Southwest Quantum Information and Technology

Sixteenth Annual Meeting, February 20-22, 2014
Santa Fe, New Mexico

Full Program | Thursday | Friday | Saturday | All Sessions

8:30am - 9:15am	Sebastian Hofferberth, Universität Stuttgart (invited)
	Single charged impurities inside a Bose-Einstein condensate
	Abstract. We investigate the interaction of a single electron as well as a single ion with a Bose-Einstein condensate (BEC). The charge impurities are produced by exciting exactly one atom from the BEC to a Rydberg state. Since the ionic core and the Rydberg electron have vastly different mass and interaction range with the surrounding ground state, we can consider both parts separately. Firstly, for low-L Rydberg states, the electron wavefunction is fully immersed in the BEC, and we observe electron-phonon coupling. We observe that single electron excite collective modes of the whole condensate. Alternatively, for high-L states the electron can be moved completely outside of the BEC, enabling us to study the interaction of the ionic core with the BEC. We are currently studying ion-ground state Feshbach resonances and investige the possibility of trapping the ion inside the BEC without any external electric fields.
SESSION 1: Quantum Information Processing with Trapped Ions
9:15am - 9:45am	John Gaebler, National Institute of Standards and Technology
	Trapped-ion quantum information processing experiments at NIST
	Abstract. We report experiments towards scalable quantum information processing with laser-cooled trapped ions. Quantum information is stored in internal (hyperfine ground) states of ions and gate operations are performed with laser and microwave fields. We describe the current status of quantum information experiments using multi-zone trap arrays to investigate the basic tasks of a quantum information processor including transport of ions between zones and sympathetic cooling. In one recent experiment we created an entangled steady state of two trapped ions using dissipation. The steady state can be maintained for a duration of several times the entanglement generation duration and the entanglement fidelity is currently limited by identified technical issues. We also briefly describe recent progress with other quantum-information-focused experiments in our group including the generation of entanglement between two ions held in distinct but coupled trap zones, efforts to reduce the electric field noise from trap surfaces, superconducting photon detectors and junctions for switching the transport pathway of ions in multi-zone traps structures. *This work is supported by IARPA, ONR, and the NIST Quantum Information Program.
9:45am - 10:15am	True Merrill, Georgia Tech Research Institute
	An on-chip toolset for surface-electrode trap based quantum processors
	Abstract. Increasing the size and complexity of ion-trap quantum computing experiments requires improvements in automation, hardware, and control. We report on several technologies which incorporate control electronics, diffractive ion imaging optics, and quantum control techniques for microwave gates in microfabricated surface-traps. We demonstrate a compact, in-vacuum 80 channel digital-to-analog converter (DAC) system controlling a surface-electrode trap. The DAC system transports 40Ca+ ions for over 70 m at 1 m/s without cooling, and the measured 0.8 quanta/ms ion-heating rate is comparable to external DAC systems. A second project incorporates diffractive Fresnel mirrors onto a trap surface for enhanced ion imaging and state detection. Optics for light collimation and refocusing are demonstrated, achieving a ~8.3 x enhancement in the total fluorescence signal. We comment on possible limits to asynchronous ion-qubit readout and strategies to mitigate decoherence from stray photons during measurement processes. Finally, we discuss composite pulse techniques for gates on 171Yb+ qubits that yield accurate quantum control despite classical control errors.