2017/05/22 by Yen-Hsiang Lin, Yen‐Hsiang Lin, Long B. Nguyen +6 · 2 citations
Computer Science · Physics and Astronomy · #Atomic physics #Charge qubit #Condensed matter physics #Dephasing #Dipole #Dissipative system #Energy (signal processing) #Flux qubit #Inverse #Phase qubit #Physics #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum mechanics #Qubit #Saturation (graph theory) #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.120.150503
published as Phys. Rev. Lett. 120, 150503 (2018)
arxiv created 2017/05/22 · openalex publication_date 2018/04/13 · arxiv updated 2018/04/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Long-lived transitions occur naturally in atomic systems due to the abundance of selection rules inhibiting spontaneous emission. By contrast, transitions of superconducting artificial atoms typically have large dipoles, and hence their lifetimes are determined by the dissipative environment of a macroscopic electrical circuit. We designed a multilevel fluxonium artificial atom such that the qubit's transition dipole can be exponentially suppressed by flux tuning, while it continues to dispersively interact with a cavity mode by virtual transitions to the noncomputational states. Remarkably, energy decay time T1 grew by 2 orders of magnitude, proportionally to the inverse square of the transition dipole, and exceeded the benchmark value of T1>2 ms (quality factor Q1>4×107) without showing signs of saturation. The dephasing time was limited by the first-order coupling to flux noise to about 4 μs. Our circuit validated the general principle of hardware-level protection against bit-flip errors and can be upgraded to the 0-π circuit [P. Brooks, A. Kitaev, and J. Preskill, Phys. Rev. A 87, 052306 (2013)PLRAAN1050-294710.1103/PhysRevA.87.052306], adding protection against dephasing and certain gate errors.