Yeang, Chen-Pang: Engineering the Entanglement: Quantum Computation, Quantum Communication, and Re-conceptualizing Information

When Einstein, Podolsky, and Rosen (EPR) presented the famous two-particle thought experiment in 1935, their purpose was to demonstrate the incompleteness of quantum mechanics and to challenge the Copenhagen interpretation. This EPR state, or “entangled state,” exhibited properties defying intuitive, causal explanations, which indicated how odd quantum mechanics is. From David Bohm to John Bell, those working on the EPR problem pursued the same goal: probing the conceptual foundation of quantum mechanics. At the end of the last century, however, a group of physicists and computer scientists turned the entangled state from a puzzle into practical resources. Setting aside the epistemic issues concerning whether quantum mechanics is complete and why entanglement is so “strange,” they took for granted the “strange” properties of this quantum result and appropriated them to explore novel ways of information processing. Why and how did this turn occur?
This paper examines the rise and ongoing development of such endeavors—known as quantum computation and quantum communication—since the 1980s. At the core of these endeavors is the process in which the “strange” features of entanglement such as instantaneous action-at-a- distance were reinterpreted as opportunities to devise parallel computing algorithms and encrypted telecommunications. But the physicists and computer scientists were not satisfied with taking entanglement only as a technique to solve special problems. They moved further to generalize a “quantum-mechanical” view of automatic computation, modifying the logical premises of computer science that Alonzo Church and Alan Turing had laid out in the 1930s. Building upon quantum computation, moreover, they conceived a new paradigm for designing communications codes that would follow a different information theory from the one Claude Shannon had established in 1948.
The recent history of quantum computation and quantum communication marks the convergence of three interrelated scientific and engineering research programs: theoretical physicists’ pursuits of quantum mechanics’ conceptual foundation, industrial-laboratory researchers’ quests for novel physical means to implement digital computers, and atomic physicists’ experiments on coherent or single quantum states. And all of them have drawn upon the intellectual resources of quantum mechanics, computer science, and information theory developed in the past century. Although no system has yet been physically implemented (albeit strong academic interests and substantial military funding), the ongoing quantum computation and quantum communication has shown a conspicuous tendency among the physicist community to weave the decades-old central puzzle of quantum mechanics with a reconceptualization of information.

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