---
_id: '8180'
abstract:
- lang: eng
  text: 'Given a bipartite quantum state rho with subsystems A and B of arbitrary
    dimensions, we study the entanglement detecting capabilities of locally noneffective,
    or cyclic, unitary operations [L. B. Fu, Europhys. Lett., vol. 75, pp. 1-7, 2006].
    Local cyclic unitaries have the special property that they leave their target
    subsystem invariant. We investigate the distance between rho and the global state
    after local application of such unitaries as a possible indicator of entanglement.
    To this end, we derive and discuss closed formulae for the maximal such distance
    achievable for three cases of interest: (pseudo)pure quantum states, Werner states,
    and two-qubit states. What makes this criterion interesting, as we show here,
    is that it surprisingly displays behavior similar to recent anomalies observed
    for non-locality measures in higher dimensions, as well as demonstrates an equivalence
    to the CHSH inequality for certain classes of two-qubit states. Yet, despite these
    similarities, the criterion is not itself a non-locality measure. We also consider
    entanglement detection in bound entangled states.'
article_type: original
author:
- first_name: Sevag
  full_name: Gharibian, Sevag
  id: '71541'
  last_name: Gharibian
  orcid: 0000-0002-9992-3379
- first_name: Hermann
  full_name: Kampermann, Hermann
  last_name: Kampermann
- first_name: Dagmar
  full_name: Bru{\ss}, Dagmar
  last_name: Bru{\ss}
citation:
  ama: Gharibian S, Kampermann H, Bru{\ss} D. On global effects caused by locally
    noneffective unitary operations. <i>Quantum Information &#38; Computation</i>.
    2009;9(11):1013-1029.
  apa: Gharibian, S., Kampermann, H., &#38; Bru{\ss}, D. (2009). On global effects
    caused by locally noneffective unitary operations. <i>Quantum Information &#38;
    Computation</i>, <i>9</i>(11), 1013–1029.
  bibtex: '@article{Gharibian_Kampermann_Bru{\ss}_2009, title={On global effects caused
    by locally noneffective unitary operations}, volume={9}, number={11}, journal={Quantum
    Information &#38; Computation}, author={Gharibian, Sevag and Kampermann, Hermann
    and Bru{\ss}, Dagmar}, year={2009}, pages={1013–1029} }'
  chicago: 'Gharibian, Sevag, Hermann Kampermann, and Dagmar Bru{\ss}. “On Global
    Effects Caused by Locally Noneffective Unitary Operations.” <i>Quantum Information
    &#38; Computation</i> 9, no. 11 (2009): 1013–29.'
  ieee: S. Gharibian, H. Kampermann, and D. Bru{\ss}, “On global effects caused by
    locally noneffective unitary operations,” <i>Quantum Information &#38; Computation</i>,
    vol. 9, no. 11, pp. 1013–1029, 2009.
  mla: Gharibian, Sevag, et al. “On Global Effects Caused by Locally Noneffective
    Unitary Operations.” <i>Quantum Information &#38; Computation</i>, vol. 9, no.
    11, 2009, pp. 1013–29.
  short: S. Gharibian, H. Kampermann, D. Bru{\ss}, Quantum Information &#38; Computation
    9 (2009) 1013–1029.
date_created: 2019-03-01T12:12:13Z
date_updated: 2023-02-28T11:04:50Z
department:
- _id: '623'
- _id: '7'
extern: '1'
external_id:
  arxiv:
  - '0809.4469'
intvolume: '         9'
issue: '11'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/0809.4469
oa: '1'
page: 1013-1029
publication: Quantum Information & Computation
publication_status: published
status: public
title: On global effects caused by locally noneffective unitary operations
type: journal_article
user_id: '71541'
volume: 9
year: '2009'
...
---
_id: '8181'
abstract:
- lang: eng
  text: We investigate signatures of non-classicality in quantum states, in particular,
    those involved in the DQC1 model of mixed-state quantum computation [Phys. Rev.
    Lett. 81, 5672 (1998)]. To do so, we consider two known non-classicality criteria.
    The first quantifies disturbance of a quantum state under locally noneffective
    unitary operations (LNU), which are local unitaries acting invariantly on a subsystem.
    The second quantifies measurement induced disturbance (MID) in the eigenbasis
    of the reduced density matrices. We study the role of both figures of non-classicality
    in the exponential speedup of the DQC1 model and compare them vis-a-vis the interpretation
    provided in terms of quantum discord. In particular, we prove that a non-zero
    quantum discord implies a non-zero shift under LNUs. We also use the MID measure
    to study the locking of classical correlations [Phys. Rev. Lett. 92, 067902 (2004)]
    using two mutually unbiased bases (MUB). We find the MID measure to exactly correspond
    to the number of locked bits of correlation. For three or more MUBs, it predicts
    the possibility of superior locking effects.
