quantum contextuality tests with a single trapped-ion qutrit
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Quantum contextuality tests with a single trapped-ion qutrit
Joseba AlonsoETH Zurich
www.tiqi.ethz.ch
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Trapped Ion Quantum Information GroupETH Zürich
www.tiqi.ethz.ch
3-D wafer trapVlad NegnevitskyChrista FlühmannMatteo MarinelliKaran MehtaChiara Decaroli
Cryo trapFlorian LeupoldChi ZhangMaciej MalinowskiPeng Zhou
PCF trapFrieder LindenfelserSimon RaggKlara Theophilo
Optical trapsMatt GrauChristoph FischerOliver Wipfli
SNSF Consolidator grant
eQual trapRobin OswaldRoland Matt
CollaboratorAdán Cabello
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Cryo surface trap3D wafer trap PCF trap
Optical trap HOA2 trap More traps
Reservoir engineering[Kienzler et al., Science (2015)]
Schrödinger-cat states[Lo et al., Nature (2015)][Kienzler et al., PRL (2016)]
Transport quantum gates[de Clercq et al., PRL (2016)][de Clercq et al., Nat. Comms (2016)]
Multi-species QIPQND measurements for error correctionLeggett-Garg inequalitiesGrid states
Bang-bang control[Alonso et al., NJP (2013)] [Alonso et al., Nat. Comms. (2016)]
Qutrit control and contextuality[Leupold et al., arXiv: 1706.07370 (2017)]
Novel traps[Lindenfelser et al., RSI (2015)]
Laser cooling[Lindenfelser et al., NJP (2017)]
Ion trap: electrodes + vacuum
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Trapped ions for contextuality tests
• Long coherence
• High-fidelity operations
• Non-destructive fluorescence detection (projective measurements)
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1. SIC à la Wajs
2. Extended KCBS tests
Outline
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Previous trapped-ions SIC tests
[G. Kirchmair et al., Nature 460 (2009)][A. Peres, Phys. Lett. A 151 (1990)]
[X. Zhang et al., Phys. Rev. Lett. 110 (2013)][S. Yu and C.H. Oh, Phys. Rev. Lett. 108 (2012)]
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SIC à la Wajs
Repeated measurementsRandom input states
No state initialization – self correctingHigh-order correlators
“Quantumness” is about measurements, not designated states
[M. Wajs et al., Phys. Rev. A 93 (2016)]
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Yu & Oh SIC set
[S. Yu and C.H. Oh, Phys. Rev. Lett. 108 (2012)] [M. Kleinmann et al., Phys. Rev. Lett. 109 (2012)]
• Qutrit: smallest contextual system• Yu & Oh set: smallest SIC set• opt3 witness: largest deviation between NCHV and QM
NCHV QM
NCHV QM
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Experiment
• Measurement choice made in real-time during sequence• 54 million sequential measurements (groups of 1000 + bright restart)
[F.M. Leupold et al., 1706.07370 (2017)]
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Yu & Oh resultsNCHV
QM
NCHV QM
[F.M. Leupold et al., 1706.07370 (2017)]http://www.tiqi.ethz.ch/publications-and-awards/public-datasets.html
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System characterizationFirst 20
data points
[F.M. Leupold et al., 1706.07370 (2017)]http://www.tiqi.ethz.ch/publications-and-awards/public-datasets.html
54M
Sharpness
Compatibility
RepeatabilityRepeatability with interleaved
compatible meas.
Signaling forwards in time Signaling backwards in time
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Cryostat vibrations
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Blind analysis
(d)
(b)
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Contextuality supplies the magic for quantum computation
[M. Howard et al., Nature 510 (2014)]
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Limits of correlations
Does QM correctly predict the limits of correlations in Nature?
NCHV QM
[A. Klyachko, M. Can, A. Binicioglu, A. Shumovsky, Phys. Rev. Lett. 101 (2008)]
• Qutrit: smallest contextual system• KCBS set
• Most fundamental compatibility structure• Largest deviation between NCHV and QM• State dependent
+1
+1
+1
±1-1
-1
-1
[B. Christensen et al., Phys. Rev. X 5 (2015)]
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Experiment
Criticisms to contextuality tests• Detection loophole• Joint measurements• Non-projective measurements• Compatibility/finite-precision
loophole
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On compatibility and finite precision
Perfect compatibility when
[R. Kujala et al., Phys. Rev. Lett. 115 (2015)]
10,000 data points
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KCBS results
10,000 data points
[M. Malinowski et al., in preparation]
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Comparison with previous KCBS tests
[M. Malinowski et al., in preparation]
Reference Platform Open loopholes and criticisms
[R. Lapkiewicz et al, Nature 474 (2011)]
Photons 0.987(2) 0.019 • Detection loophole• Simultaneous measurements• Same observable but different
setup in different contexts
[J. Ahrens et al., Sci. Rep. (2013)]
Photons 0.897(1)0.988(2)
N/A • Detection loophole• Order dependence
[D.L. Deng et al., arXiv:1301.5364 (2013)]
Photons 0.995(3)0.990(6)
0.059 • Detection loophole
[M. Um et al., Sci. Rep. (2013)]
Yb Ion <0.923 ? • Same observable but differentsetup in different contexts
• Non-projective measurements
[M. Jerger et al., Nat. Comms. (2016)]
SC 0.8846(3)0.8907(1)
0.0892(5)0.0931(5)
• Strong decoherence –incompatibility
• Non-projective measurements
This work Ca ion 0.995(2) 0.012(4) ?
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Limits of correlations: larger gons
[A. Cabello, Phys. Rev. Lett. 110 (2013)]
• Fundamental understanding of inequality violation• NCHV and QM predictions approach as N increases
+1
-1
-1
-1+1
+1
±1
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Limits of correlations: larger gons
Beyond QM
QM
Classical
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Limits of correlations: larger gons
Beyond QM
QM
Classical
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Conclusion