Dr. Alexander Grimm

Since July 2022 Alexander is the group leader of the bosonic quantum information group after joining the Paul Scherrer Institut as a tenure-track scientist in November 2019. He obtained his PhD for research done between 2011 and 2015 in the group of Max Hofheinz at CEA Grenoble. During this time, he experimentally demonstrated that inelastic Cooper pair tunneling through a voltage-biased Josephson junction can be leveraged to create a source of antibunched microwave radiation. As part of this effort, he developed a novel fabrication method for vertical NbN-MgO-NbN Josephson junctions. From 2016 to 2019 he was part of the group of Michel Devoret at Yale University as a postdoctoral associate, working on autonomous quantum error correction (QEC) in bosonic codes. There, he performed various QEC experiments including the demonstration and operation of a ‘’Kerr-cat qubit’’, a type of bosonic qubit which is encoded into superpositions of stabilized coherent states. For his contributions to the field of quantum information processing with non-linear effects in Josephson junctions he received the 2022 Nicholas Kurti prize.

Alexander has 10+ years of experience in quantum measurement and control, cryogenics, as well as superconducting circuit design and fabrication. His research interests lie in experimental bosonic quantum information processing and in the investigation of nonlinear and parametric effects in Josephson-junction-based devices. He is in particular interested in the combination of the two where the application of well-chosen microwave drives to a nonlinear superconducting resonator results in controlled dissipation and engineered Hamiltonians, both of which are useful for quantum computation as well as interesting from a fundamental physics point of view.

Selected publications. For a full list see: Google Scholar

1. A. Grimm*, N.E. Frattini*, S. Puri, S.O. Mundhada, S. Touzard, M. Mirrahimi, S.M. Girvin, S. Shankar, and M.H. Devoret, Stabilization and operation of a Kerr-Cat qubit. Nature 584, 205-209 (2020). *equal contribution
2. S. Puri, L. St-Jean, J.A. Gross, A. Grimm, N.E. Frattini, P.S. Iyer, A. Krishna, S. Touzard, L. Jiang, A. Blais, S.T. Flammia and S.M. Girvin, Bias-preserving gates with stabilized cat qubits. Science Advances 6, 34 (2020).
3. S.O. Mundhada, A. Grimm, J. Venkatraman, Z.K. Minev, S. Touzard, N.E. Frattini, V.V. Sivak, P. Reinhold, S. Shankar, M. Mirrahimi, and M.H. Devoret, Experimental Implementation of a Raman Assisted Eight-Wave Mixing Process. Phys. Rev. Appl. 12, 054051 (2019).
4. S. Puri, A. Grimm, P. Campagne-Ibarcq, A. Eickbusch, K. Noh, G. Roberts, L. Jiang, M. Mirrahimi, M.H. Devoret and S.M. Girvin, A stabilized cat in a driven nonlinear cavity: a fault-tolerant error syndrome detector. Phys. Rev. X 9, 041009 (2019).
5. S. Touzard, A. Kou, N.E. Frattini, V.V. Sivak, S. Puri, A. Grimm, L. Frunzio, S. Shankar, and M.H. Devoret, Gated Conditional Displacement Readout of Superconducting Qubits. Phys. Rev. Lett. 122, 080502 (2019).
6. A. Grimm, F. Blanchet, R. Albert, J. Leppäkangas, S. Jebari, D. Hazra, F. Gustavo, J.-L. Thomassin, E. Dupont-Ferrier, F. Portier and M. Hofheinz, Bright on-demand source of anti-bunched microwave photons based on inelastic Cooper pair tunneling. Phys. Rev. X 9, 021016 (2019).
7. V. V. Albert, S. O. Mundhada, A. Grimm, S. Touzard, M. H. Devoret and L. Jiang, Pair-cat codes: autonomous error-correction with low-order nonlinearity. Quantum Sci. Technol. 4, 035007 (2019).
8. D. Hazra, N. Tsavdaris, A. Mukhtarova, M. Jacquemin, F. Blanchet, R. Albert, S. Jebari, A. Grimm, A. Konar, E. Blanquet, F. Mercier, C. Chapelier and M. Hofheinz, Superconducting properties of NbTiN thin films deposited by high-temperature chemical vapor deposition. Phys. Rev. B 97, 144518 (2018).
9. S. Touzard, A. Grimm, Z. Leghtas, S.O. Mundhada, P. Reinhold, C. Axline, M. Reagor, K. Chou, J. Blumoff, K.M. Sliwa, S. Shankar, L. Frunzio, R.J. Schoelkopf, M. Mirrahimi and M.H. Devoret, Coherent oscillations inside a quantum manifold stabilized by dissipation. Phys. Rev. X 8, 021005 (2018).
10. S. Jebari, F. Blanchet, A. Grimm, D. Hazra, R. Albert, P. Joyez, D. Vion, D. Esteve, F. Portier and M. Hofheinz, Near-quantum-limited amplification from inelastic Cooper pair tunneling. Nature Electronics 1, 223 (2018).
11. A. Grimm, S. Jebari, D. Hazra, F. Blanchet, F. Gustavo, J.-L. Thomassin and M. Hofheinz, A selfaligned nano-fabrication process for vertical NbN-MgO-NbN Josephson junctions. Supercond. Sci. Technol. 30, 105002 (2017).
12. S.O. Mundhada, A. Grimm, S. Touzard, U. Vool, S. Shankar, M.H. Devoret and M. Mirrahimi, Generating higher-order quantum dissipation from lower-order parametric processes. Quantum Sci. Technol. 2, 024005 (2017).
13. D. Hazra, N. Tsavdaris, S. Jebari, A. Grimm, F. Blanchet, F. Mercier, E. Blanquet, C. Chapelier and M. Hofheinz, Superconducting properties of very high quality NbN thin films grown by high temperature chemical vapor deposition. Supercond. Sci. Technol. 29, 105011 (2016).
14. J. Leppäkangas, M. Fogelström, A. Grimm, M. Hofheinz, M. Marthaler and G. Johansson, Antibunched Photons from Inelastic Cooper-Pair Tunneling. Phys. Rev. Lett. 115, 027004 (2015).

