Room-Temperature Quantum Coherence Achieved by Embedding Chromophores in Metal-Organic Framework

Scientists from Kyushu University and Kobe University in Japan have made a significant breakthrough in quantum computing and quantum sensing technology. They have successfully achieved quantum coherence at room temperature by incorporating a chromophore, which is a dye molecule that absorbs light and emits color, into a metal-organic framework. Quantum coherence refers to the ability of a quantum system to maintain its quantum state without being affected by surrounding noise. This achievement has been reported in the journal Science Advances.

Quantum computing and quantum sensing rely on the utilization of qubits, which are the basic units of quantum information. Researchers currently explore various systems to implement qubits, including electron spin. Electrons possess two spin states: up and down. Spin-based qubits can exist in superposition, meaning they can be in a combination of these two states, and they can also become "entangled" with one another, whereby a change in the state of one qubit affects the state of another.

Quantum sensing technology takes advantage of the remarkable sensitivity of entangled quantum states to environmental noise, which enables higher resolution and increased sensitivity. However, achieving quantum entanglement among four electrons and making them react to external molecules has long been a significant challenge.

Previously, scientists managed to obtain electron spin at room temperature through a process called singlet fission, in which electrons are excited by chromophores. Unfortunately, at room temperature, quantum information tends to lose its quantum superposition and entanglement. As a result, quantum coherence is typically only attained at extremely low temperatures, such as liquid nitrogen temperature (-196°C/-320.8℉).

To overcome this obstacle and realize room-temperature quantum coherence, the research team incorporated pentacene-based chromophores into the organometallic framework. Their findings indicate that the organometallic framework facilitates the movement of pentacene, causing the electrons to transition from the triplet energy level to the quintet energy level while fully maintaining the quantum coherence of the quintuplet multiexciton state. By exciting the electrons with microwave pulses of light, the researchers observed that the quantum coherence of this state persisted for over 100 nanoseconds at room temperature. This achievement represents the first time that an entangled quintet has achieved quantum coherence at room temperature.

While the observed quantum coherence is of relatively short duration, this groundbreaking discovery sets the stage for the design of materials that can generate multiple qubits at room temperature. The researchers believe that this development will open up avenues for multi-quantum gate control and quantum sensing based on a diverse range of target compounds.