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SUMMARY:Controlling, measuring and displacing the trapped-ion oscillator
DESCRIPTION:I will describe a range of recent experiments on trapped-ions at ETH 
Zurich.  In the first, we have engineered spin-oscillator couplings to 
realize state-engineering, control and diagnostics for the quantum 
harmonic oscillator . Building upon recent work in which we generated 
squeezed states by reservoir engineering [1] , we have produced squeezed 
wavepacket analogues to the well known Schrodinger's cat states, 
observing re-coherence after separating the entangled wavepackets by up 
20 times the ground state r.m.s. extent, which corresponds to more than 
60 times the width of the squeezed wavepacket  [2]. Using a non-squeezed 
cat, we have demonstrated a measurement-based post-selection scheme to 
dis-entangle the spin and motion, and reveal the quantum interference 
between the two separated wavepackets [3]. Wigner function tomography of 
the resulting state was performed by driving Jaynes-Cummings physics in 
a displaced-Fock basis for a range of displacements, and using a 
squeezed Fock basis. I will also describe recent results in which we 
perform gates on trapped-ion qubits by moving ions through static laser 
beams. We use these to demonstrate parallel operations in two separated 
zones of a multi-zone ion trap using a static recycled laser beam, 
providing a path to scaling trapped-ion quantum processors with reduced 
optical complexity [4]. The presence of a large first-order Doppler 
shift led us to devise methods for estimating a time-varying Hamiltonian 
[5], resulting in a useful method for performing Doppler velocimetry of 
our ions. In separate work in a cryogenic apparatus, we have 
demonstrated the ability to control the trapping potentials on 
nano-second timescales, providing access to the sudden approximation in 
quantum mechanics, and allowing the demonstration of control of quantum 
states with up to 10 kilo-quanta [6].

[1] D. Kienzler et al. Science 347, 6217 (2015)
[2] H-Y. Lo et al., Nature 521, 7552  (2015)
[3] D. Kienzler et al. PRL 116, 140402 (2016)
[4] L. deClercq et al. PRL 116, 080502 (2016)
[5] L. deClercq et al. arXiv:1509.07083 (2015)
[6] J. Alonso et al. Nat Comms 7, 11243 (2016)

LOCATION:Erwin-Schödinger-Saal, IQOQI
DTSTART:20160412T133000
DTEND:20160412T143000
TZID: Europe/Vienna
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