VTechWorks staff will be away for the winter holidays starting Tuesday, December 24, 2024, through Wednesday, January 1, 2025, and will not be replying to requests during this time. Thank you for your patience, and happy holidays!

Browsing by Author "Zhuang, Fei"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Doubly Geometric Quantum Control
    Dong, Wenzheng; Zhuang, Fei; Economou, Sophia E.; Barnes, Edwin Fleming (American Physical Society, 2021-08-24)
    In holonomic quantum computation, quantum gates are performed using driving protocols that trace out closed loops on the Bloch sphere, making them robust to certain pulse errors. However, dephasing noise that is transverse to the drive, which is significant in many qubit platforms, lies outside the family of correctable errors. Here, we present a general procedure that combines two types of geometry—holonomy loops on the Bloch sphere and geometric space curves in three dimensions—to design gates that simultaneously suppress pulse errors and transverse noise errors. We demonstrate this doubly geometric control technique by designing explicit examples of single-qubit and two-qubit dynamically corrected holonomic gates.
  • Thumbnail Image
    Noise-resistant Landau-Zener sweeps from geometrical curves
    Zhuang, Fei; Zeng, Junkai; Economou, Sophia E.; Barnes, Edwin Fleming (2022-02-02)
    Landau-Zener physics is often exploited to generate quantum logic gates and to perform state initialization and readout. The quality of these operations can be degraded by noise fluctuations in the energy gap at the avoided crossing. We leverage a recently discovered correspondence between qubit evolution and space curves in three dimensions to design noise-robust Landau-Zener sweeps through an avoided crossing. In the case where the avoided crossing is purely noise-induced, we prove that operations based on monotonic sweeps cannot be robust to noise. Hence, we design families of phase gates based on non-monotonic drives that are error-robust up to second order. In the general case where there is an avoided crossing even in the absence of noise, we present a general technique for designing robust driving protocols that takes advantage of a relationship between the Landau-Zener problem and space curves of constant torsion.
  • Thumbnail Image
    Study and Application of the Space Curve Quantum Control Formalism
    Zhuang, Fei (Virginia Tech, 2023-05-26)
    Quantum Computation and Information requires high accuracy in gate control despite noises and imperfections from the environment and physical implementation. Here we introduce an SCQC Formalism based on dynamical decoupling and reverse engineering. Space Curve Quantum Control Formalism discovers the tight connections between quantum, geometric, and classical systems. We are able to use such connections to build noise-canceling, precise control, and time-optimal arbitrary gates.