A team of researchers from Bristol’s Quantum Engineering and Technology Labs
(QETLabs) has shown how to protect qubits from errors using photons in a
silicon chip.
Quantum computers are gaining pace. They promise to provide exponentially
more computing power for certain very tricky problems. They do this by
exploiting the peculiar behaviour of quantum particles, such as photons of
light.
However, quantum states of particles are very fragile. The quantum bits, or
qubits, that underpin quantum computing pick up errors very easily and are
damaged by the environment of the everyday world. Fortunately, we know in
principle how to correct for these errors.
Quantum error correcting codes are a method to protect, or to nurture,
qubits, by embedding them in a more robust entangled state of many
particles. Now a team led by researchers at Bristol's Quantum Engineering
and Technology Laboratories (QETLabs) has demonstrated this using a quantum
photonic chip.
The team showed how large states of entangled photons can contain individual
logical qubits and protect them from the harmful effects of the classical
world. The Bristol-led team included researchers from DTU in Copenhagen who
fabricated the chip.
Dr Caterina Vigliar, first author on the work, said: “The chip is really
versatile. It can be programmed to deliver different kinds of entangled
states called graphs. Each graph protects logical quantum bits of
information from different environmental effects.”
Anthony Laing, co-Director of QETLabs, and an author on the work said:
“Finding ways to efficiently deliver large numbers of error protected qubits
is key to one day delivering quantum computers.”
Reference:
Caterina Vigliar, Stefano Paesani, Yunhong Ding, Jeremy C. Adcock, Jianwei
Wang, Sam Morley-Short, Davide Bacco, Leif K. Oxenløwe, Mark G. Thompson,
John G. Rarity, Anthony Laing. Error-protected qubits in a silicon photonic
chip. Nature Physics, 2021;
DOI: 10.1038/s41567-021-01333-w
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