Experimental Verification of Dissipation-Time Uncertainty Relation.

Dissipation is vital to any cyclic process in realistic systems. Recent research focus on nonequilibrium processes in stochastic systems has revealed a fundamental trade-off, called dissipation-time uncertainty relation, that entropy production rate associated with dissipation bounds the evolution pace of physical processes [Phys. Rev. Lett. 125, 120604 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.120604]. Following the dissipative two-level model exemplified in the same Letter, we experimentally verify this fundamental trade-off in a single trapped ultracold ^{40}Ca^{+} ion using elaborately designed dissipative channels, along with a postprocessing method developed in the data analysis, to build the effective nonequilibrium stochastic evolutions for the energy transfer between two heat baths mediated by a qubit. Since the dissipation-time uncertainty relation imposes a constraint on the quantum speed regarding entropy flux, our observation provides the first experimental evidence confirming such a speed restriction from thermodynamics on quantum operations due to dissipation, which helps us further understand the role of thermodynamical characteristics played in quantum information processing.

In situ investigation of the surface morphology evolution of the bulk ceramic Y2Mo3O12 during crystal water release.

The surface morphology evolution of the bulk ceramic Y2Mo3O12 during the release of crystal water is followed in situ for the first time using atomic force microscopy. It is found that both the shape and size of individual grains and the integration morphology of the sample exhibit dynamic changes with increasing temperature. We believe that the surface morphology evolution of the sample with increasing temperature is closely correlated with the forces induced by the contraction and expansion of the lattice during crystal water release in two different stages.

Surface plasmon resonance and field enhancement in #-shaped gold wires metamaterial.

A #-shaped gold wires metamaterial is designed for surface enhanced Raman spectroscopy (SERS) and sensing. The tunability of surface plasmon resonance (SPR) excitations, hotspots distribution, localized field enhancement and sensitivity of the structure are investigated. In contrast to most metamaterial, the #-shaped structure exhibits two pronounced SPRs that are insensitive to the polarization of excitation light. Pure electromagnetic Raman enhancement factors of about 10(6) are achieved on the symmetrically distributed field hotspots. It is possible to break the usable wavelength range of conventional gold SERS substrates via higher order excitations of the #-shaped metamaterial. In addition, the sensitivity and the figure of merits are found to be comparable or even higher than those of conventional SERS substrates. All these factors together with the high reproducibility nature of metamaterial and its simple planer structure suggest that this structure is very promising for surface enhanced spectroscopy and sensing applications.

Antisymmetric resonant mode and negative refraction in double-ring resonators under normal-to-plane incidence.

Compared to metallic composite metamaterials of double split-ring resonators with wires, double-ring resonators without additional wires are simple to engineer. In this paper, we have numerically studied the transmittance of double split- and closed-ring resonators at normal-to-plane incidence and identified their fundamental resonance modes. It is found that the antisymmetric and symmetric resonance modes originate from the out-of-phase and in-phase oscillations of surface charges in the neighboring legs of the double-ring resonators, respectively. The coupling of the antiparallel induced currents in the neighboring legs gives rise to magnetic resonance and consequently negative permeability of the antisymmetric mode. The negative refraction transmission of the double-ring resonators at normal-to-plane incidence is verified by dispersion curve and wedge-shaped model simulations. Our study provides a route to negative refraction metamaterial design by using the antisymmetric resonance mode of the simple double-ring structure at normal-to-plane incidence which is of particular importance for the terahertz and infrared domain.

SPP-associated dual left-handed bands and field enhancement in metal-dielectric-metal metamaterial perforated by asymmetric cross hole arrays.

Dual-band left-handed transmissions in the near infrared frequencies through the metal-dielectric-metal metamaterial perforated with an array of asymmetric cross holes are demonstrated. It is shown that the left-handed bands originate from the SPP-associated magnetic response excited by different polarized light and their frequencies can be tuned by the arm's length or width of the cross-gaps. The structures are further optimized at 1.064 microm laser light excitation for elucidating the mechanism and possible application in surface enhanced Raman spectroscopy in sandwiched architectures. This study provides valuable information for the design of compact optical devices with dual left-handed bands in a single structure and may also pave the way toward stable and reproducible substrate design for surface enhanced Raman spectroscopy.

Low-frequency phonon modes and negative thermal expansion in A(MO(4))(2) (A = Zr, Hf and M = W, Mo) by Raman and Terahertz time-domain spectroscopy.

The low-frequency phonon modes of cubic ZrW(2)O(8) and HfW(2)O(8), and trigonal ZrMo(2)O(8) and HfMo(2)O(8) have been comparatively studied by Raman and terahertz time-domain spectroscopy. It is shown that there appear a number of distinctive low-frequency modes below 150 cm(-1) in the cubic ZrW(2)O(8) and HfW(2)O(8) in both Raman and terahertz spectra which are attributed to the librational and translational motions of the polyhedra whereas only one weak mode is present in the Raman but absent in the THz spectra of the trigonal ZrMo(2)O(8) and HfMo(2)O(8) in the same region, which is assigned to the interlayer breathing. It is found that the lowest optical phonon mode at about 40 cm(-1) disappears accompanied by obvious weakening of the lowest asymmetric stretching mode for ZrW(2)O(8) and HfW(2)O(8) across the order-disorder phase transition temperature. It gives direct evidence of reduction in the number of rigid unit modes (RUMs) in the high-temperature phase. It is shown that the correlated motions of the libration and transilation of the WO(4) tetrahedra and the ZrO(6)/HfO(6) octahedra with the out-of-phase asymmetric stretching of the two neighboring WO(4) tetrahedra contribute a large portion to the NTE in the low-temperature phase and some of the correlated motions may be destroyed across the order-disorder phase transition, causing a smaller negative thermal expansion in the high-temperature phase. The lack of RUMs in trigonal ZrMo(2)O(8) and HfMo(2)O(8) is the cause of their positive thermal expansion.

Electronic structure, bonding and phonon modes in the negative thermal expansion materials of Cd(CN)(2) and Zn(CN)(2).

The disordered configuration, band structures, density of states, Mulliken population, elastic constants, zone center optic phonon modes and their Grüneisen parameters of M(CN)(2) (M =  Cd, Zn) have been studied for possible cyanide-ordering patterns by the first-principles plane-wave pseudopotential method based on density functional theory. Total energy calculations predict that MC(2)N(2)-MC(2)N(2) is the most favorable configuration for Cd(CN)(2) whereas all three possible configurations are near equally favorable for Zn(CN)(2). Effective charges and bond order analyses reveal that the M(CN)(2) (M =  Cd, Zn) frameworks include much stiffer [Formula: see text] and weaker M-C/N bonds, which account for the flexing of the M-CN-M linkage during the transverse motion of the cyanide-bridge. The transverse translational and the librational modes give rise to negative Grüneisen parameters and therefore contribute to the negative thermal expansion. Transverse vibrations of the C and N atoms in the same (transverse translational modes) or opposite (librational modes) directions have the same effect of drawing the anchoring metal atoms closer. Among all the optical phonon modes, the lowest-energy transverse translational optical modes which are neither Raman nor infrared active in Cd(CN)(2) and Zn(CN)(2) give rise to the largest contribution to the negative thermal expansion.