Quantum Optics Laboratory

Atomic trapped ions are one of the most promising technologies for realising quantum information processing, quantum simulation, and quantum state engineering. The ions are well isolated from the environment, so quantum states can be stored robustly in the internal and motional states. I will describe recent experiments in which we have generated a range of Gaussian states of motion of a single trapped ion using reservoir engineering [1]. We make use of multi-frequency laser fields to couple the motional oscillator to a zero temperature reservoir. The engineered spin-motion couplings lead to cooling in a rotated state basis, producing as the ground state the desired state of interest. We use similar couplings to demonstrate novel techniques for measuring the fidelity of oscillator states. Using a single trapped ion, we also combine for the first time highly squeezed states with superpositions of distinct atomic wavepackets, creating “squeezed Schrödinger’s cats”. We achieve the largest cat state created in any technology so far and make direct measurements, which reveal key features of the squeezed states in phase space [2]. These methods provide tools for studies of quantum computing, entanglement, and metrology. 

[1] D. Kienzler, H.-Y. Lo et al., Science 347, 53 (2015).

[2] H.-Y. Lo, D. Kienzler et al., Nature 521, 336 (2015)