Quantum Magic: Nonlocal and Everlasting ⚡ экспресс
Nonlocal magic—the kind of nonstabilizerness that local unitary transformations can’t erase—captures the dance between entanglement and magic, the secret sauce behind quantum advantage. It’s now been spotted for the first time on a superconducting quantum processor, using two independent techniques: an optimal local erasure protocol and a direct, state-blind measurement of subsystem purity. The numbers from both methods line up with each other and with theory. A parameter-free noise model reveals that readout goofs and a depolarizing channel for the CZ gate are the main culprits, which lets us control local and nonlocal magic separately by scrubbing the local bit right where it lives. Nonlocal magic acts as a hardware benchmark that beats standard gate fidelity scores, pushing the needle on reliable pre-fault-tolerant machines. The same toolbox also offers a purity estimation protocol with exponential speedup and a way to decode Hawking radiation from a toy black hole.
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.
🎯 Curiously, the formulas for nonlocal magic turned out to be the key to decoding black hole radiation — so distant objects help build computers on Earth.
🎬 Extracting information from a black hole is reminiscent of 'Interstellar', where data from the singularity helped solve gravity.