Scientists from NVision Quantum Technologies have demonstrated a method to create stable quantum bits from individual molecules, addressing a major obstacle in building quantum networks. The research appears in Nature.
The team embedded a chemical compound in a crystal and cooled it to 4.5 Kelvin (approximately -269°C). They converted the compound into molecules called carbenes, each containing two unpaired electrons whose combined spin stores quantum information.
Using microwave pulses, the researchers manipulated the electrons' spin and used laser light to read the quantum state. They found they could control and read out the spin state of a single molecule while preserving the quantum properties for around 2.2 milliseconds. The frequencies of light emitted by individual molecules remained stable for more than one hour.
The challenge the work addresses is that unwanted defects and trapped electrical charges in diamond crystals and semiconductor materials typically cause fluctuations that change the frequency of light emitted by qubits, destabilizing quantum connections.
"These results establish molecular qubits as a viable platform for single-emitter quantum optics while preserving the advantages of bottom-up chemical design and processable materials," the study authors stated.
The researchers believe their approach could enable quantum networks by linking information stored in individual molecules to photons. The molecules could also be incorporated into thin films and integrated with existing photonic chips.