128-qubit system as an integrated artificial atom-photonics chip

Researchers at MIT have developed a process to manufacture and integrate “artificial atoms,” created by atomic-scale defects in microscopically thin slices of diamond, with photonics circuitry, producing the largest quantum chip of its type.

The process is a hybrid approach, in which carefully selected “quantum micro chiplets” containing multiple diamond-based qubits are placed on an aluminum nitride photonics integrated circuit.

The artificial atoms in the chiplets consist of color centers in diamonds, defects in diamond’s carbon lattice where adjacent carbon atoms are missing, with their spaces either filled by a different element or left vacant.

Colour centres in diamond have emerged as leading solid-state ‘artificial atom’ qubits because they enable on-demand remote entanglement, coherent control of over ten ancillae qubits with minute-long coherence times and memory-enhanced quantum communication.

In the MIT chiplets, the replacement elements are germanium and silicon. Each center functions as an atom-like emitter whose spin states can form a qubit. The artificial atoms emit colored particles of light, or photons, that carry the quantum information represented by the qubit.

Using their hybrid method, the team was able to build a 128-qubit system—the largest integrated artificial atom-photonics chip yet.

Finding a way to automate the process and demonstrate further integration with optoelectronic components such as modulators and detectors will be necessary to build even bigger chips necessary for modular quantum computers and multichannel quantum repeaters that transport qubits over long distance. (Phys.org)

The paper has been published in Nature.

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