Abstract

We investigate how quantum measurements affect the dynamics of quantum correlations of the system which consists of two noninteracting superconducting qubits each locally coupling to its own data bus. It is shown that the geometric discord and entanglement between two superconducting qubits can be increased by applying a sequence of selective measurements. The optimal measurement time at which the quantum correlations achieve their maximal values is also analyzed. Moreover, we find that the selective measurements on the data buses can protect quantum information of two superconducting qubits and force information to flow back to the superconducting qubits from the data buses by a witness of the trace distance.

© 2013 Optical Society of America

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  1. T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
    [CrossRef]
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  3. J. Q. You, J. S. Tsai, and F. Nori, “Scalable quantum computing with Josephson charge qubits,” Phys. Rev. Lett. 89, 197902 (2002).
    [CrossRef]
  4. T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
    [CrossRef]
  5. A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
    [CrossRef]
  6. A. Blais, A. M. van den Brink, and A. M. Zagoskin, “Tunable coupling of superconducting qubits,” Phys. Rev. Lett. 90, 127901 (2003).
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  7. A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
    [CrossRef]
  8. J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
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    [CrossRef]
  10. M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
    [CrossRef]
  11. Y. Q. Zhang and J. B. Xu, “Entanglement control in a superconducting qubit system by an electromagnetic field,” Eur. Phys. J. D 63, 483–488 (2011).
    [CrossRef]
  12. Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
    [CrossRef]
  13. J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
    [CrossRef]
  14. J. Q. You and F. Nori, “Quantum information processing with superconducting qubits in a microwave field,” Phys. Rev. B 68, 064509 (2003).
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  15. Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
    [CrossRef]
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    [CrossRef]
  18. A. Datta, A. Shaji, and C. M. Caves, “Quantum discord and the power of one qubit,” Phys. Rev. Lett. 100, 050502 (2008).
    [CrossRef]
  19. B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
    [CrossRef]
  20. B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
    [CrossRef]
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  22. E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
    [CrossRef]
  23. A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
    [CrossRef]
  24. E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
    [CrossRef]
  25. B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
    [CrossRef]
  26. T. Yu and J. H. Eberly, “Entanglement evolution in a non-Markovian environment,” Opt. Commun. 283, 676 (2010).
    [CrossRef]
  27. F. Altintas, “Geometric measure of quantum discord in non-Markovian environments,” Opt. Commun. 283, 5264 (2010).
    [CrossRef]
  28. M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
    [CrossRef]
  29. P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
    [CrossRef]
  30. S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
    [CrossRef]
  31. W. K. Wootters, “Entanglement of formation of an arbitrary state of two qubits,” Phys. Rev. Lett. 80, 2245–2248 (1998).
    [CrossRef]
  32. J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
    [CrossRef]
  33. Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
    [CrossRef]

2012 (1)

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

2011 (1)

Y. Q. Zhang and J. B. Xu, “Entanglement control in a superconducting qubit system by an electromagnetic field,” Eur. Phys. J. D 63, 483–488 (2011).
[CrossRef]

2010 (8)

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
[CrossRef]

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
[CrossRef]

B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
[CrossRef]

T. Yu and J. H. Eberly, “Entanglement evolution in a non-Markovian environment,” Opt. Commun. 283, 676 (2010).
[CrossRef]

F. Altintas, “Geometric measure of quantum discord in non-Markovian environments,” Opt. Commun. 283, 5264 (2010).
[CrossRef]

M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
[CrossRef]

2009 (2)

M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
[CrossRef]

H. P. Breuer, E.-M. Laine, and J. Piilo, “Measure for the degree of non-Markovian behavior of quantum processes in open systems,” Phys. Rev. Lett. 103, 210401 (2009).
[CrossRef]

2008 (5)

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
[CrossRef]

A. Datta, A. Shaji, and C. M. Caves, “Quantum discord and the power of one qubit,” Phys. Rev. Lett. 100, 050502 (2008).
[CrossRef]

B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
[CrossRef]

J. Clarke and F. K. Wilhelm, “Superconducting quantum bits,” Nature 453, 1031–1042 (2008).
[CrossRef]

2007 (1)

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

2006 (2)

Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
[CrossRef]

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

2005 (2)

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

2004 (1)

A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
[CrossRef]

2003 (4)

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

A. Blais, A. M. van den Brink, and A. M. Zagoskin, “Tunable coupling of superconducting qubits,” Phys. Rev. Lett. 90, 127901 (2003).
[CrossRef]

