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  • Featured in Physics
  • Open Access

High-Coherence Fluxonium Qubit

Long B. Nguyen, Yen-Hsiang Lin, Aaron Somoroff, Raymond Mencia, Nicholas Grabon, and Vladimir E. Manucharyan

  • Department of Physics, Joint Quantum Institute, and Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA

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Phys. Rev. X 9, 041041 – Published 25 November, 2019

DOI: https://doi.org/10.1103/PhysRevX.9.041041

Abstract

We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T2>100  μs (T2>400  μs in one device). Moreover, given the state-of-the-art values of the surface loss tangent and the 1/f flux-noise amplitude, the coherence time can be further improved beyond 1 ms. Our results violate a common viewpoint that the number of Josephson junctions in a superconducting circuit—over 102 here—must be minimized for best qubit coherence. We outline how the unique to fluxonium combination of long coherence time and large anharmonicity can benefit both gate-based and adiabatic quantum computing.

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Physics Subject Headings (PhySH)

Viewpoint

Fluxonium Steps up to the Plate

Published 25 November, 2019

A decade-old alternative to the leading superconducting qubit exhibits the coherence times needed for applications.

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Popular Summary

The key characteristic of a superconducting quantum bit (or qubit) is coherence time, which measures how long a qubit can hold information. We report record long coherence—reaching 0.5 ms—in fluxonium, a relatively unexplored superconducting artificial atom with properties desirable for engineering fast, controllable interactions between qubits. Our work significantly expands the toolbox of quantum superconducting circuits, especially in the context of scaling up quantum processors.

A notable feature of fluxonium is that it consists of a superconducting loop interrupted by over 100 Josephson junctions, strips of insulating material a few nanometers thick sandwiched between superconducting layers. This leads to an exceptionally large value of the total inductance of the loop, which makes fluxonium distinct and useful. Having so many junctions per qubit has been generally viewed as a liability for establishing long coherence times. Yet, we conclude that even longer coherence time is likely with our design in the near future by simply upgrading our fabrication procedures to the state of the art. Our experiment thus delivers an important lesson: Complex multijunction circuits can have superior coherence when properly designed.

The reported combination of high coherence and strong anharmonicity of fluxoniums can be readily utilized for improving the fidelity of digital logical operations and constructing analog simulators of strongly interacting quantum spin models.

Article Text

References (59)

