Quantum chips have proved somewhere between difficult and impossible to manufacture
Researchers at MIT have developed a way to manufacturer “artificial atoms” to produce what they claim is the world’s largest quantum chip of its kind.
The atoms have been created in microscopically thin slices of diamond.
The accomplishment “marks a turning point” in the field of quantum processors, said Dirk Englund, associate professor at MIT’s Department of Electrical Engineering and Computer Science, in a statement.
Standard computers, and processors, use ‘bits’ in their chips. These can be in binary positions – either on, or off.
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Apps, websites, and computer programmes are made up of information coded in this way. A one signifies the on position, while a zero signifies the off position. This is the language that makes up binary.
However, in recent years, engineers have made strides with quantum computers, which represent an entirely new way of understanding such systems. On this small scale, physicists have observed strange effects where particles can exist along a spectrum between ‘on’ and ‘off’.
As such, quantum computers use ‘qubits’ rather than bits. These can both be on and off simultaneously, or somewhere in between.
A useful parallel is a maze; a standard computer would attempt to complete it by trying every route, one after another. A quantum computer would be able to try all attempts at once.
“In the past 20 years of quantum engineering, it has been the ultimate vision to manufacture such artificial qubit systems at volumes comparable to integrated electronics,” Englund says.
Although there has been distinct progress in this field, quantum materials such as these are difficult to manufacture.
The slightest contact between an atom exhibiting quantum behaviour and another atom will immediately shunt the atom out of its quantum state. That makes it easy to build quantum prototypes, but difficult to build whole computers.
The artificial atoms in what Englund calls “quantum micro chiplets” consist of the colour centres in diamonds. These are defects in the diamond’s carbon lattice where atoms are missing.
The vacant space is filled with other atoms, such as germanium and silicon.
The artificial atoms emit the coloured particles of light to can carry the quantum information represented by the qubit.
The challenge using this model, however, is building a platform that can scale upwards, to make chips with thousands and millions of qubits.
“Artificial atoms are in a solid crystal, and unwanted contamination can affect important quantum properties such as coherence times” explains Noel H. Wan, a MIT researcher who authored the paper alongside Englund, in a statement.
“Furthermore, variations within the crystal can cause the qubits to be different from one another, and that makes it difficult to scale these systems.”
As such, the researchers decided to take a hybrid approach, rather than make the entire chip out of diamond.
Multiple chiplets are “wire[d]” into a larger chip, Wan explained, allowing the researchers to link 128 qubits together on one platform.
The next step is to test the chip’s processing skills.
Quantum computers have already undertaken tasks that classical computers could not. A quantum computer used by Google claimed to be able to complete a task in 200 seconds which would have taken 10,000 years for a traditional computer to achieve.
IBM, Intel, and Microsoft are building similar machines. These could be used for a number of purposes, such as accommodating variables such as the weather and population spikes into city planning, to simulating the beginnings of the universe.