Optimal cooling of a driven artificial atom in dissipative environment

• Published in: Физика низких температур
• Date: 2013
• ISSN: 0132-6414
• Main Authors: Du, Lingjie, Yu, Yang, Lan, D.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2013
• Subjects: Свеpхпpоводимость, в том числе высокотемпеpатуpная
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/118259
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Optimal cooling of a driven artificial atom
 in dissipative environment / Lingjie Du, Yang Yu, D. Lan // Физика низких температур. — 2013. — Т. 39, № 2. — С. 150–161. — Бібліогр.: 62 назв. — англ.

We study microwave-driven cooling in a superconducting flux qubit subjected to environment noises. For the
 weak decoherence, our analytical results agree well with the experimental observations and show that the microwave
 amplitude for optimal cooling should depend linearly on the dc flux detuning. With the decoherence
 stronger, more vibrational degrees of freedom (analogous with atomic physics) couple in, making the ordinary
 cooling method less effective or even fail. We propose an improved cooling method, which can eliminate the
 perturbation of additional vibrational degrees of freedom hence keep high efficiency, even under the strong decoherence.
 Furthermore, we point out that the decoherence can tune the frequency where microwave-driven
 Landau–Zener transition reaches maximum, displaying the feature of incoherent dynamics which is important
 for the optimal cooling of qubits and other quantum systems.