Research Group Pop

Dr. Ioan Pop Prof. Dr. Ioan Pop

Ioan Pop is a joint professor at KIT and Stuttgart University, following the so-called Jülicher model. This means the research group is located at KIT, with a presence in both the north and south campuses (integrated in the Helmholtz Association), and the teaching duties are at Stuttgart University.

Contact:

KIT
Physikalisches Institut
Wolfgang-Gaede-Str. 1
D-76131 Karlsruhe, Germany

and Institute for Quantum Materials and Technologies (IQMT)

mail ioan.pop∂kit.edu

Education

PhD: 2011 NEEL Institute, CNRS and University of Grenoble, France
Master degree: 2007 Physics, University of Grenoble, France
Diploma degree: 2006 Physics, Babeș-Bolyai University, Cluj-Napoca, Romania

Positions

2020-present: Research group leader in the Helmholtz Association
2015-2020: Startup group leader supported by the Alexander von Humboldt
foundation through a Sofja Kovalevskaja Award
2011-2015: Postdoctoral researcher, Yale University, USA
2007-2011: NEEL Institute, CNRS, Grenoble, France
2007-2010: Teaching assistant, University of Grenoble, France

Fields of research

Our research focuses on superconducting quantum circuits.

Josephson junctions have been proven to be reliable building blocks for superconducting quantum memories, high-speed processing units, amplifiers and detectors, operating in the microwave domain. In these types of electrical circuits, which can be manufactured using standard lithography, currents and voltages can exhibit quantum mechanical properties and can be controlled using microwave pulses. This makes them appealing for the study of fundamental quantum phenomena and the implementation of quantum information processing.

We are currently interested in the design and implementation of quantum circuits protected against decoherence.

