Browsing by Author "Gubaydullin, Azat"
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- Heat rectification via a superconducting artificial atom
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-12-01) Senior, Jorden; Gubaydullin, Azat; Karimi, Bayan; Peltonen, Joonas T.; Ankerhold, Joachim; Pekola, Jukka P.In developing technologies based on superconducting quantum circuits, the need to control and route heating is a significant challenge in the experimental realisation and operation of these devices. One of the more ubiquitous devices in the current quantum computing toolbox is the transmon-type superconducting quantum bit, embedded in a resonator-based architecture. In the study of heat transport in superconducting circuits, a versatile and sensitive thermometer is based on studying the tunnelling characteristics of superconducting probes weakly coupled to a normal-metal island. Here we show that by integrating superconducting quantum bit coupled to two superconducting resonators at different frequencies, each resonator terminated (and thermally populated) by such a mesoscopic thin film metal island, one can experimentally observe magnetic flux-tunable photonic heat rectification between 0 and 10%. - Photonic heat transport in three terminal superconducting circuit
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-03-23) Gubaydullin, Azat; Thomas, George; Golubev, Dmitry S.; Lvov, Dmitrii; Peltonen, Joonas T.; Pekola, Jukka P.We report an experimental realization of a three-terminal photonic heat transport device based on a superconducting quantum circuit. The central element of the device is a flux qubit made of a superconducting loop containing three Josephson junctions, which can be tuned by magnetic flux. It is connected to three resonators terminated by resistors. By heating one of the resistors and monitoring the temperatures of the other two, we determine photonic heat currents in the system and demonstrate their tunability by magnetic field at the level of 1 aW. We determine system parameters by performing microwave transmission measurements on a separate nominally identical sample and, in this way, demonstrate clear correlation between the level splitting of the qubit and the heat currents flowing through it. Our experiment is an important step towards realization of heat transistors, heat amplifiers, masers pumped by heat and other quantum heat transport devices. - Robust Strong-Coupling Architecture in Circuit Quantum Electrodynamics
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-10-25) Upadhyay, Rishabh; Thomas, George; Chang, Yu Cheng; Golubev, Dmitry S.; Guthrie, Andrew; Gubaydullin, Azat; Peltonen, Joonas T.; Pekola, Jukka P.We report on a robust method to achieve strong coupling between a superconducting flux qubit and a high-quality quarter-wavelength coplanar waveguide resonator. We demonstrate the progression from the strong to ultrastrong coupling regime by varying the length of a shared inductive coupling element, ultimately achieving a qubit-resonator coupling strength of 655 MHz, 10% of the resonator frequency. We derive an analytical expression for the coupling strength in terms of circuit parameters and also discuss the maximum achievable coupling within this framework. We experimentally characterize flux qubits coupled to superconducting resonators using one- and two-tone spectroscopy methods, demonstrating excellent agreement with the proposed theoretical model. - Thermally pumped on-chip maser
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-09-08) Thomas, George; Gubaydullin, Azat; Golubev, Dmitry S.; Pekola, Jukka P.We present a theoretical model of an on-chip three-level maser in a superconducting circuit based on a single artificial atom and pumped by a temperature gradient between thermal baths coupled to different interlevel transitions. We show that maser powers of the order of a few femtowatts, well exceeding the resolution of the sensitive bolometry, can be achieved with typical circuit parameters. We also demonstrate that population inversion in the artificial atom can be detected without measuring coherent radiation output of the maser. For that purpose, the system should operate as a three-terminal heat transport device. The hallmark of population inversion is the influx of heat power into the weakly coupled output terminal even though its temperature exceeds the temperatures of the two other terminals. The proposed method of on-chip conversion of heat into microwave radiation and control of energy-level populations by heating provide additional useful tools for circuit quantum electrodynamics experiments.