Researchers wrestling with the fragility of quantum bits have long treated coherence as an experimental art. In a comprehensive review published this week in Nature Physics, P. et al. assemble evidence from superconducting circuits, trapped ions, semiconductor spins and color centers to lay out a unified, engineering-driven roadmap for creating long-lived qubits. The paper reframes coherence as a systems problem—one that can be attacked by materials science, electromagnetic engineering and judicious control strategies as much as by improved gate design.

At the heart of the review is a catalogue of loss channels—phonons, two-level-system defects at surfaces, charge noise, and radiative decay—and practical countermeasures that have already yielded record lifetimes in disparate platforms. Isotopic purification of host crystals to remove magnetic impurities, more aggressive surface passivation and chemical cleaning to eliminate dangling bonds, and low-loss dielectric and substrate choices are highlighted as primary levers. The authors also emphasize electromagnetic engineering: 3D cavities and phononic bandgap structures that suppress unwanted emission, and metamaterial waveguides that prevent thermal and vacuum fluctuations from coupling to the qubit.

“These are not purely theoretical tricks,” said Nathalie de Leon, a co-author and Princeton professor who is also a visiting faculty researcher with Google Quantum AI. “They are reproducible engineering steps that reduce the number of catastrophic decoherence events and give experimentalists practical pathways to push coherence times further.” De Leon and colleagues point to recent demonstrations—spins in isotopically purified silicon and diamond with coherence times extended by orders of magnitude, and superconducting resonators with dramatically reduced surface losses—as evidence that the principles scale across platforms.

Control techniques remain an important complement. Dynamical decoupling, optimized pulse shaping and error-transparent gates reduce sensitivity to residual noise, while real-time calibration and continuous monitoring can catch drift before it degrades a computation. Yet the review cautions that stronger isolation often complicates control and readout: qubits that are better shielded from their environment can be harder to manipulate and measure, forcing trade-offs that must be resolved by integrated design.

The practical consequence of longer physical qubits is substantial. Error correction schemes demand many physical qubits per logical qubit, and longer coherence reduces that multiplier, cutting cooling, wiring and fabrication overhead. The authors estimate that modest increases in T1 and T2 times could reduce the number of physical qubits needed for fault tolerance by factors large enough to change which hardware projects are economically viable.

Beyond technicalities, the paper addresses societal implications: a clearer engineering roadmap could accelerate the arrival of quantum devices with scaled capabilities, raising questions about workforce readiness, cryptographic transitions and equitable access to early commercial systems. The authors call for interdisciplinary collaborations between physicists, materials scientists and engineers, plus open data on fabrication recipes, to ensure progress is robust and replicable.

The review closes with a pragmatic assertion: long coherence is not a single breakthrough but a negotiation among loss channels, materials and control. As the community adopts the paper’s prescriptions, the path to practical quantum computation may become less about chasing a single record and more about mastering a reproducible engineering discipline.