Publications Group Pop


2024
Pure kinetic inductance coupling for cQED with flux qubits
Geisert, S.; Ihssen, S.; Winkel, P.; Spiecker, M.; Fechant, M.; Paluch, P.; Gosling, N.; Zapata, N.; Günzler, S.; Rieger, D.; Bénâtre, D.; Reisinger, T.; Wernsdorfer, W.; Pop, I. M.
2024. Applied Physics Letters, 125 (6), Art.-Nr.: 064002. doi:10.1063/5.0218361
Observation of Josephson harmonics in tunnel junctions
Willsch, D.; Rieger, D.; Winkel, P.; Willsch, M.; Dickel, C.; Krause, J.; Ando, Y.; Lescanne, R.; Leghtas, Z.; Bronn, N. T.; Deb, P.; Lanes, O.; Minev, Z. K.; Dennig, B.; Geisert, S.; Günzler, S.; Ihssen, S.; Paluch, P.; Reisinger, T.; Hanna, R.; Bae, J. H.; Schüffelgen, P.; Grützmacher, D.; Buimaga-Iarinca, L.; Morari, C.; Wernsdorfer, W.; DiVincenzo, D. P.; Michielsen, K.; Catelani, G.; Pop, I. M.
2024. Nature Physics, 20 (5), 815–821. doi:10.1038/s41567-024-02400-8Full textFull text of the publication as PDF document
Hydrogen crystals reduce dissipation in superconducting resonators
Valenti, F.; Kanagin, A. N.; Angerer, A.; Buimaga-Iarinca, L.; Morari, C.; Schmiedmayer, J.; Pop, I. M.
2024. Physical Review B, 109 (5), 054503. doi:10.1103/PhysRevB.109.054503Full textFull text of the publication as PDF document
Solomon equations for qubit and two-level systems: Insights into non-Poissonian quantum jumps
Spiecker, M.; Pavlov, A. I.; Shnirman, A.; Pop, I. M.
2024. Physical Review A, 109 (5), Article no: 052218. doi:10.1103/PhysRevA.109.052218
2023
Fano Interference in Microwave Resonator Measurements
Rieger, D.; Günzler, S.; Spiecker, M.; Nambisan, A.; Wernsdorfer, W.; Pop, I. M.
2023. Physical Review Applied, 20 (1), Art.-Nr.: 014059. doi:10.1103/PhysRevApplied.20.014059Full textFull text of the publication as PDF document
Two-level system hyperpolarization using a quantum Szilard engine
Spiecker, M.; Paluch, P.; Gosling, N.; Drucker, N.; Matityahu, S.; Gusenkova, D.; Günzler, S.; Rieger, D.; Takmakov, I.; Valenti, F.; Winkel, P.; Gebauer, R.; Sander, O.; Catelani, G.; Shnirman, A.; Ustinov, A. V.; Wernsdorfer, W.; Cohen, Y.; Pop, I. M.
2023. Nature Physics, 19, 1320–1325. doi:10.1038/s41567-023-02082-8Full textFull text of the publication as PDF document
2022
Granular aluminium nanojunction fluxonium qubit
Rieger, D.; Günzler, S.; Spiecker, M.; Paluch, P.; Winkel, P.; Hahn, L.; Hohmann, J. K.; Bacher, A.; Wernsdorfer, W.; Pop, I. M.
2022. Nature Materials, 22 (2), 194–199. doi:10.1038/s41563-022-01417-9Full textFull text of the publication as PDF document
Operating in a deep underground facility improves the locking of gradiometric fluxonium qubits at the sweet spots
Gusenkova, D.; Valenti, F.; Spiecker, M.; Günzler, S.; Paluch, P.; Rieger, D.; Pioraş-Ţimbolmaş, L.-M.; Zârbo, L. P.; Casali, N.; Colantoni, I.; Cruciani, A.; Pirro, S.; Cardani, L.; Petrescu, A.; Wernsdorfer, W.; Winkel, P.; Pop, I. M.
2022. Applied Physics Letters, 120 (5), Art.-Nr.: 054001. doi:10.1063/5.0075909Full textFull text of the publication as PDF document
2021
Minimizing the Discrimination Time for Quantum States of an Artificial Atom
Takmakov, I.; Winkel, P.; Foroughi, F.; Planat, L.; Gusenkova, D.; Spiecker, M.; Rieger, D.; Grünhaupt, L.; Ustinov, A. V.; Wernsdorfer, W.; Pop, I. M.; Roch, N.
2021. Physical review applied, 15 (6), Art. Nr.: 064029. doi:10.1103/PhysRevApplied.15.064029
Quantum Nondemolition Dispersive Readout of a Superconducting Artificial Atom Using Large Photon Numbers
Gusenkova, D.; Spiecker, M.; Gebauer, R.; Willsch, M.; Willsch, D.; Valenti, F.; Karcher, N.; Grünhaupt, L.; Takmakov, I.; Winkel, P.; Rieger, D.; Ustinov, A. V.; Roch, N.; Wernsdorfer, W.; Michielsen, K.; Sander, O.; Pop, I. M.
2021. Physical review applied, 15 (6), Art. Nr.: 064030. doi:10.1103/PhysRevApplied.15.064030Full textFull text of the publication as PDF document
Reducing the impact of radioactivity on quantum circuits in a deep-underground facility