J. Q. You and F. Nori, “Quantum information processing with superconducting qubits in a microwave field,” Phys. Rev. B 68, 064509 (2003).
[CrossRef]

2002 (2)

H. Ollivier and W. H. Zurek, “Quantum discord: a measure of the quantumness of correlations,” Phys. Rev. Lett. 88, 017901 (2002).
[CrossRef]

J. Q. You, J. S. Tsai, and F. Nori, “Scalable quantum computing with Josephson charge qubits,” Phys. Rev. Lett. 89, 197902 (2002).
[CrossRef]

2001 (1)

Y. Makhlin, G. Schön, and A. Shnirman, “Quantum-state engineering with Josephson-junction devices,” Rev. Mod. Phys. 73, 357–400 (2001).
[CrossRef]

1999 (1)

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

1998 (1)

W. K. Wootters, “Entanglement of formation of an arbitrary state of two qubits,” Phys. Rev. Lett. 80, 2245–2248 (1998).
[CrossRef]

Alber, G.

M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
[CrossRef]

Ali, M.

M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
[CrossRef]

Almeida, M. P.

B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
[CrossRef]

Altintas, F.

F. Altintas, “Geometric measure of quantum discord in non-Markovian environments,” Opt. Commun. 283, 5264 (2010).
[CrossRef]

Anderson, J. R.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Astafiev, O.

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

Barbieri, M.

B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
[CrossRef]

Barz, S.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Berkley, A. J.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Blais, A.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

A. Blais, A. M. van den Brink, and A. M. Zagoskin, “Tunable coupling of superconducting qubits,” Phys. Rev. Lett. 90, 127901 (2003).
[CrossRef]

Breuer, H. P.

E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
[CrossRef]

H. P. Breuer, E.-M. Laine, and J. Piilo, “Measure for the degree of non-Markovian behavior of quantum processes in open systems,” Phys. Rev. Lett. 103, 210401 (2009).
[CrossRef]

Breuer, H.-P.

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
[CrossRef]

Brukner, C.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
[CrossRef]

Caves, C. M.

A. Datta, A. Shaji, and C. M. Caves, “Quantum discord and the power of one qubit,” Phys. Rev. Lett. 100, 050502 (2008).
[CrossRef]

Chen, M. Y.

M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
[CrossRef]

Chow, J. M.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Chuang, I. L.

M. A. Nielsen and I. L. Chuang, Quantum Computation and Quantum Information (Cambridge University, 2000).

Clarke, J.

J. Clarke and F. K. Wilhelm, “Superconducting quantum bits,” Nature 453, 1031–1042 (2008).
[CrossRef]

Dakic, B.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
[CrossRef]

Datta, A.

A. Datta, A. Shaji, and C. M. Caves, “Quantum discord and the power of one qubit,” Phys. Rev. Lett. 100, 050502 (2008).
[CrossRef]

Devoret, M. H.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Dragt, A. J.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Eberly, J. H.

T. Yu and J. H. Eberly, “Entanglement evolution in a non-Markovian environment,” Opt. Commun. 283, 676 (2010).
[CrossRef]

Facchi, P.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Francica, F.

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

Frunzio, L.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Gambetta, J. M.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Girvin, S. M.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Grajcar, M.

A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
[CrossRef]

Gubrud, M. A.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Gullo, N. L.

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

Houck, A. A.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Johansson, J.

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Johnson, B. R.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Johnson, P. R.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Kakuyanagi, K.

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

Koch, J.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Kropatschek, S.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Laine, E. M.

E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
[CrossRef]

Laine, E.-M.

E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
[CrossRef]

H. P. Breuer, E.-M. Laine, and J. Piilo, “Measure for the degree of non-Markovian behavior of quantum processes in open systems,” Phys. Rev. Lett. 103, 210401 (2009).
[CrossRef]

Lanyon, B. P.

B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
[CrossRef]

Levitov, L. S.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Lidar, D. A.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Lipp, Y. O.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Liu, Y.-X.

Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
[CrossRef]

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

Lloyd, S.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Lobb, C. J.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Ma, X.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Majer, J.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Makhlin, Y.

Y. Makhlin, G. Schön, and A. Shnirman, “Quantum-state engineering with Josephson-junction devices,” Rev. Mod. Phys. 73, 357–400 (2001).
[CrossRef]

Maniscalco, S.

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

Marzo, J. J.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Matsuzaki, Y.

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

Meno, T.

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Mooij, J. E.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Nakamura, Y.

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

Nakano, H.

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Nakazato, H.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Nemes, M. C.

