Saberi, Hamed (2011) Ancilla-assisted sequential approximation of nonlocal unitary operations. PHYSICAL REVIEW A, 84 (3): 032323. ISSN 1050-2947,
Full text not available from this repository.Abstract
We consider the recently proposed "no-go" theorem of Lamata et al. [Phys. Rev. Lett. 101, 180506 (2008)] on the impossibility of sequential implementation of global unitary operations with the aid of an itinerant ancillary system and view the claim within the language of Kraus representation. By virtue of an extremely useful tool for analyzing entanglement properties of quantum operations, namely, operator-Schmidt decomposition, we provide alternative proof to the no-go theorem and also study the role of initial correlations between the qubits and ancilla in sequential preparation of unitary entanglers. Despite the negative response from the no-go theorem, we demonstrate explicitly how the matrix-product operator (MPO) formalism provides a flexible structure to develop protocols for sequential implementation of such entanglers with an optimal fidelity. The proposed numerical technique, which we call variational matrix-product operator (VMPO), offers a computationally efficient tool for characterizing the "globalness" and entangling capabilities of nonlocal unitary operations.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | QUANTUM-SYSTEMS; SEPARABILITY; DISTILLABILITY; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics > Chair Professor Grifoni > Group Milena Grifoni |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 29 May 2020 12:35 |
| Last Modified: | 29 May 2020 12:35 |
| URI: | https://pred.uni-regensburg.de/id/eprint/20169 |
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