10 billion qubits of entanglement achieved in silicon crystal

Scientists have taken a massive step towards the construction of an incredibly fast quantum computer after successfully generating 10 billion bits of quantum entanglement, known as qubits, in a highly purified silicon crystal for the first time.

An international team of scientists at Oxford University used high magnetic fields and low temperatures to produce entanglement between the electron and neutron of an atom of phosphorous that had been embedded in the silicon crystal.

The electron and nucleus then behave like a tiny magnet creating spin which can subsequently be read as a ‘bit’ of quantum information. When controlled effectively such spins can be made to interact with each other and coaxed into an entangled state.

It is the entanglement that is considered to be the key ingredient in making quantum computers so much faster than contemporary machines.

To generate entanglement it was important to first align all the spins by using high magnetic fields and low temperatures.

“Once this has been achieved, the spins can be made to interact with each other using carefully timed microwave and radiofrequency pulses in order to create the entanglement, and then prove that it has been made,” said Stephanie Simmons of Oxford University’s Department of Materials.

According to the scientists the fact that the new method uses silicon means that it should allow easier integration with existing technology.

“Creating 10 billion entangled pairs in silicon with high fidelity is an important step forward for us,” said co-author Dr John Morton, who led the team.

“We now need to deal with the challenge of coupling these pairs together to build a scalable quantum computer in silicon.”

The study marks another step in the understanding of quantum entanglement, whereby two objects are entangled in a way that it is impossible to describe one without also describing the other, and the measurement of one object will reveal information about the other object even if they are separated by thousands of miles.

In the bewildering quantum world it is possible, for example, for a coin to be flipped and land both sides up simultaneously, rather than half the times heads and the other half tails.

It is this ability to inhabit two states simultaneously that is possible with an electron spin that can offer exciting opportunities for computing.