Molecular Qubits: Long Memory at Room Temperature express
At the heart of a future quantum computer might lie a tiny organic molecule shaped like a triangle. It has two 'extra' electrons that don't pair up. Such molecules are called diradicals, and their electrons can store information in a special, quantum way.
The authors used precise first-principles calculations to study three variants: pristine triangulene, a nitrogen-containing derivative, and a more complex crystal. They found that if all magnetic nuclei are removed (by replacing hydrogen with deuterium and placing the molecule in a nuclear-free environment), the quantum coherence time of the molecule reaches 0.21 milliseconds at 10 K. That's like a fragile soap bubble lasting almost a quarter of a second in the air — very long for the quantum world.
But the real surprise came at room temperature. The relaxation time (T1), i.e., the lifetime of the excited spin state, for the nitrogen-containing molecule was 27 milliseconds. Information doesn't get lost almost instantly, as often happens, but lives long enough to be manipulated. Moreover, the scientists showed that the spin can be controlled with light — selectively transitioning electrons between states, thus enabling data read and write.
A time of 0.21 ms at 10 K is roughly the duration of a single lightning flash. For a molecular qubit, that's an enormous span, during which hundreds of quantum operations can be performed.
The idea of molecular quantum computers echoes the 'quantum dots' in Greg Egan's novel 'Quarantine', where information is processed at the level of individual particles.