A driven Kerr oscillator with two-fold degeneracies for qubit protection

• 成果类型: Article
• 署名作者: Venkatraman, Jayameenakshi; Cortinas, Rodrigo G.; Frattini, Nicholas E.; Xiao, Xu; Devoret, Michel H.
• 署名单位: Yale University; Yale University; University of California System; University of California Santa Barbara
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11155
• DOI: 10.1073/pnas.2311241121
• 发表日期: 2024-06-11
• 关键词: quantum; interference; atom

摘要

We present the experimental finding of multiple simultaneous two -fold degeneracies in the spectrum of a Kerr oscillator subjected to a squeezing drive. This squeezing drive resulting from a three -wave mixing process, in combination with the Kerr interaction, creates an effective static two -well potential in the phase space rotating at half the frequency of the sinusoidal drive generating the squeezing. Remarkably, these degeneracies can be turned on -and -off on demand, as well as their number by simply adjusting the frequency of the squeezing drive. We find that when the detuning A between the frequency of the oscillator and the second subharmonic of the drive equals an even multiple of the Kerr coefficient K , A / K = 2 m , the oscillator displays m + 1 exact, parity -protected, spectral degeneracies, insensitive to the drive amplitude. These degeneracies can be explained by the unusual destructive interference of tunnel paths in the classically forbidden region of the double well static effective potential that models our experiment. Exploiting this interference, we measure a peaked enhancement of the incoherent well -switching lifetime, thus creating a protected cat qubit in the ground state manifold of our oscillator. Our results illustrate the relationship between degeneracies and noise protection in a driven quantum system.