18-qubit Quantum Entanglement Experiment Sets a New Record

Chinese scientists entangle three degrees of freedom for six photons

Chinese scientists have set a new record by producing the world’s first 18-qubit quantum entanglement. Each qubit can have two possible values, so the entanglement is capable of producing 2**18 or 262,144 output states.

According to the report at phys.org, the 18-qubit entanglement is not produced using 18 photons. Instead, the investigators controlled three degrees of freedom for six photons. Using multiple degrees of freedom is known as hyper-entanglement. Hyper-entanglement is difficult to achieve, but it is potentially very powerful. According to the report, exploiting three degrees of freedom for six photons is 13 orders of magnitude more efficient than an 18-bit qubit state composed of 18 photons.

“Controlling multiple DoFs is tricky, as it is necessary to touch one without disturbing any other,” said experimenter Chao-Lang Lu. “To solve this, we develop methods for reversible quantum logic operations between the photon’s different DoFs with precision and efficiencies both close to unity. We believe that our work creates a new and versatile platform for multi-photon quantum information processing with multiple DoFs.”