Electron quantum optics as signal processing

D. C. Glattli

Benjamin Roussel, Clément Cabart, Gwendal Fève +2 more

Abstract The recent developments of electron quantum optics in quantum Hall edge channels have given us new ways to probe the behavior of electrons in quantum conductors. It has brought new quantities called electronic coherences under the spotlight. In this paper, we explore the relations between electron quantum optics and signal processing through a global review of the various methods for accessing single‐ and two‐electron coherences in electron quantum optics. We interpret electron quantum optics interference experiments as analog signal processing, converting quantum signals into experimentally observable quantities such as current averages and correlations. This point of view also gives us a procedure to obtain quantum information quantities from electron quantum optics coherences. We illustrate these ideas by discussing two‐mode entanglement in electron quantum optics. We also sketch how signal processing ideas may open new perspectives for representing electronic coherences in quantum conductors and understand the properties of the underlying many‐body electronic state.

Thomas Pousset, Matteo Schiavon, Guillaume Ricard +3 more

Digital signal processing has become essential in quantum optics, particularly for continuous-variable (CV) information encoding, enabling coherent detection schemes and mitigation of linear impairments. While linear signal processing in double homodyne detection has been studied under the assumption that all post-measurement processing can be backpropagated in the optical domain, a rigorous treatment of the digitization chain, spanning optical, electronic, and sampling stages, is still lacking. In this work, we consider the continuous mode description of double homodyne detection to fully capture the maximum mode-matching coefficient achievable as a function of electronic noise, signal bandwidth, receiver electronics bandwidth, and sampling rate, that is the entry point of digital signal processing. We establish a dimensioning rule that generalizes the Nyquist-Shannon criterion to account for quantum fluctuations of the measured signal, not merely its bandwidth. Analyzing the case of additive white electronic noise, we find numerically that optimal signal-to-noise ratio is achieved when the electronic bandwidth is large enough to pass the signal yet narrower than the sampling rate in order to mitigate noise amplification, yielding a concrete design criterion for coherent detection.

J. I. Cirac, L.-M. Duan, Dieter Jaksch +1 more

Harry J. Kimble

Takashi Kurokawa, Shinji Matsuo, Chikara Amano