J Robert Johansson, Ph.D.

Previously at the iTHES research group, RIKEN.

Contact Information

PGP public key
here
ORCID
0000-0002-4500-5775
Researcher ID
C-6224-2008
ResearchGate
Robert Johansson
Figshare
Robert_Johansson/492016
Github
jrjohansson
Office phone
+81 (0) 48 - 462 - 1111 ext. 3353
Fax
+81 (0) 48 - 467 - 9650
Office address
Main Research Building Room #308
iTHES Research Group, RIKEN
2-1 Hirosawa, Wako-shi, Saitama 351-0198, JAPAN

Research

I work with theoretical and computational solid-state physics, with focus on quantum mechanics in superconducting electrical circuits. I have worked on qubits for quantum computing, artificial-atom and resonator circuits for on-chip atomic and quantum-optics-like physics in the microwave regime, and on quantum vacuum related phenomena, such as the dynamical Casimir effect.

Publications

  1. M.F. Gonzalez-Zalba, S.N. Shevchenko, S. Barraud, J.R. Johansson, A.J. Ferguson, F. Nori, and A.C. Betz Gate-Sensing Coherent Charge Oscillations in a Silicon Field-Effect Transistor, Nano Lett. 16 (3) 1614–1619 (2016) [ NanoLett, PDF ]
  2. A.M. Zagoskin, A. Chipouline, E. Il'ichev, J.R. Johansson, F. Nori, Toroidal qubits: naturally-decoupled quiet artificial atoms, Sci. Rep. 5, 16934 (2015) [ arXiv:1406.7678, SREP, PDF ]
  3. G.-W. Deng, D. Wei, J.R. Johansson, M.-L. Zhang, S.-X. Li, H.-O. Li, G. Cao, M. Xiao, T. Tu, G.-C. Guo, H.-W. Jiang, F. Nori, and G.-P. Guo, Charge number dependence of the dephasing rates of a graphene double quantum dot in a circuit QED architecture, Phys. Rev. Lett. 115, 126804 (2015). [ PRL, PDF ]
  4. G.-W. Deng, D. Wei, S.-X. Li, J. R. Johansson, W.-C. Kong, H.-O. Li, G. Cao, M. Xiao, G.-C. Guo, F. Nori, H.-W. Jiang, G.-P. Guo, Coupling two distant double quantum dots to a microwave resonator, Nano Letters 5, 02400 (2015). [ ACS NL, PDF, arXiv:1310.6118 ]
  5. X.-Y. Lü, Y. Wu, J.R. Johansson, H. Jing, J. Zhang, F. Nori Squeezed Optomechanics with Phase-matched Amplification and Dissipation, Phys. Rev. Lett. 114, 093602 (2015) [ PRL, PDF, arXiv:1412.2864 ]
  6. E.-J. Kim, J.R. Johansson, F. Nori Circuit analog of quadratic optomechanics, Phys. Rev. A 91, 033835 (2015) [ PRA, PDF, arXiv:1412.6869 ]
  7. P. D. Nation, J. R. Johansson, M. P. Blencowe, A. J. Rimberg, Iterative solutions to the steady-state density matrix for optomechanical systems, Phys. Rev. E 91, 013307 (2015). [ PRE, PDF, arXiv:1411.4356 ]
  8. J.R. Johansson, G. Johansson, F. Nori, Optomechanical-like coupling between superconducting resonators, Phys. Rev. A 90 053833 (2014). [ PRA, PDF, arXiv:1403.4341 ]
  9. J.R. Johansson, N. Lambert, I. Mahboob, H. Yamaguchi, F. Nori, Entangled-state generation and Bell inequality violations in nanomechanical resonators, Phys. Rev. B 90, 174307 (2014). [ PRB, PDF, arXiv:1402.4900, Source code ]
  10. J.R. Johansson, G. Johansson, C.M. Wilson, P. Delsing, F. Nori, Nonclassical microwave radiation from the dynamical Casimir effect, Phys. Rev. A 87, 043804 (2013). [ PRA, PDF, arXiv:1207.1988 ]
  11. J.R. Johansson, P.D. Nation, F. Nori, QuTiP 2: A Python framework for the dynamics of open quantum systems, Comp. Phys. Comm. 184, 1234 (2013). [ CPC, PDF, arXiv:1211.6518 ]
  12. J. Stehlik, Y. Dovzhenko, J.R. Petta, J.R. Johansson, F. Nori, H. Lu, A.C. Gossard, Landau-Zener-Stückelberg interferometry of a single electron charge qubit, Phys. Rev. B 86, 121303(R) (2012) [ PRB, PDF, arXiv:1205.6173 ]
  13. J.R. Johansson, P.D. Nation, F. Nori, QuTiP: An open-source Python framework for the dynamics of open quantum systems, Comp. Phys. Comm. 183, 1760 (2012). [ CPC, PDF, arXiv:1110.0573 ]