Cardani, L.; Valenti, F.; Casali, N.; Catelani, G.; Charpentier, T.; Clemenza, M.; Colantoni, I.; Cruciani, A.; D’Imperio, G.; Gironi, L.; Grünhaupt, L.; Gusenkova, D.; Henriques, F.; Lagoin, M.; Martinez, M.; Pettinari, G.; Rusconi, C.; Sander, O.; Tomei, C.; Ustinov, A. V.; Weber, M.; Wernsdorfer, W.; Vignati, M.; Pirro, S.; Pop, I. M.
2021. Nature Communications, 12 (1), Art.-Nr.: 2733. doi:10.1038/s41467-021-23032-zFull textFull text of the publication as PDF document
Subgap Kinetic Inductance Detector Sensitive to 85-GHz Radiation
Levy-Bertrand, F.; Benoît, A.; Bourrion, O.; Calvo, M.; Catalano, A.; Goupy, J.; Valenti, F.; Maleeva, N.; Grünhaupt, L.; Pop, I. M.; Monfardini, A.
2021. Physical Review Applied, 15 (4), Art.-Nr.: 044002. doi:10.1103/PhysRevApplied.15.044002Full textFull text of the publication as PDF document
2020
Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla
Borisov, K.; Rieger, D.; Winkel, P.; Henriques, F.; Valenti, F.; Ionita, A.; Wessbecher, M.; Spiecker, M.; Gusenkova, D.; Pop, I. M.; Wernsdorfer, W.
2020. Applied physics letters, 117 (12), Art.-Nr.: 120502. doi:10.1063/5.0018012
Quantum Versus Classical Switching Dynamics of Driven Dissipative Kerr Resonators
Andersen, C. K.; Kamal, A.; Masluk, N. A.; Pop, I. M.; Blais, A.; Devoret, M. H.
2020. Physical review applied, 13 (4), Art. Nr.: 044017. doi:10.1103/PhysRevApplied.13.044017
Microscopic charging and in-gap states in superconducting granular aluminum
Yang, F.; Gozlinski, T.; Storbeck, T.; Grünhaupt, L.; Pop, I. M.; Wulfhekel, W.
2020. Physical review / B, 102 (10), Art.-Nr. 104502. doi:10.1103/PhysRevB.102.104502
Implementation of a Transmon Qubit Using Superconducting Granular Aluminum
Winkel, P.; Borisov, K.; Grünhaupt, L.; Rieger, D.; Spiecker, M.; Valenti, F.; Ustinov, A. V.; Wernsdorfer, W.; Pop, I. M.
2020. Physical review / X, 10 (3), Art.Nr. 031032. doi:10.1103/PhysRevX.10.031032Full textFull text of the publication as PDF document
Nondegenerate Parametric Amplifiers Based on Dispersion-Engineered Josephson-Junction Arrays
Winkel, P.; Takmakov, I.; Rieger, D.; Planat, L.; Hasch-Guichard, W.; Grünhaupt, L.; Maleeva, N.; Foroughi, F.; Henriques, F.; Borisov, K.; Ferrero, J.; Ustinov, A. V.; Wernsdorfer, W.; Roch, N.; Pop, I. M.
2020. Physical review applied, 13 (2), Art. Nr.: 024015. doi:10.1103/PhysRevApplied.13.024015
DEMETRA: Suppression of the Relaxation Induced by Radioactivity in Superconducting Qubits
Cardani, L.; Casali, N.; Catelani, G.; Charpentier, T.; Clemenza, M.; Colantoni, I.; Cruciani, A.; Gironi, L.; Gruenhaupt, L.; Gusenkova, D.; Henriques, F.; Lagoin, M.; Martinez, M.; Pirro, S.; Pop, I. M.; Rusconi, C.; Ustinov, A.; Valenti, F.; Vignati, M.; Wernsdorfer, W.
2020. Journal of low temperature physics, 199, 475–481. doi:10.1007/s10909-019-02265-9
2019
Onset of phase diffusion in high kinetic inductance granular aluminum micro-SQUIDs
Friedrich, F.; Winkel, P.; Borisov, K.; Seeger, H.; Sürgers, C.; Pop, I. M.; Wernsdorfer, W.
2019. Superconductor science and technology, 32 (12), 125008. doi:10.1088/1361-6668/ab4918Full textFull text of the publication as PDF document
Granular aluminium as a superconducting material for high-impedance quantum circuits
Grünhaupt, L.; Spiecker, M.; Gusenkova, D.; Maleeva, N.; Skacel, S. T.; Takmakov, I.; Valenti, F.; Winkel, P.; Rotzinger, H.; Wernsdorfer, W.; Ustinov, A. V.; Pop, I. M.
2019. Nature materials, 18 (8), 816–819. doi:10.1038/s41563-019-0350-3
Phonon traps reduce the quasiparticle density in superconducting circuits
Henriques, F.; Valenti, F.; Charpentier, T.; Lagoin, M.; Gouriou, C.; Martínez, M.; Cardani, L.; Vignati, M.; Grünhaupt, L.; Gusenkova, D.; Ferrero, J.; Skacel, S. T.; Wernsdorfer, W.; Ustinov, A. V.; Catelani, G.; Sander, O.; Pop, I. M.
