Uploaded September 2022 | Updated September 2026, 1 day ago
A nonrelativistic quantum wave packet spreading inside a cavity with perfectly reflecting walls. The boundary of the cavity is described by the x⁴ + y⁴ = 1 curve.
A nonrelativistic quantum wave packet spreading inside a cavity with perfectly reflecting walls. The boundary of the cavity is described by the x⁴ + y⁴ = 1 curve.

![Quantum Fractals [QBE Ep. 3]
Episode 3 of Quantum on the Back of an Envelope [QBE].
🔗 Watch the full series here: https://www.youtube.com/playlist?list=PLIGRVb L3EpDzApE5EnAOYyTAyagvi1W
In this episode of Quantum on the Back of an Envelope, we explore quantum fractals through one of the simplest quantum-mechanical systems: the particle in a box. The fractal wave function discussed here is based on the paper: M. V. Berry, Quantum fractals in boxes, J. Phys. A: Math. Gen. 29, 6617 (1996). Quantum Fractals [QBE Ep. 3]](https://i.ytimg.com/vi/_iHbpTirOS4/mqdefault.jpg)






![Quantum Zeno Effect [QBE Ep. 4]
Episode 4 of Quantum on the Back of an Envelope [QBE].
🔗 Watch the full series here: https://www.youtube.com/playlist?list=PLIGRVb L3EpDzApE5EnAOYyTAyagvi1W
In this episode of Quantum on the Back of an Envelope, we explore how frequent observations more precisely, projective measurements can dramatically alter the time evolution of a quantum system, and in some cases even freeze it altogether. This fascinating phenomenon is known as the quantum Zeno effect. Quantum Zeno Effect [QBE Ep. 4]](https://i.ytimg.com/vi/lgYDb7gKhKM/mqdefault.jpg)
![Spontaneous Singularities [QBE Ep. 1]
Episode 1 of Quantum on the Back of an Envelope [QBE].
🔗 Watch the full series here: https://www.youtube.com/playlist?list=PLIGRVb L3EpDzApE5EnAOYyTAyagvi1W
In this first episode of Quantum on the Back of an Envelope, we explore an unexpected phenomenon in quantum mechanics: how a perfectly smooth wave function, evolving under the Schrödinger equation, can spontaneously develop a singularity over time. Spontaneous Singularities [QBE Ep. 1]](https://i.ytimg.com/vi/oNhus9iAyys/mqdefault.jpg)
