Utilizing terahertz time domain spectroscopy, we have characterized the electromagnetic response of a planar array of split ring resonators (SRRs) fabricated upon a high resistivity GaAs substrate. The measured frequency dependent magnetic and electric resonances are in excellent agreement with theory and simulation. For two polarizations, the SRRs yield a negative electric response (epsilon < 0). We demonstrate, for the first time, dynamical control of the electrical response of the SRRs through photoexcitation of free carriers in the substrate. An excited carrier density of approximately 4 x 10(16) cm(-3) is sufficient to short the gap of the SRRs, thereby turning off the electric resonance, demonstrating the potential of such structures as terahertz switches. Because of the universality of metamaterial response over many decades of frequency, these results have implications for other regions of the electromagnetic spectrum.
We present a class of artificial materials that exhibit a tailored response to the electrical component of electromagnetic radiation. These electric metamaterials are investigated theoretically, computationally, and experimentally using terahertz time-domain spectroscopy. These structures display a resonant response including regions of negative permittivity ⑀ 1 ͑͒ Ͻ 0 ranging from ϳ500 GHz to 1 THz. Conventional electric media such as distributed wires are difficult to incorporate into metamaterials. In contrast, these localized structures will simplify the construction of future metamaterials, including those with negative index of refraction. As these structures generalize to three dimensions in a straightforward manner, they will significantly enhance the design and fabrication of functional terahertz devices.
Planar electric split ring resonator (eSRR) metamaterials and their corresponding inverse structures are designed and characterized computationally and experimentally utilizing finite element modeling and THz time domain spectroscopy. A complementary response is observed in transmission. Specifically, for the eSRRs a decrease in transmission is observed at resonance whereas the inverse structures display an increase in transmission. The frequency dependent effective complex dielectric functions are extracted from the experimental data and, in combination with simulations to determine the surface current density and local electric field, provide considerable insight into the electromagnetic response of our planar metamaterials. These structures may find applications in the construction of various THz filters, transparent THz windows, or THz grid structures ideal for constructing THz switching/modulation devices.
We present the design, fabrication, and experimental implementation of surface ion traps with Y-shaped junctions. The traps are designed to minimize the pseudopotential variations in the junction region at the symmetric intersection of three linear segments. We experimentally demonstrate robust linear and junction shuttling with greater than 10 6 round-trip shuttles without ion loss. By minimizing the direct line of sight between trapped ions and dielectric surfaces, negligible day-to-day and trap-to-trap variations are observed. In addition to high-fidelity single-ion shuttling, multiple-ion chains survive splitting, ion-position swapping, and recombining routines. The development of two-dimensional trapping structures is an important milestone for ion-trap quantum computing and quantum simulations. arXiv:1105.1834v1 [quant-ph]
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