Heat Transport in Superconducting Quantum Circuits

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School of Science | Doctoral thesis (article-based) | Defence date: 2019-12-17
Degree programme
65 + app. 65
Aalto University publication series DOCTORAL DISSERTATIONS, 225/2019
Superconducting microwave circuits are a ubiquitous and important tool for devices that exploit the phenomena of superconductivity and cryogenic temperatures as an environment for achieving the generation, manipulation, and detection of quantum states - required for the ongoing development of quantum technologies. In particular, superconducting circuits are a promising platform for the universal quantum computer, which will require an unprecedented density of quantum-coherent elements to perform large-scale quantum-enhanced calculations and simulations, using the framework of cavity quantum electrodynamics.Dissipation and heat in these superconducting circuits is a key source of error and inefficiency, however the thermodynamics in this regime is poorly understood despite its increasing relevancy.This thesis describes the integration of superconducting resonators and artificial atoms derived from superconducting quantum circuits with ultra-sensitive bolometry, for looking at heat transport through superconducting circuits. We will describe the physics and operation of each of these elements, before combining and utilising them to perform heat transport measurements through a superconducting artificial atom coupled to two resonators, each terminated by a normal-metal mesoscopic resistor, with the resistor temperature measured and temperature gradients across the circuit induced by superconducting tunnel-probes. We will present tunable heat transport through this system, firstly when the resonators are symmetric, allowing us to observe the role of dissipation-limited coupling of the resonators to the artificial atom on the locality of the heat transport, then on an asymmetric system, demonstrating a directional rectification of the heat transport. Additionally, we will discuss how each element of the system can be individually characterised, in particular the quality factor of superconducting resonators in the highly-dissipative limit, by exploiting the superconducting transition to perform a background reference. It is suggested that this hybrid quantum system, and these initial experiments provide a promising platform in the emergent field of circuit quantum thermodynamics. We believe that the techniques and tools developed during this thesis present key steps towards the understanding of the thermodynamics of quantum circuits, towards the realisation of devices that can explore heat transport in the quantum limit, such as a quantum heat engine.
Supervising professor
Pekola, Jukka P., Prof., Aalto University, Department of Applied Physics, Finland
superconducting quantum circuit, microwaves, qubit, tunnel junction, quantum heat valve, dissipation, heat bath, NIS thermometry
Other note
  • [Publication 1]: Richard E. George, Jorden Senior, Olli-Pentti Saira, Jukka P. Pekola, Sebastian E. de Graaf, Tobias Lindström, Yuri A. Pashkin. Multiplexing Superconducting Qubit Circuit for Single Microwave Photon Generation. J Low Temp Phys, 2017, 189, 60–75.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201708036346
    DOI: 10.1007/s10909-017-1787-x View at publisher
  • [Publication 2]: Yu-Cheng Chang, Bayan Karimi, Jorden Senior, Alberto Ronzani, Joonas T. Peltonen, Hsi-Sheng Goan, Chii-Dong Chen, Jukka P. Pekola. Utilization of the superconducting transition for characterizing low-quality-factor superconducting resonators. Appl. Phys. Lett., 2019, 115, 022601.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201907304578
    DOI: 10.1063/1.5098310 View at publisher
  • [Publication 3]: Alberto Ronzani, Bayan Karimi, Jorden Senior, Yu-Cheng Chang, Joonas T. Peltonen, Chii-Dong Chen, Jukka P. Pekola. Tunable photonic heat transport in a quantum heat valve. Nature Physics, 2018, 14, 991-995.
  • [Publication 4]: Jorden Senior, Azat Gubaydullin, Bayan Karimi, Joonas T. Peltonen, Joachim Ankerhold, Jukka P. Pekola. Heat rectification via a superconducting artificial atom. Submitted to Nature Communications Physics in 2019.