Spin Chains for Quantum Information Processing

TL;DR

This paper compares two protocols for generating entanglement in spin chains, finding that virtual excitation-based methods outperform others in speed, robustness, and practical implementation for quantum information processing.

Contribution

It introduces and systematically evaluates a virtual excitation protocol that surpasses traditional methods in efficiency and resilience for quantum entanglement distribution.

Findings

Virtual excitation protocol achieves faster entanglement generation.

The virtual protocol is more robust against imperfections and noise.

Effective models explain the protocol's resilience and scalability.

Abstract

Classical computation relies heavily on information manipulation. Each component of a hardware needs to communicate with others, and this is done by encoding information into strings of bits and application of logical operations. When dealing with quantum technologies, there arises a new set of paradigms and devices, based on manipulations of qubits, the quantum analogues of conventional bits. This work investigates the generation and distribution of quantum entanglement, a uniquely non-classical correlation, across spin chains, which serve as promising platforms for quantum information processing. We systematically compare two distinct entanglement generation protocols: Protocol 1 (P1), based on alternating weak and strong couplings that create a band structure enabling an effective trimer-model approximation, and Protocol 2 (P2), which employs symmetric boundary couplings and virtual excitations to establish a direct effective interaction between the chain ends. Our results demonstrate that a protocol based on virtual excitations and optimized boundary couplings consistently outperforms its counterpart in speed, achieved entanglement, and robustness against fabrication imperfections and noise. Furthermore, by employing effective model reductions and open quantum systems techniques we provide a comprehensive framework for understanding the resilience of distributed entanglement in solid-state quantum devices. The characteristics of the virtual-coupling protocol highlight its potential for experimental implementation in scalable quantum technologies.