Chair: (Murray Holland)
8:30am - 9:15amJohn Bollinger, National Institute of Standards and Technology, Boulder (invited)
Quantum control and simulation with large trapped-ion crystals
Abstract. I will describe efforts to improve the control of large, single-plane crystals of several hundred ions in Penning traps and employ these crystals for quantum sensing and quantum simulation. We isolate and control two internal levels or “spin” degree of freedom in each ion with standard techniques. Long-range interactions between the ions are generated through the application of spin-dependent optical-dipole forces that couple the spin and motional degrees of freedom of the ions. When this coupling is tuned to produce a coupling with a single motional mode (typically the center-of-mass mode), this system is described by the iconic Dicke model. Long-range Ising interactions and single-axis twisting are produced through this spin-motion coupling. To benchmark dynamics, we measure out-of-time-order correlations (OTOCs) that quantify the build-up of correlations and the spread of quantum information. We also employ spin-dependent optical dipole forces to sense center-of-mass motion that is small compared to the ground state zero-point fluctuations. This enables the detection of weak electric fields and may provide an opportunity to place limits on dark matter couplings due to particles such as axions and hidden photons that couple to ordinary matter through weak electric fields.
9:15am - 9:45amMegan Ivory, University of Washington
Novel trap for 2D ion crystal experiments
Abstract. Quantum computation has thus far been limited by number of available qubits. In trapped ions, most computation has been performed in linear Paul traps to avoid micromotion which is thought to lead to low gate fidelities. Recent theoretical work by the Duan group shows that micromotion can be compensated with the use of segmented laser pulses, allowing for fidelities <99.99% in two-dimensional ion crystals of >100 ions. Here, we seek to experimentally demonstrate high-fidelity quantum gates in Ba+ ions in a planar crystal. To do so, we have developed a novel trap system specifically for producing Ba+ crystals. The trap geometry is based on simulations we developed for modeling trapped ion dynamics and equilibrium positions. The electrodes are comprised of a segmented ring which allows us to dynamically tune the transverse trap frequencies to produce both planar and linear traps. We present progress towards the demonstration of large ion crystals of varying trap frequency anisotropies. In addition to high-fidelity quantum gates in planar ion crystals, the system in development can also be used for quantum chemistry simulations and the study of crystalline order, defects, and phase transitions.
9:45am - 10:15amCrystal Noel, University of California Berkeley
Electric-field noise from thermally-activated fluctuators in a surface ion trap
Abstract. Electric field noise is a major limiting factor in the performance of ion traps and other quantum devices. Despite intensive research over the past decade, the nature and cause of electric field noise near surfaces is not very well understood. We probe electric-field noise near the surface of an ion trap chip in a previously unexplored high-temperature regime. A saturation of the noise amplitude occurs around 500 K, which, together with a small change in the frequency scaling, points to thermally activated fluctuators as the origin of the noise. The data can be explained by a broad distribution of activation energies around 0.5 eV. These energies suggest atomic displacements as a relevant microscopic mechanism, likely taking place at the metal surface.

SQuInT Chief Organizer
Akimasa Miyake, Associate Professor

SQuInT Local Organizers
Rafael Alexander, Postdoctoral Fellow
Chris Jackson, Postdoctoral Fellow

SQuInT Administrator
Gloria Cordova
505 277-1850

SQuInT Assistant
Wendy Jay

SQuInT Founder
Ivan Deutsch, Regents' Professor, CQuIC Director

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