"...this is a big step. There are no large barriers to scaling this same computer to a bigger number of qubits. The researchers will have to reduce photon losses in their waveguides, and they will have to reduce the amount of leakage from the laser that drives everything (currently it leaks some light into the computation circuit, which is very undesirable). The thermal management will also have to be scaled. But, unlike previous examples of optical quantum computers, none of these is a “new technology goes here” barrier.
What is more, the scaling does not present huge amounts of increased complexity. In superconducting qubits, each qubit is a current loop in a magnetic field. Each qubit generates a field that talks to all the other qubits all the time. Engineers have to take a great deal of trouble to decouple and couple qubits from each other at the right moment. The larger the system, the trickier that task becomes. Ion qubit computers face an analogous problem in their trap modes. There isn’t really an analogous problem in optical systems, and that is their key advantage."
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[ 3.2 ms ] story [ 15.1 ms ] threadTo make it easier for people, in the article Chris Lee cites this paper by Xanadu researchers: https://www.nature.com/articles/s41586-021-03202-1
arxiv version: https://arxiv.org/pdf/2103.02109.pdf, which is what I've put in the url of this post.
Chris summarizes his thoughts as:
"...this is a big step. There are no large barriers to scaling this same computer to a bigger number of qubits. The researchers will have to reduce photon losses in their waveguides, and they will have to reduce the amount of leakage from the laser that drives everything (currently it leaks some light into the computation circuit, which is very undesirable). The thermal management will also have to be scaled. But, unlike previous examples of optical quantum computers, none of these is a “new technology goes here” barrier.
What is more, the scaling does not present huge amounts of increased complexity. In superconducting qubits, each qubit is a current loop in a magnetic field. Each qubit generates a field that talks to all the other qubits all the time. Engineers have to take a great deal of trouble to decouple and couple qubits from each other at the right moment. The larger the system, the trickier that task becomes. Ion qubit computers face an analogous problem in their trap modes. There isn’t really an analogous problem in optical systems, and that is their key advantage."