Breakthrough: Room Temperature Chromophore Qubits Harness Four Electron Spins

Kyushu and Kobe Universities have joined forces to achieve a groundbreaking feat in quantum computing and sensing technologies. According to Kyushu University, their recent findings have successfully maintained quantum coherence of four electron spins at room temperature.

The researchers focused on a specific chromophore, a pentacene-based dye molecule, which was chosen to host the entangled electron spins. The spins within this molecule can be excited at room temperature through a process called "singlet fission". However, achieving quantum coherence among these spins has traditionally required extremely low temperatures, such as those found in liquid nitrogen.

To overcome this limitation, the researchers incorporated the chromophore into a unique metal-organic framework (MOF) known as "UiO". This MOF allowed for the dense accumulation of chromophores and provided nanopores that enabled controlled rotation of the chromophore at a restricted angle.

By embedding the chromophore within the UiO MOF, the researchers were able to increase the temperature tolerance of the system. This framework facilitated the transition of electrons from a triplet state to a quintet state, while also maintaining quantum coherence of the quintet multi-exciton state at room temperature. When stimulated by microwave pulses, the quantum coherence persisted for over 100 nanoseconds.

Professor Yasuhiro Kobori of Kobe University expressed his excitement, stating, "This is the first instance of room-temperature quantum coherence of entangled quintets." The achievement opens up new possibilities for the development of longer-lasting qubits.

Kyushu University's Nobuhiro Yanai added, "In the future, it will be possible to generate quintet multiexciton state qubits more efficiently by searching for guest molecules that induce suppressed motions and by developing suitable MOF structures. This breakthrough paves the way for room-temperature molecular quantum computing and quantum sensing of various target compounds."

The research, titled "Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework," has been published in Science Advances.