Two Atoms Against Chaos: A Quantum Memory Record express
A typical quantum bit is destroyed by the slightest disturbance — heat, magnetic fields. Physicists made a pair of atoms work together so that disorder wouldn't erase the record. Information was encoded not in each atom individually, but in the difference of their states — like the tension of a rope between two buoys. Any noise rocks both buoys equally, so the distance between them stays constant. Using precise laser tracking, the scientists monitored this difference.
The experiment with ytterbium ions showed: a linked pair held quantum information for 10.5 hours — as if the rope between buoys remained taut throughout a stormy day. This stability is comparable to the precision of pulsars. A single qubit previously decayed within an hour. In that time, you could perform 36 billion error-free operations — more than most quantum computers will need. The method builds on the work of David Wineland, a pioneer of ion traps, and opens the path to reliable systems without bulky shielding.
Original abstract
as written by the authors arXiv:2603.19631
Quantum systems promise to revolutionize information processing science and technology [1-3]. The preservation of quantum coherence, the defining property of qubits, fundamentally constrains the performance of quantum information processing with quantum memories [4]. While trapped atomic ions theoretically support million-year coherence based on spontaneous emission [5-7], experimental demonstrations have reached far less, only about an hour [8-13]. Here we combine clock-state qubits with decoherence-free subspace (DFS) encoding to achieve coherence exceeding ten hours. Using correlation-based phase tracking in 171Yb+ ion pairs sympathetically cooled by 138Ba+ ion, we demonstrate this without magnetic shielding or enhanced microwave phase stabilization that previously limited coherence times. DFS encoding references the qubit phase to the inter-ion energy difference to reject microwave phase noise and common-mode magnetic fluctuations, while clock states provide environmental insensitivity. Throughout measurements extended to 1600 seconds, we observe minimal coherence decay, with exponential fits yielding a coherence time of (3.77 +/- 1.09) x 10^4 seconds. Our results establish DFS encoding as a form of passive error correction that eliminates technical noise constraints, unlocking the million-year coherence potential of atomic ions for scalable quantum information processing.
If a quantum operation took one microsecond, 36 billion such operations could be performed in 10 hours without a single error.
Such stable memory is reminiscent of the computational core from the novel "The Quantum Thief," capable of storing a personality forever.