The state of entanglement has been created in silicon for the first time. The feat could lead to quantum computers made like ordinary computer chips.

Particles in the quantum realm are entangled if the act of measuring one affects the state of the others, no matter how distant they are. As entangled particles can be in two or more states at once, the phenomenon is key to quantum computing. That’s because it lets you work with many potential values simultaneously. But entanglement has been difficult to create in silicon.

John Morton of the University of Oxford and colleagues succeeded by using a half-millimetre-wide crystal of silicon studded with phosphorus atoms. Cooling this to a few degrees above absolute zero and applying a magnetic field aligned the spins of one phosphorus electron per atom.

They then applied two microwave pulses. One sent these electrons into a fuzzy quantum state, in which the spin of each electron had a 50-50 chance of being either up or down. The second forced the spin of each electron’s nearest phosphorus nucleus to align with it, producing billions of pairs of entangled objects (Nature, DOI: 10.1038/nature09696).


To turn this into a silicon quantum computer, the team must create a “huge 2D grid of entanglement”, in which nuclei are entangled with other phosphorus nuclei, as well as electrons, says Morton. To achieve this, electrons will be shuttled through the structure, stitching entangled states together like a thread, he says. By measuring the electron spins in a certain order, computations could be performed.

In a further step, last year, an Australian team measured the spin of a lone electron in silicon. However, Thomas Schenkel of Lawrence Berkeley National Laboratory in Berkeley, California, warns that “there’s not going to be a quantum computer based on this next week”.