  1. M. H. Devoret and R. J. Schoelkopf, Superconducting Circuits for Quantum Information: An Outlook, Science 339, 1169 (2013).
  2. R. J. Schoelkopf and S. M. Girvin, Wiring Up Quantum Systems, Nature (London) 451, 664 (2008).
  3. R. Barends, J. Kelly, A. Megrant, A. Veitia, D. Sank, E. Jeffrey, T. C. White, J. Mutus, A. G. Fowler, B. Campbell et al., Superconducting Quantum Circuits at the Surface Code Threshold for Fault Tolerance, Nature (London) 508, 500 (2014).
  4. S. Boixo, V. N. Smelyanskiy, A. Shabani, S. V. Isakov, M. Dykman, V. S. Denchev, M. H. Amin, A. Yu. Smirnov, M. Mohseni, and H. Neven, Computational Multiqubit Tunnelling in Programmable Quantum Annealers, Nat. Commun. 7, 10327 (2016).
  5. A. Kandala, A. Mezzacapo, K. Temme, M. Takita, M. Brink, J. M. Chow, and J. M. Gambetta, Hardware-Efficient Variational Quantum Eigensolver for Small Molecules and Quantum Magnets, Nature (London) 549, 242 (2017).
  6. R. Versluis, S. Poletto, N. Khammassi, B. Tarasinski, N. Haider, D. J. Michalak, A. Bruno, K. Bertels, and L. DiCarlo, Scalable Quantum Circuit and Control for a Superconducting Surface Code, Phys. Rev. Applied 8, 034021 (2017).
  7. C. Song, K. Xu, W. Liu, C.-P. Yang, S.-B. Zheng, H. Deng, Q. Xie, K. Huang, Q. Guo, L. Zhang, P. Zhang, D. Xu, D. Zheng, X. Zhu, H. Wang, Y.-A. Chen, C.-Y. Lu, S. Han, and J.-W. Pan, 10-Qubit Entanglement and Parallel Logic Operations with a Superconducting Circuit, Phys. Rev. Lett. 119, 180511 (2017).
  8. J. S. Otterbach, R. Manenti, N. Alidoust, A. Bestwick, M. Block, B. Bloom, S. Caldwell, N. Didier, E. S. Fried, S. Hong et al., Unsupervised Machine Learning on a Hybrid Quantum Computer, arXiv:1712.05771.
  9. C. Neill, P. Roushan, K. Kechedzhi, S. Boixo, S. V. Isakov, V. Smelyanskiy, A. Megrant, B. Chiaro, A. Dunsworth, K. Arya et al., A Blueprint for Demonstrating Quantum Supremacy with Superconducting Qubits, Science 360, 195 (2018).
  10. J. M. Martinis, K. B. Cooper, R. McDermott, M. Steffen, M. Ansmann, K. D. Osborn, K. Cicak, S. Oh, D. P. Pappas, R. W. Simmonds et al., Decoherence in Josephson Qubits from Dielectric Loss, Phys. Rev. Lett. 95, 210503 (2005).
  11. C. Wang, C. Axline, Y. Y. Gao, T. Brecht, Y. Chu, L. Frunzio, M. H. Devoret, and R. J. Schoelkopf, Surface Participation and Dielectric Loss in Superconducting Qubits, Appl. Phys. Lett. 107, 162601 (2015).
  12. R. H. Koch, D. P. DiVincenzo, and J. Clarke, Model for 1/f Flux Noise in Squids and Qubits, Phys. Rev. Lett. 98, 267003 (2007).
  13. F. Yoshihara, K. Harrabi, A. O. Niskanen, Y. Nakamura, and J. S. Tsai, Decoherence of Flux Qubits due to 1/f Flux Noise, Phys. Rev. Lett. 97, 167001 (2006).
  14. J.-L. Orgiazzi, C. Deng, D. Layden, R. Marchildon, F. Kitapli, F. Shen, M. Bal, F. R. Ong, and A. Lupascu, Flux Qubits in a Planar Circuit Quantum Electrodynamics Architecture: Quantum Control and Decoherence, Phys. Rev. B 93, 104518 (2016).
  15. F. Yan, S. Gustavsson, A. Kamal, J. Birenbaum, A. P. Sears, D. Hover, T. J. Gudmundsen, D. Rosenberg, G. Samach, S. Weber et al., The Flux Qubit Revisited to Enhance Coherence and Reproducibility, Nat. Commun. 7, 12964 (2016).
  16. C. M. Quintana, Yu Chen, D. Sank, A. G. Petukhov, T. C. White, D. Kafri, B. Chiaro, A. Megrant, R. Barends, B. Campbell et al., Observation of Classical-Quantum Crossover of 1/f Flux Noise and Its Paramagnetic Temperature Dependence, Phys. Rev. Lett. 118, 057702 (2017).
  17. J. S. Kline, M. R. Vissers, F. C. S. da Silva, D. S. Wisbey, M. Weides, T. J. Weir, B. Turek, D. A. Braje, W. D. Oliver, Y. Shalibo et al., Sub-Micrometer Epitaxial Josephson Junctions for Quantum Circuits, Supercond. Sci. Technol. 25, 025005 (2012).
  18. P. Kumar, S. Sendelbach, M. A. Beck, J. W. Freeland, Z. Wang, H. Wang, C. C. Yu, R. Q. Wu, D. P. Pappas, and R. McDermott, Origin and Reduction of 1/f Magnetic Flux Noise in Superconducting Devices, Phys. Rev. Applied 6, 041001 (2016).
  19. J. Koch, T. M. Yu, J. Gambetta, A. A. Houck, D. I. Schuster, J. Majer, A. Blais, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, Charge-Insensitive Qubit Design Derived from the Cooper Pair Box, Phys. Rev. A 76, 042319 (2007).
