We probe electric-field noise in a surface ion trap for ion-surface distances d between 50 and 300 µm in the normal and planar directions. We find the noise distance dependence to scale as d −2.6 in our trap and a frequency dependence which is consistent with 1/f noise. Simulations of the electric-field noise specific to our trap geometry provide evidence that we are not limited by technical noise sources. Our distance scaling data is consistent with a noise correlation length of about 100 µm at the trap surface, and we discuss how patch potentials of this size would be modified by the electrode geometry.
We describe the design, fabrication, and operation of a novel surface-electrode Paul trap that produces a radio-frequency-null along the axis perpendicular to the trap surface. This arrangement enables control of the vertical trapping potential and consequentially the ionelectrode distance via dc-electrodes only. We demonstrate confinement of single 40 Ca + ions at heights between 50 µm and 300 µm above planar copper-coated aluminium electrodes. We investigate micromotion in the vertical direction and show cooling of both the planar and vertical motional modes into the ground state. This trap architecture provides a platform for precision electric-field noise detection, trapping of vertical ion strings without excess micromotion, and may have applications for scalable quantum computers with surface ion traps.
We demonstrate coupling between the motions of two independently trapped ions with a separation distance of 620 µm. The ion-ion interaction is enhanced via a room-temperature electrically floating metallic wire which connects two surface traps. Tuning the motion of both ions into resonance, we show flow of energy with a coupling rate of 11 Hz. Quantum-coherent coupling is hindered by strong surface electric-field noise in our device. Our ion-wire-ion system demonstrates that room-temperature conductors can be used to mediate and tune interactions between independently trapped charges over distances beyond those achievable with free-space dipole-dipole coupling. This technology may be used to sympathetically cool or entangle remotely trapped charges and enable coupling between disparate physical systems.
Abstract. We have evaluated three computer approaches to 3-D reconstruction -passive computational binocular stereo and active structured lighting and photometric stereo -in regard to human face reconstruction for modelling virtual humans. An integrated experimental environment simultaneously acquired images for 3-D reconstruction and data from a 3-D scanner which provided an accurate ground truth. Our goal was to determine whether today's computer vision approaches are accurate and fast enough for practical 3-D facial reconstruction applications. We showed that the combination of structured lighting with symmetric dynamic programming stereo has good prospects with reasonable processing time and accuracy.
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