J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
[CrossRef]

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M. A. Nielsen and I. L. Chuang, Quantum Computation and Quantum Information (Cambridge University, 2000).

Nori, F.

Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
[CrossRef]

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

J. Q. You and F. Nori, “Quantum information processing with superconducting qubits in a microwave field,” Phys. Rev. B 68, 064509 (2003).
[CrossRef]

J. Q. You, J. S. Tsai, and F. Nori, “Scalable quantum computing with Josephson charge qubits,” Phys. Rev. Lett. 89, 197902 (2002).
[CrossRef]

Oliveira, J. G.

J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
[CrossRef]

Ollivier, H.

H. Ollivier and W. H. Zurek, “Quantum discord: a measure of the quantumness of correlations,” Phys. Rev. Lett. 88, 017901 (2002).
[CrossRef]

Omelyanchouk, A. N.

A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
[CrossRef]

Orlando, T. P.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Pascazio, S.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Pashkin, Yu. A.

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

Paterek, T.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Piilo, J.

E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
[CrossRef]

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
[CrossRef]

H. P. Breuer, E.-M. Laine, and J. Piilo, “Measure for the degree of non-Markovian behavior of quantum processes in open systems,” Phys. Rev. Lett. 103, 210401 (2009).
[CrossRef]

Plastina, F.

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

Ramos, R. C.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Rau, A. R. P.

M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
[CrossRef]

Ringbauer, M.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Rossi, R.

J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
[CrossRef]

Saito, S.

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Schoelkopf, R. J.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Schön, G.

Y. Makhlin, G. Schön, and A. Shnirman, “Quantum-state engineering with Josephson-junction devices,” Rev. Mod. Phys. 73, 357–400 (2001).
[CrossRef]

Schreier, J. A.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Schuster, D. I.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Semba, K.

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Shaji, A.

A. Datta, A. Shaji, and C. M. Caves, “Quantum discord and the power of one qubit,” Phys. Rev. Lett. 100, 050502 (2008).
[CrossRef]

Shnirman, A.

Y. Makhlin, G. Schön, and A. Shnirman, “Quantum-state engineering with Josephson-junction devices,” Rev. Mod. Phys. 73, 357–400 (2001).
[CrossRef]

Smirne, A.

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

Strauch, F. W.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Sun, C. P.

Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
[CrossRef]

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

Takayanagi, H.

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Tasaki, S.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Tian, L.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Tokuse, A.

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

Tsai, J. S.

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

J. Q. You, J. S. Tsai, and F. Nori, “Scalable quantum computing with Josephson charge qubits,” Phys. Rev. Lett. 89, 197902 (2002).
[CrossRef]

Tu, Matisse W. Y.

M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
[CrossRef]

Ueda, M.

J. Johansson, S. Saito, T. Meno, H. Nakano, M. Ueda, K. Semba, and H. Takayanagi, “Vacuum Rabi oscillations in a macroscopic superconducting qubit LC oscillator system,” Phys. Rev. Lett. 96, 127006 (2006).
[CrossRef]

Vacchini, B.

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

van den Brink, A. M.

A. Blais, A. M. van den Brink, and A. M. Zagoskin, “Tunable coupling of superconducting qubits,” Phys. Rev. Lett. 90, 127901 (2003).
[CrossRef]

van der Wal, C. H.

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Vedral, V.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
[CrossRef]

Wallraff, A.

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

Walther, P.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Wei, L. F.

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

Wellstood, F. C.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

White, A. G.

B. P. Lanyon, M. Barbieri, M. P. Almeida, and A. G. White, “Experimental quantum computing without entanglement,” Phys. Rev. Lett. 101, 200501 (2008).
[CrossRef]

Wilhelm, F. K.

J. Clarke and F. K. Wilhelm, “Superconducting quantum bits,” Nature 453, 1031–1042 (2008).
[CrossRef]

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W. K. Wootters, “Entanglement of formation of an arbitrary state of two qubits,” Phys. Rev. Lett. 80, 2245–2248 (1998).
[CrossRef]

Xu, H.

A. J. Berkley, H. Xu, R. C. Ramos, M. A. Gubrud, F. W. Strauch, P. R. Johnson, J. R. Anderson, A. J. Dragt, C. J. Lobb, and F. C. Wellstood, “Entangled macroscopic quantum states in two superconducting qubits,” Science 300, 1548–1550 (2003).
[CrossRef]

Xu, J. B.