  20. M. Steffen, S. Kumar, D. P. DiVincenzo, J. R. Rozen, G. A. Keefe, M. B. Rothwell, and M. B. Ketchen, High-Coherence Hybrid Superconducting Qubit, Phys. Rev. Lett. 105, 100502 (2010).
  21. V. E. Manucharyan, J. Koch, L. I. Glazman, and M. H. Devoret, Fluxonium: Single Cooper-Pair Circuit Free of Charge Offsets, Science 326, 113 (2009).
  22. Y.-H. Lin, L. B. Nguyen, N. Grabon, J. S. Miguel, N. Pankratova, and V. E. Manucharyan, Demonstration of Protection of a Superconducting Qubit from Energy Decay, Phys. Rev. Lett. 120, 150503 (2018).
  23. J. Koch, V. Manucharyan, M. H. Devoret, and L. I. Glazman, Charging Effects in the Inductively Shunted Josephson Junction, Phys. Rev. Lett. 103, 217004 (2009).
  24. V. E. Manucharyan, N. A. Masluk, A. Kamal, J. Koch, L. I. Glazman, and M. H. Devoret, Evidence for Coherent Quantum Phase Slips across a Josephson Junction Array, Phys. Rev. B 85, 024521 (2012).
  25. G. Zhu, D. G. Ferguson, V. E. Manucharyan, and J. Koch, Circuit QED with Fluxonium Qubits: Theory of the Dispersive Regime, Phys. Rev. B 87, 024510 (2013).
  26. K. N. Nesterov, I. V. Pechenezhskiy, C. Wang, V. E. Manucharyan, and M. G. Vavilov, Microwave-Activated Controlled-z Gate for Fixed-Frequency Fluxonium Qubits, Phys. Rev. A 98, 030301(R) (2018).
  27. A. Kou, W. C. Smith, U. Vool, R. T. Brierley, H. Meier, L. Frunzio, S. M. Girvin, L. I. Glazman, and M. H. Devoret, Fluxonium-Based Artificial Molecule with a Tunable Magnetic Moment, Phys. Rev. X 7, 031037 (2017).
  28. I. Chiorescu, Y. Nakamura, C. J. P. M. Harmans, and J. E. Mooij, Coherent Quantum Dynamics of a Superconducting Flux Qubit, Science 299, 1869 (2003).
  29. A. Kou, W. C. Smith, U. Vool, I. M. Pop, K. M. Sliwa, M. Hatridge, L. Frunzio, and M. H. Devoret, Simultaneous Monitoring of Fluxonium Qubits in a Waveguide, Phys. Rev. Applied 9, 064022 (2018).
  30. S. Gladchenko, D. Olaya, E. Dupont-Ferrier, B. Doucot, L. B. Ioffe, and M. E. Gershenson, Superconducting Nanocircuits for Topologically Protected Qubits, Nat. Phys. 5, 48 (2009).
  31. M. T. Bell, I. A. Sadovskyy, L. B. Ioffe, A. Yu. Kitaev, and M. E. Gershenson, Quantum Superinductor with Tunable Nonlinearity, Phys. Rev. Lett. 109, 137003 (2012).
  32. M. T. Bell, J. Paramanandam, L. B. Ioffe, and M. E. Gershenson, Protected Josephson Rhombus Chains, Phys. Rev. Lett. 112, 167001 (2014).
  33. G. J. Dolan, Offset Masks for Lift-Off Photoprocessing, Appl. Phys. Lett. 31, 337 (1977).
  34. L. Frunzio, A. Wallraff, D. Schuster, J. Majer, and R. Schoelkopf, Fabrication and Characterization of Superconducting Circuit QED Devices for Quantum Computation, IEEE Trans. Appl. Supercond. 15, 860 (2005).
  35. R. Kuzmin, R. Mencia, N. Grabon, N. Mehta, Y.-H. Lin, and V. E. Manucharyan, Quantum electrodynamics of a superconductor-insulator phase transition, Nat. Phys. 15, 930 (2019).
  36. R. Kuzmin, N. Mehta, N. Grabon, R. Mencia, and V. E. Manucharyan, Superstrong Coupling in Circuit Quantum Electrodynamics, arXiv:1809.10739.
  37. D. I. Schuster, A. Wallraff, A. Blais, L. Frunzio, R.-S. Huang, J. Majer, S. M. Girvin, and R. J. Schoelkopf, ac Stark Shift and Dephasing of a Superconducting Qubit Strongly Coupled to a Cavity Field, Phys. Rev. Lett. 94, 123602 (2005).
  38. A. A. Clerk, M. H. Devoret, S. M. Girvin, F. Marquardt, and R. J. Schoelkopf, Introduction to Quantum Noise, Measurement, and Amplification, Rev. Mod. Phys. 82, 1155 (2010).
  39. J. M. Martinis, M. Ansmann, and J. Aumentado, Energy Decay in Superconducting Josephson-Junction Qubits from Nonequilibrium Quasiparticle Excitations, Phys. Rev. Lett. 103, 097002 (2009).
  40. G. Catelani, R. J. Schoelkopf, M. H. Devoret, and L. I. Glazman, Relaxation and Frequency Shifts Induced by Quasiparticles in Superconducting Qubits, Phys. Rev. B 84, 064517 (2011).
  41. G. Catelani, J. Koch, L. Frunzio, R. J. Schoelkopf, M. H. Devoret, and L. I. Glazman, Quasiparticle Relaxation of Superconducting Qubits in the Presence of Flux, Phys. Rev. Lett. 106, 077002 (2011).
