1
|
Teixeira W, Mörstedt T, Viitanen A, Kivijärvi H, Gunyhó A, Tiiri M, Kundu S, Sah A, Vadimov V, Möttönen M. Many-excitation removal of a transmon qubit using a single-junction quantum-circuit refrigerator and a two-tone microwave drive. Sci Rep 2024; 14:13755. [PMID: 38877065 PMCID: PMC11178887 DOI: 10.1038/s41598-024-64496-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 06/09/2024] [Indexed: 06/16/2024] Open
Abstract
Achieving fast and precise initialization of qubits is a critical requirement for the successful operation of quantum computers. The combination of engineered environments with all-microwave techniques has recently emerged as a promising approach for the reset of superconducting quantum devices. In this work, we experimentally demonstrate the utilization of a single-junction quantum-circuit refrigerator (QCR) for an expeditious removal of several excitations from a transmon qubit. The QCR is indirectly coupled to the transmon through a resonator in the dispersive regime, constituting a carefully engineered environmental spectrum for the transmon. Using single-shot readout, we observe excitation stabilization times down to roughly 500 ns, a 20-fold speedup with QCR and a simultaneous two-tone drive addressing the e-f and f0-g1 transitions of the system. Our results are obtained at a 48-mK fridge temperature and without postselection, fully capturing the advantage of the protocol for the short-time dynamics and the drive-induced detrimental asymptotic behavior in the presence of relatively hot other baths of the transmon. We validate our results with a detailed Liouvillian model truncated up to the three-excitation subspace, from which we estimate the performance of the protocol in optimized scenarios, such as cold transmon baths and fine-tuned driving frequencies. These results pave the way for optimized reset of quantum-electric devices using engineered environments and for dissipation-engineered state preparation.
Collapse
Affiliation(s)
- Wallace Teixeira
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland.
| | - Timm Mörstedt
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Arto Viitanen
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Heidi Kivijärvi
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - András Gunyhó
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Maaria Tiiri
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Suman Kundu
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Aashish Sah
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Vasilii Vadimov
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
| | - Mikko Möttönen
- QCD Labs, Department of Applied Physics, QTF Centre of Excellence, Aalto University, P.O. Box 13500, FI-00076, Aalto, Finland
- QTF Center of Excellence, VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044, VTT, Finland
| |
Collapse
|
2
|
Subero D, Maillet O, Golubev DS, Thomas G, Peltonen JT, Karimi B, Marín-Suárez M, Yeyati AL, Sánchez R, Park S, Pekola JP. Bolometric detection of Josephson inductance in a highly resistive environment. Nat Commun 2023; 14:7924. [PMID: 38040683 PMCID: PMC10692220 DOI: 10.1038/s41467-023-43668-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 11/10/2023] [Indexed: 12/03/2023] Open
Abstract
The Josephson junction is a building block of quantum circuits. Its behavior, well understood when treated as an isolated entity, is strongly affected by coupling to an electromagnetic environment. In 1983, Schmid predicted that a Josephson junction shunted by a resistance exceeding the resistance quantum RQ = h/4e2 ≈ 6.45 kΩ for Cooper pairs would become insulating since the phase fluctuations would destroy the coherent Josephson coupling. However, recent microwave measurements have questioned this interpretation. Here, we insert a small Josephson junction in a Johnson-Nyquist-type setup where it is driven by weak current noise arising from thermal fluctuations. Our heat probe minimally perturbs the junction's equilibrium, shedding light on features not visible in charge transport. We find that the Josephson critical current completely vanishes in DC charge transport measurement, and the junction demonstrates Coulomb blockade in agreement with the theory. Surprisingly, thermal transport measurements show that the Josephson junction acts as an inductor at high frequencies, unambiguously demonstrating that a supercurrent survives despite the Coulomb blockade observed in DC measurements.