article_type: original
author:
- first_name: Animesh
  full_name: Datta, Animesh
  last_name: Datta
- first_name: Sevag
  full_name: Gharibian, Sevag
  id: '71541'
  last_name: Gharibian
  orcid: 0000-0002-9992-3379
citation:
  ama: Datta A, Gharibian S. Signatures of nonclassicality in mixed-state quantum
    computation. <i>Physical Review A</i>. 2009;79(4). doi:<a href="https://doi.org/10.1103/physreva.79.042325">10.1103/physreva.79.042325</a>
  apa: Datta, A., &#38; Gharibian, S. (2009). Signatures of nonclassicality in mixed-state
    quantum computation. <i>Physical Review A</i>, <i>79</i>(4). <a href="https://doi.org/10.1103/physreva.79.042325">https://doi.org/10.1103/physreva.79.042325</a>
  bibtex: '@article{Datta_Gharibian_2009, title={Signatures of nonclassicality in
    mixed-state quantum computation}, volume={79}, DOI={<a href="https://doi.org/10.1103/physreva.79.042325">10.1103/physreva.79.042325</a>},
    number={4}, journal={Physical Review A}, publisher={American Physical Society
    (APS)}, author={Datta, Animesh and Gharibian, Sevag}, year={2009} }'
  chicago: Datta, Animesh, and Sevag Gharibian. “Signatures of Nonclassicality in
    Mixed-State Quantum Computation.” <i>Physical Review A</i> 79, no. 4 (2009). <a
    href="https://doi.org/10.1103/physreva.79.042325">https://doi.org/10.1103/physreva.79.042325</a>.
  ieee: 'A. Datta and S. Gharibian, “Signatures of nonclassicality in mixed-state
    quantum computation,” <i>Physical Review A</i>, vol. 79, no. 4, 2009, doi: <a
    href="https://doi.org/10.1103/physreva.79.042325">10.1103/physreva.79.042325</a>.'
  mla: Datta, Animesh, and Sevag Gharibian. “Signatures of Nonclassicality in Mixed-State
    Quantum Computation.” <i>Physical Review A</i>, vol. 79, no. 4, American Physical
    Society (APS), 2009, doi:<a href="https://doi.org/10.1103/physreva.79.042325">10.1103/physreva.79.042325</a>.
  short: A. Datta, S. Gharibian, Physical Review A 79 (2009).
date_created: 2019-03-01T12:12:58Z
date_updated: 2023-02-28T11:05:02Z
department:
- _id: '623'
- _id: '7'
doi: 10.1103/physreva.79.042325
extern: '1'
external_id:
  arxiv:
  - '0811.4003'
intvolume: '        79'
issue: '4'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/0811.4003
oa: '1'
publication: Physical Review A
publication_identifier:
  issn:
  - 1050-2947
  - 1094-1622
publication_status: published
publisher: American Physical Society (APS)
status: public
title: Signatures of nonclassicality in mixed-state quantum computation
type: journal_article
user_id: '71541'
volume: 79
year: '2009'
...
---
_id: '37680'
article_number: '167902'
author:
- first_name: Ch.
  full_name: Silberhorn, Ch.
  last_name: Silberhorn
- first_name: N.
  full_name: Korolkova, N.
  last_name: Korolkova
- first_name: G.
  full_name: Leuchs, G.
  last_name: Leuchs
citation:
  ama: Silberhorn Ch, Korolkova N, Leuchs G. Quantum Key Distribution with Bright
    Entangled Beams. <i>Physical Review Letters</i>. 2002;88(16). doi:<a href="https://doi.org/10.1103/physrevlett.88.167902">10.1103/physrevlett.88.167902</a>
  apa: Silberhorn, Ch., Korolkova, N., &#38; Leuchs, G. (2002). Quantum Key Distribution
    with Bright Entangled Beams. <i>Physical Review Letters</i>, <i>88</i>(16), Article
    167902. <a href="https://doi.org/10.1103/physrevlett.88.167902">https://doi.org/10.1103/physrevlett.88.167902</a>
  bibtex: '@article{Silberhorn_Korolkova_Leuchs_2002, title={Quantum Key Distribution
    with Bright Entangled Beams}, volume={88}, DOI={<a href="https://doi.org/10.1103/physrevlett.88.167902">10.1103/physrevlett.88.167902</a>},
    number={16167902}, journal={Physical Review Letters}, publisher={American Physical
    Society (APS)}, author={Silberhorn, Ch. and Korolkova, N. and Leuchs, G.}, year={2002}
    }'
  chicago: Silberhorn, Ch., N. Korolkova, and G. Leuchs. “Quantum Key Distribution
    with Bright Entangled Beams.” <i>Physical Review Letters</i> 88, no. 16 (2002).
    <a href="https://doi.org/10.1103/physrevlett.88.167902">https://doi.org/10.1103/physrevlett.88.167902</a>.
  ieee: 'Ch. Silberhorn, N. Korolkova, and G. Leuchs, “Quantum Key Distribution with
    Bright Entangled Beams,” <i>Physical Review Letters</i>, vol. 88, no. 16, Art.
    no. 167902, 2002, doi: <a href="https://doi.org/10.1103/physrevlett.88.167902">10.1103/physrevlett.88.167902</a>.'
  mla: Silberhorn, Ch., et al. “Quantum Key Distribution with Bright Entangled Beams.”
    <i>Physical Review Letters</i>, vol. 88, no. 16, 167902, American Physical Society
    (APS), 2002, doi:<a href="https://doi.org/10.1103/physrevlett.88.167902">10.1103/physrevlett.88.167902</a>.
  short: Ch. Silberhorn, N. Korolkova, G. Leuchs, Physical Review Letters 88 (2002).
date_created: 2023-01-20T09:44:56Z
date_updated: 2023-01-30T13:06:06Z
department:
- _id: '288'
- _id: '15'
- _id: '623'
- _id: '230'
doi: 10.1103/physrevlett.88.167902
intvolume: '        88'
issue: '16'
keyword:
- General Physics and Astronomy
language:
- iso: eng
publication: Physical Review Letters
publication_identifier:
  issn:
  - 0031-9007
  - 1079-7114
publication_status: published
publisher: American Physical Society (APS)
status: public
title: Quantum Key Distribution with Bright Entangled Beams
type: journal_article
user_id: '26263'
volume: 88
year: '2002'
...