Abstract
In spin-based nanosystems for quantum information processing, electron spin qubits are subject to decoherence due to their interactions with nuclear spin environments. In this paper, we present an exact master equation for a central spin-1/2 system in time-dependent external fields and coupled to a spin-half bath in terms of hyperfine interaction. The master equation provides a unified description for free and controlled dynamics of the central spin and is formally independent of the details and size of spin environments. Different from the previous approaches, the master equation remains exact even in the presence of external control fields. Using the parameters for realistic nanosystems with nonzero nuclear spins, such as GaAs, we investigate the Overhauser’s effect on the decoherence dynamics of the central spin under different distributions of bath-spin frequencies and system-bath coupling strengths. Furthermore, we apply the leakage elimination operator, in a nonperturbative manner, to this system to suppress the decoherence induced by hyperfine interaction.
Highlights
Understanding the nonequilibrium dynamics of quantum systems interacting with a large number of uncontrollable degrees of freedom is a rapidly emerging topic, developed in various fields, such as quantum optics and quantum devices based on mesoscopic and nanoscale solid systems[1,2]
For one of these spin qubits, the electron wave function is localized inside the nanoscale region and the nuclear spins coupled to the central spin form a nanoscale spin bath, which is dramatically different from the conventional Markovian bosonic bath
We have proposed an exact master equation for a central spin coupled to a spin bath by hyperfine interaction, which represents a family of physical spin-bath models ubiquitously existing in semiconductor systems
Summary
Understanding the nonequilibrium dynamics of quantum systems interacting with a large number of uncontrollable degrees of freedom is a rapidly emerging topic, developed in various fields, such as quantum optics and quantum devices based on mesoscopic and nanoscale solid systems[1,2]. Hyperfine interaction, the most relevant noise sources for the central spins in quantum technologies, the nuclear spin bath is highly non-Markovian and the central electron spin in a quantum dot has a comparatively long coherence time[16,17,18,19]. To formulate these interesting observations, an exact master equation for the central electron spin in spin environment, in analogy to that for the spin in bosonic bath[20], is desired for future QD quantum computer based on full polarization of nuclear spins. By using our exact master equation it is clearly shown that an ideal Markovian process is not controllable, which has been missing in the conventional Wigner-Weisskopf approximation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