  14. P.D. Nation, J.R. Johansson, M.P. Blencowe, F. Nori, Stimulating Uncertainty: Amplifying the Quantum Vacuum with Superconducting Circuits, Rev. Mod. Phys. 84, 1 (2012). [ RMP, PDF, arXiv:1103.0835 ].
  15. N. Lambert, J.R. Johansson, F. Nori, A macro-realism inequality for opto-electro-mechanical systems, Phys. Rev. B 82, 245421 (2011). [ PRB, PDF, arXiv:1106.3138 ].
  16. C.M. Wilson, G. Johansson, A. Pourkabirian, M. Simoen, J.R. Johansson, T. Duty, F. Nori, P. Delsing, Observation of the dynamical Casimir effect in as superconducting circuit, Nature 479, 376 (2011). Physics Breakthroughs 2011 [ Nature, PDF, Supplementary information, arXiv:1105.4714].
    See also Nature News and Views Quantum physics: Shaking photons out of the vacuum by D.A.R. Dalvit. [ Nature, PDF ].
    Selected as one of the top ten physics breakthoughs in 2011 by Physics World [PDF]
  17. J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in superconducting microwave circuits, Phys. Rev. A 82, 052509 (2010). [PRA, PDF, arXiv:1007.1058].
  18. N. Lambert, Y. Chen, J.R. Johansson, F. Nori, Quantum chaos and critical behavior on a chip, Phys. Rev. B 80, 165308 (2009). [PRB, PDF, arXiv:0905.4794].
  19. J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in a superconducting coplanar waveguide, Phys. Rev. Lett. 103, 147003 (2009). Physics viewpoint Editor's suggestion [PRL, PDF, arXiv:0906.3127].
    Featured as a Synopsis in Physics [PDF]. Selected as Editor's Suggestion.
  20. S. Ashhab, J.R. Johansson, A.M. Zagoskin, F. Nori, Single-artificial-atom lasing using a voltage-biased superconducting charge qubit, New J. Phys. 11, 023030 (2009). [NJP, PDF, HTML, arXiv:0803.1209].
  21. M. Grajcar, S. Ashhab, J.R. Johansson, F. Nori, Lower limit on the achievable temperature in resonator-based sideband cooling, Phys. Rev. B 78, 035406 (2008). [PRB, PDF, arXiv:0709.3775v1].
  22. L.F. Wei, J.R. Johansson, L.X. Cen, S. Ashhab, F. Nori, Controllable coherent population transfers in superconducting qubits for quantum computing. Phys. Rev. Lett. 100, 113601 (2008). [PRL, PDF, arXiv:0801.4417].
  23. J.R. Johansson, L.G. Mourokh, A.Yu. Smirnov, F. Nori, Enhancing the conductance of a two-electron nanomechanical oscillator, Phys. Rev. B 77, 035428 (2008). [PRB, PDF, cond-mat/0702237].
  24. Y.-X. Liu, L.F. Wei, J.R. Johansson, J.S. Tsai, F. Nori, Superconducting qubits can be coupled and addressed as trapped ions, Phys. Rev. B 76, 144518 (2007). [PRB, PDF, cond-mat/0509236].
  25. A.M. Zagoskin, J.R. Johansson, S. Ashhab, F. Nori, Quantum information processing using frequency control of impurity spins in diamond, Phys. Rev. B 76, 014122 (2007). [PRB, PDF, cond-mat/0703170].
  26. S. Ashhab, J.R. Johansson, A. Zagoskin, F. Nori, Two-level systems driven by large-amplitude fields, Phys. Rev. A 75, 063414 (2007). [PRA, PDF, quant-ph/0702032]
  27. S. Ashhab, J.R. Johansson, F. Nori, Decoherence in a scalable adiabatic quantum computer, Phys. Rev. A. 74, 052330 (2006). [PRA, PDF, quant-ph/0608212].
  28. A. M. Zagoskin, S. Ashhab, J.R. Johansson, F. Nori, Quantum two-level systems in Josephson junctions as naturally formed qubits, Phys. Rev. Lett. 97, 077001 (2006). [PRL, PDF, cond-mat/0603753].
  29. S. Ashhab, J.R. Johansson, F. Nori, Rabi oscillations in a qubit coupled to a quantum two-level system, New J. Phys. 8, 103 (2006). [NJP, PDF, cond-mat/0602577].
  30. S. Ashhab, J.R. Johansson, F. Nori, Decoherence dynamics of a qubit coupled to a quantum two-level system, Physica C, 444, 45-52 (2006). [Physica C, PDF, cond-mat/0512677].

