Professor Lieven Vandersypen and his team claim this is an important demonstration, as it should enable quantum bits to connect across the chip, allowing to scale up to large numbers of qubits – a current worldwide venture many are embarking.
QuTech in TU Delft is said to be developing several types of quantum chips based on silicon. "This is a material that we are very familiar with," Professor Vandersypen noted.
Silicon is said to be a promising material for quantum technology. PhD candidate Guoji Zheng said: "We can use electrical fields to capture single electrons in silicon for use as quantum bits (qubits). This is an attractive material as it ensures the information in the qubit can be stored for a long time."
Large numbers of qubits are necessary to make useful computations. "To use a lot of qubits at the same time, they need to be connected to each other; there needs to be good communication,” said researcher Nodar Samkharadze. Currently, the electrons captured as qubits in silicon can only make direct contact with their immediate neighbours, which according to Samkharadze, ‘makes it tricky to scale up to large numbers of qubits’.
The breakthrough of using photons for long-distance interactions within quantum systems was a major goal for silicon and significant progress has been seen in recent years.
The TU Delft team claim it has demonstrated that a single electron spin and a single photon can be coupled on a silicon chip. This, in principle, should enable transferring of quantum information between a spin and a photon. "This is important to connect distant quantum bits on a silicon chip, thereby paving the way to upscaling quantum bits on silicon chips,” Zheng said.
"My team achieved this result in a relatively short time and under great pressure from worldwide competition,” Professor Vandersypen concluded. "The goal now is to transfer the information via a photon from one electron spin to another.”
