can reconstruct the arbitrary two-qubit state by performing some appropriate unitary transformations on his particles after he has known the measured results of the sender and the controller.     

基于六粒子纠缠态和Bell态测量的量子信息分离

通过介绍六粒子纠缠态的新应用研究,提出了一个二粒子任意态的信息分离方案.在这个方案中,发送者Alice、控制者Charlie和接受者Bob共享一个六粒子纠缠态,发送者先执行两次Bell基测量;然后控制者执行一次Bell基测量;最后接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,从而能够重建要发送的...     

Simultaneous measurement of strain and temperature with a long-period fiber grating inscribed Sagnac interferometer

A Sagnac interferometer with a long-period fiber grating (LPG) inscribed in the polarization-maintaining fiber (PMF) is proposed and experimentally demonstrated for simultaneous measurement of strain and temperature. Due to the different responses of the LPG and the Sagnac interferometer to strain and temperature, simultaneous measurement can be achieved by monitoring the wavelength shifts and the intensity changes of a resonance dip of the sensor setup. The experimental results show that the achieved sensitivities to strain and temperature are 6.4 × 10^− 3 dB/με and 0.65 nm/°C, respectively.     

Magnetic pole pinning at rectangular defects on MnAs/GaAs(0 0 1)

Strong magnetic poles at characteristic rectangular defects have been observed using a magnetic force microscope on a MnAs(  1 0 0) thin film with the thickness of 30 nm. The MnAs thin film was epitaxially grown on a GaAs(0 0 1) substrate. The magnetic poles were in one-arranging direction, being independent of the magnetization direction of the film. The poles were pinned at the edges of the rectangular defects until just below the Curie temperature, and formed a stable magnetic-field loop on the MnAs surface. The stability of the magnetic pole pinning shows the distinctive feature of the magnetic domain structure on the surface with a strong anisotropy, which was built in the heterostructure of MnAs and GaAs.     

Frequency combinations in the magnetoresistance oscillations spectrum of a linear chain of coupled orbits with a high scattering rate

The oscillatory magnetoresistance spectrum of the organic metal (BEDO)₅Ni(CN)₄. 3C₂H₄(OH)₂ has been studied up to 50 T, in the temperature range from 1.5 K to 4.2 K. In high magnetic field, its Fermi surface corresponds to a linear chain of quasi-two-dimensional orbits coupled by magnetic breakdown (MB). The scattering rate consistently deduced from the data relevant to the basic α and the MB-induced β orbits is very large which points to a significant reduction of the chemical potential oscillation. Despite of this feature, the oscillations spectrum exhibits many frequency combinations. Their effective masses and (or) Dingle temperature are not in agreement with either the predictions of the quantum interference model or the semiclassical model of Falicov and Stachowiak.