  42. I. M. Pop, K. Geerlings, G. Catelani, R J. Schoelkopf, L. I. Glazman, and M. H. Devoret, Coherent Suppression of Electromagnetic Dissipation due to Superconducting Quasiparticles, Nature (London) 508, 369 (2014).
  43. U. Vool, I. M. Pop, K. Sliwa, B. Abdo, C. Wang, T. Brecht, Y. Y. Gao, S. Shankar, M. Hatridge, G. Catelani et al., Non-Poissonian Quantum Jumps of a Fluxonium Qubit due to Quasiparticle Excitations, Phys. Rev. Lett. 113, 247001 (2014).
  44. C. Wang, Y. Y. Gao, I. M. Pop, U. Vool, C. Axline, T. Brecht, R. W. Heeres, L. Frunzio, M. H. Devoret, G. Catelani et al., Measurement and Control of Quasiparticle Dynamics in a Superconducting Qubit, Nat. Commun. 5, 5836 (2014).
  45. D. G. Ferguson, A. A. Houck, and J. Koch, Symmetries and Collective Excitations in Large Superconducting Circuits, Phys. Rev. X 3, 011003 (2013).
  46. G. Viola and G. Catelani, Collective Modes in the Fluxonium Qubit, Phys. Rev. B 92, 224511 (2015).
  47. P. V. Klimov, J. Kelly, Z. Chen, M. Neeley, A. Megrant, B. Burkett, R. Barends, K. Arya, B. Chiaro, Yu Chen et al., Fluctuations of Energy-Relaxation Times in Superconducting Qubits, Phys. Rev. Lett. 121, 090502 (2018).
  48. D. P. Pappas, M. R. Vissers, D. S. Wisbey, J. S. Kline, and J. Gao, Two Level System Loss in Superconducting Microwave Resonators, IEEE Trans. Appl. Supercond. 21, 871 (2011).
  49. L. DiCarlo, J. M. Chow, J. M. Gambetta, L. S. Bishop, B. R. Johnson, D. I. Schuster, J. Majer, A. Blais, L. Frunzio, S. M. Girvin et al., Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor, Nature (London) 460, 240 (2009).
  50. M. W. Johnson, M. H. S. Amin, S. Gildert, T. Lanting, F. Hamze, N. Dickson, R. Harris, A. J. Berkley, J. Johansson, P. Bunyk et al., Quantum Annealing with Manufactured Spins, Nature (London) 473, 194 (2011).
  51. C. Rigetti, J. M. Gambetta, S. Poletto, B. L. T. Plourde, J. M. Chow, A. D. Córcoles, J. A. Smolin, S. T. Merkel, J. R. Rozen, G. A. Keefe et al., Superconducting Qubit in a Waveguide Cavity with a Coherence Time Approaching 0.1 ms, Phys. Rev. B 86, 100506(R) (2012).
  52. T. M. Hazard, A. D. P. A. Gyenis, A. Di Paolo, A. T. Asfaw, S. A. Lyon, A. A. H. A. Blais, and A. A. Houck, Nanowire Superinductance Fluxonium Qubit, Phys. Rev. Lett. 122, 010504 (2019).
  53. W. Zhang, K. Kalashnikov, W.-S. Lu, P. Kamenov, T. DiNapoli, and M. E. Gershenson, Microresonators Fabricated from High-Kinetic-Inductance Aluminum Films, Phys. Rev. Applied 11, 011003 (2019).
  54. L. Grünhaupt, M. Spiecker, D. Gusenkova, N. Maleeva, S. T. Skacel, I. Takmakov, F. Valenti, P. Winkel, H. Rotzinger, A. V. Ustinov et al., Granular Aluminum: A Superconducting Material for High Impedance Quantum Circuits, Nat. Mater. 18, 816 (2019).
  55. A. Shearrow, G. Koolstra, S. J. Whiteley, N. Earnest, P. S. Barry, F. J. Heremans, D. D. Awschalom, E. Shirokoff, and D. I. Schuster, Atomic Layer Deposition of Titanium Nitride for Quantum Circuits, arXiv:1808.06009, https://doi.org/10.1063/1.5053461.
  56. D. Niepce, J. Burnett, and J. Bylander, High Kinetic Inductance NbN Nanowire Superinductors, Phys. Rev. Applied 11, 044014 (2019).
  57. G. Ithier, E. Collin, P. Joyez, P. J. Meeson, D. Vion, D. Esteve, F. Chiarello, A. Shnirman, Y. Makhlin, J. Schriefl, and G. Schön, Decoherence in a Superconducting Quantum Bit Circuit, Phys. Rev. B 72, 134519 (2005).
  58. R. J. Schoelkopf, A. A. Clerk, S. M. Girvin, K. W. Lehnert, and M. H. Devoret, Qubits as Spectrometers of Quantum Noise, in Quantum Noise in Mesoscopic Physics, edited by Y. V. Nazarov (Springer, Dordrecht, 2003), pp. 175–203.
  59. J. Gambetta, A. Blais, D. I. Schuster, A. Wallraff, L. Frunzio, J. Majer, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf, Qubit-Photon Interactions in a Cavity: Measurement-Induced Dephasing and Number Splitting, Phys. Rev. A 74, 042318 (2006).

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Phys. Rev. X 9, 041041– Published 25 November, 2019
  • Received 6 November 2018
  • Revised 15 September 2019
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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