1. The Kerr-cat Qubit: Stabilization, Readout, and Gates, APS March Meeting, Denver, USA, 2020 (delivered digitally: link)
2. The Kerr-cat Qubit: Stabilization, Readout, and Gates, NCCR QSIT general meeting, Arosa, Switzerland, 2020
3. Stabilization, Readout, and Operation of a Kerr-Cat Qubit in a Superconducting Resonator, University of New South Wales, Sydney, Australia, 2019
4. The Kerr-cat Qubit: Stabilization, Readout, and Gates, University of Sydney, Sydney, Australia, 2019
5. Stabilizing a noise-biased qubit in a Kerr-nonlinear resonator, Byron bay quantum invitational (BBQI), Byron bay, Australia, 2019
6. The Kerr-cat Qubit: Stabilization, Readout, and Gates, University of Chicago PME special seminar, Chicago, USA, 2019
7. Stabilization and operation of a protected qubit in a Kerr-nonlinear resonator, IQ Sherbrooke EPIQ seminar, Sherbrooke, Canada, 2019
8. Engineering statistics of photons emitted by inelastic Cooper-pair tunneling, PQE conference, Snowbird, Utah, USA, 2016
9. Josephson photonics: Statistics of photons emitted by inelastic Cooper-pair tunneling, ETH QSIT seminar, Zürich, Switzerland, 2015

1. S. Puri, A. Grimm, P. Campagne-Ibarcq, S. M. Girvin, M. H. Devoret, Fault-tolerant measurements and gates for quantum information processing, PCT US2019/039945, filed June 29, 2018.
2. V.V. Albert, S.O. Mundhada, A. Grimm, S. Touzard, M. H. Devoret, L. Jiang, Techniques for error correction of a logical qubit and related systems and methods, PCT US2019/012438, filed January 5, 2019.