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Optimized heat transfer at exceptional points in quantum circuits



Matti Partanen, Jan Goetz, K-Y Tan, Kassius Kohvakka, Vasilii Sevriuk, Russell Lake, Roope J. Kokkoniemi, Joni Ikonen, Dibyendu Hazra, Akseli Makinen, Eric Hyyppa, Leif Gronberg, Visa Vesterinen, Matti Silveri, Mikko Mottonen


Superconducting quantum circuits are potential candidates to realize a large-scale quantum computer. The envisioned large density of integrated components, however, requires a proper thermal management and control of dissipation. To this end, it is advantageous to utilize tunable dissipation channels and to exploit the optimized heat flow at exceptional points (EPs). Here, we experimentally realize an EP in a superconducting microwave circuit consisting of two resonators. The EP is a singularity point of the Hamiltonian, and corresponds to the most efficient heat transfer between the resonators without oscillation of energy. We observe a crossover from underdamped to overdamped coupling via the EP by utilizing photon-assisted tunneling as an \emphin situ} tunable dissipative element in one of the resonators. The methods studied here can be applied to different circuits to obtain fast dissipation, for example, for initializing qubits to their ground states. In addition, these results pave the way towards thorough investigation of parity--time (PT) symmetric systems and the spontaneous symmetry breaking in superconducting microwave circuits operating at the level of single energy quanta.
Bulletin of the American Physical Society


quantum physics, microwave circuits, Hamiltonians, nanoelectronics, circuit, dissipation, photon-assisted tunneling, qubits, quantum electrodynamics


Partanen, M. , Goetz, J. , Tan, K. , Kohvakka, K. , Sevriuk, V. , Lake, R. , Kokkoniemi, R. , Ikonen, J. , Hazra, D. , Makinen, A. , Hyyppa, E. , Gronberg, L. , Vesterinen, V. , Silveri, M. and Mottonen, M. (2019), Optimized heat transfer at exceptional points in quantum circuits, Bulletin of the American Physical Society, [online],, (Accessed April 16, 2024)
Created October 6, 2019, Updated October 12, 2021