Controlling Two-Qubit Entangled States in Ion-Trap Systems

Lingyan Ai -, Xiangbo Gou -, Chunrui Chang

艾凌艳, 杜刚, 朱诗亮 +1 more

Xiu Ru Lin, Wan-Jun Su

Recently, a genuine five-qubit entangled state [Formula: see text] has been proposed by Man et al. In this paper, we present a simple scheme for generating such a state in ion trap and cavity QED, respectively. This study offers a new approach to faithful controlled teleportation of an arbitrary two-qubit state in these two systems.

Chitra Rangan, Anthony M. Bloch, Christopher R. Monroe +1 more

We present new results on the quantum control of systems with infinitely large Hilbert spaces. A control-theoretic analysis of the control of trapped-ion quantum states via optical pulses is performed. We demonstrate how resonant bichromatic fields can be applied in two contrasting ways--one that makes the system completely uncontrollable and the other that makes the system controllable. In some interesting cases, the Hilbert space of the qubit-harmonic oscillator can be made finite, and the Schrödinger equation controllable via bichromatic resonant pulses. Extending this analysis to the quantum states of two ions, a new scheme for producing entangled qubits is discovered.

Alexandra Olaya-Castro, Neil F. Johnson, Luis Quiroga

We present an efficient scheme for the controlled generation of pure two-qubit states possessing any desired degree of entanglement and a prescribed symmetry. This is achieved in two-qubit-cavity QED systems (e.g., cold-trapped ions and flying atoms) via on-resonance ion- or atom-cavity couplings, which are time dependent and asymmetric, yielding a trapping vacuum state condition which does not arise for identical couplings. A duality in the role of the coupling ratio yields states with a given concurrence but opposing symmetries. Both the trapping state condition and the resulting entanglement power are robust against decoherence channels.

Yotam Shapira, Ravid Shaniv, Tom Manovitz +2 more