Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 35: Poster 2
Q 35.2: Poster
Mittwoch, 14. März 2012, 16:30–19:00, Poster.I+II
Experimental quantum measurement reversal using quantum error correction — Philipp Schindler1, Julio Barreiro1, •Daniel Nigg1, Michael Chwalla1,2, and Rainer Blatt1,2 — 1Institut fuer Experimentalphysik, Universitaet Innsbruck, Technikerstrasse 25, A-6020 Innsbruck — 2Institut fuer Quantenoptik und Quanteninformation der Oesterreichischen Akademie der Wissenschaften, Technikerstrasse 21a, A-6020 Innsbruck
We report on the reversal of a quantum measurement using a 3-qubit phase flip quantum error correction algorithm. This algorithm is capable of correcting phase flips and therefore also dephasing on a single qubit. A measurement in the computational basis (Iz) of a single qubit is described by a projection onto the corresponding axis of the Bloch sphere, which can also be interpreted as complete phase damping. This means that the measurement of a single qubit can be undone with a three qubit error correction code protecting against phase-flips. We use the algorithm presented in [1] and adapt it to be able to measure a single qubit once the information is encoded into the protected state. As measurements in ion trap quantum computers heat the motional state of the system it is necessary to re-cool the system before performing the correction step. This cooling has to be performed without affecting the quantum state of the qubits. We use the Raman cooling technique to re-cool the ion string within the sequence. We assess the fidelityof this measurement reversal using quantum process tomography.
[1] P. Schindler, et. al., Science 332, 1059(2011)