Mon July 29, 2019 11:00 am
Mixed-species and integrated trapped-ion quantum information processing
Location:26-214
Karan Mehta, ETH Zurich
Quantum error correction will be essential for realizing the full potential of quantum information processing devices; this requires significant jumps in robustness and accuracies of basic operations, as well as numbers of controllable qubits. I will discuss work demonstrating basic ingredients for error correction in a small trapped-ion register, as well as on integration for stability and scale. We have performed up to 50 sequential measurements of correlations between two beryllium ion microwave qubits using an ancillary optical-frequency qubit in a calcium ion, and implemented feedback that allows us to stabilize two-qubit subspaces as well as maximally entangled Bell states [1]. The use of multiple ion species allows ancilla measurement and reset with negligible unwanted coupling to the information qubits. Integration of the required classical control hardware into ion traps will play a major role in scaling such techniques. Integrated optics in particular promises reduced drifts, stable tight focusing, and parallelizability. Building on previous work [2], we have designed planar ion traps with integrated silicon nitride photonics intended for multi-qubit operations with calcium ions. The commercially-fabricated chips exhibit low (<2 dB measured) fiber-waveguide coupling losses on multiple channels at visible wavelengths. We are currently operating these traps at low temperature with fiber arrays attached, and I will describe our progress towards multi-qubit operations in this setting. Such optics may also enable new physical gate implementations; I will discuss one that takes advantage of the phase-stability of waveguide approaches formulti-qubit gates in standing wave fields [3], eliminating the primary speed limit in the widely used Molmer-Sorensen interaction.
[1] Negnevitsky, Marinelli, et al. Nature 563, 527-531 (2019).
[2] Mehta, et al. Nat. Nano. 11, 1066-1070 (2016).
[3] Mehta, et al., Proc. SPIE 10933 (2019).
Bio: Karan Mehta received BS. Degrees from UCLA in Electrical Engineering and Physics in 2010, and his PhD in EECS with Rajeev Ram at MIT in 2017. He is currently a postdoctoral fellow with Jonathan Home at ETH Zurich.