Physics Colloquium: David Kaiser, MIT

About this event

Scenes from the Quantum Century: From Curious Hippies to Novel Tests of Bell's Inequality

The hundredth anniversary of quantum mechanics in 2025-26 offers opportunities to consider how some of our core ideas were introduced, debated, tested, and ultimately accepted. One of the most central conceptual ingredients of quantum theory is entanglement, nowadays so important to the burgeoning field of quantum information science and technology. Yet the history of quantum entanglement---and of physicists' efforts to understand whether entanglement is a robust feature of the world rather than merely an intriguing hypothesis---has been far from straightforward. In this talk I will describe how a colorful group of physicists during the 1970s wrestled with entanglement and with John Bell's now-famous inequality, exploring the subtle interplay between quantum nonlocality and relativity amid the California counterculture scene. More recently, retracing the history of efforts to conduct experimental tests of Bell's inequality helped to catalyze novel tests, which have aimed to close a series of loopholes, including my group's recent "Cosmic Bell" experiments. These experiments provided compelling evidence for quantum entanglement while constraining certain classes of alternative models---which exploit a particularly subtle loophole---more thoroughly than ever before.