Engineering and studying few-electron states in ballistic conductors is a key step towards understanding entanglement in quantum electronic systems. In this Letter, we introduce the intrinsic two-electron coherence of an electronic source in quantum Hall edge channels and relate it to two-electron wavefunctions and to current noise in an Hanbury Brown--Twiss interferometer. Inspired by the analogy with photon quantum optics, we propose to measure the intrinsic two-electron coherence of a source using low-frequency current correlation measurements at the output of a Franson interferometer. To illustrate this protocol, we discuss how it can distinguish between a time-bin entangled pure state and a statistical mixture of time shifted electron pairs.
Electronic coherence is of utmost importance for the access and control of quantum-mechanical solid-state properties. Using a purely electronic observable, the photocurrent, we measure an electronic coherence time of 22 +/- 4 fs in graphene. The photocurrent is ideally suited to measure electronic coherence as it is a direct result of quantum path interference, controlled by the delay between two ultrashort two-color laser pulses. The maximum delay for which interference between the population amplitude injected by the first pulse interferes with that generated by the second pulse determines t…
Wigner function approach to single electron coherence in quantum Hall edge channels
最近的电子量子光学实验进行按需单电子源要求的混合时间/频率的方法来电子量子相干性。在这里，我们提出了一个维格纳函数表示的一阶电子相干性，并显示，它提供了一个自然的可视化的激发最近演示的单电子源发出。它还提供了一个统一的观点，单粒子和两粒子干涉实验。特别是，我们介绍了单电子相干性的非经典标准，并讨论它的背景下，马赫-曾德尔干涉。最后，电子的Hanbury Brown和Twiss和Hong Ou Mandel实验被解释为Wigner函数的重叠，从而将它们与信号处理联系起来。
The transverse coherence of electrons is of utmost importance in high resolution electron microscopes, point-projection microscopes, low-energy electron microscopy and various other applications. Pulsed versions of many of these have recently been realized, mostly relying on femtosecond laser-triggering electron emission from a sharp needle source. We here observe electron interference fringes and measure how the interference visibility becomes reduced as we increase the electron bunch charge. Due to the extremely strong spatio-temporal confinement of the electrons generated here, we observe t…