Preprints

  1. G.-W. Deng, D. Wei, J.R. Johansson, M.-L. Zhang, S.-X. Li, H.-O. Li, G. Cao, M. Xiao, T. Tu, G.-C. Guo, H.-W. Jiang, F. Nori, G.-P. Guo, Circuit QED with a graphene double quantum dot and a reflection-line resonator, arXiv:1310.6118 (2013). [ arXiv:1310.6118 ]

Conference Proceedings

  1. For ISQM-TOKYO'08, at Hitachi Research Laboratory, Tokyo Aug. 2008.
    J.R. Johansson, S. Ashhab, A.M. Zagoskin, F. Nori, Single-artificial-atom lasing and its suppression by strong pumping. [PDF]
  2. For MS+S2006 at NTT Basic Research Laboratory, Hon-Atsugi 2006.
    S. Ashhab, J.R. Johansson, F. Nori, Decoherence and Rabi oscillations in a qubit coupled to a quantum two-level system.
    Controllable Quantum States, p. 83 (World Scientific, Singapore, 2008). [PDF, cond-mat/0604475].

Software

QuTiP logo QuTiP is an open source framework for solving the dynamics of open quantum systems written in Python. Developed in collaboration with P.D. Nation.

Wavefunction wavefunction is a Python package for calculating wavefunctions, energy levels, transition rates, etc., for 1 and 2 dimensional potentials. It includes examples for the harmonic oscillator, flux and current bias phase qubits, the Morse potential, and Flux qubits.

QDpack Quantum Dynamics package. A numerical package for simulation of quantum system (unitary evolution, dissipative evolution, steady state, expectation values and correlation functions, etc).

enplot logo Simple one-line command-line tool for plotting data in CSV and related formats. It uses Python/Scipy/matplotlib as backend, and displays plots on the screen or saves them to files.

GSL extention A collection of functions that extend the Gnu Scientific Library (GSL), including conversion between real and complex matrices, exponential of complex-valued matrices (a Taylor-series implementation, and a generalization of the algorithm for real-valued matrices used in the GSL, i.e. the Moler and Van Loan algorithm), and calculation of eigenvalues and eigenvectors for complex-valued GSL matrices by using the ZGEEV LAPACK routine.

MLIB A small stand-alone C library of math functions, including data structures and functions for polynomials, evaluation of Hermite polynomials, factorials, real-valued and complex-valued adaptive quadrature (integral evaluation).