2019. Applied physics letters, 115 (21), Art.-Nr.: 212601. doi:10.1063/1.5124967
Electrodynamics of granular aluminum from superconductor to insulator: Observation of collective superconducting modes
Levy-Bertrand, F.; Klein, T.; Grenet, T.; Dupré, O.; Benoît, A.; Bideaud, A.; Bourrion, O.; Calvo, M.; Catalano, A.; Gomez, A.; Goupy, J.; Grünhaupt, L.; Luepke, U. v.; Maleeva, N.; Valenti, F.; Pop, I. M.; Monfardini, A.
2019. Physical review / B, 99 (9), Art. Nr.: 094506. doi:10.1103/PhysRevB.99.094506
Interplay between Kinetic Inductance, Nonlinearity, and Quasiparticle Dynamics in Granular Aluminum Microwave Kinetic Inductance Detectors
Valenti, F.; Henriques, F.; Catelani, G.; Maleeva, N.; Grünhaupt, L.; Von Lüpke, U.; Skacel, S. T.; Winkel, P.; Bilmes, A.; Ustinov, A. V.; Goupy, J.; Calvo, M.; Benoît, A.; Levy-Bertrand, F.; Monfardini, A.; Pop, I. M.
2019. Physical review applied, 11 (5), 054087. doi:10.1103/PhysRevApplied.11.054087
2018
Circuit quantum electrodynamics of granular aluminum resonators
Maleeva, N.; Grünhaupt, L.; Klein, T.; Levy-Bertrand, F.; Dupre, O.; Calvo, M.; Valenti, F.; Winkel, P.; Friedrich, F.; Wernsdorfer, W.; Ustinov, A. V.; Rotzinger, H.; Monfardini, A.; Fistul, M. V.; Pop, I. M.
2018. Nature Communications, 9, Article: 3889. doi:10.1038/s41467-018-06386-9Full textFull text of the publication as PDF document
Tunable ohmic environment using Josephson junction chains
Rastelli, G.; Pop, I. M.
2018. Physical review / B, 97 (20), Art.-Nr.: 205429. doi:10.1103/PhysRevB.97.205429
Simultaneous Monitoring of Fluxonium Qubits in a Waveguide
Kou, A.; Smith, W. C.; Vool, U.; Pop, I. M.; Sliwa, K. M.; Hatridge, M.; Frunzio, L.; Devoret, M. H.
2018. Physical review applied, 9 (6), Art.-Nr. 064022–1. doi:10.1103/PhysRevApplied.9.064022
Fluxon-based quantum simulation in circuit QED
Petrescu, A.; Türeci, H. E.; Ustinov, A. V.; Pop, I. M.
2018. Physical review / B, 98 (17), Art.Nr. 174505. doi:10.1103/PhysRevB.98.174505
Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum
Grünhaupt, L.; Maleeva, N.; Skacel, S. T.; Calvo, M.; Levy-Bertrand, F.; Ustinov, A. V.; Rotzinger, H.; Monfardini, A.; Catelani, G.; Pop, I. M.
2018. Physical review letters, 121 (11), 117001. doi:10.1103/PhysRevLett.121.117001
Driving Forbidden Transitions in the Fluxonium Artificial Atom
Vool, U.; Kou, A.; Smith, W. C.; Frattini, N. E.; Serniak, K.; Reinhold, P.; Pop, I. M.; Shankar, S.; Frunzio, L.; Girvin, S. M.; Devoret, M. H.
2018. Physical review applied, 9 (5), 054046. doi:10.1103/PhysRevApplied.9.054046
Bistability in a mesoscopic Josephson junction array resonator
Muppalla, P. R.; Gargiulo, O.; Mirzaei, S. I.; Venkatesh, B. P.; Juan, M. L.; Grünhaupt, L.; Pop, I. M.; Kirchmair, G.
2018. Physical review / B, 97 (2), Art.Nr. 024518. doi:10.1103/PhysRevB.97.024518
2017
Inductively shunted transmon qubit with tunable transverse and longitudinal coupling
Richer, S.; Maleeva, N.; Skacel, S. T.; Pop, I. M.; DiVincenzo, D.
2017. Physical review / B, 96 (17), Art.Nr. 174520. doi:10.1103/PhysRevB.96.174520
An argon ion beam milling process for native AlOₓ layers enabling coherent superconducting contacts
Grünhaupt, L.; Lüpke, U. von; Gusenkova, D.; Skacel, S. T.; Maleeva, N.; Schlör, S.; Bilmes, A.; Rotzinger, H.; Ustinov, A. V.; Weides, M.; Pop, I. M.
2017. Applied physics letters, 111 (7), Art. Nr. 072601. doi:10.1063/1.4990491
2016
Quantization of inductively shunted superconducting circuits
Smith, W. C.; Kou, A.; Vool, U.; Pop, I. M.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.
2016. Physical review / B, 94 (14), 144507. doi:10.1103/PhysRevB.94.144507
Planar Multilayer Circuit Quantum Electrodynamics
Minev, Z. K.; Serniak, K.; Pop, I. M.; Leghtas, Z.; Sliwa, K. M.; Hatridge, M. J.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.
2016. Physical Review Applied, 5 (4), 044021. doi:10.1103/PhysRevApplied.5.044021