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Title: Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing

Abstract

In this paper we provide an operational method to detect multipartite entanglement in ensemble-based quantum computing. This method is based on the concept of the entanglement witness. We decompose the entanglement witness for each class of multipartite entanglement into nonlocal operations in addition to local measurements. Individual single-qubit measurements are performed simultaneously; hence complete detection of entanglement is performed in a single-run experiment. In this sense, our scheme is superior to the generally used entanglement witnesses that require a number of experiments and preparation of copies of quantum state for detection of entanglement.

Authors:
;  [1]; ;  [2]
  1. Department of Physics, Kinki University, 3-4-1 Kowakae, Higashi Osaka 577-8502 (Japan)
  2. Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)
Publication Date:
OSTI Identifier:
20982263
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032317; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; INFORMATION THEORY; QUANTUM COMPUTERS; QUANTUM ENTANGLEMENT; QUANTUM MECHANICS; QUBITS

Citation Formats

Rahimi, Robabeh, Nakahara, Mikio, SaiToh, Akira, and Kitagawa, Masahiro. Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.032317.
Rahimi, Robabeh, Nakahara, Mikio, SaiToh, Akira, & Kitagawa, Masahiro. Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing. United States. doi:10.1103/PHYSREVA.75.032317.
Rahimi, Robabeh, Nakahara, Mikio, SaiToh, Akira, and Kitagawa, Masahiro. Thu . "Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing". United States. doi:10.1103/PHYSREVA.75.032317.
@article{osti_20982263,
title = {Single-experiment-detectable multipartite entanglement witness for ensemble quantum computing},
author = {Rahimi, Robabeh and Nakahara, Mikio and SaiToh, Akira and Kitagawa, Masahiro},
abstractNote = {In this paper we provide an operational method to detect multipartite entanglement in ensemble-based quantum computing. This method is based on the concept of the entanglement witness. We decompose the entanglement witness for each class of multipartite entanglement into nonlocal operations in addition to local measurements. Individual single-qubit measurements are performed simultaneously; hence complete detection of entanglement is performed in a single-run experiment. In this sense, our scheme is superior to the generally used entanglement witnesses that require a number of experiments and preparation of copies of quantum state for detection of entanglement.},
doi = {10.1103/PHYSREVA.75.032317},
journal = {Physical Review. A},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
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  • We propose to encode quantum information in rotational excitations in a molecular ensemble. Using a stripline cavity field for quantum-state transfer between the molecular ensemble and a Cooper-pair-box two-level system, our proposal offers a linear scaling of the number of qubits in our register with the number of rotationally excited states available in the molecules.
  • We investigate quantum many-body systems where all low-energy states are entangled. As a tool for quantifying such systems, we introduce the concept of the entanglement gap, which is the difference in energy between the ground-state energy and the minimum energy that a separable (unentangled) state may attain. If the energy of the system lies within the entanglement gap, the state of the system is guaranteed to be entangled. We find Hamiltonians that have the largest possible entanglement gap; for a system consisting of two interacting spin-1/2 subsystems, the Heisenberg antiferromagnet is one such example. We also introduce a related concept,more » the entanglement-gap temperature: the temperature below which the thermal state is certainly entangled, as witnessed by its energy. We give an example of a bipartite Hamiltonian with an arbitrarily high entanglement-gap temperature for fixed total energy range. For bipartite spin lattices we prove a theorem demonstrating that the entanglement gap necessarily decreases as the coordination number is increased. We investigate frustrated lattices and quantum phase transitions as physical phenomena that affect the entanglement gap.« less