Talks and Lectures

  1. Simulating optomechanics with quantum nanoelectronics [PDF]
    short talk at iTHES Colloquium, Jan 8th, 2015.
  2. Dynamical Casimir Effect and Entangled-Photon Generation in Superconducting Circuits [PDF]
    at Relativistic Quantum Information North 2014, Korea, June 30 - July 4, 2014.
  3. Entangled-state generation in nanomechanical resonators and optomechanical-like coupling in microwave circuits [PDF]
    at NTT Basic Reserach Laboratory, Japan, April 17, 2014.
  4. Dynamical Casimir effect in superconducting circuits [PDF]
    at DTU, Denmark, Jan 31, 2014.
  5. Computational quantum dynamics with QuTiP [PDF]
    at DTU, Denmark, Jan 30, 2014.
  6. Scientific computing with Python [PDF]
    at DTU, Denmark, Jan 30, 2014.
  7. Circuit QED with a graphene double quantum dot and a reflection-line resonator [PDF]
    at Chalmers University, Sweden, Jan 29, 2014.
  8. Entangled-state generation and detection with multimode nanomechanical resonators [PDF]
    at Chalmers University, Sweden, Jan 29, 2014.
  9. Amplification of vacuum fluctuations and the dynamical Casimir effect in superconducting circuit [PDF]
    Interdisciplinary mini-workshop on nonequilibrium physics at Kyoto University, Japan, Dec 7-8, 2013.
  10. Engineered quantum mechanics with nano-electronics [PDF]
    at RIKEN, Japan, August 26th, 2013.
  11. QuTiP: Quantum Toolbox in Python, with circuit-QED applications
    Semiconductor Quantum Chip group, at USTC in Hefei, China, June 27th, 2013.
  12. Scientific computing with Python [Notebooks]
    A lecture series (12 hours) on scientific computing using Python, given at the Applied Quantum Physics Laboratory at Chalmers in Göteborg, Sweden, December 5 - 12, 2012.
  13. Dynamical Casimir effect in superconducting circuits [PDF]
    at the Particle Physics Theory Group at Osaka University, November 27, 2012.
  14. Frequency-tunable resonators and the Dynamical Casimir effect in microwave circuits [PDF]
    Lecture on QuTiP: Quantum Toolbox in Python with case studies in Circuit-QED [PDF]
    The 25th Workshop on Nanoscale and Mesoscopic Systems in Pohang, Korea, November 1-2, 2012.
  15. Dynamical Casimir effect in superconducting circuits [PDF]
    QuLink seminar at NII in Tokyo, Japan, October 22, 2012.
  16. QuTiP: Quantum Toolbox in Python [PDF]
    SciPy 2012, Scientific Computing with Python in Austin, USA, July 16th - 21st, 2012.
  17. Popular science lecture on Research with supercomputers [PDF].
    Tsuru high school, Yamanashi, March 14th 2012.
  18. Dynamical Casimir effect in superconducting circuits [PDF]
    New trends in the physics of the quantum vacuum: from condensed matter, to gravitation and cosmology in Trento, Italy, June 27th to July 1st 2011.
  19. Quantum vacuum amplification in superconducting circuits [PDF]
    International Workshop on the Dynamical Casimir Effect in Padova, Italy, June 6th to 8th 2011.
  20. Dynamical Casimir effect in a coplanar waveguide.
    For the March meeting, Mar. 2010. [PDF].
    Talk at NEC in Tsukuba, Feb. 2010. [PDF].
    Talk at RIKEN Sept. 4th, 2009, and at Chalmers Sept. 28th, 2009. [PDF].
  21. Single-artificial-atom lasing. [PDF].
    Talk at the Quantum Computing workshop at the ITAMP institute at Harvard University, Boston, Oct 6-17, 2008.
  22. Single-artificial-atom lasing (see above).
    Talk at Chalmers, Jul 15th, 2008.
  23. Dynamics of a superconducting qubit coupled to quantum two-level systems in its environment. [PPT].
    Optical Society of America (OSA) workshop on Entanglement and Quantum Decoherence, in Nara, Jan 27-30, 2008.
  24. Decoherence in adiabatic quantum computing. [PDF]
    Discussion style talk at Chalmers, Dec 19th, 2006.
  25. Dynamics and decoherence of a qubit coupled to a two-level system. [PDF]
    Talk at Chalmers, Feb 2nd, 2006.

Lecture notes

Some notes for lectures I have given is available at this github page, including
  1. Computational quantum physics with QuTiP [github repository]
    A series of computationally oriented lectures on quantum mechanics and quantum optics.
  2. Scientific computing with Python [github repository]
    A series of lectures on scientific computing using Python, given at the Applied Quantum Physics Laboratory at Chalmers (December, 2012).

Thesis

My Ph.D. thesis on "Quantum mechanics in superconducting circuits and nanomechanical devices" [PDF] was defended on Oct. 2nd, 2009. My supervisors were by Prof. Göran Johansson at Chalmers University of Technology, and Prof. Franco Nori at RIKEN.

Posters

  1. QuTiP: The quantum toolbox in python [PNG]
    at FIRST annual meeting at U. Tokyo, Dec. 2013.
  2. Nonclassical microwave radiation from the dynamical Casimir effect
    at ICQIT 2013 at NII in Tokyo, Jan. 2013.
  3. Dynamical Casimir effect in a superconducting coplanar waveguide,
    at ISQPT at NII in Tokyo, Apr. 2010.
  4. Dynamical Casimir effect in a superconducting coplanar waveguide,
    US, Aug. 2009.
  5. Photon generation in superconducting transmission lines using Josephson-junction devices,
    at Nobel Symposium - Qubits for Future Quantum Computers, Gothenburg, Sweden, May 2009.
  6. Single-artificial-atom lasing using a voltage-biased superconducting charge qubit,
    at the ISNTT 2009, at NTT Basic Research Laboratory, Hon-Atsugi, Jan. 2009,
    and 3rd Intl. Seminar series on Nanoscience and Engineering in Superconductivity for Young Scientists, Tokyo, Nov. 2008.
  7. Artificial-single-atom lasing and its suppression by strong pumping,
    at ISQM-TOKYO'08, at Hitachi Research Laboratory, Tokyo, Aug. 2008.
  8. Dynamics and decoherence of a qubit coupled to a two-level system,
    at MS+S2006 at NTT Basic Research Laboratory, Hon-Atsugi, Feb. 2006.

Copyright © J Robert Johansson.