CERN Scientists Create First Antimatter Qubit, Maintaining Quantum Coherence for Record 50 Seconds

Scientists from CERN’s BASE experiment (Baryon Antibaryon Symmetry Experiment) have, for the first time, successfully created and stabilized a quantum bit formed from an antiproton—the antimatter counterpart of the proton, possessing an opposite electric charge. Remarkably, the team managed to maintain the particle in a coherent quantum state—where its spin orientation oscillated smoothly between two possible configurations—for a record-breaking duration of 50 seconds.

The key to this achievement lay in the use of a Penning trap—an intricate system of electromagnetic fields designed to isolate charged particles from external disturbances. Within this exquisitely controlled environment, the antiproton behaves like a microscopic quantum pendulum, transitioning between “up” and “down” spin states under the influence of precisely timed radiofrequency pulses. This behavior constitutes a coherent quantum process—a foundational element for all quantum technologies, from sensing to computation.

Antiprotons, being spin-carrying particles, respond to external magnetic fields much like infinitesimal magnets. However, in typical environments, their delicate quantum states are rapidly destroyed by ambient noise—magnetic, thermal, and electrostatic. In the BASE experiment, researchers succeeded in suppressing these disruptive factors almost entirely. As a result, they achieved an unprecedented 50-second coherence time for the antiproton’s spin state—a milestone for such measurements and a direct indicator of the extraordinary isolation and control exercised over the particle. Coherence time is a critical parameter in quantum experimentation, and in this instance, it was extended by several orders of magnitude compared to prior attempts.

To attain such precise control, the team employed a technique known as coherent spectroscopy, whereby quantum transitions are induced using synchronized radio pulses. The researchers liken this process to rhythmically pushing a swing—when timed just right, the motion remains stable and predictable. Here, however, the “swing” is an antiproton oscillating between two quantum states, suspended in superposition—a hallmark quantum phenomenon in which the particle exists in multiple states simultaneously until observed.

Until now, all attempts to measure the antiproton’s magnetic moment relied on incoherent methods, which were susceptible to noise and lacked precision. The new technique changes the paradigm: scientists can now directly manipulate the particle’s state and conduct ultra-precise measurements. As Dr. Stefan Ulmer, founder and lead of the BASE project, emphasized, the use of coherent spectroscopy in future experiments could improve the precision of antiproton magnetic moment measurements by a factor of 10 to 100. This is vital for testing CPT symmetry—a cornerstone of the Standard Model asserting that the properties of matter and antimatter should be perfectly mirrored. Any deviation from this symmetry could signal the presence of new physics.

The experiment comprised several stages. First, an antiproton was isolated within a multilayered system of traps designed for transport, control, and measurement. Then, a sequence of radiofrequency pulses initiated coherent spin-state transitions. A decisive factor in the experiment’s success was the elimination of major sources of decoherence, including magnetic field instabilities and parasitic thermal fluctuations. Consequently, researchers were able to observe—for the first time—sustained coherent dynamics of an antiparticle in a regime accessible to direct study.

Though this antimatter qubit has yet to be integrated into quantum computing, its significance for fundamental physics is profound. It may serve as a unique tool for ultra-precise spectroscopy, the development of next-generation quantum sensors, and experiments probing the limits of the Standard Model.

The research team is already pursuing the next phase of the project through the BASE-STEP initiative—a new facility aimed at relocating antiprotons into ultralow-noise environments. According to Dr. Barbara Latacz, the paper’s lead author, this could extend coherence times to an astonishing 500 seconds. Such a leap would open the door to the most in-depth exploration of antiparticle magnetic properties in the history of physics.

Thus, science has, for the first time, not only glimpsed the quantum dynamics of a solitary antiproton but has also acquired the means to master it. This discovery not only deepens our understanding of antimatter—it may well mark the beginning of a new chapter in the quest to uncover the fundamental laws that govern the universe.