Testing magnetic a decoherence-free subspace and its limits.

CHRISTIAN TOMÁS SCHMIEGELOW

Mar del Plata

Congreso; Quantum Optics VII; 2015

p { margin-bottom: 0.08in; }We present experimental resultsbenchmarking the decoherence-free subspace formed by the groundmagnetic Zeeman levels of two 40Ca+ ions. Theodd entangled states of a pair of qubits can form a decoherence-freesubspace if both qubits are close enough to fell the same externalfluctuations. However, if the two physical systems carrying thequbits are far enough, they will no longer feel the same externalfluctuations and the decoherence subspace breaks. We show how farthis decoherence free subspace holds for the magnetic Zeemansub-levels of two trapped calcium ions by bringing them apart in asegmented linear Paul trap. We do so by preparing different entangledstates of an ion crystal which we then separate by distances from afew um to up to a few mm, wait and finally tomograph.