A formula that predicts the effects of environmental noise on quantum information

An advancement crucial for designing and building quantum computers capable of working in an imperfect world.


Ambient noise modifies the phase of various branches of a wave function in an unanticipated manner, which is a crucial barrier to the development of quantum computing. Dephasing is the alteration of a quantum system’s phase, and it can work against the success of quantum computation. Dephasing can occur in devices such as optical fibers, which transfer information in light. Dephasing can occur in devices such as optical fibers, which transfer information in light.

Scientists from Cornell Engineering and the University of Amsterdam have created a formula that predicts the impacts of environmental noise on quantum information. This development is essential for designing and constructing quantum computers that can operate in an imperfect world.

Scientists analyzed a model called the bosonic dephasing channel to study the impact of noise on the transmission of quantum information. It represents the dephasing acting on a single light mode at a definite wavelength and polarization.

Quantum capacity, or the number of qubits that may be securely transported per use of fiber, is the value that quantifies the impact of noise on quantum information. The challenge of determining the quantum capacity of the bosonic dephasing channel for all conceivable types of dephasing noise is fully analytically resolved in the current paper.

Scientists noted“To overcome the effects of noise, one can incorporate redundancy in the message to ensure that the quantum information can still be retrieved at the receiving end. This is similar to saying “Alpha, Beta, Charlie” instead of “A, B, C” when speaking on the phone. Although the transmitted message is longer, the redundancy ensures that it is understood correctly.”

“The new study quantifies how much redundancy needs to be added to a quantum message to protect it from dephasing noise. This is significant because it enables scientists to quantify the effects of noise on quantum computing and develop methods to overcome these effects.”

Journal Reference:

  1. Lami, L., Wilde, M.M. Exact solution for the quantum and private capacities of bosonic dephasing channels. Nat. Photon. (2023). DOI: 10.1038/s41566-023-01190-4


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