Getting Entangled with Sean Hodgman

July 14, 2026

AI Summary

5 min read

Sean Hodgman, a physicist at the Australian National University, works with helium atoms cooled to about a millionth of a degree above absolute zero. At that temperature, the atoms lose their individual identities and merge into a single quantum state called a Bose-Einstein condensate—essentially a "fuzzy smear" of matter where every atom shares the same wavelength. This macroscopic quantum object, about a tenth of a millimeter wide inside its trap, becomes the starting point for experiments on quantum entanglement.

How entanglement is created and detected

Hodgman’s group creates entanglement by taking a Bose-Einstein condensate, splitting it in two with a laser kick, and colliding the two halves. When two helium atoms collide, they can go in two possible pairs of directions (northwest-southeast or northeast-southwest). Classically, they would take one path or the other. Quantum mechanically, they take both paths at once. The two atoms become entangled in their momentum—the direction they travel—so that you cannot describe either atom’s motion independently. You must use a single wave function for the pair.

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What you'll learn

1 (02:37) **Introducing Sean Hodgman & His Lab** - Physicist at ANU works with ultracold helium atoms to study quantum mechanics.
2 (04:31) **Why Ultracold Atoms? The Bose-Einstein Condensate Explained** - Cooling atoms slows them down, making their quantum wave functions large enough to observe.
3 (07:06) **Einstein’s Problem with Entanglement** - Einstein co-invented quantum physics but hated the "spooky action at a distance" implied by entanglement.
4 (09:27) **How Hodgman Entangles Atoms** - The team uses the BEC as a source, splitting it and colliding the two halves together.
5 (12:24) **How Long Does Entanglement Last?** - The entangled state is extremely fragile and lasts only about a millisecond.
6 (15:12) **Why Momentum Entanglement Matters** - Atoms interact much more strongly with gravity than photons do.
7 (18:15) **Understanding Superposition & Measurement** - A listener asks how superposition works when particles are on different paths (e.g., one in orbit, one in a lab).

+ Full timestamped outline available in the app

Show Notes

How do you get entangled particles? Neil deGrasse Tyson and comic co-host Chuck Nice unpack the experimental side of entanglement, superposition, and the quantum underpinnings of our universe with experimental physicist, Sean Hodgman.

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