Dear quanta,
Tomorrow we will meet at 11am in 6-310 and go around the room and give
updates. This will be our last group meeting for the semester.
In the afternoon we will have a talk which gives a sense of how up for
grabs the basic categories of quantum computers still are.
Friday, Dec 13, 2019, 1:30pm, 6C-442
Laser-free trapped-ion quantum logic using an oscillating magnetic field
gradient at radio frequency
Raghavendra Srinivas (NIST & U.C. Boulder)
Trapped-ion quantum logic is usually performed using laser-induced coupling
of the ions’ internal spin states to their motion. Laser-free spin-motion
coupling methods, which eliminate photon scattering errors and offer
benefits for scalability, have been proposed and demonstrated using static
magnetic field gradients or magnetic field gradients oscillating at GHz
frequencies [1-4]. We present a new method of spin-motion coupling for
trapped ions without lasers, instead using microwaves and a magnetic field
gradient oscillating at radio frequency [5]. We demonstrate and
characterize this method with trapped Mg+ ions, cooling a single mode of
motion to close to its ground state, and generating entangled states of two
ions. This implementation offers important technical advantages over other
laser-free techniques, while also enabling laser-free entangling gates with
reduced sensitivity to qubit frequency errors [6]. These experiments are
performed in a surface-electrode trap that incorporates current-carrying
electrodes to generate the microwave fields and the oscillating magnetic
field gradient. Currently, we achieve a Bell-state fidelity of 0.996(2)
with ground-state-cooled ions and 0.991(3) for ions cooled to the Doppler
limit (nbar = 2).
[1] Mintert and Wunderlich PRL 87, 257904 (2001)
[2] Weidt et al. PRL 117, 220501 (2016)
[3] Ospelkaus et al. Nature 476, 181 (2011)
[4] Harty et al. PRL 117, 140501 (2016)
[5] Srinivas et al. PRL 122, 163201 (2019)
[6] Sutherland et al. NJP 21, 033033 (2019)
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