Coherent Control of the Rotational Degree of Freedom of a Two-Ion Coulomb Crystal

Abstract

We demonstrate the preparation and coherent control of the angular momentum state of a twoion crystal. The ions are prepared with an average angular momentum of 7780 freely rotating at 100 kHz in a circularly symmetric potential, allowing us to address rotational sidebands. By coherently exciting these motional sidebands, we create superpositions of states separated by up to four angular momentum quanta. Ramsey experiments show the expected dephasing of the superposition which is dependent on the number of quanta separating the states. These results demonstrate coherent control of a collective motional state described as a quantum rotor in trapped ions. Moreover, our work offers an expansion of the utility of trapped ions for quantum simulation, interferometry, and sensing.

Shortcuts to adiabatic rotation of a two-ion chain

“…A natural extension of this work would be considering different boundary conditions, for example a final rotating trap with θ(t f ) = 0, as in reference [16], to transfer an angular momentum to the chain. Another possible future extension would be adding noises and perturbations to make the protocols robust with respect to them.…”

“…The excess energy found with the optimal parameters for the normal modes is negligible in the range of final times depicted in figure 2. Once the free parameters are defined such that the design of θ minimises the excitation energy of the normal modes, we perform the quantum evolution driven by the full Hamiltonian with (16) to check the performance of the designed protocol. We use the "Split-Operator Method", and the initial ground state is found performing an evolution in imaginary time.…”

“…We use the "Split-Operator Method", and the initial ground state is found performing an evolution in imaginary time. Figure 2 shows the final excitation, i.e., the excess energy with respect to the initial energy after performing the evolution with the full Hamiltonian (3) using the potential (16). In figure 2 (a) this excitation is depicted in a linear scale, and in figure 2 (b) in a logarithmic scale.…”

“…Trap rotations, to impart some angular momentum to an ion or ion chain, or to reorient the longitudinal axis of the trap, have been implemented in experiments with improving accuracy [13,16,14,19], and investigated theoretically [20,21].…”

Precision measurement with trapped ions

“…终态中自旋上态概率理论值为 2019年, West [48] 在一个专门用于旋转传感的离子阱 系统物质波干涉仪中研究了这些系统效应, 发现对 势阱的良好控制可以使干涉仪不受实验缺陷的影 响. 同年, Urban等人 [49] 示范了在圆对称势下双离子 库仑晶体量子转子的相干控制. 这些先期工作为后 续更多基于离子阱的量子干涉测量和传感研究开辟 了道路.…”