Y. Q. Zhang and J. B. Xu, “Entanglement control in a superconducting qubit system by an electromagnetic field,” Eur. Phys. J. D 63, 483–488 (2011).
[CrossRef]

Yamamoto, T.

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

You, J. Q.

Y.-X. Liu, J. Q. You, L. F. Wei, C. P. Sun, and F. Nori, “Optical selection rules and phasedependent adiabatic state control in a superconducting quantum circuit,” Phys. Rev. Lett. 95, 087001 (2005).
[CrossRef]

J. Q. You and F. Nori, “Quantum information processing with superconducting qubits in a microwave field,” Phys. Rev. B 68, 064509 (2003).
[CrossRef]

J. Q. You, J. S. Tsai, and F. Nori, “Scalable quantum computing with Josephson charge qubits,” Phys. Rev. Lett. 89, 197902 (2002).
[CrossRef]

Yu, T.

T. Yu and J. H. Eberly, “Entanglement evolution in a non-Markovian environment,” Opt. Commun. 283, 676 (2010).
[CrossRef]

Zaffino, R. L.

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

Zagoskin, A. M.

A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
[CrossRef]

A. Blais, A. M. van den Brink, and A. M. Zagoskin, “Tunable coupling of superconducting qubits,” Phys. Rev. Lett. 90, 127901 (2003).
[CrossRef]

Zeilinger, A.

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Zhang, W.-M.

M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
[CrossRef]

Zhang, Y. Q.

Y. Q. Zhang and J. B. Xu, “Entanglement control in a superconducting qubit system by an electromagnetic field,” Eur. Phys. J. D 63, 483–488 (2011).
[CrossRef]

Zurek, W. H.

H. Ollivier and W. H. Zurek, “Quantum discord: a measure of the quantumness of correlations,” Phys. Rev. Lett. 88, 017901 (2002).
[CrossRef]

Eur. Phys. J. D (1)

Y. Q. Zhang and J. B. Xu, “Entanglement control in a superconducting qubit system by an electromagnetic field,” Eur. Phys. J. D 63, 483–488 (2011).
[CrossRef]

Eurphys. Lett. (1)

E. M. Laine, J. Piilo, and H. P. Breuer, “Witness for initial system-environment correlations in open-system dynamics,” Eurphys. Lett. 92, 60010 (2010).
[CrossRef]

Nat. Phys. (1)

B. Dakić, Y. O. Lipp, X. Ma, M. Ringbauer, S. Kropatschek, S. Barz, T. Paterek, V. Vedral, A. Zeilinger, Č. Brukner, and P. Walther, “Quantum discord as resource for remote state preparation,” Nat. Phys. 8, 666–670 (2012).
[CrossRef]

Nature (3)

T. Yamamoto, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, and J. S. Tsai, “Demonstration of conditional gate operation using superconducting charge qubits,” Nature 425, 941–944 (2003).
[CrossRef]

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A. Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, “Coupling superconducting qubits via a cavity bus,” Nature 449, 443–447 (2007).
[CrossRef]

J. Clarke and F. K. Wilhelm, “Superconducting quantum bits,” Nature 453, 1031–1042 (2008).
[CrossRef]

Opt. Commun. (2)

T. Yu and J. H. Eberly, “Entanglement evolution in a non-Markovian environment,” Opt. Commun. 283, 676 (2010).
[CrossRef]

F. Altintas, “Geometric measure of quantum discord in non-Markovian environments,” Opt. Commun. 283, 5264 (2010).
[CrossRef]

Phys. Rev. A (7)

M. Ali, A. R. P. Rau, and G. Alber, “Quantum discord for two-qubit X states,” Phys. Rev. A 81, 042105 (2010).
[CrossRef]

P. Facchi, S. Tasaki, S. Pascazio, H. Nakazato, A. Tokuse, and D. A. Lidar, “Control of decoherence: analysis and comparison of three different strategies,” Phys. Rev. A 71, 022302 (2005).
[CrossRef]

A. Smirne, H.-P. Breuer, J. Piilo, and B. Vacchini, “Initial correlations in open-systems dynamics: the Jaynes-Cummings model,” Phys. Rev. A 82, 062114 (2010).
[CrossRef]

E.-M. Laine, J. Piilo, and H.-P. Breuer, “Measure for the non-Markovianity of quantum processes,” Phys. Rev. A 81, 062115 (2010).
[CrossRef]

J. G. Oliveira, R. Rossi, and M. C. Nemes, “Protecting, enhancing, and reviving entanglement,” Phys. Rev. A 78, 044301 (2008).
[CrossRef]

