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Further compactifying linear optical unitaries

delete2021-07-13
delete27
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Bryn A. Bell *
I
Ian A. Walmsley
DOI:10.1063/5.0053421delete
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Abstract

Abstract

En 中文
Quantum integrated photonics requires large-scale linear optical circuitry, and for many applications, it is desirable to have a universally programmable circuit, able to implement an arbitrary unitary transformation on a number of modes. This has been achieved using the Reck scheme, consisting of a network of Mach-Zehnder interferometers containing a variable phase shifter in one path as well as an external phase shifter after each Mach-Zehnder. It subsequently became apparent that with symmetric Mach-Zehnders containing a phase shifter in both paths, the external phase shifters are redundant, resulting in a more compact circuit. The rectangular Clements scheme improves on the Reck scheme in terms of circuit depth, but it has been thought that an external phase-shifter was necessary after each Mach-Zehnder. Here, we show that the Clements scheme can be realized using symmetric Mach-Zehnders, requiring only a small number of external phase-shifters that do not contribute to the depth of the circuit. This will result in a significant saving in the length of these devices, allowing more complex circuits to fit onto a photonic chip, and reducing the propagation losses associated with these circuits. We also discuss how similar savings can be made to alternative schemes, which have robustness to imbalanced beam-splitters.
Keywords:
QUANTUM
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Journal

APL Photonics cover
APL Photonics
IF:
5.3
Papers:
1.5K
Citations:
5.5K

Organization

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Imperial College London
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8.3W
Papers: 7.3W
Citations: 11.1W