Abstract
The opportunity to build quantum technologies operating with elementary quantum systems with more than two levels is now increasingly being examined, not least because of the availability of such systems in the laboratory. It is therefore essential to understand how these single systems initially in highly non-classical states decohere on different time scales due to their coupling with the environment. In this work, we consider the depolarization, both isotropic and anisotropic, of a quantum spin of arbitrary spin quantum number $j$ and focus on the study of the most superdecoherent states. We approach this problem from the perspective of the collective dynamics of a system of $N=2j$ constituent spin-$1/2$, initially in a symmetric state, undergoing collective depolarization. This allows us to use the powerful language of quantum information theory to analyze the fading of quantum properties of spin states caused by depolarization. In this framework, we establish a precise link between superdecoherence and entanglement. We present extensive numerical results on the scaling of the entanglement survival time with the Hilbert space dimension for collective depolarization. We also highlight the specific role played by anticoherent spin states and show how their Markovian isotropic depolarization alone can lead to the generation of bound entangled states.
Highlights
The elementary building blocks for storing and processing information on quantum devices are quantum bits or qubits
Entangled symmetric states appear to be more fragile to collective depolarization than to individual depolarization, which we attribute to superdecoherence that is absent for individual depolarization
We presented a general study of the depolarization dynamics of an arbitrary spin using tools from quantum information theory
Summary
The elementary building blocks for storing and processing information on quantum devices are quantum bits or qubits. Efforts to use elementary quantum systems with more than two degrees of freedom for quantum technologies have been intensified by the availability of such systems in experiments operating in the quantum regime These so-called qudits can be implemented with a variety of systems, e.g., using the orbital angular momentum of light [1], the electronic spin of magnetic atoms [2], the internal levels of trapped ions [3], superconducting circuits [4], or the rotational degree of freedom in molecules [5]. We want to study how fast quantum correlations decrease over time, which pure states decohere the most rapidly, or how long it takes before the state enters a ball of absolutely separable states. Most of the technical derivations of this work are relegated to the Appendixes
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.
