Scientists Demonstrate Two Silicon Quantum Bits That Communicate Across Long Distances

Scientists at Princeton University have demonstrated that two silicon quantum bits can communicate across relatively long distances. The breakthrough is said to be a turning point for the technology. The team has demonstrated that two quantum-computing components known as silicon "spin" cubits can interact even when spaced relatively far apart on the computer chip.

Scientists say that the ability to transmit messages across that distance on a silicon chip unlocks new capabilities for the quantum hardware. Eventually, the team hopes to have multiple quantum bits arranged in a two-dimensional grid that can perform more computations.

Scientists are currently working with qubits that are made using tech that involves superconducting circuits. Many technologists think that silicon-based qubits are more promising for quantum computing in the long run. Silicon-based qubits could be made at a low cost.

The Princeton team connected the qubits with a "wire" that carries light in a manner analogous to the fiber optic wires that deliver internet signals to homes. In this case, the wire is a narrow cavity with a single photon that picks up a message from one qubit and transmits it to the next. In the test, the qubits were about half a centimeter apart.

The key step the team developed was finding a way to get the qubits and the photon to speak the same language by tuning all three to vibrate at the same frequency. This is the first demonstration of entangling electron spins in silicon separated by distances much larger than the devices housing those spins. One researcher notes that not too long ago, there was doubt about whether this was possible. The study was funded in part by the Army Research Office.