Controlling long ion strings for quantum simulation and precision measurements

Abstract

Scaling a trapped-ion based quantum simulator to a large number of ions creates a fullycontrollable quantum system that becomes inaccessible to numerical methods. When highly anisotropic trapping potentials are used to confine the ions in the form of a long linear string, several challenges have to be overcome to achieve high-fidelity coherent control of a quantum system extending over hundreds of micrometers. In this paper, we describe a setup for carrying out many-ion quantum simulations including single-ion coherent control that we use for demonstrating entanglement in 50-ion strings. Furthermore, we present a set of experimental techniques probing ion-qubits by Ramsey and Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences that enable detection (and compensation) of power-line-synchronous magnetic-field variations, measurement of path length fluctuations, and of the wavefronts of elliptical laser beams coupling to the ion string.

Experimental observation of thermalization with noncommuting charges

“…We perform the experiment on a trapped-ion quantum simulator [8]. A linear string of N = 6-15 40 Ca + ions is confined in a linear Paul trap (Fig.…”

“…The magnetic-field variations occur predominantly at temporally stable 50-Hz harmonics. We reduce the resulting Zeeman-level shifts via feed-forward to a fieldcompensation coil [8]. The amplitudes end up below 3 Hz, for all 50-Hz harmonics between 50 Hz and 900 Hz.…”

“…Two disparate, but conceptually kindred, fields have advanced rapidly over the past few years. In many-body physics, quantum simulators have grown to tens or even hundreds of particles [1][2][3][4][5][6][7] that can be indvidually controlled and measured [8,9]. Experiments have elucidated how closed quantum many-body systems thermalise internally [10][11][12].…”

Ion Coulomb Crystals in Storage Rings for Quantum Information Science

“…Stationary ions may be in the same inertial reference frame as the lasers and other systems used to control and measure eigenstates, but a single set of lasers can only operate on a small number of ions in the trap. Very long ion chains would not be easily addressable [12]. Moving ions, while in a different inertial reference frame, will pass by the system that control and measure the eigenstates.…”

Effective non-local parity-dependent couplings in qubit chains

“…An alternative solution is to implement non-local terms by controlling multiple two-body couplings simultaneously [23][24][25][26][27]. A prime example of such a method is the perfect state transfer along a qubit chain [28][29][30][31][32][33][34][35][36], where an excitation at an initial location is transferred to a final location along the chain.…”