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A quantum computer is like an exquisite dish. There are recipes for ordinary kitchens, but special quantum states are secret ingredients that turn the dish into a masterpiece. One of them is 'magic'. The term was coined by John Preskill in 2018. Magic comes in local form — you can remove it by changing components — and nonlocal, which like a sauce permeates the entire dish and preserves the taste no matter what you do to the parts.

Physicists have for the first time measured this nonlocal sauce on a superconducting chip. They used two methods: the first erased local magic with complex operations, leaving the overall; the second estimated the purity from ordinary noise, similar to measuring entropy — disorder. Both gave the same numbers. The main disturbances are readout errors and noise in the gate, which works like a conditional gate. Remarkably, local magic can be erased right during operation without affecting nonlocal magic.

Now this will allow honest testing of quantum processors without full error correction. The most unexpected twist: the same math helps decode the radiation of black holes, studied by Stephen Hawking. Perhaps the keys to spacetime are hidden in nonlocal magic.

Original abstract

as written by the authors arXiv:2511.15576

Non-local magic is the non-stabilizerness that no local unitary operation can erase. It captures the joint action of entanglement and magic underlying quantum advantage, and it has never been measured on quantum hardware. Here we report its first experimental demonstration, on a superconducting quantum processing unit, through two independent routes: an optimal local-erasure protocol and a direct, state-agnostic measurement of subsystem purity. The two agree with each other and with theory. Exploiting direct access to the device, we construct a noise model with no free parameters that identifies readout error and a depolarizing controlled-Z channel as the dominant mechanisms, and we show that local and non-local magic can be addressed separately, erasing local magic in situ while preserving the non-local part. Non-local magic provides a hardware benchmark beyond standard gate-fidelity protocols and points toward more reliable pre-fault tolerant devices.The same tools underlie a purity-estimation protocol with exponential speedup and the decoding of Hawking radiation in a black-hole toy model.