Quantum Record: 120 Entangled Qubits express
Picture an orchestra of 120 musicians playing in perfect unison — one false note and the harmony crumbles. That's the metaphor for a record-breaking quantum ensemble. Physicists have for the first time entangled 120 superconducting qubits, the building blocks of future computers. These qubits operate only at near absolute zero temperatures and look like miniature antennas visible to the naked eye. This state, dubbed a 'Schrödinger's cat' after Erwin Schrödinger, binds 120 objects into one whole where each, like the legendary cat, exists in two states at once.
The fragility of quantum linkage is like a delicate melody in the wind — the slightest breeze, or thermal noise, sows chaos. To keep the tune, scientists pulled a clever trick: they briefly loosened the connections, caught the errors, and tightened the particles back into unison. Even with 56% accuracy, it's a breakthrough for 120 elements.
These experiments aren't just a numbers game. They'll help create powerful algorithms and might even explain the link between spacetime curvature and black holes. Research involving Anton Zeilinger brings us closer to an era of reliable quantum machines.
Original abstract
as written by the authors arXiv:2510.09520
Entanglement is the quintessential quantum phenomenon and a key enabler of quantum algorithms. The ability to faithfully entangle many distinct particles is often used as a benchmark for the quality of hardware and control in a quantum computer. Greenberger-Horne-Zeilinger (GHZ) states, also known as Schr\"odinger cat states, are useful for this task. They are easy to verify, but difficult to prepare due to their high sensitivity to noise. In this Letter we report on the largest GHZ state prepared to date consisting of 120 superconducting qubits. We do this via a combination of optimized compilation, low-overhead error detection and temporary uncomputation. We use an automated compiler to maximize error-detection in state preparation circuits subject to arbitrary qubit connectivity constraints and variations in error rates. We measure a GHZ fidelity of 0.56(3) with a post-selection rate of 28%. We certify the fidelity of our GHZ states using multiple methods and show that they are all equivalent, albeit with different practical considerations.
The experiment took place in complete darkness at temperatures a fraction of a degree above absolute zero — a stray photon would have shattered the delicate quantum balance.
Instant communication via entangled particles is a staple of sci-fi. In Ursula K. Le Guin's novels, the 'ansible' device allowed interstellar conversations, even though real physics forbids faster-than-light information transfer.