A. M. Zagoskin, M. Grajcar, and A. N. Omelyanchouk, “Selective amplification of a quantum state,” Phys. Rev. A 70, 060301 (2004).
[CrossRef]

Y.-X. Liu, C. P. Sun, and F. Nori, “Scalable superconducting qubit circuits using dressed states,” Phys. Rev. A 74, 052321 (2006).
[CrossRef]

Phys. Rev. B (4)

J. Q. You and F. Nori, “Quantum information processing with superconducting qubits in a microwave field,” Phys. Rev. B 68, 064509 (2003).
[CrossRef]

M. Y. Chen, Matisse W. Y. Tu, and W.-M. Zhang, “Entangling two superconducting LC coherent modes via a superconducting flux qubit,” Phys. Rev. B 80, 214538 (2009).
[CrossRef]

T. P. Orlando, J. E. Mooij, L. Tian, C. H. van der Wal, L. S. Levitov, S. Lloyd, and J. J. Marzo, “Superconducting persistent-current qubit,” Phys. Rev. B 60, 15398–15413 (1999).
[CrossRef]

Y. Matsuzaki, S. Saito, K. Kakuyanagi, and K. Semba, “Quantum Zeno effect with a superconductin qubit,” Phys. Rev. B 82, 180518 (2010).
[CrossRef]

Phys. Rev. Lett. (11)

H. P. Breuer, E.-M. Laine, and J. Piilo, “Measure for the degree of non-Markovian behavior of quantum processes in open systems,” Phys. Rev. Lett. 103, 210401 (2009).
[CrossRef]

B. Dakić, V. Vedral, and Č. Brukner, “Necessary and sufficient condition for non-zero quantum discord,” Phys. Rev. Lett. 105, 190502 (2010).
[CrossRef]

S. Maniscalco, F. Francica, R. L. Zaffino, N. L. Gullo, and F. Plastina, “Protecting entanglement via the quantum Zeno effect,” Phys. Rev. Lett. 100, 090503 (2008).
[CrossRef]

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Rev. Mod. Phys. (1)

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Figures (8)

Fig. 1.
Fig. 1.

Geometric discord of the superconducting qubits is plotted as a function of the parameters Ωt and |μ0| for Δ=0.5 in free time evolution.

Fig. 2.
Fig. 2.

(a) Geometric discord of the superconducting qubits is plotted as a function of the parameters |μ0| and Δ with one time of selective measurement at τ=π/(2Ω) on the data buses for χ=1. (b) The optimal relation of the systemic parameters for the maximal geometric discord: Δ is plotted as a function of the parameters |μ0| and χ with one time of selective measurement at τ=(2k1)π/(2Ω).

Fig. 3.
Fig. 3.

Geometric discord of the superconducting qubits is plotted as a function of the parameters |μ0| and Ωτ with one time of selective measurement on the data buses at time τ for Δ=0.5.

Fig. 4.
Fig. 4.

Geometric discord of the superconducting qubits is plotted as a function of the parameters Ωt with Δ=0.5 and |μ0|2=0.65 for n (n=5, 10, and 20, respectively) times of selective measurements on the data buses.

Fig. 5.
Fig. 5.

(a) Optimal measurement interval of the superconducting qubits is plotted as a function of the parameters |μ0| and selective measurement times n on the data buses with Δ=0.5. (b) The optimal measurement interval of the superconducting qubits is plotted as a function of the parameters |μ0| and Ω, with the selective measurement times n=1.

Fig. 6.
Fig. 6.

Concurrence of the superconducting qubits is plotted as a function of the parameters |μ0| and Ωτ with one time of selective measurement on the data buses at time τ for Δ=0.5.

Fig. 7.
Fig. 7.

Trace distance D˜ of two states of superconducting qubits is plotted as a function of the parameters Ωt with |μ0|2=0.7, Δϑ=π, and Δ=0 for the freely evolving state (blue line) and with one selective measurement (red line) at time t.

Fig. 8.
Fig. 8.

Maximizing trace distance processing of two states of superconducting qubits is plotted as a function of the measurement times n with |μ0|2=0.8, Δϑ=π, and Ω=1.