Collapse
Affiliation(s)
- Diego Subero
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland.
| | - Olivier Maillet
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
- Université Paris-Saclay, CEA, CNRS, SPEC, 91191, Gif-sur-Yvette, France
| | - Dmitry S Golubev
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - George Thomas
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Joonas T Peltonen
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Bayan Karimi
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
- QTF Centre of Excellence, Department of Physics, Faculty of Science, University of Helsinki, 00014, Helsinki, Finland
| | - Marco Marín-Suárez
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Alfredo Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autonoma de Madrid, 28049, Madrid, Spain
| | - Rafael Sánchez
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autonoma de Madrid, 28049, Madrid, Spain
| | - Sunghun Park
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autonoma de Madrid, 28049, Madrid, Spain
| | - Jukka P Pekola
- PICO Group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| |
Collapse
|
3
|
Buffoni L, Gherardini S, Zambrini Cruzeiro E, Omar Y. Third Law of Thermodynamics and the Scaling of Quantum Computers. PHYSICAL REVIEW LETTERS 2022; 129:150602. [PMID: 36269957 DOI: 10.1103/physrevlett.129.150602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
The third law of thermodynamics, also known as the Nernst unattainability principle, puts a fundamental bound on how close a system, whether classical or quantum, can be cooled to a temperature near to absolute zero. On the other hand, a fundamental assumption of quantum computing is to start each computation from a register of qubits initialized in a pure state, i.e., at zero temperature. These conflicting aspects, at the interface between quantum computing and thermodynamics, are often overlooked or, at best, addressed only at a single-qubit level. In this Letter, we argue how the existence of a small but finite effective temperature, which makes the initial state a mixed state, poses a real challenge to the fidelity constraints required for the scaling of quantum computers. Our theoretical results, carried out for a generic quantum circuit with N-qubit input states, are validated by test runs performed on a real quantum processor.
Collapse
Affiliation(s)
| | - Stefano Gherardini
- PQI-Portuguese Quantum Institute, 1049-001 Lisboa, Portugal
- CNR-INO, Area Science Park, Basovizza, I-34149 Trieste, Italy
- LENS, University of Florence, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | | | - Yasser Omar
- PQI-Portuguese Quantum Institute, 1049-001 Lisboa, Portugal
- Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Centro de Física e Engenharia de Materiais Avançados (CeFEMA), Physics of Information and Quantum Technologies Group, 1049-001 Lisboa, Portugal
| |
Collapse
|
4
|
Maillet O, Subero D, Peltonen JT, Golubev DS, Pekola JP. Electric field control of radiative heat transfer in a superconducting circuit. Nat Commun 2020; 11:4326. [PMID: 32859939 PMCID: PMC7455700 DOI: 10.1038/s41467-020-18163-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 08/10/2020] [Indexed: 11/18/2022] Open
Abstract
Heat is detrimental for the operation of quantum systems, yet it fundamentally behaves according to quantum mechanics, being phase coherent and universally quantum-limited regardless of its carriers. Due to their robustness, superconducting circuits integrating dissipative elements are ideal candidates to emulate many-body phenomena in quantum heat transport, hitherto scarcely explored experimentally. However, their ability to tackle the underlying full physical richness is severely hindered by the exclusive use of a magnetic flux as a control parameter and requires complementary approaches. Here, we introduce a dual, magnetic field-free circuit where charge quantization in a superconducting island enables thorough electric field control. We thus tune the thermal conductance, close to its quantum limit, of a single photonic channel between two mesoscopic reservoirs. We observe heat flow oscillations originating from the competition between Cooper-pair tunnelling and Coulomb repulsion in the island, well captured by a simple model. Our results highlight the consequences of charge-phase conjugation on heat transport, with promising applications in thermal management of quantum devices and design of microbolometers.
Collapse
Affiliation(s)
- Olivier Maillet
- QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland.
| | - Diego Subero
- QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Joonas T Peltonen
- QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Dmitry S Golubev
- QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Jukka P Pekola
- QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| |
Collapse
|