Quantum physics has enabled several technological developments, including computers, smartphones, and GPS. It is currently opening up new avenues of research in cryptography (the art of encoding messages) in order to construct ultra-secure telecommunications networks. However, after a few hundred kilometres within an optical cable, the photons that contain the qubits or 'quantum bits' (the information) vanish. Hence, they require repeaters,' a type of relay,' partly based on quantum memory.
A team from the UNIGE (University of Geneva) has established a world record by storing a qubit in a crystal (a "memory") for close to 20 milliseconds. The study is an immense achievement within the Telecommunications Market as it may lead to construction of long-distance quantum telecommunications networks.
The team considerably enhanced this duration by storing a qubit for 20 milliseconds. Researchers even made it to 100 milliseconds with only a slight loss of quality. As in past studies, the UNIGE researchers employed crystals doped with metals known as 'rare earth' (europium in this case). This can absorb and then re-emit light. These crystals were held at -273,15°C (absolute zero) because the thermal agitation of the crystal disrupts atom entanglement beyond ten °C above this temperature.
The team put a one-thousandth of a Tesla magnetic field to the crystal and employed dynamic decoupling methods, including transmitting powerful radio waves to the crystal. The consequence of these strategies is to dissociate rare-earth ions from environmental perturbations and boost storage performance by 40. The group also reduced the storage of a quantum state carried by a photon to a time scale that humans can estimate. The findings of this research represent a significant step forward in creating long-distance quantum telecommunications networks.
However, scientists will also have to figure out how to create a memory that can store more than one photon at a time. So that they have 'entangled' photons that guarantee confidentiality. The main aim is to design a system that performs well on all of these aspects and can be marketed within ten years.