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Experimental realization of the quantum universal NOT gate

Nature volume 419, pages 815–818 (2002)Cite this article

Abstract

In classical computation, a ‘bit’ of information can be flipped (that is, changed in value from zero to one and vice versa) using a logical NOT gate; but the quantum analogue of this process is much more complicated. A quantum bit (qubit) can exist simultaneously in a superposition of two logical states with complex amplitudes, and it is impossible1,2,3 to find a universal transformation that would flip the original superposed state into a perpendicular state for all values of the amplitudes. But although perfect flipping of a qubit prepared in an arbitrary state (a universal NOT operation) is prohibited by the rules of quantum mechanics, there exists an optimal approximation2 to this procedure. Here we report the experimental realization of a universal quantum machine4 that performs the best possible approximation to the universal NOT transformation. The system adopted was an optical parametric amplifier of entangled photon states, which also enabled us to investigate universal quantum cloning.

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Figure 1: The state space of a qubit is a Poincaré sphere.
Figure 2: Layout of the apparatus used for the experimental verification of the universality of the optical parametric amplifier (OPA).
Figure 3: Experimental verification of the universality of the OPA system for different field polarizations, either linear (Π), circular, or generally elliptical.
Figure 4: Experimental realization of the U-NOT gate. A single photon, N = 1, was injected with a definite π-state into the NL crystal of the OPA along the mode k1.
Figure 5: Experimental verification of the optimum conditions of the U-NOT gate.

References

  1. Bechmann-Pasquinucci, H. & Gisin, N. Incoherent and coherent eavesdropping in the six-state protocol of quantum cryptography. Phys. Rev. A 59, 4238–4248 (1999)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  2. Bužek, V., Hillery, M. & Werner, R. F. Optimal manipulations with qubits: Universal-NOT gate. Phys. Rev. A 60, R2626–R2629 (1999)

    Article  ADS  MathSciNet  Google Scholar 

  3. Gisin, N. & Popescu, S. Spin flips and quantum information for antiparallel spins. Phys. Rev. Lett. 83, 432–435 (1999)

    Article  ADS  CAS  Google Scholar 

  4. Alber, G. et al. Quantum Information: An Introduction to Basic Theoretical Concepts (Springer Tracts in Modern Physics Vol. 173, Springer, Berlin, 2001)

    MATH  Google Scholar 

  5. Derka, R., Bužek, V. & Ekert, A. K. Universal algorithm for optimal estimation from finite ensembles via realizable generalized measurement. Phys. Rev. Lett. 80, 1571–1575 (1998)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  6. De Martini, F. Amplification of quantum entanglement. Phys. Rev. Lett. 81, 2842–2845 (1998)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  7. Simon, C., Weihs, G. & Zeilinger, A. Optimal quantum cloning by stimulated emission. Phys. Rev. Lett. 84, 2993–2996 (2000)

    Article  ADS  CAS  Google Scholar 

  8. De Martini, F., Mussi, V. & Bovino, F. Schroedinger cat states and optimal universal quantum cloning by parametric amplification. Opt. Commun. 179, 581–589 (2000)

    Article  ADS  CAS  Google Scholar 

  9. Lamas-Linares, A., Simon, C., Howell, J. C. & Bouwmeester, D. Experimental quantum cloning of single photons. Science 296, 712–714 (2002)

    Article  ADS  CAS  Google Scholar 

  10. De Martini, F., Di Giuseppe, G. & Padua, S. Multiparticle quantum superpositions and stimulated entanglement by parity selective amplification of entangled states. Phys. Rev. Lett. 87, 150401 (2001)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We thank M. Hillery, C. Simon, S. Popescu, M. D'Ariano for discussions, and V. Mussi, A. Mazzei, F. Bovino, S. Padua for early experimental collaboration. This work was supported by the FET European Networks ATESIT, EQUIP, QUBITS, MURST, and INFM.

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Authors and Affiliations

  1. Dipartimento di Fisica and Istituto Nazionale di Fisica della Materia, Università “La Sapienza”, 00185, Roma, Italy

    F. De Martini, F. Sciarrino & C. Sias

  2. Research Center for Quantum Information, Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 842 28, Bratislava, Slovakia

    V. Bužek

  3. Department of Mathematical Physics, National University of Ireland, Maynooth, Ireland

    V. Bužek

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  1. F. De Martini
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  2. V. Bužek
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  4. C. Sias
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Correspondence to F. De Martini.

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De Martini, F., Bužek, V., Sciarrino, F. et al. Experimental realization of the quantum universal NOT gate. Nature 419, 815–818 (2002). https://doi.org/10.1038/nature01093

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