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Environmentally decoupled sds -wave Josephson junctions for quantum computing

Nature volume 398, pages 679–681 (1999)Cite this article

Abstract

Quantum computers have the potential to outperform their classical counterparts in a qualitative manner, as demonstrated by algorithms1 which exploit the parallelism inherent in the time evolution of a quantum state. In quantum computers, the information is stored in arrays of quantum two-level systems (qubits), proposals for which include utilizing trapped atoms and photons2,4, magnetic moments in molecules5 and various solid-state implementations6,10. But the physical realization of qubits is challenging because useful quantum computers must overcome two conflicting difficulties: the computer must be scalable and controllable, yet remain almost completely detached from the environment during operation, in order to maximize the phase coherence time11. Here we report a concept for a solid-state ‘quiet’ qubit that can be efficiently decoupled from the environment. It is based on macroscopic quantum coherent states in a superconducting quantum interference loop. Our two-level system is naturally bistable, requiring no external bias: the two basis states are characterized by different macroscopic phase drops across a Josephson junction, which may be switched with minimal external contact.

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Figure 1: Schematic of the junction.
Figure 2: Energy–phase diagrams for the SDS′ SQUID loop.

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References

  1. Ekert, A. & Jozsa, R. Quantum computation and Shor's factoring algorithm. Rev. Mod. Phys. 68, 733–753 (1996).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  2. Cirac, J. I. & Zoller, P. Quantum computations with cold trapped ions. Phys. Rev. Lett. 74, 4091–4094 (1995).

    Article  ADS  CAS  Google Scholar 

  3. Monroe, C., Meekhof, D., King, B., Itano, W. & Wineland, D. Demonstration of a fundamental quantum logic gate. Phys. Rev. Lett. 75, 4714–4717 (1995).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  4. Turchette, Q., Hood, C., Lange, W., Mabushi, H. & Kimble, H. J. Measurement of conditional phase shifts for quantum logics. Phys. Rev. Lett. 75, 4710–4713 (1995).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  5. Gershenfeld, N. A. & Chuang, I. L. Bulk spin-resonance quantum computation. Science 275, 350–356 (1997).

    Article  MathSciNet  CAS  Google Scholar 

  6. Loss, D. & DiVincenzo, D. P. Quantum computation with quantum dots. Phys. Rev. A 57, 120–126 (1998).

    Article  ADS  CAS  Google Scholar 

  7. Shnirman, A., Schön, G. & Hermon, Z. Quantum manipulations of small Josephson junctions. Phys. Rev. Lett. 79, 2371–2374 (1997).

    Article  ADS  CAS  Google Scholar 

  8. Averin, D. V. Adiabatic quantum computation with Cooper pairs. Solid State Commun. 105, 659–664 (1998).

    Article  ADS  CAS  Google Scholar 

  9. Bocko, M. F., Herr, A. M. & Feldman, M. J. Prospects for quantum coherent computation using superconducting electronics. IEEE Trans. Appl. Supercond. 7, 3638–3641 (1997).

    Article  ADS  Google Scholar 

  10. Kane, B. E. Asilicon-based nuclear spin quantum computer. Nature 393, 133–137 (1998).

    Article  ADS  CAS  Google Scholar 

  11. Haroche, S. & Raimond, J.-M. Quantum computing: dream or nightmare? Phys. Today 49, 51–52 (1996).

    Article  Google Scholar 

  12. Wollman, D. A., Van Harlingen, D. J., Lee, W. C., Ginsberg, D. M. & Leggett, A. J. Experimental determination of the superconducting pairing state in YBCO from the phase coherence of YBCO-Pb DC SQUID's. Phys. Rev. Lett. 71, 2134–2137 (1993).

    Article  ADS  CAS  Google Scholar 

  13. Kirtley, J. R. et al. Symmetry of the order parameter in the high-T csuperconductor YBa2Cu3O7−δ. Nature 373, 225–228 (1995).

    Article  ADS  CAS  Google Scholar 

  14. Il'ichev, E. et al. Anomalous periodicity of the current-phase relationship of grain-boundary Josephson junctions in high-T csuperconductors. Preprint cond-mat/9811017 at 〈http://xxx.lanl.gov〉 (1998).

  15. Tinkham, M. in Introduction to SuperconductivityCh. 6.4 and 7.3, (McGraw-Hill, Singapore, 1996).

  16. Likharev, K. K. & Semenov, V. K. RSFQ logic/memory family: A new Josephson-junction technology for sub-terahertz-clock-frequency digital systems. IEEE Trans. Appl. Supercond. 1, 3–28 (1991).

    Article  ADS  Google Scholar 

  17. Joyez, P., Lafarge, P., Filipe, A., Esteve, D. & Devoret, M. H. Observation of parity-induced suppression of Josephson tunneling in the superconducting single electron transistor. Phys. Rev. Lett. 72, 2458–2461 (1994).

    Article  ADS  CAS  Google Scholar 

  18. Ishii, C. Josephson currents through junctions with normal metal barriers. Prog. Theor. Phys. 44, 1525–1547 (1970).

    Article  ADS  Google Scholar 

  19. Caldeira, A. O. & Leggett, A. J. Quantum tunneling in a dissipative system. Ann. Phys. 149, 374–456 (1983).

    Article  ADS  Google Scholar 

  20. Ambegaokar, V., Eckern, U. & Schön, G. Quantum dynamics of tunneling between superconductors. Phys. Rev. Lett. 48, 1745–1748 (1982).

    Article  ADS  CAS  Google Scholar 

  21. Golubov, A. A. & Kuprianov, M. Yu. Theoretical investigation of Josephson tunnel junctions with spatially inhomogeneous superconducting electrodes. J. Low Temp. Phys. 70, 83–130 (1988).

    Article  ADS  Google Scholar 

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Acknowledgements

We thank A. Kitaev, D. Loss, A. Millis and B. Spivak for discussions. This work was supported by the Fonds National Suisse.

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Authors and Affiliations

  1. Department of Physics and Astronomy, Rutgers University, Piscataway, 08854, New Jersey, USA

    Lev B. Ioffe

  2. Theoretische Physik, ETH-Hönggerberg, CH-8093, Zrich, Switzerland

    Vadim B. Geshkenbein, Alban L. Fauchère & Gianni Blatter

  3. Landau Institute for Theoretical Physics, Moscow, 117940, Russia

    Lev B. Ioffe, Vadim B. Geshkenbein & Mikhail V. Feigel'man

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  1. Lev B. Ioffe
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Correspondence to Gianni Blatter.

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Ioffe, L., Geshkenbein, V., Feigel'man, M. et al. Environmentally decoupled sds -wave Josephson junctions for quantum computing. Nature 398, 679–681 (1999). https://doi.org/10.1038/19464

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