Quantum gate in the decoherence-free subspace of trapped-ion qubits

¹ Institut für Physik, Johannes Gutenberg-Universität Mainz - 55099 Mainz, Germany, EU
² Department of Physics, Sofia University - James Bourchier 5 blvd, 1164 Sofia, Bulgaria, EU

^a petar.ivanov@uni-ulm.de

Received: 19 July 2010
Accepted: 20 October 2010

Abstract

We propose a geometric phase gate in a decoherence-free subspace with trapped ions. The quantum information is encoded in the Zeeman sublevels of the ground state and two physical qubits to make up one logical qubit with ultra-long coherence time. Single- and two-qubit operations together with the transport and splitting of linear ion crystals allow for a robust and decoherence-free scalable quantum processor. For the ease of the phase gate realization we employ one Raman laser field on four ions simultaneously, i.e. no tight focus for addressing. The decoherence-free subspace is left neither during gate operations nor during the transport of quantum information.