Equations (38)

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D(ρ)=minϱ0Ω0ρϱ02,
ρ=14(11+i=13xiσi1+j=13yj1σi+i,j=13tijσiσj).
D(t)=14(x⃗2+T2Kmax),
K=x⃗x⃗T+TTT.
Df(t)=14[(2T112+T332+x32max(T112,T332+x32)].
H=H0+HI,
H0=j=12[12ωqjσjz+(Φj22Lj+Qj22Cjωj2)],
HI=j=12[χj(ωjCjΦjiωjLjQj)σj++H.c.],
ωqj=12Ij2(ΦejΦ0j2)2+TRLj2
U(t)=j=12eiω(kj12)t[cos(Ωjt)iΔjΩjcos(Ωjt)Sj0iχjkjΩjsin(Ωjt)(Sj++Sj)],
kj=12(|eje||gjg|)+Cjωj2Φj2+Ljωj2Qj2
Sj+=1kj|ge|(Cjωj2ΦjiLjωj2Qj),Sj=(Sj+),Sj0=12(|eje||gjg|),
[Sj+,Sj]=2Sj0,[Sj0,Sj±]=±Sj±,
aj=Cjωj2ΦjiLjωj2Qj,aj=Cjωj2Φj+iLjωj2Qj,
[ai,aj]=0,[ai,aj]=δij.
|ϕ(0)=μ0|e,e12+1|μ0|2eiϑ|g,g12,
|ψ=(μ0|e,e12+1|μ0|2eiϑ|g,g12)|0,0AB.
|ψ(t)=(μ1|e,e12+μ4|g,g12)|0,0AB+μ2(|e,g12|0,1AB+|g,e12|1,0AB)+μ3|g,g12|1,1AB.
μ1=μ0exp(iωt)[cos(Ωt)iΔ2Ωsin(Ωt)]2,μ2=iμ0χΩexp(iωt)sin(Ωt)[cos(Ωt)iΔ2Ωsin(Ωt)],μ3=μ0χ2Ω2exp(iωt)sin2(Ωt),μ4=1|μ0|2eiϑexp(iωqt),
ρ12(t)=Tr(ρ(t))=(|μ1|200μ1*μ40|μ2|20000|μ2|20μ1μ4*00|μ3|2+|μ4|2).
|ψ(nτ)=(μ˜n|e,e12+v˜n|g,g12)|0,0AB,
μ˜n=μ0μnexp(inωτ)[cos(Ωτ)iΔ2Ωsin(Ωτ)]2n,v˜n=1|μ0|2eiϑμnexp(inωqτ)
μn=|μ0|2[cos2(Ωτ)+Δ24Ω2sin2(Ωt)]2n+1|μ0|2.
ρZ(nτ)=(|μ˜n|200μ˜nv˜n*00000000μ˜n*v˜n00|v˜n|2).
DZ(nτ)=4D0[cos2(Ωτ)+Δ24Ω2sin2(Ωτ)]2n{1+[cos2(Ωτ)+Δ24Ω2sin2(Ωτ)]2n+12D0[(cos2(Ωτ)+Δ24Ω2sin2(Ωτ))2n1]}2,
Δ=±2χ11|μ0|212n,
τ=1ΩarcsinΩχ11|μ0|212n,
C=max(0,2λ1i=14λi),
λ1,2=(ρ11ρ44±|ρ14|)2=|μ0|2[cos2(Ωt)+Δ24Ω2sin2(Ωt)]2·(|μ0|2[χΩsin(Ωt)]4+1|μ0|2±1|μ0|2)2,λ3,4=ρ22ρ33=|μ0|2[χΩsin(Ωt)]4[cos2(Ωt)+Δ24Ω2sin2(Ωt)]2.
CZ(nτ)=2|μ˜n||1μ˜n2|.
D˜(ρs,ϱs)=12trE|ρϱ|,
D˜(UρU,UϱU)=D˜(ρ,ϱ),
σ(t)=dD˜(ρs,ϱs)dt.
N=maxρs(0),ϱs(0)i[D˜(ρs(ti+1),ϱs(ti+1))][D˜(ρs(ti),ϱs(ti))],
D˜(ρs,ϱs)=12tr|Δρs(t)|,
Δρs(t)=(|μ1|2|μ1|200μ1μ4*μ1μ4*0|μ2|2|μ2|20000|μ2|2|μ2|20μ1*μ4μ1*μ400|μ3|2+|μ4|2|μ3|2|μ4|2).
D˜f=2|μ0|1|μ0|2[cos2(Ωt)+Δ24Ω2sin2(Ωt)],
D˜Z(nτ)=2μ01|μ0|2[cos2(Ωτ)+Δ24Ω2sin2(Ωτ)]n{|μ0|2[cos2(Ωτ)+Δ24Ω2sin2(Ωτ)]2n+1|μ0|2}.

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